JOURNAL
)F THE
^lOMRAY NATURAL HISTORY SOCIETY
, .^RIL 2000
Vol. 97 (1)
|
/ |
.... V |
|
|
M.R. ALMEIDA |
BOARD OF EDITORS Editor J.C. DANIEL |
AJITH KUMAR |
|
M.K. CHANDRASHEKARAN |
T.C. NARENDRAN |
|
|
B.F. CHHAPGAR |
A.R. RAHMANI |
|
|
R. GADAGKAR |
J.S. SINGH |
|
|
INDRANEIL DAS |
R. WHITAKER |
|
|
A.J.T. JOHNSINGH ^ - |
Assistant Editor GAYATRI WATTAL UGRA |
> |
INSTRUCTIONS TO CONTRIBUTORS
1. Papers which have been published or have been offered for publication elsewhere should not be submitted.
2. Papers should be submitted in duplicate, typed double space. Preferably an additional copy should be submitted on a floppy diskette (3.5") using Word Star.
3. Trinomials referring to subspecies should only be used where identification has been authentically established by comparison of specimens actually collected.
4. Photographs for reproduction must be clear, with good contrast. Prints should be at least 9 x 12 cm and on glossy glazed paper. Text-figures, line drawings and maps should be in Indian ink, preferably on tracing paper. Maps and figures will not be acceptable if labelled free hand.
5. References to literature should be placed at the end of the paper, alphabetically arranged under author’s name, with the abridged titles of journals or periodicals in italics and titles of books or papers in roman type, thus:
Aluri, Raju J.S. & C. Subha Reddi (1995): Ecology of the pollination in two cat-mint species. J. Bombay nat. Hist. Soc. 92(1): 63-66.
Prater, S.H. (1948): The Book of Indian Animals. Bombay Natural History Society, Mumbai, pp. 35-48.
6. Each paper should be accompanied by an abstract, normally not exceeding 200 words, and 6-8 keywords. Keywords should include the scientific names of important species discussed.
7. 25 reprints will be supplied free of cost to authors of main articles. In the case of new descriptions, reviews and miscellaneous notes, authors will be sent a free copy of the Journal.
8. The editors reserve the right, other things being equal, to publish a member’s contribution earlier than a non-member’s.
Hornbill House,
Shaheed Bhagat Singh Road, Mumbai-400 023.
Editors,
Journal of the Bombay Natural History Society
POPULATION DENSITIES OF THE BLACKNAPED PlARE LEPUS NIGRICOLLJS
NIGR1COLLIS AT ROLLAPADU WILDLIFE SANCTUARY, KURNOOL DISTRICT, ANDHRA PRADESH ( With six text-figures )
By Ranjit Manakadan and Asad Rafi Rahmani 3
BREEDING BIOLOGY OF THE MALABAR GREY HORNBILL ( OCYCEROS G RISE US )
IN SOUTHERN WESTERN GHATS, INDIA (With one text-figure)
By Divya Mudappa 15
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVATION IN THE INDIAN TRANS-HIMALAYA
By Charudutt Mishra 25
AN ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NATIONAL PARK, SRI LANKA ( With three text-figures)
By Charles Santiapillai, Mangala de Silva, Sarath Dissanayake, B.V.R. Jayaratne
and S. Wijeyamohan 33
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MACAQUES (MAC AC A SILENVS) IN THE WILD ( With three text-figures)
By Ajith Kumar 42
SEASONAL CHANGES OF TROPICAL FOREST BIRDS IN THE SOUTHERN WESTERN GHATS ( With seven text-figures)
By E.A. Jayson and D.N. Mathew 52
PLODIA INTERPUNCTELLA (HUBNER) (PHYCITIDAE : LEPIDOPTERA) AS A POTENTIAL PEST OF DRY FRUITS
By S.P. Rad, H.R. Pajni and Neelima Talwar 62
FRESHWATER CLADOCERA (CRUSTACEA : BRANCHIOPODA) OF THE ANDAMAN AND NICOBAR ISLANDS ( With one text-figure)
By K. Venkataraman 67
LONGICORN BEETLES (CERAMBYCINAE, PRIONINAE : CERAMBYCIDAE) OF BUXA TIGER RESERVE, JALPAIGURI, WEST BENGAL ( With twelve text-figures)
By Dinendra Raychaudhuri and Sumana Saha 74
FISHES OF THE CYPRINID GENUS SEMIPLOTUS BLEEKER 1859, WITH DESCRIPTION OF A NEW SPECIES FROM MANIPUR, INDIA ( With one text-figure and one plate)
By Waikhom Vishwanath and Laishram Kosygin 92
FOOD AND FEEDING HABITS OF INDIAN BARBETS, MEGALAIMA SPP.
( With three text-figures)
By Hafiz S.A. Yahya
103
NEW DESCRIPTIONS
SPINY EELS OF THE GENUS MACROGNATHUS LACEPEDE FROM MANIPUR,
WITH DESCRIPTION OF A NEW SPECIES ( With four text-figures )
By L. Arunkumar and H. Tombi Singh 117
THREE NEW GENERA OF WHITEFLIES M OH A NA S UN DA RA MI ELLA , SHANTHINIAE AND V A SA NTH A RAJ I ELLA (ALEYRODIDAE : HOMOPTERA) FROM INDIA ( With three text-figures)
By P. Manidurai Manoharan David 123
LYSIONOTUS PALINENSIS — A NEW SPECIES OF GESNERIACEAE FROM ARUNACHAL PRADESH, INDIA ( With one text-figure)
By G.D. Pal 131
REVIEWS
1 . BIRDS OF NEPAL: FIELD ECOLOGY, NATURAL HISTORY AND CONSERVATION
Reviewed by Asad R. Rahmani 133
2. BIOGEOGRAPHY OF THE REPTILES OF SOUTH ASIA
Reviewed by Meghana Gavand 133
3. MOSSES OF KH AND ALA AND MAHABALESHWAR IN THE WESTERN GHATS, INDIA
Reviewed by P.K.K. Nair 134
MISCELLANEOUS NOTES
MAMMALS
1 . Instances of fruit bat mobbing the barn owl
By Sunil Zaveri 136
2. Possible occurrence of the lesser woolly horseshoe bat ( Rhinolophus beddomei) in Chinnar Wildlife Sanctuary
By Kumaran Sathasivam 136
3. Dead snow leopard Uncia uncici at Yabuk, Dongkung (5500 m) in north Sikkim
By Usha Ganguli-Lachungpa 137
4. On the longevity of the tiger {Panther a tigris) in captivity
By L.N. Acharjyo, B.C. Prusty and
S.K. Patnaik 138
5. Sighting of barking deer ( Muntiacus muntjac) in Kalakad-Mundanthurai Tiger Reserve,
Tamil Nadu
By Jayanti Ray, Justus Joshua and
J. Ronald 139
6. Type specimens of mammals in the collections of the Bombay Natural History Society
By Meghana Gavand and Naresh Chaturvedi 1 40
AVES
7. Night herons and little cormorants in Thrissur, Kerala
By Leela Madhavan 142
8. Grey heron wresting fish from herringgull
By Lavkumar Khacher 142
9. Additional site records of black stork Ciconia nigra (Linn.) in Andhra Pradesh
By V. Vasudeva Rao. V. Nagulu and C. Srinivasulu 143
10. Stealing of redwattled lapwing Vanellus indicus (Boddaert) and yellow-wattled lapwing Vanellus malabaricus (Boddaert) eggs by cowherds
By K. V. Srini vas and S. Subramanya 143
11. A note on the feeding of lesser coucal {Centropus toulou)
BySamiranJha 144
12. Occurrence of the yellowbrowed bulbul Hypsipetes indicus (Jerdon) in the Nalamalla Hills, Andhra Pradesh
By Srinivasulu and V. Vasudeva Rao 144
13. Termite attack on nest material leading to desertion of eggs by birds
By K. V. Srini vas and S. Subramanya 145
14. Range extension of the purplerumped sunbird Nectarinia zeylonica
By Lavkumar Khacher 146
15. Water acquisition strategy adopted by goldfinch ( Carduelis carduelis)
By R. Suresh Kumar 147
REPTILES
16. Occurrence of draco or flying lizard Draco dussumieri in Chittoor district, Andhra Pradesh
By S. Balachandran and Aasheesh Pittie 1 47
1 7. Occurrence of yellow-bellied Pelamis platurus (Linn.) Reptilia : Hydrophidae, in coastal waters off Digha, West Bengal
By S. Mitra, J. Sarkar and T.K. Chatterjee .. 148
AMPHIBIA
1 8. A record audio feat by an anuran
By Sanjeev B. Nalavade 149
FISHES
19. Range extension of Pangio goaensis (Cyprini formes : Cobitidae) to the Chaliyar drainage of Kerala
By K. Rema Devi, K.G. Emiliyamma and
R.S. Lalmohan 150
20. Fishes of Nambiyar river, Kalakad- Mundanthurai Tiger Reserve, Tamil Nadu By M. Arunachalam, A. Sankaranarayanan,
J.A. Johnson, A. Manimekalan, R. Soranam,
P.N. Shanthi and C. Vijaykumar 1 53
21 . A profile of the food and feeding of hillstream teleosts ofGarhwal Himalayas By N. Singh and R. Subbaraj 155
INSECTS
22. A supplementary list of the host-plants of Indian Lepidoptera
By Peter Snietacek and Rajani Smetacek .... 157
23. On the predation of the Giant Redeye Gangara thyrsis (Fabricius) (Family : Hesperiidae; Order : Lepidoptera)
By S. Karthikeyan 160
24. Mating behaviour of the Common Mormon Papilio polytes (Family : Papilionidae)
By Arnab Bose 160
OTHER INVERTEBRATES
25. Mycophagous arthropods from the Andaman Islands
By Prashanth Mohanraj and K. Veenakumari 1 61
26. On Daphniopsis tibetana Sars, 1903, (Cladocera) collected from a high altitude Himalayan lake, India
By K. Venkataraman 162
BOTANY
27. fndigofera mysorensis Rottler ex DC. (Leguminosae : Papilionoideae) — An endemic species of Peninsular India from West Bengal By S. Mitra, S. Bandyopadhyay and
A. K. Sarkar 165
28 . Range extension of Nepenthes khasiana i n the Jaintia hills, Meghalaya
By Anwaruddin Choudhury 166
29. Scleria laxa R. Br. (Cyperaceae) - A new record for India from Nicobar Islands
By P.V. Sreekumar 167
30. Rhaphidophora calophyllum Schott (Araceae) — An addition to the flora of the Andaman & Nicobar Islands
By K. Sasikala and E. Vajravelu 169
Cover photograph: Wild Tusker
Editorial
The problems facing the Asian elephant in India are a reflection of the state of environ- mental conservation in India. As a species able to live in a wide spectrum of vegetational types, the elephant acts as an indicator species of the condition of its biotic environment. A sub-optimal habitat is unable to meet the demands made on it by a herd of elephants, whose presence will result in further deterioration. Elephants in such habitats are compelled to seek sustenance elsewhere, and come into conflict with man. At the present rate of habitat loss, and degradation of existing habitats, it is doubtful if present populations can survive. One has to consider seriously the possibility that the Asian elephant will be known mainly as a domesticated animal in the 21st century.
In India, an enormous area of prime elephant habitat has been lost since 1 860, to the plantations of coffee, tea, rubber and teak which were carved out of existing forests. After 1950, hydroelectric projects ravaged elephant habitat through the submerging of forests and unscrupulous exploitation of the remnant forests. In central India, the forests holding elephants cover the single largest deposit of iron-ore in Asia, and mining has been a continuing process since 1909. The states of northeast India, which used to be the stronghold of the elephant in India, are the areas where the main human-elephant conflict has developed. Exploding human populations have destroyed crucial elephant habitat for cultivation and plantations, extinguishing traditional migratory routes; and slash-and-burn cultivation has devastated habitats, making unlikely the survival of the elephant in some of the states.
There is also the question of ivory poaching. Though not on as massive a scale as of the African species, the selective removal of tuskers has played havoc in the sex ratio of many populations. The elephant is an apex species, able by its size and its interaction with its habitat, particularly in its quest for food, to influence the direction of development of its biotic environment. It has been one of the causes for the process of change in its ecosystem. Such a function is no longer acceptable in an environment managed by man, where the process of change has been speeded up. The range of the elephant has, through the ages, shrunk considerably. This process was accelerated, however, as the industrial revolution in the latter half of the last century brought a mechanized commercial culture into the countries of its occurrence. The tools used by man in a region decide its future, and the tools of an alien culture, now in use for gathering natural resources for commerce and to meet the needs of an ever-increasing human population, have destroyed a natural slow-moving ecosystem. The elephant has become in the process too large an animal to find sustenance and living room in the shrinking world of nature.
The conservation of the Asian elephant in Asia cannot be the concern of only the forest departments and environmentalists. Conserving the elephant involves the conservation of prime wildlife habitats. This needs a multidisciplinary effort, where the local people, the administrators and land-use planners have to be involved at all levels. Conserving the elephant, therefore, means conserving the human environment, and it has to be a part of the development plans of each state of Asia as a whole. The Asian elephant is a part of the culture of man in tropical Asia. It is an integral part of the religions of the region and one hopes, will not be sacrificed in the search for a better life for the people of the region.
J.C. DANIEL
ACKNOWLEDGEMENT
We are grateful to the Ministry of Science and Technology, Govt, of India,
FOR ENHANCED FINANCIAL SUPPORT FOR THE PUBLICATION OF THE JOURNAL.
JOURNAL
OF THE
BOMBAY NATURAL HISTORY SOCIETY
April 2000 Vol. 97 No. 1
POPULATION AND ECOLOGY OF THE INDIAN FOX VULPES BENGALENS1S AT ROLLAPADU WILDLIFE SANCTUARY, ANDHRA PRADESH. INDIA1
Ranjit Manakadan and Asad Rafi Rahmani2
( With six text-figures)
Key words: Indian fox, Vulpes bengcilensis , Ardeotis nigriceps , population, diet, breeding season, Rollapadu Wildlife Sanctuary, Andhra Pradesh
The population of the Indian fox Vulpes bengcilensis , its spatial and temporal abundances, den distribution, characteristics and use, predation on eggs and chicks of the great Indian bustard Ardeotis nigriceps , and general ecology were studied from February 1993 to April 1995 at the Rollapadu Wildlife Sanctuary (RWS), Andhra Pradesh state, India. The population and spatial abundance of the fox was estimated by enumeration and monitoring of dens, animal sightings at den sites and from censuses.
The population of the fox at RWS was estimated to be around 40-50 adult animals in 1993 and 1994, which declined to about 10 animals in 1995 due to an epidemic. Densities of the fox were significantly higher in the protected grasslands {0.65/40 ha ± 0.99 (S.D)} than unprotected grasslands (0. 1 5/40 ha ± 0.49). A total of 1 35 dens (active and non-active), comprising of 33 'den groups', were located in the study area. There was a concentration of dens in and around protected grasslands. Den use by the Indian fox at RWS was confined to the pup rearing season (February to June/July). We did not record any evidence of fox predation on bustard eggs and chicks.
increase after the establishment of the Sanctuary in the early 1980s to protect the great Indian bustard and its habitat (Manakadan and Rahmani 1989, 1993, 1997). The Indian fox is known to be a predator of eggs and probably chicks of the bustard (Rahmani and Manakadan 1987). This was suspected to be one of the reasons for the decreasing numbers of the great Indian bustard at RWS over the years, in spite of good protection to the bird and its habitat. We undertook this study to estimate the population of the Indian fox at RWS; compare its abundance in protected and unprotected sites in the Sanctuary; assess reasons for the differences in abundance between sites (which could explain the increase in
Introduction
The Indian fox Vulpes bengcilensis is a widespread species in India, ranging from the foothills of the Himalayas to Kanyakumari (Prater 1980). In spite of its wide distribution and proximity to human habitation in many areas, it has not been studied adequately (Johnsingh 1978). The population of the Indian fox in Rollapadu Wildlife Sanctuary (RWS), Andhra Pradesh had undergone a remarkable
'Accepted April, 1999 2Bombay Natural History Society,
Hombill House, Shaheed Bhagat Singh Road,
Mumbai 400023, Maharashtra, India.
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY, 97(1). APR. 2000
3
POPULATION AND ECOLOGY OF THE INDIAN FOX
4
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
Fig. I : Location of fox dens in the study area
POPULA TIONAND ECOLOGY OF THE INDIAN FOX
populations over the years after protection); investigate the role of the fox as a predator of bustard eggs and chicks; and collect other ecological information on the species.
Study Area
Rollapadu is 18 km southeast of Nandikotkur (15°58' N lat. & 78° 18' E long.), Kurnool dist., Andhra Pradesh. It lies in the plains between the Nallamalai and Yerramalai hills, at about 200 m above msl. The terrain is gently undulating with predominantly poor red soil. The region is semi-arid with an average annual rainfall of 668 mm, received from both the southwest (June to August) and northeast (September to December) monsoon. Summer (March to May) peaks at 42°C and winter (November to February) is mild at 17° C.
Rollapadu Wildlife Sanctuary (area: 6.14 sq. km) was established in 1982, after the "rediscovery’ of the great Indian bustard A rdeotis nigriceps, and was declared a sanctuary in 1988. The sanctuary proper consists primarily of three grassland plots or enclosures: Enclosure-I (320 ha), about 500 m north of Rollapadu, and Enclosure-II (40 ha) and III (120 ha), both about 1.5 km to the northeast of Rollapadu (Fig. 1). These enclosures are demarcated by trench-cum- mound (TCM) walls to exclude livestock and people. However, Enclosure-Ill was opened to grazing after protests by the locals about the lack of grazing land for their livestock. The extent of protection to Enclosure-II varied from year to year during the study. The three enclosures are separated from each other by grazing lands and crop fields. Both the grazing lands and the enclosures are predominantly grasslands, with scrub dominated areas along streams.
The other major fauna of the Sanctuary include the blackbuck Antilope cervicapra , wolf Canis lupus, jackal Canis aureus, jungle cat Felis chaus, common mongoose Herpestes edwardsi, blacknaped hare Lepus nigricollis nigricollis, common Indian monitor Varanus bengalensis
and lesser florican Sypheotides indica. The grassland is a major roosting ground for harriers (largely Circus pygargus and C. macrourus ) wintering in the Indian subcontinent. For more details, see Rahmani and Manakadan (1986) and Manakadan and Rahmani (1989, 1993 & 1997).
Methodology
Studies were conducted from February 1993 to April 1995, during daylight hours on unmarked animals. Prior to the studies, we had a fairly good idea of the population and distribution of the fox in RWS from July 1992, due to our field visits during other multi- disciplinary studies of the project.
Population: A pilot survey was conducted during the breeding season in 1993 to assess den distribution in the study area. The survey was concentrated in the three enclosures and grazing lands adjoining them, to get an insight into the breeding season, den characteristics and distribution of the fox in the Sanctuary. Den searches were more intensive during the breeding season of 1994 and 1995. Searches in 1994 began in February, when the dens located in 1993 were found to have been dug up afresh, indicating the start of the breeding (pup rearing) season. The area searched (Fig. 1) was divided into smaller blocks and combed intensively for dens by two or three people. The locations of these dens were plotted on a map (Fig. 1) and details, such as active or non- active, number of holes per den, distances between dens, and site characteristics were recorded. After the survey, all the dens were visited once a week to collect data on den use. Sightings of animals (adults and young) at den sites were recorded. We also looked for indirect signs of animal presence, such as freshly unearthed soil, additional holes dug up, pugmarks, presence of scats and food remains at den sites. Visits were made till June (when the animals abandoned the dens with the onset of the monsoons) in 1994, and till May in 1995 (after the breeding season).
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
5
POPULA r I ON AND ECOLOG Y OF THE INDIAN FOX
Population estimate: Based on the number of dens located, den use data, and number of adult foxes seen at den sites, a rough estimate of the adult population at RWS was determined. Where animals were never seen at active dens throughout the study period, and especially if the den formed part of a complex of dens (termed den group) as in the majority of cases, we presumed that the den / den group belonged to a pair, as two animals for each den group was the norm in most of the den groups.
Densities in grazing land and enclosures: Four sites of 40 ha each were selected in each of the two habitat types. Except for one site in the grazing land, which was predominantly scrub, all the other sites were grasslands. The sites were thoroughly covered on foot fortnightly — on different days — in the evenings from July 1994 to April 1995. Though the sites were searched on different days, repeated flushing of animals from the same areas suggested that the animals were territorial and that there was no significant movement between sites. Each site was searched in an hour’s time, by walking at a steady pace, in an irregular and generally zigzag manner. Some light noise (humming, dragging of feet, tapping with a stick) was made to flush the resting, sleeping or hidden foxes inside dens or among vegetation. Loud noise was avoided as it would alert the animal a good distance away, allowing it to slip away without being detected. On flushing a fox, the direction in which it ran and the place it stopped was observed to avoid duplication of counts. The fox sightings were expressed as number of foxes/40 ha.
Food Availability: Data on the abundance of the known food items of the fox, such as fruits (number of fruiting trees) and grasshoppers in the two habitat types was obtained from other studies carried out during the project. Grasshoppers were sampled by the sweep net sampling method (100 sweeps per site), and was done fortnightly at all four sites in both the habitat types. The density of fruiting trees was
enumerated by laying 40 quadrats (size 50 x 50 m) each in both the habitat types, and noting the species of trees or shrubs, their numbers and heights. An index of rodent abundance was obtained by enumeration of burrows along one kilometre transects (with a width of two metres), laid at random in both the habitat types. The transects were done during summer (breeding season of the fox). Fifteen transects each were laid in the enclosure and grazing land during 1994 and 1995. For more details, see Manakadan and Rahmani (1997).
Diet: Scats of fox were collected whenever seen, but mostly during the breeding season, when they were available around den sites. The scats were mixed with warm water, strained and dried. After drying, the remains of animal and plant parts were recorded visually. The percentage composition was not estimated systematically, as the main purpose of the exercise was to look for remains of bustard eggs or chicks.
Results
Dens: The breeding (pup rearing) season of the fox in RWS was determined to be between February to May from 3 years observations. The breeding season was heralded by the re- excavation of old dens or digging of new ones in February. Scats of pups were found around den sites during April and May. Pups were seen around the den sites till the onset of the monsoon, after which the dens were abandoned. Thus, den use by the Indian fox at RWS was largely restricted to the pup rearing period.
Fox dens were recorded in grassland or light scrub habitats — none in dense scrub areas. Dens were dug in the flat ground or in trench cum mound walls (TCM) of the enclosures. Two dens were recorded along the slopes of a stream. The number of holes or openings per den varied from one to as high as 43, but two to seven holes were most common (Figs. 2, 3). All the holes of a den were not used, two to seven active holes per den were most frequent. The frequency of
6
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
POPULA TION AND ECO LOG Y OF THE INDIA N FOX
Frequency of dens
Number of holes
Fig. 2: Number of holes per den
Frequency of dens
Fig. 3: Number of active holes per den (1994)
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
7
POPULA TION AND ECOLOGY OF THE INDIAN FOX
Table 1
DETAILS AND STATUS OF DEN GROUP (BASED ON 1994 DATA)
|
Den Group No. |
No. of dens per group |
No. of foxes recorded/ estimated |
1994 |
Status in 1993 |
1995 |
|
1 |
1 |
0 |
NA |
- |
NA |
|
2 |
4 |
2* |
A |
A |
A |
|
3 |
6 |
2** |
LL-A |
A |
NA |
|
4 |
5 |
0 |
NA |
A |
NA |
|
5 |
3 |
0 |
0 |
A |
NA |
|
6 |
5 |
2* |
A |
A |
NA |
|
7 |
8 |
9 |
NA |
A |
NA |
|
8 |
5 |
2* |
A |
A |
NA |
|
9 |
5 |
0 |
0 |
NA |
NA |
|
10 |
5 |
2* |
B |
A |
NA |
|
11 |
1 |
0 |
0 |
NA |
NA |
|
12 |
4 |
2** |
B |
A |
NA |
|
13 |
7 |
9 |
A |
B |
NA |
|
14 |
2 |
1* |
A |
A |
NA |
|
15 |
9 |
2* |
B |
B |
NA |
|
16 |
2 |
0 |
0 |
- |
NA |
|
17 |
1 |
2(?) |
LL-A |
- |
NA |
|
18 |
2 |
1* |
A |
B |
NA |
|
19 |
7 |
2* |
B |
A |
A |
|
20 |
4 |
2** |
B |
- |
NA |
|
21 |
5 |
2* |
B |
A |
NA |
|
22 |
3 |
0 |
0 |
- |
NA |
|
23 |
3 |
0 |
0 |
- |
NA |
|
24 |
8 |
2**(j *\ |
A |
A |
A |
|
25 |
3 |
9 |
LL-NA - |
NA |
|
|
26 |
3 |
2(?) |
A |
- |
NA |
|
27 |
3 |
7** |
B |
- |
NA |
|
28 |
1 |
1* |
A |
A |
NA |
|
29 |
5 |
2**(1 *) |
A |
- |
A |
|
30 |
3 |
9 |
A |
- |
A |
|
31 |
4 |
2**(1*) |
A |
- |
B |
|
32 |
4 |
2(?) |
A |
A |
NA |
|
33 |
4 |
9 |
LL-NA B |
NA |
* - from sightings
** - from signs (scats or intensive burrowing)
2**( 1 *) - 1 seen, but probably used by a pair.
? - uncertain
A - Active burrows regularly used, dug or redug NA - Not active, dug early in the season, but later largely or totally unused.
O - Dens of previous years: not dug at all during the year of survey .
B - Breeding (pups or scats of pups seen)
LL-A - Located late (afterbreeding season); -probably active
LL-NA - Located late (after breeding season); - probably not active
- Not located - all or some of the dens of the den group were not located.
active openings in the eight breeding dens of 1994 were six for three dens, five for two dens, three for two dens and nine for one den.
Many of the dens in the grazing land had rodent burrows around them, indicating that these sites had been appropriated from rodents. In some cases, the rodents continued to live in some of the burrows not enlarged by the fox. Re- use of dens by rodents after the fox had abandoned the dens during the monsoon was recorded in some cases. On two occasions, large monitor lizards Varanus bengalensis were recorded entering active fox dens. Once, a large monitor lizard, flushed by us near a den site, ran into a fox den, from which a family of gerbils rushed out and ran into their burrows a few metres from the fox den. Seven of the fox dens were appropriated by jackals or wolves (Fig. 1).
During the preliminary non-intensive searches for dens in 1993, a total of 52 dens were located (33 active and 19 non-active). Breeding activity was detected in 4 dens: 1 in Enclosure-1,
2 in Enclosure-II and 1 in the grazing land. During intensive searches in 1994, a total of 135 dens were located, of which 52 were active. Of the 135 dens, 51 were in Enclosure-1, 15 in Enclosure-II, 9 in Enclosure-Ill and 60 in the* grazing land. As much as 31% of the dens in the grazing land were close to Enclosure-I and II. Breeding activity was recorded in eight dens: three dens each in Enclosure-I and Enclosure- II; one each in Enclosure-Ill and grazing land. During the breeding season in 1995, no additional dens were located. Of the dens located in 1994, only eight dens were reused (active). Breeding was confirmed at only one den in the grazing land.
From the data on sightings of animals and den use, it was evident that many of the foxes used more than one den. From this data, the 135 dens located during the intensive survey in 1994 were grouped into 33 den groups, of which 22 were active (Table 1 & Fig. 1). Dens of a group generally tended to be clumped in an area, the distances between dens varying from as close as
8
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
POPULA TJONAND ECOLOGY OF THE INDIAN FOX
No. of occurrences
Den group size classes Fig. 4: Number of dens per den group (1994) No. of occurrences
Den group size classes
Fig. 5: Number of active dens per den group ( 1 994)
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
9
POPULA TION AND ECO LOG Y OF THE INDIA N FOX
12 m to 100 m. In some cases, the distance of a den from the main cluster was more than 200 m (e.g., den group no. 10 - Fig. 1), but these were clumped to the group, based on sightings and movements of adult and young foxes between dens. In some cases, we grouped two clusters of adjoining dens into one (e.g., den group no. 7), as one of these clusters was hardly used and was probably the denning site of the pair in the area during a previous year. The distances between den groups varied, and were less in the enclosures {Enclosure-I: 463.6 m ±283.8 (S.D.), Enclosure- II: 275.0 m ±302.9, Enclosure-Ill: (400.0 ±424.3) than the grazing land (633.3 m ±314.3)}. The number of dens per den group varied from one to nine dens, with three to five dens being most frequent (Fig. 4). However, not all dens in a den group were active during a year, one to three active dens was most common (Fig. 5). We presume that each (active) den group belonged to either a pair of foxes or rarely individuals, but cannot be certain as the animals
were not collared, the nocturnal movements were not monitored, and a few dens showed all signs of regular use (especially those in the grazing lands), but no animals were sighted in them.
Population: We regularly saw five pairs of foxes around Enclosure-I (den group 3, 6, 8, 10 & 13), four pairs around Enclosure-II (den group 14, 15, 19, 21), three pairs in the grazing lands east of Enclosure-Ill (den group 25,31 and 33), and a single individual at den group 28 during our field trips in 1993 and 1994 — a total of 25 foxes. Judging from the number of dens and groups, den use data, and sightings of the animal around dens during the census, it is estimated that about 40-50 foxes were present in the study area during the 1994 breeding season. About the same numbers should have been present during 1993. In 1995, the population dropped to about 10 animals due to an epidemic.
The foxes were usually seen in pairs around the den-groups. Two instances of four adult animals frequenting a common area was
1.2 1
0.8 0.6 0.4 0.2 0
July-1 July-ll Aug- 1 Aug-ll Sep-I Sep-ll
Mean numbers/40 ha
Fortnights (1994)
□ Grazing Land □Enclosure
Fig. 6: Abundance (sighting / 40 ha) of the Indian fox in the two habitats
10
JOURNAL. BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
POPULA TIONAND ECOLOGY OF THE INDIAN FOX
observed. In the first instance, it was during the early monsoon period, when four animals (probably pairs from nearby waterlogged dens) regularly sheltered under a fallen tree as the grass cover was burnt off in a summer fire. In the other instance four adult animals were flushed from a non-breeding den in summer. Otherwise, pairs were the norm and even in clumped den areas, the pairs kept to themselves. Solitary animals were flushed from dens on a few occasions, but the possibility of the mate sleeping elsewhere unnoticed cannot be ruled out. The only den where solitary animals were repeatedly flushed, was at den group 28, which comprised of only one den with a single enhance. Additionally, this was the only single-hole den from which we had actual sightings of the animal.
Abundance of the fox was significantly higher (U=140, P<0.05) in the enclosure (mean 0.65/40 ha, S.D. ± 0.99) than in the grazing land (mean 0.15/40 ha S.D. ±0.49). The fox was recorded during all the fortnights in the enclosures from the first week of July 1994, till the first week of September 1994 (Fig. 6). In the grazing land, the fox was recorded only during two fortnights between July to August 1994. In both cases, the foxes were close to Enclosure-II, and ran into it on being approached. All the sightings in the grazing land and enclosures were m ‘grassland habitats’, none in scrubland. After the second week of September 1994, there were only rare sightings of the fox in the Sanctuary. The remains of five foxes and two wolves were found at different places between July to September. The locals too reported seeing dead foxes. After the epidemic, the only sightings were of single animals, one each in Enclosure-II and the grazing land (den group No. 31) during March and April 1995.
Food Availability
Fruits: Of the two species of fruits
recorded to be eaten by the fox, the density of Cassia fistula was higher in the enclosure (1.8 trees/ha) than in the grazing land (0.2 trees/ha).
Though the density of Zizyphus mauritiana was about the same in the enclosure and the grazing land, the trees were relatively taller in the enclosure (mean = 1.5 m) than in the grazing land (mean = 0.65 m), and yielded more fruit. Other fruits that could probably be part of the diet of the fox are Morinda tinctovia and Phoenix sylvestris. Trees of these two species were more abundant in the enclosure (0.6 and 5.2 trees/ha respectively) than in the grazing land ( 1 tree/ha for P. sylvestris ; M. tinctoria not recorded). The higher densities of fruiting trees and fruit yield, and restrictions on harvesting of fruits in the enclosures, make the availability of fruits greater in the enclosure than grazing land.
Grasshoppers: Insect sampling showed that there was a slightly higher abundance of grasshoppers in the enclosure than in the grazing land. Besides numerical abundance, there was greater insect biomass availability in the enclosure due to the predominance of a larger species of grasshopper ( Acorypha ), compared to a smaller species ( Chrotogonus ) in grazing land. Studies on the great Indian bustard have shown that Acorypha is preferred to Chrotogonus , especially by adult birds (Manakadan and Rahmani 1990). The fox would also find feeding on the larger species more profitable.
Rodents: Rodent burrows were recorded only in the grazing land in 1994 and 1995. Of the 1 5 transects each laid in the grazing land for both the years, a total of seventeen burrows (2 active and 15 non active) were recorded in five transects during 1994, and nine burrows (6 active and 3 non-active) were located in 5 transects during 1995.
Diet: Analysis of 58 scats showed the presence of rodents, hare, monitor lizard and grasshoppers (predominantly Acorypha sp.) among the animal matter. Among vegetable matter, seeds of groundnut Arcichis hypogea , Zizyphus mauritiana and Cassia fistula were recorded. Remains of eggs or chicks of the great Indian bustard were not recorded. Scats of pups were almost solely made up of rodent fur.
1 1
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
POPULA TIONAND ECOLOGY OF THE INDIAN FOX
Threats: The potential predators of the fox at RWS are the wolf, jackal, jungle cat, monitor lizard (on young), and large raptors. Wolves and jackals were seen digging (to eat cubs?) or appropriating fox dens during the breeding season. Large monitor lizards were also seen entering dens on a few occasions. The remains of two foxes, with the flesh stripped off neatly from the bones, were found, indicating that the kills were made by birds of prey. A local reported seeing a dog killing a fox (during the epidemic), but we observed play between a fox and a half grown dog (at a good distance away from each other). The local people do not eat the fox, but two communities, the Pardhis based at Nandikotkur and a nomadic beggar community, hunt and eat them. We recorded three dens that were smoked and dug out in the grazing land. Poachers do not hunt in or near the enclosures, for fear of being caught by the Forest Department.
Discussion
Fox populations often increase steadily with the years, reach levels of overpopulation or saturation, and then decline rapidly due to epidemics (Rausch 1958, Prater 1980, Wandeler et al. 1974, Malcolm 1986, and Ginsberg and Macdonald 1990). In RWS, the population of the fox had increased from half a dozen animals during 1985-87 (Manakadan and Rahmani 1987) to about 40-50 animals during 1992-94. It then dropped down to about 1 0 animals in 1 995 due to an epidemic. Canine distemper and rabies are common among canids and could be an important factor in controlling populations, especially of the fox, due to their greater numbers and density (Mech 1970, Wandeler et al. 1974 and Malcolm 1986). The increase in population of the fox in the Sanctuary could have been a natural occurrence, or brought about by the protection of the species and its habitat after the establishment of the Sanctuary.
Scrub control is suggested as a manage- ment tool to aid detection and avoidance of
terrestrial predators of the San Joaquin kit fox Vulpes macrotis mutica (Warrick and Cypher 1998) and the desert kit fox Vulpes macrotis arsipus (Zoellick et al 1998). Tree and shrub growth at RWS has increased significantly, especially bordering streams (Manakadan and Rahmani 1997), and the fox or its dens were not recorded in such habitats. Scrub control appears necessary in such areas, as it gives cover to potential predators of the fox, such as wolf, jackal and jungle cat, to stalk the species. The fox was recorded in light scrub areas, which appear important for resting and shelter during the day (especially during the non-denning period), and may be vital to the species to escape aerial predators (such as eagles), especially in over- grazed or burnt areas.
Digging of dens in trench cum mound (TCM) walls is easier due to the loose soil and mbble on the trenches, and this may explain the concentration of dens in the enclosures and TCM walls. Most areas of grazing land had shallow soil, exposed rock beds and a calcareous layer, which made digging of dens difficult. In the case of the Arctic fox A lope x lagopus, Eberhardt et al. (1982) mentioned that den sites were restricted to areas where the permafrost was sufficiently deep and soil characteristics allowed burrowing. It is also likely that absence of poaching results in the concentration of dens in an area. This is because the young have greater chances of survival, and on maturity, some of them dig dens in the vicinity of their parents’ dens, especially since foxes are social canids. This may explain the clumped distribution of dens and den groups in the protected enclosures, in contrast to relatively dispersed distribution in the grazing land.
Although TCM walls may attract the fox for denning, it is primarily protection, habitat improvement and lack of disturbance that have attracted them to the enclosures. This explains why dens were concentrated in Enclosure-I and II (protected plots), but not in Enclosure-Ill (unprotected). Malcolm (1986). and Ginsberg
12
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY. 97(1), APR. 2000
POPULA TIONAND ECOLOGY OF THE INDIAN FOX
and Macdonald ( 1 990 - quoting various sources) reason that clumping of fox dens is an indication of good habitat. Trottier (1992) mentioned that the swift fox Vulpes velox prefers grass of moderate height. This may also be true for the Indian fox, for respite from the heat and protection from aerial predators, especially eagles. The protected enclosures were relatively free of human disturbance. Foxes in the grazing land were frequently disturbed by the movements of people, graziers and dogs. During our visits to the dens, sightings of animals were common around den sites in the enclosures, but were rare in the grazing land. It was not clear whether the foxes in the grazing land come out of their dens only at dusk to avoid frequent disturbance (and were hence missed during our visits), or they took refuge elsewhere during the day.
Multiple den use is likely to be both, a strategy to confuse predators (jackal and wolf) and for sanitation. In the desert kit fox Vulpes macrotis cirsipus, individuals were reported to use 3-16 dens, while pahs use 9-16 dens (Zoellick et al. 1998). Canids are known to move their pups regularly to different dens (Sargeant et al. 1975), and this has also been reported in the Indian fox (Johnsingh 1978). Sargeant et al. (1975) recorded splitting of litters among two or more dens in the red fox Vulpes vulpes. In this study, it was observed that usually after breeding and occupancy of a den for about two months, die pair shifted to another den nearby and even to a third den later on. Half grown pups then frequent all such dens of the den group.
Johnsmgh (1978), from his studies in Madurai dist., Tamil Nadu, recorded dens with either two holes or the more common multiple opening dens (maximum of 23 holes). In this study, except for a few single hole dens, the rest were multiple hole dens (up to 43 openings). A greater number of holes per den probably indicates the use of the dens by the same pair for many years, as stated by Johnsingh (1978).
However, unlike Johnsingh’ s findings, areas around dens in RWS had less vegetation compared to the surrounding areas. This is because the soil at RWS has a calcareous layer. This layer when brought to the surface by the foxes digging, hinders plant growth.
The extent of predation on bustard eggs and chicks by the fox was not established. Remains of eggs or chicks were not recorded in the scats analysed, probably because most scats were not collected in the major breeding season of the bustard. It is also unlikely for egg shell pieces to appear in the scats, as the fox might lick the egg contents and leave the shell. In some cases of nest predation recorded during this and the earlier study [predator not known] shell pieces were found strewn around the nest sites. As for chicks, not much identifiable matter could be expected in the scats, except for the bill or claws.
A major drawback of our studies on the Indian fox was that we could not investigate the nocturnal activities of this largely nocturnal species. Also, it was not possible to identify individuals from body characteristics since the animals were not marked. A study of radio- collared animals with the help of night vision equipment is essential to get precise information on the species.
Acknowledgements
This study is a part of the Grassland Ecology Project of the Bombay Natural History Society and the Centre of Wildlife & Ornithology, Aligarh Muslim University, funded by the U.S. Fish and Wildlife Service, and sponsored by the Ministry of Environment and Forests, Govt, of India. We thank the Andhra Pradesh Forest Department for permission to work in the Sanctuary, and the cooperation and help rendered by the staff of Rollapadu Wildlife Sanctuary.
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
13
POP U LA TION AND ECOLOG Y OF THE INDIA N FOX
References
Eberhardt, L.E., W.C. Hanson, J. Bergston, R.A. Garrot & E.R. Hanson (1982): Arctic fox home range characteristics in an oil development area. J. Wild/. Manage. 46: 183-190.
Ginsberg, J.R. & D.W. Macdonald ( 1 990): Foxes, wolves, jackals and dogs. An action plan for the conservation of canids. IUCN, Gland, Switzerland.
Johnsingh, A.J.T. ( 1 978): Some aspects of the ecology and behaviour of the Indian fox Vulpes bengalensis. J. Bombay nat. Hist. Soc. 75: 397-405.
Malcolm, J.R. (1986): Socio-ecology of bat-eared fox ( Otocyon megalotis). J. Zool. London (A) 206: 457- 467.
Manakadan, R. & A.R. Rahmani (1989): Rollapadu Wildlife Sanctuary. J. Bombay nat. Hist. Soc. 86: 368-380
Manakadan, R. & A.R. Rahmani (1990): Growth and development of a captive great Indian bustard chick. Avicidtural Magazine 96: 133-140.
Manakadan, R. & A.R. Rahmani (1993): A decade of conservation of the great Indian bustard at Rollapadu Wildlife Sanctuary, Kurnool district, Andhra Pradesh. Proc. Changing Scenario of Bird Ecology and Conservation (Ed: A. Verghese, S. Sridhar & A.K. Chakravarthy), Ornithological Society of India, Bangalore.
Manakadan. R. & A.R. Rahmani (1997): Rollapadu Wildlife Sanctuary (pp: 1 17-180). In: A study of the ecology of grasslands of the Indian plains with particular reference to their endangered fauna. Final Report, (Ed: A. R. Rahmani). Bombay Natural History Society. Mumbai. Pp 549.
Mech. L.D. (1970): The Wolf : Ecology and Behaviour of an Endangered Species. Natural History Press,
Doubleday. New York.
Prater, S.H. (1980): The Book of Indian Animals. 3rd Edition. Bombay Natural History Society, Bombay.
Rahmani, A.R. (1989): The Great Indian Bustard. Final Report. Bombay Natural History Society. Bombay.
Rahmani, A.R. & R. Manakadan (1986): Study of the Ecology of Certain Endangered Species of Wildlife and their Habitats: The Great Indian Bustard. Rollapadu Wildlife Sanctuary. Bombay Natural History Society, Bombay.
Rahmani, A.R. & R. Manakadan (1987): Interspecific behaviour of the Great Indian Bustard Ardeotis nigriceps. J. Bombay nat. Hist. Soc. 83: 17-31.
Rausch, R. (1958): Some observations on rabies in Alaska, with special reference to wild canids. J. Wild!. Manage. 22: 246-260.
Sargeant, A.B., W.K. Pfeifer & S.H Allen (1975): A spring aerial census of red foxes in North Dakota. J. Wildl. Manage. 39: 30-39.
Trottier, G.C. (1992): Conservation of Canadian Prairie Grasslands: A Landowner’s Guide. Canadian Wildlife Service, Canada.
Wandeler, A., .1. Muller, G. Wachendorfer. W. Schale, U. Forster & F. Stack (1974): Rabies in wild carnivores in Central Europe. Ill Ecology and biology of the fox in relation to control operations. Zbl. Vet. Med. B. 21: 765-773.
Warrick, G.D. & B.L. Cypher (1998): Factors affecting the spatial distribution of San Joaquin Kit Foxes. J. Wildl. Manage. 62: 707-717.
Zoellick, B.W., N.S. Smith & R.S. Henry ( 1 989): Habitat use and movements of Desert Kit Foxes in Western Arizona J. Wildl. Manage. 53: 955-961 .
■ ■ ■
14
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1). APR. 2000
BREEDING BIOLOGY OF THE MALABAR GREY HORNBILL {OCYCEROS GRISEUS) IN SOUTHERN WESTERN GHATS, INDIA.'
Divya Mudappa2 ( With one text-figure)
Key words: hornbill, tropical rainforest, frugivory, seed dispersal, cavity- nesting, breeding biology
The Malabar grey hornbill ( Ocyceros griseus) is a frugivore, endemic to the tropical rainforests and moist deciduous forests of the Western Ghats hill ranges, India. I studied its breeding biology in the Anamalai hills (Indira Gandhi Wildlife Sanctuary), Tamil Nadu state, by monitoring 10 nests and their middens, and conducting intensive observations at a focal nest. The nesting period lasted an average of 86 days (N=4), and observations at the focal nest revealed the pre- and post-hatching phases to be 40 and 46 days, respectively. At the end of the nesting period, the females and the young simultaneously broke out of the nests. A total of 2397 items of food were delivered by the male hornbill to the inmates of the focal nest. They included 6 species of lipid-rich and 8 species of sugar-rich fruits, and at least 14 kinds of animal matter. Lipid-rich fruits formed a major component (c. 37%) of the diet during nesting. Ficus fruits formed 26%, and animal matter 13.8% of the diet of the incarcerated hornbills. The frequency of sugar- and lipid-rich fruits delivered per hour of observation was significantly greater in the pre-hatching phase. While the frequency of animal food delivered was higher in the post-hatching phase. Although the Malabar grey hornbill used a wide range of food resources, it was observed that a few species of rare, tropical trees producing lipid-rich fruits during the nesting period, play an important role in the maintenance of the species.
Introduction
Hornbills (Aves : Bucerotidae and Bucorvidae) are a group of large, forest and savanna birds restricted to the Old World tropics. There are 54 species of hornbills in the world (Kemp 1988, 1995), nine of which occur in India (Ali and Ripley 1987). Only in the last two decades, a few studies have provided valuable insights into the ecology of these unique cavity- nesting birds (Hussain 1984, Kannan 1994, Kemp 1976, 1978, 1988, Kinnaird 1993, Leighton 1982, Poonswad 1995, Poonswad and Tsuji 1989, 1994, Reddy et al. 1990, Reddy and
'Accepted June, 1 998
:Centre for Ecological Research and Conservation 3076/5 IV Cross, Gokulam Park Mysore 570 002, Karnataka, India.
Basalingappa 1995). Hornbills are secondary cavity-nesters, and the forest-dwelling species are predominantly fmgivorous. Their breeding cycles are synchronous with food productivity of the forest (i.e., fruiting phenology; Kannan 1994), but they are also dependent on keystone resources like Ficus for their survival in times of low food availability. They exhibit wide-ranging movements to meet their specialized food requirements (Poonswad 1994). Functionally, they have been described as keystone mutualists (Gilbert 1980) as they play an important role in the dispersal of many rare rainforest tree species (Kinnaird 1998, Whitney et al. 1998).
The present study aimed to determine the nesting habitat requirements and breeding biology of the Malabar grey hornbill, endemic to the Western Ghats. The former aspect is dealt
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
15
BREEDING BIOLOGY OF THE MALABAR GREY HORNBILL
with elsewhere (Mudappa and Kannan 1997). This paper describes in detail: 1) nesting activities and behaviour of the male and female hornbill, 2) duration of nesting period and distinct phases of the nesting cycle, and 3) qualitative and quantitative data on the food delivered by the male to the incarcerated female and young, in relation to the phases of the nesting period. The results are compared with other hornbill species, their reproduction and survival strategies, and the implications for the conservation of this rainforest endemic are discussed.
Study Area
The study was undertaken between December 1993 and May 1994 at the Indira Gandhi Wildlife Sanctuary (10° 13' - 10°33' N and 76°49' - 77°21' E, an area of 968 km2) in the Anamalai Hills of the southern Western Ghats, in Tamil Nadu state, India. A one-month long preliminary study was carried out in the area in May- June 1993, when 15 nests were discovered and seeds from the middens were collected and identified for future reference. The nests selected for intensive observation and monitoring were in the 5.1 km2 wet evergreen' forest patch of Karian Shola National Park. This forest, classified as a Southern Tropical Wet Evergreen Forest (Champion and Seth 1968), receives an annual rainfall of about 1500 mm. The terrain is hilly, and the altitude ranges from 350 m to 2400 m above msl in the Sanctuary, which extends into Parambikulam Wildlife Sanctuary and Eravikulam National Park in the adjacent Kerala state. The forest is contiguous with moist deciduous, teak ( Tectona grandis) and bamboo forests in the surrounding areas.
Study Species
Of the 9 species of hornbills in India, the Malabar grey hornbill ( Ocyceros griseus), is the smallest. It is endemic to the Indian subcontinent.
occuring only in the heavy rainfall tracts of the Western Ghats hill ranges. Most of the information on the Malabar grey hornbill and other Indian hornbills is anecdotal- with notes on natural history. Early papers dealing with nidification of the Malabar and the common grey hornbills ( Ocyceros birostris) are those of Bingham (1879), Hall (1918), Lowther (1942), and Abdulali (1942). More comprehensive information on their ecology and behaviour was provided by Ali and Ripley (1970, 1987) and Kemp (1978).
The Malabar grey hornbill is sexually dimorphic: the male has a large, bright orange bill and golden brown iris, while the female has a relatively small and pale-coloured bill and dark brown iris. The species is monogamous, the nesting pair usually exhibiting high nest-site fidelity, occupying the same nest-cavities every year (Kemp 1978, Ali and Ripley 1987, Mudappa and Kannan 1997). The Malabar grey hornbill exhibits biparental care like most other monogamous birds with altricial young (Clutton- Brock 1991). While the incubating female is incarcerated, the male provisions her and the other inmates of the nest.
Methods
Active nests of the Malabar grey hornbill were located with the help of a local field assistant, by following the parent birds, and by checking for signs of previous nesting, such as seeds and faecal remains (midden) at the base of the nest trees. Fifteen nests were located during the preliminary study in May 1993. Seeds collected from the midden were catalogued and used for reference during the study. Twelve additional nests were discovered during the initial half of the study (December 1 993 to March 1994). Ten nests were chosen for monitoring during the nesting period (the period of incarceration of the female and the young) in Karian Shola National Park. Of these, one was
16
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
BREEDING BIOLOGY OF THE MALABAR GREY HORN BILL
selected on the basis of logistics for intensive observation.
Intensive observation of a focal nest: The
✓
focal nest was observed from the last week of January 1994 to May 1994, for approximately six-hour intervals on every alternate day (more or less uniformly) throughout the three-month nesting period. Observations were made between 0700 h and 1300 h. The forenoon was chosen for nest observation, while the rest of the day was used to visit the other nine nests.
I observed the nest to gather information on the quantity and quality of food delivered by the male to the incarcerated inmates. The food was broadly classified as plant and animal food. The plant food was further categorised as: a) figs, b) sugar-rich non- fig, and c) lipid-rich fruits, based on McKey (1975) and Snow (1981). Observations were made from a ground hide about 18m from the base of the focal nest through a 7x50 binoculars or a 20x50 spotting scope. For each visit by the male hornbill to the nest, I recorded the number and type of food items delivered, the duration of the visit (to the nearest 5 seconds), and the total number of visits during each sampling/observation session. Ad libitum observations on other activities like nest-cavity sealing, cleaning, excretion, begging by the inmates, and the behaviour of the male during the time of food delivery were recorded. At the end of each session, the seeds and other faecal remains in the midden were examined, identified, classified, and counted.
Nest midden monitoring: Ten nests (including the focal nest) were visited regularly to note the status of nesting, quantify the regurgitated or excreted seeds of the fruits eaten by the inmates, and to identify the other debris in the midden. Of the food items consumed by the nest-cavity inmates, only non-digestible parts such as seeds of fruits, elytra of insects, and reptile scales occur in the midden. All distinguishable midden remains were collected, identified, counted, and recorded. The midden
below the nest-tree was cleared of all debris after each visit. Small seeds and animal matter in the faecal remains could not be quantified. The presence of Malabar grey hornbill feathers in the midden was taken to indicate moulting. Similarly, the presence of egg-shell in the midden, or the characteristic begging calls of the young, were evidence of hatching or the presence of chick(s) in the nest.
Statistical analyses: The frequency of food items delivered during the nesting period was calculated. Differences between the food (type and quantity) consumed between the two distinct phases (pre- and post-hatching) of the nesting period were tested for statistical significance using Mann- Whitney U test (Seigel and Castellan 1988), using SPSS/PC+ computer software (Norusis 1990). The difference in the occurrence of seeds (frequency) in the midden was tested for significance, using the non- parametric Mann- Whitney U Test similar to the analysis of direct feeding observation.
Results
Characteristics and occupation of focal nest: The focal nest cavity was located at about 14 m on an Artocarpus lakoocha (Moraceae) tree. The diameter at breast height (1.2 m) of the focal nest tree was 56 cm, the height 25 m, and the estimated diameter at nest height was 50 cm. The cavity entrance was circular in shape, and oriented towards northwest. My field assistant observed a bird entering the nest cavity in the first week of February. This was probably an instance of nest preparation, cleaning, and widening of the nest entrance.
After this, there was regular movement of the breeding pair in the vicinity of the nest- tree. On February 17, the female hornbill was seen entering the nest-cavity. The cavity entrance was then half-sealed. The male and the female visited the nest (8 times in 6 hrs). During these visits, they appeared to be enlarging the cavity entrance.
JOURNAL , BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
17
BREEDING BIOLOGY OF THE MALABAR GREY HORNBILL
The female was in the nest on February 18, and was seen sealing the cavity entrance, leaving only a slit, through which the male fed the inmates during the nesting period.
The male was never observed to be involved in nest sealing, repair, or delivering any kind of sealing material, unlike the female which often repaired the seal with its bill. The female was seen cleaning the nest-cavity by throwing out a lot of seeds and woody debris. The female hornbill used her own excreta, rich in Ficus seeds, as material for sealing the cavity entrance. The inmates effected nest sanitation by squirting their excreta out through the slit-like opening of the cavity entrance.
Nesting period: The nesting season lasted for about three months, between February and May in the study population of the Malabar grey hornbills. The nesting period could be distinguished into two main phases: the pre- hatching and the post-hatching phase. However, each phase in turn has been further divided into 3 sub-phases (fortnightly) for analysis. The nesting period in the focal nest was 86 days, commencing from February 18 (incarceration of the female) to May 15 (emergence of chick and female from the nest). The mean duration of the nesting period was 86 days (± 2.7 S.D.; N=4).
In the focal nest, the young hatched 40 days after the incarceration of the female. The post- hatching phase was 46 days. Only one chick appeared to have fledged. The female and young broke out of the nest together. Details of the nesting period in the ten nests are given in Table 1 .
Clutch size and moulting: The clutch size in the breeding population could not be determined. In the focal nest, only one young was seen. One nest when examined on March 1 , 1994, had only one egg. A week later, there were two eggs in this nest. The female resealed the cavity entrance and bred successfully.
Flight feathers were collected from the midden occasionally, particularly in the month of April. The rectrices were never found and the
Table 1
DATES OF INCARCERATION AND FLEDGING IN THE STUDY NESTS
|
Nest number Date of incarceration |
Fledging date |
|
|
1. |
1 7 February |
1 6 May |
|
2. |
1 5 February |
3 May |
|
3. |
1 8 February |
13 May* |
|
4. |
1 8 February |
15 May* |
|
5. |
21 February |
1 6 May |
|
6. |
1 8 February |
1 8 April** |
|
7. |
4 March* |
1 1 May* |
|
8. |
1 7 March* |
13 May |
|
9. |
3 March* |
1 6 May |
|
10. |
1 8 February |
1 5 May |
* — The chick fledged between this day and 20 May ** — Abandoned
* - Nests discovered after the nesting had commenced
female of the focal nest had tail feathers throughout the nesting period. These could be seen while the bird was ejecting the faecal matter through ‘the slit. However, rectrices had been collected from the midden of six nests during the preliminary study in 1993. Thus, it is likely that the moult in this species is partial.
Food delivery by the male hornbill: The focal nest was observed for a total of 161 hours and 45 minutes. All through the nesting period, the male provisioned the incarcerated female and later, the young also. A total of 2,397 food items, which included 1 1 kinds of fruit, 5 species of vertebrates, and at least 8 types of invertebrates, including 6 types of insects, were delivered by the male (Appendix). Lipid-rich fruits predominated in the diet of the incarcerated hornbills, constituting 36.9% of the food delivered. Other food categories were Ficus 26%, sugar-rich fruits 22.6%, and animal matter 13.8%. If there were several items, these were regurgitated one by one. Large fruits and vertebrate prey were usually brought as single items.
The number of food items delivered peaked during the pre-hatching phase, and declined thereafter, being minimum before the fledging of the young. The frequency of lipid-rich and
18
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
BREEDING BIOLOGY OF THE MALABAR GREY HORN BILL
APPENDIX
PLANT AND ANIMAL FOOD DELIVERED AT THE NEST BY THE MALE MALABAR GREY HORNBILL
A: Plant food (fruit)
|
S.No. Species |
Habit |
Number |
Number |
|
|
(Family) |
in pre- |
in post- |
||
|
hatching |
hatching |
|||
|
phase |
phase |
|||
|
Sugai 1. |
r-rich Fruit Ficus spp. (Moraceae) |
Tree/ Strangler |
443 |
123 |
|
2. |
Mi mu sops elengi (Sapotaceae) |
Tree |
17 |
_ |
|
3. |
B ridel ia sp. (Eupborbiaceae) |
Climber |
417 |
13 |
|
4. |
Elaegnus conferta (Elaegnaceae) |
Climber |
4 |
_ |
|
5. |
Linocera intermedia (Sapindaceae)+ |
Tree |
||
|
6. |
Syzygium spp. (Myrtaceae)+ |
Tree |
_ |
|
|
7. |
Filicium decipiens (Oleaceae)* |
Tree |
_ |
|
|
8. |
Zizyphus nummularia (Rhamnaceae) |
Shrub |
61 |
|
|
9. |
Glycosmis pentaphylla (Rutaceae) |
Shrub |
11 |
_ |
|
Lipid-rich Fruit |
||||
|
10. |
Uvaria sp. (Annonaceae) |
Climber |
510 |
63 |
|
11. |
Neolitsea sp. (Lauraceae) |
Tree |
173 |
52 |
|
12. |
Cinnamomum sp. (Lauraceae) |
Tree |
||
|
13. |
Persea macarantlia (Lauraceae)* |
Tree |
_ |
|
|
14. |
Litsea sp. (Lauraceae )+ |
Tree |
_ |
_ |
|
15. |
Beilschmedia sp. (Lauraceae) |
Tree |
_ |
19 |
|
16. |
Myristica dactyloides (Myristicaceae)* |
Tree |
A: Plant food (fruit) (contd.)
|
S.No. Species (Family) |
Flabit |
Number in pre- hatching phase |
Number in post- hatching phase |
|
|
17. |
Knema attenuate (Myristicaceae)* |
Tree |
||
|
18. |
Polya Ithia sp. (Annonaceae)+ |
Tree |
- |
- |
|
19. 20. |
Other Fruits Strychnos nux-vomica ( Logan iaceae)* Unidentified** |
Tree |
- |
+ — Found in the midden of the focal nest * — Found in the middens of other (non-focal) nests ** — Ten species whose seeds were found in small numbers in the middens (three were found in the midden of the focal nest)
B: Animal Food Vertebrates
1. Young bird
2. Snake
3. Lizard ( Calotes sp.)
4. Gecko
5. Frog
Invertebrates
1 . Beetle
2. Cricket/Grasshopper
3. Cicada
4. Stick Insect
5. Caterpillars
6. Winged insect (wasp, termite, etc.)
7. Millipede/Centipede
8. Scorpions
Total number of animal food items delivered during the nesting period = 491.
non-fig sugar-rich fruits was significantly higher in the pre-hatching phases (Mann- Whitney U test, N=16, U=24, pO.OOl and U=36, p<0.001, respectively). Figs were eaten consistently throughout the nesting period. The frequency (number per hour of observation) of animal
matter delivered was greater in the post-hatching phase (Mann-Whitney U test, U=41, p=0.047 for invertebrates and U=64, p=0,014 for vertebrates; Fig. 1). Within the pre-hatching phase, the frequency of lipid-rich fruits was significantly higher than the other types (Kruskal-Wallis
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
19
Minutes/hour Number/hour Minutes/hour
BREEDING BIO LOG Y OF THE MA LA BA R GRE Y HORNBIL L
Fig. 1 : a. Time spent at nest by the male, b. Visiting rate of the male, and c. Frequency of different food items delivered to the inmates by the male during the nesting period.
20
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
BREEDING BIOLOGY OF THE MALABAR GREY HORN BILL
X2= 1 3 .48, df=3, p<0.001), while in the post- hatching phase, animal food was significantly greater (%2=23.26, df=3, p<0.001).
Time spent at nest and visitation rate of the male: The time spent and the visitation rate of the male hornbill was influenced by the number and type of items delivered. Time spent (minutes per hour of observation) was significantly higher (Mann- Whitney U test, U=38, p<0.01) in the pre-hatching than in the post-hatching phase, as a greater number (69.5%) of small fruits (< 1.5 cm) was delivered (each had to be regurgitated individually). The visitation rate did not differ between the phases (Fig. 1).
Feeding habits — evidence from middens: Supplementary data from the middens of the ten nests showed that nine additional species of fruits were consumed by the incarcerated hornbills (e.g. Strychnos nux- vomica, Litsea sp., Persea macarantha, see Appendix). A few seeds of ten unidentified plant species were collected from some middens. There was no significant difference between the pre- and post-hatching phases in the frequency of the lipid-rich fruit seeds collected in the midden. The frequency of non-fig sugar-rich fruit seeds in the midden was found to be significantly greater in the pre-hatching phase (Mann- Whitney U test, N=21, U=T 16, p=0.007).
Predation on Malabar grey hornbill and nest intrusion: Two cases of mortality of Malabar grey hornbills were recorded. The first was of a young bird found towards the end of the nesting period during the preliminary study in 1993. The second was presumably an adult, whose remains were found in the middle of the nesting period in 1994, close to a regularly monitored nest which had been abandoned five days earlier.
The focal nest was once visited by three hill mynas ( Gracula religiosa ) that flew away at the approach of the male hornbill. A Malabar giant squirrel ( Ratufa indica) and the dusky- striped palm squirrel ( Funambulus sublineatus )
were other inquisitive visitors to the nest, but were apparently disregarded by the incarcerated female.
Discussion
The 32 species of Oriental hornbills are essentially forest-dwelling, arboreal birds (Kemp 1988, 1995). These species, including the Malabar grey hornbill, are long-lived, and have a distinct and relatively long nesting period. The nesting period of the Malabar grey hornbill lasted an average of 86 (± 2.7 days) during this study. The success of this bird as a rainforest specialist can be attributed to its life-history strategies (the long and peculiar nesting behaviour), and the adaptation in food habits.
Predation of adult Malabar grey hornbills by animals other than man is rare. Even during the vulnerable period of incarceration, the chances of predation are low, because the nest- cavity entrance is sealed, and the female with her large, armoured bill can protect the nest from intruders. This protection, along with the cavity nesting habit, can be the reason for the long incubation period of these birds.
Overall, the nesting periocl and food delivery by the Malabar grey hornbill in the area, as in the case of great pied hornbill ( Buceros bicornis ), seems to be associated with fruiting phenology, and the onset of the southwest monsoon (Kannan 1994). Studies in Thailand (Poonswad et al. 1988) have found the nesting of hornbills to commence and terminate later than in this region, probably because of the later monsoon. Hornbills subsist on an array of diverse, locally rare, tree species (e.g. members of the Lauraceae; Kannan and James 1999). The nesting period coincides with the peak in fruit availability, as shown by the fruiting phenology study of Kannan and James (1999). Large numbers of rainforest trees of the families Lauraceae, Burseraceae, and Myristicaceae {op cit.) contribute to the abundance of fruit.
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
21
BREEDING BIOLOGY OF THE MALABAR GREY HORN BILL
Lipid-rich fruits formed the most abundant component of the food delivered. The coincidence of nesting with peak in lipid-rich fruit availability could be as a result of long-term co-evolutionary process (McKey 1975). The high lipid content of these fruits may be necessary to meet the requirements of the nesting, moulting, and growing birds (Snow 1981).
Protein, carbohydrate, and water is obtained from sugar-rich fruits (including figs) and animal matter, which supplement the lipid- rich diet of the nesting hornbills. Notably, the Malabar grey hornbill fed less on Ficus fruits (26%) than the great pied, oriental pied (Anthracoceros coronatus ), and wreathed {Aceros undulatus) hornbills (Kannan and James 1997, Tsuji 1996). The smaller white-throated brown hornbill ( Ptilolaemus tickelli ), however, is shown to feed less on figs.
Smaller-sized hornbills are able to feed on a wider range of fruit and animal food, probably due to their smaller body size which enables them to access even the understorey shrub species, thus reducing the predominance of any one type of food. The Malabar grey hornbill consumes a greater variety of sugar-rich, particularly understorey fruits, as well as fruits of small trees and climbers, unlike the larger syntopic great pied hornbill which prefers large, canopy and emergent trees (Kannan 1994).
A wide range of food items are fed to the nest inmates. The kind of food delivered influenced the visitation -rate, and the time spent at nest by the male. The time spent was significantly higher in the pre-hatching phase as there was a greater number of small fruits (both lipid- and sugar-rich fruits, i.e., 61% of all small fruits) delivered at the nest. The time spent at the nest decreased towards the end of the nesting period, when large fruits and animal food were brought for the inmates and delivered as a single item per visit. The visitation rate did not differ between the phases, though the number of fruits delivered per visit decreased in the post-hatching
phase. This was probably compensated by the nutritive quality (lipid-rich fruits and animal food), and larger size of the food items delivered (eg. fruits of Myristica sp., Beilschmedia spp.). There was a drastic fall in the number of visits during the last few days of the nesting period. Welty (1982) proposed that the steady decline in feeding frequency may be a naturally evolved strategy of the parent to encourage the nearly- fledged young to leave the nest.
The differences in the food delivered during the nesting period can be explained by one or a combination of the following factors: (i) It could be related to the availability of fruits due to the usually high seasonal and synchronous fruiting of tree species bearing lipid-rich fruits (Snow 1981, Leighton and Leighton 1983, Kannan and James 1999), while the sugar-rich fruits are available all through the year. Community fruiting patterns in the study area were found to be largely determined by the trees producing lip id-rich fruits like Lauraceae, Annonaceae, which form a major proportion of tree species in the area (Kannan 1994). It was observed that certain fruits such as Alseodaphne semecarpifolia , Litsea sp., and Persea macaranthci , which were common and abundant in the middens during the preliminary study in 1993, were absent in 1994. So, inter-annual differences in fruiting patterns, and intra- seasonal staggering in the fruiting patterns of the Lauraceae in the rainforests is likely to play a major role in the nesting and nesting success of the hornbills (Snow 1981, Leighton 1982, Leighton and Leighton 1983, Kannan and James 1999).
(ii) Another possibility is that the hornbill selects high quality nutritive food for the growing chicks in the post-hatching phase, feeding them largely lipid-rich fruits and animal matter, which may be of co-evolutionary significance. The increased delivery of animal food toward the end of the nesting season may reflect an increase in abundance of insect prey in the forest just after
22
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
BREEDING BIOLOGY OF THE MALABAR GREY HORNBILL
the rains. The supplementation of high quality animal matter, however, coincides with the hatching of the chick and may provide the growing chick with essential nutrients.
(iii) Hombills are known to be territorial, ranging between 3 to 30 km2 (white-throated brown and great pied hornbills, respectively) depending on the size of the bird (Poonswad and Tsuji 1994). Seeds of some fruits (eg. Filicium decipiens , Polyalthia sp.) were found in the middens of only a few nests, probably because these fruiting trees were abundant in the territories of the hornbills inhabiting those nests.
Conclusion
The Western Ghats have been identified as one of the biodiversity hotspots in the world (Myers 1990, 1991). However, large scale deforestation for dam construction, agriculture and other developmental activities has resulted in the loss of over 40% forest cover in the last 70 years (Chattopadhyay 1985, Menon and Bawa 1997). This in turn has restricted the range of many species, including many endemics such as
Refer
Abdulali, H. (1942): The nesting of the Malabar Grey Hornbill. J. Bombay nat. Hist. Soc. 43:102-103.
Ali, S. & S. D. Ripley. (1970): Handbook of the birds of India and Pakistan. Vol 4. Oxford University Press. Pp. 130-133.
All S. & S. D. Ripley. ( 1 987): Compact handbook of the birds of India and Pakistan. Oxford University Press, Delhi.
Bingham, C. T. (1879) Notes on the nidification of some hornbills. Stray Feathers 5:459-463. Chattopadhyay, S. (1985): Deforestation in parts of Western Ghats region (Kerala), India. J. Environ. Manage. 20: 219-230.
Champion, H. G. & S. K. Seth (1968): A Revised Survey of the Forest types of India. Manager of Publications, Government of India, New Delhi.
Clutton-Brock, T. H. (1991): The evolution of parental care. Princeton University Press, Princeton.
Gilbert, L. E. (1980): Food-web organization and the
the Malabar grey hornbill. Hornbills play an important role in the dynamics of their habitats because of their specialised frugivorous habits (McKey 1975, Snow 1981, Leighton 1982) and as effective dispersers of many tree species (Kinnaird 1998, Whitney et al. 1998).
The Malabar grey hornbill, like other members of the family Bucerotidae, act as keystone species in the range of its distribution (Gilbert 1980). This endemic, specialist frugivore of the rainforest of the Western Ghats plays an important role in the dynamics of the moist evergreen forest it inhabits, dispersing the seeds of a few rare rainforest tree species. Conservation of their habitat is imperative as they have specialised feeding and nesting requirements (Mudappa and Kannan 1997).
ACKNO W LEDG EM ENTS
The research was supported by a grant from the Oriental Bird Club, U. K. I thank R. Kannan for guidance and encouragement and Ganesh, my assistant, for help in field work. I thank the Tamil Nadu Forest Department for permission to carry out the study.
ENC ES
conservation of neotropical diversity. Pp. 1 1-34. In Soule M. E. and Wilcox, B. A. (eds.). Conservation Biology, Sinauer, Sunderland, Massachusetts.
Hall, E. F. (1 91 8): Notes on the nidification of the Common Grey Hornbill (Lophoceros birostris). J ’. Bombay nat. Hist. Soc. 25: 503-505.
Hussain, S. A. (1984): Some aspects of the biology and ecology of Narcondam Hornbill ( Rhyticeros narcondami). J. Bombay nat. Hist. Soc. 81: 1-18. Kannan, R. (1994): Ecology and conservation of the Great Pied Hornbill ( Buceros bicornis) in the Western Ghats of southern India. Unpubl. Ph. D. thesis, University of Arkansas, Arkansas.
Kannan, R. & D. A. James (1997): Breeding biology of the great pied hornbill ( Buceros bicornis ) in the Anamalai hills of southern India. J. Bombay nat. Hist. Soc. 94: 451-465.
Kannan, R. &D.A. James (1999): Fruiting phenology and the conservation of the great pied hornbill ( Buceros
JOURNAL. BOMBAY NATURAL HISTORY SOCIETY. 97(1), APR. 2000
23
BREEDING BIOLOGY OF THE MALABAR GREY HORN BILL
bicornis ) in the Western Ghats of Southern India. Biotropica 31 : 167-177.
Kemp, A. C. (1976): A study of the ecology, behaviour and systematics of Tockus hombills (Aves: Bucerotidae). The Transvaal Mus. Memoir 20.
Kemp, A. C. ( 1 978): A review of the hombills: biology and radiation. The Living Bird 17: 105-136.
Kemp, A. C. ( 1 988): The systematics and zoogeography of Oriental and Australasian hombills (Aves: Bucerotidae). Bonn. zool. Beitr. 39:315-345.
Kemp, A.C. (1995): The hombills. Oxford University Press. Oxford, England
Kemp, A. C. & M. I. Kemp (1975): Report on a study of hombills in Sarawak, with comments on their conservation. World Wildlife Fund Project Report 2/ 74.
Kinnaird, M. F. (1993): Variation in fruit resources and the effects on vertebrate frugivores: the role of disturbance regimes in Sulawesi rainforests. Report, LIPI. Jakarta, Indonesia.
Kinnaird, M. F. (1998): Evidence for effective seed dispersal by the Sulawesi red-knobbed hornbill Aceros cassidix. Biotropica 30: 50-55.
Leighton, M. (1982): Fruit resource and patterns of feeding, spacing and grouping among sympatric Bornean hombills (Bucerotidae). Unpubl. Ph. D. thesis, University of California, Davis.
Leighton, M. & D. R. Leighton (1983): Vertebrate responses to fruiting seasonality within a Bornean rainforest, pp 181-196. In: Sutton, S. L., Whitmore, T. C., and Chadwick, A. C. (eds.) Tropical Rain Forest: Ecology and Management. Blackwell Scientific Publications, Oxford
Lowther, E. H. N. (1942): Notes on some Indian birds. J. Bombay nat. Hist. Soc. 43:386-401.
McKey, D. ( 1 975): The ecology of coevolved seed-dispersal system. Pp. 159-199. In Gilbert L. E. and P. H. Raven (eds.). Coevolution of animals and plants. University of Texas Press, Austin.
Menon, S. & K. S. Bawa (1997): Applications of geographical information systems, approach to bio- diversity conservation in the Western Ghats. Curr. Sci. 73: 134-145.
Mudappa, D. (1994): Nesting habitat of the Malabar Grey Hornbill ( Ocyceros griseus ) in the Anaimalais, southern Western Ghats, India. M. S. dissertation, Salim Ali School of Ecology, Pondicherry University, Pondicherry.
Mudappa, D. & R. Kannan ( 1 997): Nest-site selection by the Malabar Grey Hornbill ( Ocyceros griseus ) in southern Western Ghats, India. Wilson Bull. 102: \ 1 1- 119.
Myers, N. ( 1 990): The biodiversity challenge: expanded hot-spots analysis. Environmentalist 10: 243-256.
Myers, N. (1991): Tropical forests: present status and future outlook. Clim. Change 19: 3-12.
NoruSis, M. J. (1990): SPSS/PC+: Statistics 4.0. SPSS Inc., Chicago.
Poonswad, P. (1995): Nest-site characteristics of four sympatric species of hombills in Khao Yai National Park, Thailand. Ibis 137: 183-191.
Poonswad, P. & A. Tsuji ( 1 989): Conservation of hombills in Thailand. Presentation at the joint meeting of ICBP Asian section and east Asian bird protection conference, 1989. Bangkok, Thailand.
Poonswad, P. & A. Tsuji ( 1 994): Ranges of the males of the Great Hornbill Buceros bicornis , Brown Hornbill Ptilolaemus tickelli and Wreathed Hornbill Rhyticeros undulatus in Khao Yai National Park, Thailand. Ibis 736:79-86.
Poonswad, P., A. Tsuji, R. Liewviriyakjt & N. Jirawatkavi (1988): Effects of external factors on hornbill breeding and population. World Conference on breeding endangered species in captivity, Cincinatti, Ohio.
Reddy, M. S., K. S. Muralidhar, M. R. Gandhi & S. BASALiNGAPPAtl990): Distribution and variation in number of Malabar Pied Hombills Anthracoceros coronatus (Boddaert) in selected areas of north Kanara forest of Western Ghats in Karnataka (India). The Indian Zoologist 1 4:63-13.
Reddy, M. S. & S. Basalingappa (1995): The food of Malabar Pied Hornbill. Jour. Ecol. Soc. 8: 23-28.
Seigel, S. & N. J. Castellan, Jr., (1988): Non-parametric Statistics for the behavioural sciences. McGraw-Hill, New York. 399 pp.
Snow, D. (1 98 1 ): Tropical frugivorous birds and their food plants: a world survey. Biotropica 13: 1-14.
Tsuji, A. (1996): Hombills: Masters of tropical forests, Hornbill Research Foundation, Bangkok
Welty, J. C. (1982): The Life of Birds. 3rd edn. Saunders College Publishing
Whitney, K.D., M.K. Fogiel, A.M. Lamperti, K.M. Holbrook, D.J. Stauffer, B.D. Hardesty, V.T. Parker & T.B. Smith (1998): Seed dispersal by Ceratogymna hombills in the Dja Reserve, Cameroon. / Trop. Ecol. 74:351-371
24
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVATION IN THE INDIAN TRANS -HIMALAYA1
Charudutt Mishra2,3
Key words: management, protected area, policy, livestock, Uncia uncia,
Canis lupus
The founding postulate of the preservationist conservation philosophy — that local human communities cause land degradation and biodiversity loss — is increasingly being questioned for its scientific validity. That this postulate may not hold in many cases is being used, inter alia , in support of calls for more inclusive conservation policies in developing countries. Such policies would allow, or even encourage, consumptive human use of natural resources within designated wildlife-protected areas. However, the latter approach again rests upon the assumption that local human communities and their impacts on natural resources are constant. The present paper questions this assumption using a case study from a hitherto isolated region of the Indian Trans-Himalaya. I describe the ongoing socio-economic flux in an agropastoral Buddhist community dependent upon the resources of a protected area, and the impacts of this transition on wildlife conservation. The analysis shows radical changes in the local economy and land use in the last decade, that ultimately proceed from extrinsic factors (market forces, changes in Government policy). Immediate conservation problems have proximately arisen from both extrinsic (uncontrolled tourism) as well as intrinsic (escalation of livestock stocking rate) changes. The analysis underscores the need for conservation policies to be sensitive to the transient nature of local human communities, even in seemingly isolated protected areas.
Introduction
The thrust of India’s conservation policy has been preservationist, wherein emphasis has been placed on minimising or eliminating consumptive human uses within areas designated for protection of wildlife. Despite such an exclusionary official policy, more than 80 % of Indian wildlife reserves are inhabited by local human communities that continue to use the natural resources in them, albeit within state-imposed restrictions (Kothari et al. 1989). Such restrictions on traditional resource use following the creation of protected areas are responsible for local hostility and the absence of local support for conservation efforts (Kothari et al 1995, Guha 1997, Saberwal 1997). This
'Accepted June, 1998
^Centre for Ecological Research and Conservation,
3076/5, IV, Cross Gokulam Park,
Mysore 570002, Karnataka, India.
3 Present address: Tropical Nature Conservation and Vertebrate Ecology Group, Wageningen University, 69 Bomsesteeg, 6708 PD Wageningen, The Netherlands.
hostility gets further aggravated in the face of serious human-wildlife conflicts in many protected areas, and the subsequent bureaucratic apathy faced by the local people (Guha 1997, Mishra 1997a, Saberwal 1997, Saberwal et al. 1994) Not surprisingly then, as in many other developing countries (Prins 1992), the merits of the Indian preservationist approach are being increasingly questioned on social, economic, ethical, political, pragmatic and even ecological grounds. Critics have contended that the preservationist policy has been based on scientifically unsubstantiated assumptions that local human communities cause land degradation and the loss of biodiversity (Saberwal 1996, Guha 1997). There is an increasing call for 'rethinking conservation’ and embracing a more inclusive policy, which, in theory, allows for biodiversity conservation alongside local human resource use (e.g. Kothari et al. 1995, Saberwal 1996). However, the latter thesis again rests upon an important yet unsubstantiated assumption that views local human communities, their life-styles,
JOURNAL , BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
25
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVA TION
and the magnitude of their impacts, as static and immune to change (Mishra and Rawat 1998). It is this assumption that is questioned here. The aim is neither to denounce nor advocate the demands for ‘democratic’ multiple use policies; under the complex sociopolitical situations in most developing countries, strict adherence to either stand will prove counter-productive for wildlife conservation. The purpose of this paper, instead, is to show that irrespective of the official conservation policy ( 1 ) local human communities even in the remotest regions of the develop- ing world are undergoing rapid social and land use transition, (2) this transition has potentially important consequences for wildlife conserva- tion, and following from this, (3) conservation policies need to be extremely sensitive to these changes.
Focusing on three agropastoral Buddhist villages (80 households) dependent upon the resources of a protected area, this paper describes the ongoing socio-economic transition in the Spiti region (31° 42' to 32° 58' N lat. and 77° 21' to 78° 35' E long.) of the Indian Trans-Himalaya. Located close to the politically sensitive Sino-Indian border, in difficult mountainous terrain, Spiti remained a remote area with restricted geographical as well as administrative access until 1992. In this paper, I specifically document the socio-economic trends in the region over the last 25 years, and subsequently discuss their consequences for wildlife conservation. The urgent research and management inputs required for conservation both at the local and regional levels are also outlined.
Study Area
The Trans-Himalayan region includes the high altitude plateau of Tibet and the Tibetan marginal mountains, an area of over 2.6 million km2. The c. 186,000 km2 within India, despite its conservation significance, forms one of the
least represented biogeographic zones in the Indian protected area network (Rodgers and Panwar 1988).
The Spiti region in the Trans-Himalayan Lahaul and Spiti dist. (Himachal Pradesh) spans an area of 12,210 km2 in the catchment area of the Spiti river, with a human population of 9,59 1 (in 1991; Directorate of Economics and Statistics 1996) which is largely Buddhist (Kaushik 1993). Spiti had no wildlife reserves until the last decade. The establishment of the 675 km2 Pin Valley National Park (31° 44' to 32° IT N lat., and 77° 45' to 78° 06' E long.) in 1987, and the 1400 km2 Kibber Wildlife Sanctuary (32° 5' to 32° 30' N lat. and 78° 1' to 78° 32' E long.) in 1992, has resulted in 17% of Spiti’s land area being designated as wildlife reserve. The protected area boundaries, however, are only nominal, considering they were drawn around existing settlements and villages whose inhabitants continue using these areas for grazing, fuel and fodder collection.
Kibber Wildlife Sanctuary lies in the northern catchment of Spiti and is flanked by Ladakh to the north and Tibet to the east. The Sanctuary, like the rest of the Trans-Himalaya, lies in the rain shadow of the Greater Himalaya, and ranges in altitude from c. 3,600 m to 6,700 m above msl. Temperatures range between -30°C to 3°C in the winter, and between 1°C to 28°C in summer (Rana 1994). Vegetation in the area has been broadly classified as dry alpine steppe (Champion and Seth 1968). The Sanctuary is flanked by 13 villages along its southern boundary inhabited by an agropastoral Buddhist community, whose agricultural activities are restricted to the short growing season between May and September. Barley Hordeum vulgare and green pea Pisum sativum are the main crops. Livestock includes goat, sheep, cattle, yak, dzomo (female hybrid of cattle and yak), donkey and horse. Goat, cattle and dzomo are used for both milk and meat. Sheep are used for wool and yaks for ploughing, in
26
JOURNAL. BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSER VA TION
addition to meat. Donkeys are used as draught animals, and raised partly for trade. Horses, apart from being used for religious ceremonies, are raised mainly for trade (Mishra 1997a).
The mammalian fauna of the Sanctuary includes snow leopard Uncia uncia , wolf Canis lupus , red fox Vulpes vulpes, pale weasel Mustela altaica, stone marten Mcirtes foina , Himalayan mouse hare Ochotona sp., bharal Pseudois nayaur , and ibex Capra ibex.
Methods
Unpublished archival records of the State Government were scrutinised (see Mishra 1997a for details of sources) for information relating to human population and past literacy rates, livestock population, and developmental changes in the region over the last 25 years. Of the 13 villages surrounding Kibber Wildlife Sanctuary, three, which together comprised 1 9% of the population living around the park, were selected as samples for the study (for details see Mishra 1997a). This included Kibber, the largest in the area (316 inhabitants), and two small villages nearby, Gete (36) and Tashigang (24). Structured interviews were conducted with at least one member from each household in the three villages, to obtain information regarding present family size and literacy, livestock and land holdings, and past and current agricultural practices. Human and livestock population growth rates (r) were calculated using the exponential growth curve equation (Nt = N0ert where Nt is the population at time t, N0 is the starting population, and e the base of natural logarithms). Crop yield per unit area was obtained for different crops by interviewing two experienced farmers, and the lower limit of the reported range used to obtain a conser- vative estimate of crop production. Casual interviews and observations during the course of field work yielded information on tourism and its impacts.
Results
Human population and development
The human population in the thirteen villages bordering Kibber Wildlife Sanctuary increased only marginally (at an annual growth rate of 0.09%) between 1971 and 1991 (1985 people in 1991; data for 1996 not available). Likewise, between 1971 and 1996, the three study villages saw a total population increase of only 6.5%, an average annual growth rate of 0.25% (Mishra 1997a). Children <18 years comprise 49% of the present population of the study villages. Literacy rate has doubled (from 22% to 48%) in the last 25 years. Presently, 31% of the adult males (n = 91), and 26% of the adult females (n = 100) are literate. In the school-going age group (c. 5 to 1 8 years), there is 97% literacy (n = 127). Among other indicators of development, this period has seen an increase in the number of schools and the electrification of all three study villages (Table 1). Two of the three villages, Gete and Tashigang, which earlier had no roads, have been connected by motorable roads.
Agriculture
The number of people per unit of irrigated land has remained nearly constant over the last 25 years (Table 1), with the current average land holding per household at 1.13 ha. The cropping pattern, however, has changed in the last decade. Prior to 1986, agriculture was for subsistence.
Table 1
PATTERNS IN SOME INDICATORS OF DEVELOPMENT OVER THE LAST 25 YEARS IN THREE SAMPLED VILLAGES OF KIBBER WILDLIFE SANCTUARY
|
Indicator 1 |
971 |
1996 |
|
No. of medical care centres |
1 |
1 |
|
No. of post offices |
1 |
1 |
|
No. of schools |
1 |
4 |
|
Irri gated land (ha) |
83 |
91* |
|
People per ha irri gated land |
4.2 |
4.1 |
|
No. of villages with electricity |
0 |
3 |
|
No. of villages connected by motorable road |
1 |
3 |
*in 1987
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
27
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVA TION
The main crops were barley and a local variety of pea (the latter largely for supplementing livestock feed), cultivated on two-thirds and one-third of the land holding respectively. Since 1986, however, one-third of the land holding is cultivated for green peas, one-third for barley, and the remaining is partly planted with local pea and partly left fallow. The entire harvest of green pea is sold as a cash crop. The estimated annual production of green pea per household is 2,587 kg, which translates into a per capita profit (corrected for transport costs) of US$ 210 per year (1994-95 conversion rate of 1 US$ = 31.4 Indian Rupees; World Bank 1996). The estimated annual production of barley per household is currently 1,294 kg.
This change in cropping pattern has significantly affected an age-old barter trade between the inhabitants of the study area and a semi-nomadic pastoral community, the Changpa of Ladakh. Changpa herders have been coming into Spiti for at least a few centuries (Kapadia 1996). They come in summer with their livestock (> 1,000 goat and sheep) when the high mountain passes ( c . 5,600 m) become negotiable. The main trade involved barley, which earlier was in surplus, and was bartered with the Changpa largely in exchange for wool, salt and rugs. Owing to the replacement of barley with the commercially valuable green pea, and the resulting absence of surplus barley, the development of a market economy, and the improvement in transportation, communication, and supplies in Spiti, this trade is on the verge of breakdown. However, the trade continues for Spiti horses and donkeys, which are still in demand with the Changpa.
Livestock
The annual growth rate of livestock holdings in the study villages increased from 2.6% (between 1971 and 1987) to 3.5% after 1987 (up to 1996; Mishra 1997a). The growth rate of livestock throughout Spiti after 1987 was
3.2% (10,458 heads in 1988 to 1 1,881 heads in 1992). In the last 25 years, the ratio of livestock to human population in the study villages has increased from 1.85 (the year 1971, in Gete and Tashigang) to 2.80 (1996, in all three villages).
In terms of herd composition, Gete and Tashigang (data for Kibber for the year 1 97 1 were not available) show an increase in all livestock species between 1971 and 1987, though the maximum increase was accounted for by goat and sheep (42%). After 1987, the number of donkeys and cow Idzomo declined, while the other species continued to increase (Table 2). In Kibber, the trend after 1987 was almost the same with all the species except cow Idzomo continuing to increase. Thus, in the last ten years, the population of cow Idzomo in all the sampled Table 2
LIVESTOCK POPULATION TRENDS OVER 25 YEARS IN THREE SAMPLED VILLAGES (DATA POOLED FOR THE VILLAGES GETE AND TASHIGANG) OF KIBBER WILDLIFE SANCTUARY
|
Species |
1971 |
Gete and Tashigang * 1987 1996 |
Kibber village* 1987 1996 |
||
|
Yak |
9 |
14 |
29 |
28 |
110 |
|
Cattle/ dzomo |
13 |
32 |
28 |
113 |
98 |
|
Horse |
6 |
11 |
18 |
34 |
57 |
|
Donkey |
11 |
17 |
11 |
93 |
114 |
|
Sheep/ goat |
76 |
101 |
137 |
322 |
452 |
|
Total |
115 |
175 |
223 |
590 |
831 |
*data for 1 971 were not available
villages has declined marginally, while yak has increased more than threefold (Table 2). Goat and sheep again accounted for the maximum increase (57 %) during this period.
Tourism
Prior to 1992, foreign nationals were not allowed in Spiti, and even non-domicile Indians needed to obtain special permits from the State Government to enter the region. With the relaxation of Government policy since 1992, there has been a sudden growth in tourism.
28
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVA TION
Kibber, one of the study villages, had three functional hotels and one more under construction when this study was conducted, as opposed to none before 1993. These small hotels (3-4 rooms), catering to both Indian and foreign tourists, are run by local villagers. Many villages of Spiti now have makeshift hotels. The tourist inflow is restricted to between June and September. Between June and August 1996, a hotel owner reported a net profit of c. US$ 637 (Chering Dorje, Kibber, pers. comm. 1996). Demand for local guides and donkeys by trekking tourists also causes a substantial inflow of money at the local level, which could not, however, be quantified.
Discussion
Human population
Most habitat change and biodiversity loss in developing countries has been attributed to socio-economic change in growing rural populations (Machlis 1992). The Indian population, 74% of which is rural, has indeed grown at an annual rate of 2. 1 7% in the past two decades, yielding a current density of close to 300 per sq. km (Repetto 1994). In contrast, the absolute human density of Spiti is very low (0.78 per sq. km). The unusual absence of population growth could largely be a consequence of the relatively intact system of primogenitary inheritance over most of Spiti (and polyandry in one region) where the younger siblings become celibate monks (Mamgain 1975, Punjab Government 1994). The stable population size seems to have stabilised the pressure for fuelwood on the protected area. However, it is important to keep in mind that most of the area in Spiti is uninhabited due to its inhospitable cold desert mountainous environment. Consequently, 31% of Spiti’ s present population is concentrated in and around the two protected areas, and is dependent on them for grazing and fuelwood (Pin Valley has a human population of 1500 inside
and around the National Park area; Mishra 1997b). A study estimates an annual per capita extraction of 2 17 kg of shrubs and dung (for fuel), and fodder (for winter supplemental feeding) by the resident population from Pin Valley (Bhatnagar 1996). It is also prudent to note that, faced with modernization, other trans-Himalayan Buddhist communities are undergoing rapid population growth following a breakdown of social population regulation mechanisms, and this might happen in Spiti as well (Goldstein 1 98 1 , Fox et al. 1 994, Mishra and Humbert-Droz 1998).
Changes in agriculture and animal husbandry
The most significant socio-economic change in the region during the last decade has been the shift from a barter-based sub- sistence economy, to a market economy, resulting from, inter alia , changes in cropping pattern. The return per household from green pea harvest, the new cash crop, is almost as high as the average annual per capita income for Himachal Pradesh (US$ 248, 1994-95; World Bank 1996).
Along with agriculture, there is indication of commercialisation of animal husbandry as well (livestock trade was earlier restricted to barter with the Changpa). This is evidenced in the three-fold increase of yaks in the last decade, which are now partly being raised in the villages of Kibber Wildlife Sanctuary for selling in other areas of Spiti (Chhewang D. Zangpo, Pin Valley, pers. comm. 1996). This contrasts with other yak rearing communities in the Himalaya, where the yak population is known to be declining rapidly (Negi and Gadgil 1997, J.L. Fox pers. comm. 1996.). Between 1988 and 1992, the yak population of Spiti increased from .786 to 897 heads.
Livestock of the study villages graze in the Sanctuary area nearly throughout the year, though their diet is supplemented by stall feeding in winter. This supplemental forage is partly
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
29
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVA TION
collected during the growing season from the Sanctuary area, and partly from the cropfields. In addition, the State Government has initiated a scheme to provide supplemental feed at subsidised rates. Given the present trend and the augmented ability to purchase supplemental feed, livestock holdings are likely to continue growing in the near future. The increasing livestock stocking rate seems to be intensifying the pressure on the protected area resources for fodder.
Escalating livestock stocking rate is a countrywide phenomenon in India, the last two censuses indicating a 1.2% annual growth rate (419 million in 1982 to 445 million in 1987). With 67% wildlife sanctuaries and 83% national parks subject to livestock grazing (Kothari et al. , 1989), the urgency for evaluating the impacts of livestock on wildlife resources is obvious. In Kibber, the increase in stocking rate (together with poor anti-predatory livestock management) seems to be the main reason behind the recent escalation in instances of livestock depredation by large carnivores (the snow leopard and the wolf; Mishra 1997a). Even now, livestock outnumber bharal, the dominant wild ungulate and natural prey of the wild carnivores, by an order of magnitude. To reduce this depredation, villagers have been killing the wolf, and elsewhere, I have expressed concern that persecution of the snow leopard is likely to begin unless specific research and management measures are undertaken to understand and reduce this conflict (Mishra 1997a).
At a broader level, there is a need for assessing the impact of grazing on plant communities and evaluating the forage relations between livestock and wild herbivores. The potential for regulating livestock stocking rates and range use to enhance conservation objectives has long been recognised (e.g., Anderson and Scherzinger 1975, Willms etal. 1980), and such studies are a pre-requisite to designing effective multiple-use management policies for Indian protected areas.
Uncontrolled tourism
Uncontrolled tourism in wildlife reserves has usually resulted in conservation problems (Budowski 1976, deGroot 1983, Kenchington 1989). Kibber presently lacks even a record of the number of tourists visiting the Sanctuary. With the sudden development of tourism, the age-old trade route between Kibber and Ladakh (used by the Changpa ; c. 125 km) has now become a popular trekking route. This route passes along wetlands in Ladakh that are important breeding sites for water birds, including rare and threatened species (Mishra and Humbert-Droz 1998). A rather conspicuous impact of this tourism has been the pollution of this route with discarded garbage (including non-degradable metal cans and polythene), especially around about 15 camping sites.
In addition, Kibber Wildlife Sanctuary, like some other regions of Spiti, has deposits of nautiloid, balamnite, and ammonite fossils (Y.V. Bhatnagar, pers. comm. 1997). Locals reported that fossils were being removed from the area even before Spiti was opened to tourists. However, this was confined to geologists and amateur collectors. Tourism has now created a market for fossils, which is causing a rapid depletion of the fossil reserves of Kibber Wildlife Sanctuary and elsewhere in Spiti. Depending upon its size and quality, a fossil may fetch US$ 3 to USS 15. I could not, however, assess the magnitude of this trade. The need for a culturally and ecologically well designed tourism plan for Spiti is apparent, and has already been expressed (Kaushik 1993, 1994).
Conclusions
Spiti remained geographically as well as politically remote and isolated until 1992, and the so far intact social population regulation mechanisms have kept the local human population under control. However, a rapid socio-economic transition is in progress,
30
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVA TION
exemplified by improvements in transporta- tion, increase in literacy, changes in cropping pattern (the adoption of a cash crop), breakdown of barter trade, expansion of livestock holdings, and a sudden development of an unplanned tourism industry. This is ultimately driven by far-reaching extrinsic factors such as the influence of commercial markets and changes in Government policy. The transition from a subsistence (barter-based) economy to a market economy, and changes in land use in Kibber Wildlife Sanctuary, have resulted in conservation problems such as the escalation of human- wildlife conflict (livestock depredation by wild carnivores), increased pressure on the protected area for fodder, pollution, and the depletion of fossil reserves. These have proximately been brought about by intrinsic (escalating livestock stocking rates) as well as extrinsic (tourism) factors.
This paper joins a growing body of literature documenting the significant influence of market forces even in relatively remote regions of the developing world (e.g. Goldstein 1981, Goldstein and Beall 1989, Fox et al. 1994, Negi and Gadgil 1997, Mishra and Humbert-Droz 1998). It further shows that the resultant
Refer
Anderson, E.W. & R.J. Scherzinger (1975): Improving quality of winter forage for elk by cattle grazing.
J. Range Manage. 28\ 120-125.
Bhatnagar. K. ( 1 996): A study on people’s dependence, attitudes and ecodevelopment in Pin Valley National Park, Himachal Pradesh. Unpublished report. Worldwide Fund for Nature (India), New Delhi, India.
Budowski, G. (1976): Tourism and environmental conservation: conflict, coexistence, or symbiosis? Enviro. Conserv. 3: 27-31.
Champion, H.G. & S.K. Seth ( 1 968): A Revised Survey of the Forest Types of India. Manager of Publications, Delhi, India, pp 404.
deGroot, R.S. (1983): Tourism and conservation in the Galapagos islands. Biol. Conserv. 26: 291-300 Directorate of Economics and Statistics (1996):
transition in socio-economy and landuse in local human communities can result in complex conservation problems. Conservation policies therefore, ought to bear in mind the transient nature of local human communities residing even in seemingly remote protected areas.
Acknowledgements
I thank Dr. K. Ullas Karanth, the Wildlife Conservation Society, Bronx, NY, and the Netherlands Foundation for the Advancement of Tropical Research (WOTRO), a body residing under the Netherlands Organization for Scientific Research (NWO) for financial support. My gratitude for technical support to the Department of Forest Farming and Conservation, Himachal Pradesh, and the Director, Wildlife Institute of India. I thank Y.V. Bhatnagar, K. Bhatnagar, T. Dorje, Dr. J.L. Fox, L. Gyalson, N. Manjrekar, and B.S. Rana, for discussions; Dr. S.P. Goyal and Dr. A.J.T. Johnsingh for encouragement, and Dr. R.S. Chundawat, Dr. S.N. Mishra, Madhusudan Katti, and T.R.S. Raman for comments. The contribution of M.D. Madhusudan in restructuring the paper is gratefully acknowledged.
ENCES
Economic review. Directorate of Economics and Statistics, Himachal Pradesh Government. Shimla, India.
Fox, J.L., C. Nurbu, S. Bhatt, & A. C'handola (1()94): Wildlife conservation and land-use changes in the trans-Himalayan region of Ladakh, India. Mount. Res. Develop. 14: 39-60.
Goldstein, M.C. (1981): High altitude Tibetan populations in the remote Himalaya: social transformation and its demographic, economic, and ecological consequences. Mount. Res. Develop. I: 5-18. Goldstein, M.C. &C.M. Beall (1989): Nomads of western Tibet: survival of a way of life. Serindia Publications. London, 191 pp.
Guha, R. (1997): The authoritarian biologist and the arrogance of anti-humanism: wildlife conservation in the third world. The Ecologist 27: 14-20
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
31
SOCIOECONOMIC TRANSITION AND WILDLIFE CONSERVA TION
Kapadia, H. (1996): Spiti: adventures in the trans-Himalaya. Indus Publishing Company, New Delhi, India.
Kaushik, S. (1993): Towards a tourism strategy in Spiti. Equitable Tourism Options, Bangalore, India.
Kaushik. S. (1994): The blossoming of an affair: a Spiti update. Equitable Tourism Options, Bangalore, India.
Kenchington, R.A. (1989): Tourism in Galapagos Islands: the dilemma of conservation. Environ. Conserv. 16: 227-232.
Kothari, A., P. Pande, S. Singh & D. Variava (1989): Management of National Parks and Wildlife Sanctuaries in India: a status report. Indian Institute of Public Administration, New Delhi, India, 298 pp.
Kothari, A., S. Suri & N. Singh (1995): People and protected areas: rethinking conservation in India. The Ecologist 25: 188-195.
Machlis, G.E. (1992): The contribution of sociology to biodiversity research and management. Biol. Conserv. 62: 161-170.
Mamgain. M.D. (1975): Himachal Pradesh district gazetteers: Lahaul and Spiti. Greater Punjab Press, Chandigarh, India.
Mishra, C. (1997a): Livestock depredation by large carnivores in the Indian Trans-Himalaya: conflict perceptions and conservation prospects. Environ. Conserv. 24: 338-343.
Mishra, C. (1997b): Livestock grazing and wildlife conservation in the Indian Trans-Himalaya: a preliminary survey. Unpublished report for the Wildlife Conservation Society, Bronx. NY. Centre for Ecological Research and Conservation, Mysore, India, 22 pp.
Mishra, C. and B. Humbert-Droz ( 1 998): Avifauna! survey of Tsomoriri Lake and adjoining Nuro Sumdo wetland in Ladakh, Indian trans-Himalaya. Forktail 14: 865-867.
Mishra, C. & G.S. Rawat ( 1 998): Livestock grazing and biodiversity conservation: comments on Saberwal.
Conserv. Biol. 12: 1 1 2-7 1 4.
Negi, H.R. & M. Gadgil (1997): Conserving livestock genetic resources: a case study of Kinnaur in Himachal Pradesh. .1. Human Ecol. 6 (Special issue): 317-324.
Prins, H.H.T. (1992): The pastoral road to extinction: competition between wildlife and traditional pastoral ism in East Africa. Environ. Conserv. 19: 117-123.
Punjab Government (1994): Gazetteer of the Kangra District, parts II to IV- Kulu, Lahaul and Spiti, 1897. Indus Publishing Company, New Delhi, India.
Rana, B.S. ( 1 994): Management plan of Kibber Wildlife Sanctuary. Department of Forest Farming and Conservation, Wildlife Wing, Shimla. Himachal Pradesh, 81 pp.
Repetto, R. (1994): The ‘Second India’ revisited: population, poverty, and environmental stress over two decades. World Resources Institute, Washington D.C., USA.
Rodgers, W.A. & H.S. Panwar (1988): Planning a protected area network in India. Vol. I - the Report. Wildlife Institute of India, Dehra Dun. India, 341 pp.
Saberwal, V.K. ( 1996): Pastoral politics: gaddi grazing, degradation and biodiversity conservation in Himachal Pradesh, India. Conserv. Biol 10: 741-749.
Saberwal, V.K. ( 1 997): Saving the tiger: more money or less power? Conserv. Biol. 1 1: 8 1 5-8 1 7.
Saberwal, V.K., J.P. Gibbs, R. Chellam & A.J.T. Johnsingh (1994): Lion-human conflict in Gir Forest, India. Conserv. Biol. 8: 501-507.
Willms, W., A.W. Bailey & A. McLean (1980): Effect of burning or clipping Agropyron spicatum in autumn on the spring foraging behavior of mule deer and cattle. J. Appl. Ecol. 17: 69-84.
World Bank (1996): India: country economic memorandum. World Bank Report 1 58882 IN . World Bank. Washington, DC, USA.
32
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1). APR. 2000
AN ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NATIONAL PARK, SRI LANKA1
Charles Santiapillai, Mangala de Silva2, Sarath Dissanayake3, B. V.R. Jayaratne4 and S. Wijeyamohan5
( With three text-figures)
Key words: Marsh crocodile, Crocodylus palustris, estuarine crocodile, C. porosus , Ruhuna National Park, basking, feeding, conservation
A study was carried out in Block I (140 sq. km) of the Ruhuna National Park (RNP) opportunistically from October 1 99 1' to October 1 994, in order to study the two species of crocodiles occurring in Sri Lanka, viz. Crocodylus palustris and C. porosus. A total of 341 sightings of the two species were made on 77 occasions, 307 sightings on C. palustris and 34 sightings on C. porosus. Among C. palustris , solitary animals made up most of the observations (55.8%) while pairs accounted for 13.0%. Of the 22 water-holes that were surveyed, 13 (59%) had only one crocodile. Although both species could be seen at any time of the day, the number basking increased with the increase in the ambient temperature, and peaked around noon. C. porosus basked alone, and C. palustris communally. The population structure consisted of 44% hatchlings, 6% juveniles, 24% subadults and 26% adults. Only adults of C. porosus were observed. Hatchling losses can be very high through predation by birds and mammals. Both species feed on a variety of food, ranging in size from aquatic insects and Crustacea (in hatchlings) to fish, frogs, birds and large mammals (in adults). The minimum crude density values for C. palustris and C. porosus are estimated to be 0.72 and 0.07 animals per sq. km respectively. The populations of both species in Block I appear to be secure and viable.
Introduction
Of the 13 species of ‘true’ crocodiles (Subfamily: Crocodylinae) that are extant in the world, 8 species occur in Asia, of which 2 are found in Sri Lanka, namely the freshwater, or marsh crocodile, or mugger ( Crocodylus palustris) and the saltwater or estuarine crocodile (C. porosus). While C. palustris is listed as ‘vulnerable’ by IUCN (Groombridge, 1993), C. porosus has been transferred to the Tow risk’ category, given the tens of thousands known to
‘Accepted April, 1999
department ofZoology, University of Peradeniya, Sri Lanka ?National Wildlife Training Centre, Giritale, Sri Lanka JWasgomuwa National Park, Hasalaka, Sri Lanka 'Faculty of Applied Sciences,
Vavuniya Campus of the Jaffna University,
Vavuniya, Sri Lanka
be present in numerous localities across its geographical range. However, in Sri Lanka, given its low number and restricted distribution, C. porosus is more threatened than C. palustris. According to Whitaker and Whitaker (1989), “Sri Lanka has more mugger crocodiles than the rest of the subcontinent put together, mostly concentrated in the two national parks, Yala (=RNP) and Wilpattu.” Even though this may not be strictly true now, it indicates the high number of mugger crocodiles still occurring in Sri Lanka. Both species found in Sri Lanka are listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
Crocodiles were once plentiful in Sri Lanka. The man-made reservoirs or tanks in the Dry Zone were teeming with crocodiles (Baker
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
33
ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NATIONAL PARK
1853; Tennent 1859; Hennessey 1949). But today, both species have declined in range and number as a result of poaching and loss of habitat. Crocodiles are almost confined to the first peneplain in Sri Lanka. They represent an excellent renewable natural resource and, therefore, their conservation can be made much easier if such a resource is used for the benefit of the people who share the land with them (Child, 1987). Unfortunately, crocodiles have a poor image in Sri Lanka. They are considered dangerous, and few would really regret their disappearance. The general public is unaware of the beneficial role played by crocodiles in wetlands. Legislation alone cannot save a species if the public is against its conservation. As Sale (1985) points out, a sound scientific understanding of a natural resource is fundamental to the management of that resource. Nowhere is this more true than in Sri Lanka, where the aims of crocodile management are straightforward preservation of the species within protected areas, with no interest in utilization despite the high economic value of the skin. So far, there has been no ecological study of crocodiles in Sri Lanka. Deraniyagala (1953) provides detailed information on the taxonomy, range and ecology of the two species of crocodile in Sri Lanka, while Whitaker and Whitaker (1979) carried out the first comprehensive survey of crocodiles in Sri Lanka. More recently, Porej (1997) studied the distribution of the two species along the south-western coast of Sri Lanka. An island-wide reassessment of their status was carried out by Santiapillai & de Silva (1998, under review).
Study Area
The study was carried out in Block I of the Ruhuna National Park, in southeast Sri Lanka in the low country Dry Zone (Fig.l). Block I is about 140 sq. km in extent, and is separated from the rest of the park by the Menik Ganga (= river)
in the northeast. The vegetation of the park has been classified by Mueller-Dombois (1972) into three physiognomic categories: (a) forest (with at least 20% of crown biomass above 5m in height), (b) scrub (less than 20% of crown biomass above 5m), and (c) grassland or plains. The dominant forest trees are Manilkara hexandra (palu), Drypetes sepiaria (weera) in well drained soil, and Limonia acidissima (divul) and Salvadora persica (malithan) in poorly drained areas (Balasubramaniam et «/., 1980). The coastal region in Block I has numerous water-holes of varying size and salinity, surrounded by grasslands where the main species are Eragrostis viscosa, Dactyl otaenium aegyptium , Sporobolus diandrus , Echinochloa colonum, Setaria pallidifusca and Alloteropsis cimicina (Balasubramaniam et al. , 1980). The fauna includes threatened species such as the Asian elephant Elephas maximus (E), leopard Panthera pardus (T), sloth bear Ursus ursinus (I), and water buffalo Bubalus buba'lis (V). In addition, there are several herbivores: wild pig Sus scrofa , sambar Cervus unicolor , spotted deer Axis axis and mouse deer Tragulus meminna , which are potential prey species of the crocodiles. Other reptiles include the common monitor lizard Varanus bengalensis, cobra Naja naja, Russell’s viper Daboia russelli. At least three species of sea turtles, the green Chelonia mydas (E), olive Ridley Lepidochelys olivacea (E) and leatherback Dermochelys coriacea (E), nest along the beach (Hewavisenthi, 1990). The most numerous crocodile in Ruhuna National Park is the marsh crocodile or mugger (C. palustris).
Methods
The study on crocodiles was incidental to a much larger study on the mammals of the Ruhuna National Park and was carried out in Block I opportunistically from October 1991 to October 1994. All observations were made from a vehicle, using a pair of 7 x 52 binoculars, from
34
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NATIONAL PARK
Menik
Pannagamuwak~-o
Fig. 1 : Map of Block I of Ruhuna National Park showing the waterholes
0600 to 1 900 hr, during which time most of the water-holes in the park were visited. At every sighting of crocodiles, their number, location, habitat and behaviour were noted. Whenever possible, the species was identified based on field criteria such as the shape of the dorsal osteoderms
— subquadrangular plates transversely sutured to one another in C. palustris , and ovoid and separated by skin in C. porosus (Deraniyagala, 1953). But this was not easy, for as Daniel (1983) points out, the two species are difficult to distinguish in the field. When the two species
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
35
ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NA TIONAL PARK
are in water, they are almost impossible to tell apart. Besides, smaller individuals are difficult to distinguish in the field. Wherever possible, the length of the animals was estimated visually. Four categories were recognized: hatchlings (<0.5 m), juveniles (0. 5-1.0 m), subadults (1. 1-2.0 m), and adults (>2 m). The crocodiles were also monitored from 0600 to 1900 hrs at Buttuwa Wewa during the peak of the dry season in early October 1991, just prior to the northeast monsoon rains, to study their basking behaviour. An attempt was made to estimate the minimum number and density of crocodiles by taking into account the maximum number recorded from each waterhole within a sampling session (7-10 days).
Results
A total of 341 crocodiles (of both species) were recorded in 77 observations, of which 307 sightings were on C. pcilustris and 34 on C.
porosus. Among C. porosus, solitary animals made up 55.8%, while pairs accounted for 13.0% (Fig. 2). The largest group seen during the survey consisted of 44 animals (39, C. pcilustris and 5, C. porosus ), in the Buttuwa reservoir. It is likely that many of the pairs observed in Buttuwa reservoir are adult male and female marsh crocodiles. Of the 22 water-holes that were surveyed, 13 (59%) had only one crocodile (C. pcilustris) each. Crocodiles were observed to move from one waterhole to another during the dry season. As the dry season progresses from May to September, many of the smaller water- holes become bone dry, and the crocodiles (C. pcilustris ), move either to large water-holes such as the Buttuwa Wewa, Wilapala Wewa, Keen Wewa and Katagamuwa tank, or concentrate along the Menik Ganga. In the dry season, one crocodile (C. pcilustris) was observed more than a kilometre from the nearest water- hole in the neighbouring Block II. At the peak of the drought, marsh crocodile numbers along
% of observations
36
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NATIONAL PARK
the banks of Menik ganga can be as high as 35 animals per km. Furthermore, if the drought is prolonged, the Menik ganga mostly dries up, leaving scattered pools of water along the banks. These pools, which are no more than 0.5 m in depth, and a few sq. m in area, may be inhabited by up to 4 marsh crocodiles. The largest estuarine crocodile seen measured about 3.0 m at Diganwala, while the largest marsh crocodile was about 2.5 m at Gonalabba lagoon.
Table 1
SIZE AND COMPOSITION OF MARSH CROCODILES (C. PALUSTRIS) IN RNF (N = 50)
|
size class (m) |
number |
percentage |
category |
|
<0.5 |
22 |
44 |
hatchling |
|
0.5-1 .0 |
3 |
6 |
juvenile |
|
1 .0-2.0 |
12 |
24 |
subadult |
|
>2.0 |
13 |
26 |
adult |
When the maximum number observed in each waterhole within a sampling session (7-10 days) was taken into account, there were 101
marsh crocodiles and 10 estuarine crocodiles in Block I. This amounts to a minimum crude density of 0.72 per sq. km of C. pdlustris , and 0.07 per sq. km of C. porosus in Block I. Among C. palustris, 44% were hatchlings, 6% were juveniles, 24% subadults, while sexually mature animals made up 26% (Table 1). The observed C. porosus were all adults. However, the hatchlings and juveniles taken as C. palustris may have included some C. porosus as well, since these two species are difficult to distinguish in the field from a distance, especially when they are small. Crocodiles could not be sexed in the field.
Crocodiles were seen throughout much of the day, either in water, or basking on land. In Block I, both species were observed basking on the embankment of the reservoirs or on the banks of rivers and streams. The pattern of basking observed at Buttuwa Wewa was generally the same in both species (Fig. 3). The ambient temperature increased as the day progressed, and there was a substantial increase in the number
number of crocodiles
600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800
time
C. palustris
C. porosus
Fig. 3: Pattern of basking activity shown by both species of crocodile
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
37
ECOLOGICAL STUDY OF CROCODILES INRUHUNA NA TIONAL PARK
of C. palustris observed basking, with the maximum number recorded from 1 1 00 to 1 200 hrs. A much smaller number of C. porosus, while showing a similar trend, were observed basking from 0800 hrs, reaching a peak from 1100 to 1500 hrs, and subsequently declining until 1700 hrs. Another behavioural difference that may help in the identification of species in the field concerns basking. Marsh crocodiles were seen basking communally, while estuarine crocodiles were never observed basking together. However, the estuarine crocodile was also seen basking in the company of marsh crocodiles. While basking, one C. palustris was observed defaecating, after which it moved its hind leg over the pile of faeces and shifted its hind parts a little away, then continued basking. Basking crocodiles varied in the length of time they kept their mouths open, the maximum period being 2 hrs.
Both species of crocodile were observed feeding on frogs, which are abundant in almost all the water-holes in Block I. In the dry season, frogs may form a substantial part of the crocodiles’ diet at the smaller water-holes where there are no fish or crustaceans such as crabs or prawns, since the water-holes dry up. However, in the lagoons such as Gonalabba, Uraniya and larger water-holes at Heenwewa, Wilapala Wewa or Palatupana, into which Tilapia were introduced, crocodiles fed largely on such fish. Two marsh crocodiles were seen at night attacking a dead buffalo, in Uraniya plains. Marsh crocodiles were also observed feeding on the carcass of spotted deer, and sambar. In the present study, estuarine crocodiles were not observed feeding on carrion, although it is quite likely that they do. They were not observed doing so, though they were seen at night away from the water-holes. Marsh crocodiles were seen pulling the carcasses either from land or near the water’s edge into water and eating them. Once the carcass is under water, it is out of reach of other scavengers such as jackal ( Canis aureus) and wild pig ( Sus scrofa). In Ruhuna National
Park, crocodiles of both species catch most of their terrestrial prey near the edge of the water. Much of the feeding appears to take place at night.
Hatchling losses can be very high due to predation. In Block I, hatchlings were seen among the roots of Rhizophora trees in the mangroves at Buttuwa, where the prop-roots form a three dimensional mesh, which even some large wading birds find difficult to penetrate. The only birds large enough to attack hatchlings are the black-necked stork ( Ephippiorhynchus asiaticus), lesser adjutant stork ( Leptoptilos javanicus ), spot-billed or grey pelican ( Pelecanus roseus ), and raptors such as crested hawk eagle (Spizaetus cirrhatus), crested serpent eagle ( Spilornis cheela), brahminy kite (Haliastur indus) and white -bellied sea eagle ( Haliaeetus leucogaster). According to Park officials, egg predation by jackal ( Canis aureus ), monitor lizard (Varanus bengalensis) and wild pig can be substantial.
Discussion
In addition to the crocodiles that were observed in Block I of RNP, another 150-200 marsh crocodiles were recorded from the Katagamuwa Wewa (Fauna International Trust, 1993; de Silva, pers. obs.), which lies just outside the northwest comer of Block I (Fig. 1). As these marsh crocodiles regularly move in and out of Block I, they could be considered a part of the crocodile population of Block I. If these crocodiles are also taken into account, then the minimum cmde density of the marsh crocodile in Block I could be as high as 1.99-2.16 animals per sq. km. Marsh crocodiles live in groups, but male estuarine crocodiles, being aggressive and highly territorial, tend to live alone. Furthermore, in estuarine crocodiles, the large territorial males may service a number of females, and thus keep potential competitors at bay (Webb and Manolis, 1989). This may explain the movement of some
38
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
ECOLOGICAL STUDY OF CROCODILES IN RU HUN A NA TIONAL PARK
males far into the interior, away from the estuaries. The number of crocodiles inhabiting a particular waterhole depends not only on the productivity of the waterhole, but also on its size. Usually, large waterholes such as Wilapala Wewa and Buttuwa Wewa support relatively large numbers of crocodiles, in particular C. palustris, all year round.
In general, female crocodiles grow more slowly and reach maturity at a smaller size than males, which continue growing and usually exceed females in maximum size (Ross, 1998). According to Webb and Manolis (1989), in saltwater crocodiles, the females reach sexual maturity at the age of 12 years (2.3 m total length), while the males become sexually mature at the age of 16 years (3.4 m total length). But female marsh crocodiles of 6 years and 8 months of age (2.2 m) have also been known to reach sexual maturity in India (Whitaker and Whitaker, 1989).
As crocodiles cannot maintain a constant body temperature by physiological means, heating and cooling are of particulai importance to them (Webb and Manolis, 1989). Crocodilians have a preferred body temperature of about 30-33°C, and to achieve this temperature range, they move to and fro between water and land. Basking crocodiles usually orient themselves in such a way as to get the maximum exposure to the sun. But as their body gets heated, they reduce the heat uptake by turning and facing the sun, and opening their mouth to cool the brain through evaporative cooling (Webb and Manolis, 1989). Crocodiles in general are very sluggish, and their short periods of activity are usually followed by long periods of inactivity. Wading birds were seen feeding quite close to the basking crocodiles.
Crocodiles are very effective aquatic predators. They are also opportunistic feeders, and catholic in their diet. Most wild crocodiles are known to be attracted to carrion (Webb and Manolis, 1989). In Katagamuwa tank, marsh crocodiles are known to feed communally on fish,
when water is low (Fauna International Trust, 1993). Although game animals fall prey to crocodiles, such predation is unlikely to have a significant effect on their numbers. It is likely that the bulk of the crocodiles’ food in the park consists of fish, frogs and water birds, which are most abundant the year round. As the dry season progresses, many of the water-holes dry up. Fish become concentrated in a few water-holes, which attract crocodiles from other areas. Crocodiles can go for months without feeding (Whitaker and Whitaker, 1989). They are known to feed on a variety of food items that range in size from freshwater mussels to water buffalo (Webb and Manolis, 1989). Their food changes with their size: beginning with aquatic insects, Crustacea, small fish, and as they grow larger, vertebrates such as fish, turtles, birds and mammals (Ross, 1998). Much of the feeding appears nocturnal, for which they are well equipped with good eye sight. The retinal tapetum situated at the back of the eyeball is an image intensifier, allowing crocodiles to see better even in low light intensities (Webb and Manolis, 1989).
The predators on crocodile hatchlings, apart from those observed in Block I, include larger crocodiles, freshwater turtles, large predatory fish and python (Webb & Manolis, 1989). Although crocodiles lay many eggs, only 1 % of the hatchlings may survive to maturity, largely due to predation. The estuarine crocodile also suffers heavy losses when flash floods inundate estuaries where its mound nests are found.
Given the high number of crocodiles, especially marsh crocodiles, present in Block I of RNP, and the fact that these animals maintain genetic exchange with crocodiles from the rest of the Park, it is clear that both species of crocodile present in Block I constitute secure and viable populations. Factors such as desiccation of eggs during severe drought and avian predation on hatchlings appear to help regulate crocodile numbers in the Park.
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
39
ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NA TIONAL PARK
Conservation and Management
There has never been any conservation programme designed specifically for crocodiles in Sri Lanka. While, they are being killed as vermin or poached for meat and skin outside the protected areas, their prospects for long-term survival appear good in a few protected areas such as the Ruhuna National Park in the southeast and the Wilpattu National Park in the northwest. The policy of allowing nature to follow its own course appears to have benefited crocodiles within these protected areas. Crocodiles being large predators, require very large areas of undisturbed wetlands to survive (Ross, 1998). Such areas are becoming increasingly difficult to find in Sri Lanka, as a result of the increase of its human population, currently estimated to be over 18 million. Therefore, protected areas appear to be the last refuge for wildlife. There have been no recent reports of crocodiles being poached within the Park, although several were killed outside.
The approach to management of crocodiles in the park is therefore a conservative one, in that the crocodile habitats are secure and remote from centres of high human population. So far, management measures have boosted the numbers of the crocodiles inside RNP. The crocodile, being an exceptionally adaptable predator, is able to survive on a broad spectrum of prey species. So the emphasis in crocodile conservation policy
Refer
Baker, S. W.H. ( 1 853): The Rifle and the Hound in Ceylon.
Repr. 1970. Tisara Prakasakyo, Dehiwela. Balasubramaniam, S., C. Santiapillai & M.R. Chambers (1980): Seasonal shifts in the pattern of habitat utilization by the spotted deer ( Axis Erxleben, 1 777) in the Ruhuna National Park, Sri Lanka. Spixiana. 3: 157-166.
Bellairs, A. d’A. (1987): The Crocodilia. 5-7. In: (eds.) G.J.W. Webb, S.C. Manolis, & PJ. Whitehead. Wildlife Management: Crocodiles and Alligators. Surrey Beatty & Sons, Chipping Norton, Australia. Child, G. F. T. ( 1 987): The management of crocodiles in
must be on maintaining a variety of prey, and preventing the pollution and destruction of the Park’s wetlands. The national parks, however, remote from human population centres, are still prone to environmental disturbances outside their boundaries.
The crocodile is well adapted to respond to a “sanctuary strategy”. There are good grounds to believe that it will increase in number under protection, which is by far easier, cheaper and more likely to be successful, than re-introduction. Local people strongly object to the translocation of a potentially dangerous predator such as the crocodile, to their neighbourhood. Law enforcement will become ineffective in the face of public hostility to crocodiles. The dissemination of factual information on crocodiles and their role in the ecosystem may help change the people’s attitude.
In the final analysis, the survival of crocodiles is intimately linked with their acceptance by local people and the attitude of their politicians. What is needed is the widest possible acceptance of crocodiles as a renew able natural resource. Their conservation can be made easier, if this resource is used for the benefit of the people who share the land with them (Child, 1987). If crocodiles are properly managed, either in farms or as wild populations, they can become a considerable economic asset to the countries that contain them (Bellairs, 1987).
E N C E S
Zimbabwe. 49-62. In: (eds.) G.J.W. Webb, S.C. Manolis & P.J. Whitehead. Wildlife Management: Crocodiles and Alligators. Surrey Beatty & Sons, Chipping Norton, Australia.
Daniel, J.C. (1983): The Book of Indian Reptiles.Bombay Natural History Society, Bombay.
Deraniyagala, P.E.P. ( 1 953): A Coloured Atlas of some Vertebrates from Ceylon. The Ceylon Government Press, Colombo.
Fauna International Trust. (1993): Yala National Park.
Aitken Spence Printing (Pvt.) Ltd. Colombo. Groombridge, B.(ed.). (1993): 1994 IUCN Red List of
40
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
ECOLOGICAL STUDY OF CROCODILES IN RUHUNA NA TIONAL PARK
Threatened Animals. IUCN Gland, Switzerland.
Hennessey. D.J.G. (1949): Green Aisles: A story of the jungles of Ceylon. Colombo Book Centre, Colombo.
Hewavisenthi, S. ( 1 990): Exploitation of marine turtles in Sri Lanka: historic background and the present status. Marine Turtle Newsletter 48: 14-19.
Mueller-Dombois, D. (1972): Crown distortion and elephant distribution in the woody vegetation of Ruhuna National Park, Ceylon. Ecology. 53: 208-226.
Porej, D. (1997): Crocodile Survey and Public Relations Program. Crocodile Specialist Group Newsletter. 16(3): 910.
Ross, J.P. (ed.) (1998): Crocodiles. Status Survey and Conservation Action Plan. 2nd edition. 1UCN/SSC Crocodile Specialist Group, IUCN, Gland, Switzerland.
Santiapillai, C. & M. de Silva ( 1 998): Status of Crocodiles in Sri Lanka, (under review).
Sale, J. B. H (1985): Wildlife Research in the Indomalayan Realm. 1 37-149. In: (ed.) J.W. Thorsell. Conser\>ing
Asia’s Natural Heritage: The planning and Management of Protected Areas in the Indomalayan Realm. IUCN Gland, Switzerland.
Tennent, Sir. .1 .E. ( 1 859): Ceylon: an account of the island physical, historical and topographical, with notes on its natural history, antiquities and productions. 6th edn. Tisara Prakasakyo, Dehiwela, Sri Lanka.
Webb, G. & C. Manolis ( 1 989): Crocodiles of Australia. Reed Books, Australia.
Whitaker, R. &Z. Whitaker (1979): Preliminary crocodile survey — Sri Lanka. J. Bombay nat. Hist. Soc. 76: 66-85.
Whitaker, R. (1987): The Management ofCrocodihans in India. 63-72. In: (eds.) G.J.W. Webb. S.C. Manolis & P.J. Whitehead. Wildlife Management Crocodiles and Alligators. Surrey Beatty & Sons. Chipping Norton, Australia.
Whitaker, R. & Z. Whitaker (1989): Ecology of the Mugger Crocodile. 276-296. In: Crocodiles: their ecology, management, and conservation. IUCN Gland, Switzerland.
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
41
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MACAQUES {MAC AC A SILENUS) IN THE WILD1
Ajith Kumar2 (With three text-figures)
Key words: reproductive suppression, sexual swelling, Maccica silenus , mounting frequency
Adult female lion-tailed macaques often harass sexually interacting adult male and female members of the group. The extent of harassment and its implication for reproduction by females was studied in a group in the Anaimalai (presently Indira Gandhi) Wildlife Sanctuary, Tamil Nadu, India. Nearly 1 560 hours of observation were made on the same group during nine months in 1979-80 and 15 months in 1982-84. A total of 577 sexual interactions between single adult male and females were recorded. Most of the sexual mountings occurred when the females had sexual swelling with a peak 2-4 days prior to deflation of the swelling. Most of the harassment was by females with sexual swelling. Harassment decreased the probability of mating taking place once a sexual interaction had been initiated (from 0.582 to 0.07). Aggressive harassment significantly reduced the duration of mating (from 9.12 secs to 6.16 secs), and thus probably prevented ejaculation. The percentage of sexual interactions that were harassed increased with the number of females with sexual swelling. Postponement of conception due to harassment might be a major reason for the absence of a synchrony in conceptions and births similar to that seen in sexual swelling soon after the summer amenorrhea. Sexual harassment is unlikely to serve as a behavioural means of population regulation. This is because fewer females show sexual swelling as the group becomes larger, probably due to increasing competition for food resources. The major reason for the occurrence of sexual harassment in the lion-tailed macaque might be competition among females for mating. This competition results from a high synchrony in sexual swelling among the females, the tendency for groups to have only one adult male, a high female to male (5:1) ratio, and multiple mount pattern in the male.
Introduction
Reproductive suppression of ovulating females occurs in some primates. In Theropithecus gelada, females actively disrupt each other’s copulation (Mori, 1979). In the same species anovulatory cycles and premature termination of menstrual cycles and implantation occur in low ranking females from social stress due to harassment by high ranking females (Dunbar, 1980). Reproductive suppression from social stress also occurs in Papio cynocephalus (Wasser, 1983). In captivity, female rhesus monkeys could be prevented from mating by
'Accepted June, 1998
:Salim Ali Centre for Ornithology and Natural History Ana ikatti, Coimbatore 641 108,
Tamil Nadu, India.
aggression from high ranking females (Keveme, 1983). Reproductive suppression of ovulating females has also been demonstrated in captive Miopithecus talapoin (Abbot et al. , 1986). In marmoset monkeys ( Callithrix jacchus) ovulation by subordinate females is physio- logically suppressed by the mere presence of the dominant females (Abbot, 1988).
Lion-tailed macaque, Confined to the rain forests of the Western Ghats of South India, mostly live in one male units with a mean group size of 18-20 animals (Kumar, 1995a). The reproductive biology is characterized by a high sex ratio in favour of females ( 1 :5), a conspicuous sexual swelling phase to which compulatory mountings are mostly confined, and a low birth rate (0.30/female year) compared to other macaques (Kumar 1987, 1995a). There is also a
42
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1). APR. 2000
SEXUAL HARASSMENT AMONG FEMALE LION- TAILED MA CA QUES
high degree of synchrony in the incidence of sexual swelling among the females. Harassment of the mating pair by others, especially by adult females, is frequent. This study examines the extent of harassment of matings pairs and its implication for reproduction by the females. Whether such harassment could play a population regulatory role is also discussed, since birth rate has been found to decrease with increasing group size (Kumar, 1995b).
Methods
The analysis is based primarily on data collected during an ecological study on one group in the Anaimalai (presently Indira Gandhi) Wildlife Sanctuary, Tamil Nadu State, from March 1979 to March 1980, and from December 1982 to March 1984. The group was located in Varagaliyar shola, about 25 km south of Top Slip, the Sanctuary headquarters. Varagaliyar shola is about 20 sq. km in area and is the largest of the rain forest fragments in the Sanctuary. This shola had five or six groups of lion-tailed macaque. The main study group had only one adult male during both the study periods. There was no
Table 1
COMPOSITION OF THE MAIN STUDY GROUP IN THE INDIRA GANDHI WILDLIFE SANCTUARY IN 1979-80 AND 1982-84
|
Year |
Adult males |
Subadult males |
Adult females |
Immatures |
Total |
|
Jan 1979 |
1 |
0 |
5 |
6 |
12 |
|
Mar 1980 |
1 |
0 |
5 |
9 |
15 |
|
Dec 1982 |
1 |
1 |
6 |
9 |
17 |
|
Mar 1984 |
1 |
1 |
9 |
12 |
23 |
subadult male in 1979-80, and one in 1982-84. The number of adult females varied from 5 in 1979-80 to 9 in 1982-84 (Table 1).
Data on the incidence and duration of sexual cycles come from records on the sexual status (presence or absence of swelling) of
females in the study group. These records were made during five to eight days of dawn to dusk observation of the group every month, and at least once in a week during the remaining part of the month. All sexual interactions between the adult male and females were recorded ad libitum during dawn to dusk observation, along with the sexual status of the female. The copulatory calls of the females (see below), given during more than 80% of the sexual mounting and audible up to 75 m, was used as an indicator of mounting. Mounting frequency/hour was estimated for each day by dividing the number of mountings (seen and heard) by the number of hours of observation. Only days with dawn to dusk observation were selected for analyses, since mounting showed a strong diurnal variation. Five to eight days of such observations were earned out each month between March 1979 and January 1980 (except for July and August when no data was collected) and again between December 1982 and February 1984 (except for January and February 1984 when only two days of observations were done each month). A total of 631 hours of ad libitum records were made in nine months in 1979-80 and 937 hours in 15 months in 1982-84. Besides the study group, six other groups were monitored at intervals of 30-40 days in 1979-80 and 1982- 84. Data on seasonality of births were taken from these groups (see Kumar, 1987).
Results
Female Sexual Cycle: The female sexual cycle in the lion- tailed macaque is characterized by the cyclical appearance of sexual swelling in the perineal region and at the base of the tail which is conspicuous (Fooden, 1975). The swelling phase had a mean length of 14.1 days (range 8-19 days, n=7) and the non-swelling phase had a mean length of 16.4 days (range 6- 25, n=7). The combined duration of these phases gave a mean cycle length of 30.5 days. More than 80% of the mountings by the adult male occurred
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
43
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MA CA QUES
Fig. 1 : Mounting frequency (per hour) by the adult male on successive days of a sexual swelling cycle of a female: mean for six sexual cycles. The sexual cycles were aligned by the day on which the swellings
disappeared (day 0).
when the female had sexual swelling. Nearly 84% of these mountings were accompanied by copulatory calls of the females, compared to only 9.1% in the case of females without swelling (x2 = 24.9, df=l,/?<0.001 ). The mounting frequency started to increase 3 to 4 days before the appearance of the swelling and reached a peak (of about 3/hour) four days prior to its disappearance. It then dropped abruptly almost to zero on the last day of swelling (Fig. 1). The interval between the appearance of the swelling and peak sexual activity varied from 10 to 15 days, with a mean of 12.2 days (n=6).
When data from 1979-80 and 1982-84 were combined, swellings were seen in the study group m all months of the year except March and April. In May, swelling was seen only in the last week in 1979 and none in 1983 (Fig. 2). Although there are no systematic data from the other groups, no swellings were seen in them during March-May of 1979 and 1983. It appears.
therefore, that there is a summer amenorrhea in the lion-tailed macaque in the months of March and April, probably extending to May. There was a synchrony of sexual cycles in the study group soon after the first cycle following the summer amenorrhea (Fig. 2). In 1979, the sexual cycle of two females started in the last week of May, and in June all the five females of the group had sexual cycles. The sexual cycle of two subadult females started only in September-October. All the four adult females which showed swelling in 1982-83 did so in synchrony in October 1983, one sexual cycle after the first cycle of the season. (Four of the remaining five females were in post- partum amenorrhea. The fifth, the oldest female of the group, did not show swelling in 1982-84). The cycle of the subadult female started only one month later.
Sexual Harassment: Sexual harassment consisted of activities by members of the group that apparently interfered with sexual
44
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY. 97(1), APR. 2000
SEXUAL HARASSMENT AMONG FEMALE LION- TAILED MA CA QUES
Months (1979-80)
Months (1983-84)
| | One sexual swelling cycle | Sexual swellings leading to conception
Fig. 2: The distribution of sexual cycles and conceptions in the adult females of the study group
in 1970-80 and 1982-84.
interactions between adult male and female. Such interference occurred in 12.8% of the 577 sexual interactions observed. Interference occurred at the premounting stage (i.e. after the initiation of sexual interaction but before mounting) or at the mounting stage. Most of the interference were at the latter stage (70.3%).
Out of 74 harassments recorded, 23.0% were by infants and juveniles. These occurred mostly at the mounting stage, and consisted of rushing to the mating pair, and then moving about rapidly in short arcs about 2-3 m away (with tail-wagging and uttering ‘ uh uh ’ sounds)
until the mounting was over. Mountings involving females with and without sexual swellings were equally harassed by the immatures (Fisher exact test p= 0.33). Moreover, mounting did not appear to discontinue as a result of such harassment.
Harassment by the subadult and adult females was related to the sexual status of the female interacting with the male. In 1982-84. 11.9% of the 270 sexual interactions involving females with swelling were harassed by other adult females, while none of the 69 mountings involving females without swelling were
JOURNAL BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
45
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MACAQUES
harassed (%2=7.7, df=l, /?<0.01). In 1979-80, 13.1% of the 145 sexual interactions involving females with swelling were harassed by other adult females as opposed to only 2.2% of 90 sexual interactions involving female without sexual swelling (%2=6.8, df=l, /?<0.01). About 5.2% of the sexual interactions were harassed by the subadult and adult females at the pre- mounting stage and a further 12.1% at the mounting stage.
Harassment at the pre-mounting stage consisted of a female presenting to the adult male while another female was presenting, often between the male and the first female. Sometimes a female rushed to a presenting female with aggressive calls and chased it away from the male or physically prevented the male from mounting by pulling it by the tail or by standing in the way. Harassment at the premounting stage occasionally resulted in the redirection of mounting to the harasser (21.4%). More often it prevented mounting from taking place. The percentage of sexual initiations which ended in mounting when harassed by adult females (7.0%) was significantly lower than those which were not harassed (58.2%, %2=12.0, df=l, /?<0.001).
Harassment at the mounting stage consisted of rushing to the pair with growls, and chasing and often physically attacking the female. Presenting in front of the mounted pair was also seen. Mounting of the harasser soon after mounting the harassed female occurred in 1 1 . 1 % of the cases. When harassment was overtly aggressive the harassed female often ran or jumped away before the male had dismounted. Significantly fewer of the harassed mountings were accompanied by copulatory calls (63.3%) than those which were not harassed (83.6%, X2=4.6, df=l, p<0.05). Harassed mountings had a shorter duration (mean=7.75 secs, s.e=0.89, n=12), than normal mountings (mean=9. 12 secs, s.e=0.35, n=95). However, duration of only those which were aggressively harassed (mean=6.16 secs. s.e=0.72, n=9) was significantly shorter
(/-test, t= 2.6, p< 0.05).
In short, harassment (a) was mostly by adult females with sexual swelling; (b) was targeted at females with sexual swelling (c) drastically decreased the probability of mounting taking place after the initiations of a sexual interaction, from 0.582 to 0.07; (d) caused a premature termination of mounting and thus probably prevented ejaculation; and (e) redirected mounting from the harassed to the harasser.
Harassment and Synchrony in Sexual Swelling: The frequency of harassment varied with the number of females with swelling. At the pre-mounting stage, 1.3% of the sexual interactions were harassed with two females with swelling and 13.7% with four such females (X2=14.5, df=3, /?<0.001, Table 2). Harassment at the mounting stage also increased with the number of females with swelling in the group, although the difference was not significant (X2=5.09, df=3, /?>0.10). Harassment at the mounting stage was significantly more frequent when there were three females with swelling (33.3%) compared to when there was only one (7.3%, Fisher exact test, p=0.04).
Table 2
PERCENTAGE OF SEXUAL INTERACTIONS, HARASSED AT THE PREMOUNTING AND MOUNTING STAGES BY ADULT FEMALES, AND ESTIMATED PERCENTAGE OF MATING CURTAILED
|
Number of females with swelling |
Sexual interactions seen |
% harassed premount mount stage |
% harassed mounting stage |
|
0 |
69 |
0 |
0 |
|
1 |
108 |
1.9 |
7.3 |
|
2 |
75 |
1.3 |
14.3 |
|
3 |
14 |
7.1 |
33.3 |
|
4 |
73 |
13.7 |
1 1.6 |
The frequency of mounting by the male showed significant differences between days, depending on the number of females with swelling. (Kruskal-Wallis one-way analysis of variance (K-W test), x2=13.4,p<0.005. Table 3). However, it did not increase in proportion to the
46
JOURNAL. BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MACAQUES
Table 3
MOUNTING FREQUENCY (PER HOUR) BY THE ADULT MALE AND SUBADULT MALE WHEN THERE WERE 0 TO 4 FEMALES WITHSEXUAL SWELLING IN THE GROUP
Number of females with swelling
|
0 |
1 |
2 |
3 |
4 |
||
|
Adult male |
Mean |
0.09 |
0.42 |
1.66 |
1.37 |
1.53 |
|
Min. |
0.00 |
0.00 |
1.14 |
0.27 |
1.24 |
|
|
Max. |
2.50 |
1.24 |
2.53 |
2.45 |
1.90 |
|
|
Subadult |
Mean |
0.04 |
0.04 |
0.23 |
0.30 |
0.22 |
|
Male |
Min. |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
|
Max. |
1.50 |
0.10 |
0.38 |
0.82 |
0.36 |
number of females with swelling, but appeared to reach a plateau when there were two females with swelling. The single subadult male in the group in 1982-84 had a mating frequency that was considerably lower than that of the adult male, but seemed to increase as the number of females with swelling increased (Table 3). However, the duration of mounting was considerably shorter for the subadult male (often less than 5 secs), and also did not show the characteristic multiple mount pattern of the adult male.
Consequences of Harassment: If harass- ment significantly reduces the frequency of ejaculatory mating, this could result in a reduction in the chances of conception by female. This is particularly so if harassment is asymmetrically distributed among the females, for example due to social dominance. Dominance interactions were relatively few and occurred mainly on major feeding trees when visibility was poor. As a result, the dominance hierarchy of females in the main study group was not precisely known. Moreover, it was often impossible to identify the females because of the speed with which harassments occurred and poor visibility. Therefore, the reproductive consequences of harassment was examined indirectly. The distribution of conceptions and births in the study group was used to test whether females were less likely conceive when there were more than one female with swelling. If this is so, then
conceptions and births would not show a synchrony similar to that shown by sexual swelling, but would be more evenly spread out across the months.
The date of births in the group during the study period were known. For these, the months of conception were estimated using a gestation period of 172 days (Lindburg and Lasley. 1985). Conceptions did not have a peak corresponding to that of sexual swelling at the beginning of the season (Fig. 1). Of the five females which had swellings in June 1979, only one conceived during that month. There were no data on sexual cycles in July and August, but only one each of four remaining females conceived in July and August. The cycles of the remaining two females continued in synchrony until one conceived in December. Since the second study ended before the births from the 1983-84 mating season (September 1983 to February 1984), stoppage of cycling by females was taken as indicating conception. Two females which showed swelling in September 1 983 did so again in October, when the four females which showed sexual swelling during that mating season, did so in synchrony. The cycle of only one stopped after that month. The remaining three females showed swelling in November (along with a subadult female), but only two conceptions occurred. The cycle of the remaining adult female continued until December 1983. The subadult female’s cycle continued until the end of the field study in February 1984.
Population regulation: Sexual harassment could potentially play a population regulatory role since the number of females that postpone conception, especially to the next reproductive year, could increase with group size. If this is the case, then the births in the larger groups should be more dispersed among the months. This was tested with data on births from the mam study group and six other groups that were periodically monitored. The seven groups were divided into two group size classes (12-18 and
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
47
SEXUAL HARASSMENT AMONG FEMALE LION - TAILED MA CA QUES
Months
Months
Fig. 3: The distribution of births in two group-size classes, 12-18 (above) and 19-28 (below).
Each square represents one birth.
19-28) based on the mean group size during the study period (Fig. 3). Both the classes had the same mean birth date (Caughley 1977), June 15, but the coefficient of variation for the smaller class (205.0%) was nearly twice that of the larger class (112.2%). Thus, contrary to what was expected, births in the smaller groups were more dispersed through the year than the larger groups. It is also noteworthy that the main study group had a shorter mating season in 1983-84 when the group size was 17, compared to that in 1979- 80 when the group size was 12 (Fig. 2).
Discussion
Sexual harassment by adult females probably occurs as a consequence of the high synchrony of sexual swelling among the females of a group, a high female/male ratio (5:1), and the tendency for the groups to be one-male units. These could lead to considerable sexual competition among the females. The multiple- mounting pattern of the male (Fooden, 1975; Kumar and Kurup, 1985) might also impose constraints on the mating potential of the male.
48
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1). APR. 2000
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MACAQUES
This competition could increase with the number of females in sexual synchrony. The extent to which harassment could affect the probability of conception would depend on the stage of the sexual cycle in relation to ovulation and the degree of asymmetry in the direction of harassment. Even though the frequency of mounting in the first week of swelling was highly variable even when there was only one sexually active female (Kumar, 1987), the peak between 2-5 days prior to deflation indicates that mountings at this stage of the cycle might be critical to conception. Thus, harassment in the last week of swelling could severely affect the probability of conception. At extreme asymmetry, in the direction of harassment, all the curtailed mountings could be of the low-ranking females. In addition, if harassments between females of different ranks differed in aggressiveness (for example, those by dominant females being more aggressive) mounting by the low-ranking females could be curtailed more than those of dominant females since aggressive harassments were more effective in curtailing mounting.
Birth rate in the lion-tailed macaques is a decreasing function of group size and the number of adult females in the group (Kumar, 1995b). Sexual harassment could lead to such an effect and thus serve as a population regulatory factor, if two conditions are met: i) the proportion of females coming into sexual synchrony during the mating season should be constant with group size, so that their absolute number would increase with group size; and ii) groups should be either one male units irrespective of group size, or when there is more than one male, only one of them is reproductively active during all the phases of the sexual cycle of the females. If these conditions are met, then the mating season should be more prolonged with increasing group size, as more females postpone conception. Therefore, births should be more dispersed in the larger groups and have a higher coefficient of variation. The limited data on the main study group shows that
the mating season gets shorter, and not longer as predicted, as the group becomes larger. Also, contrary to the second prediction, births were relatively less dispersed in the larger groups than in the smaller groups. This was probably because of the violation of the above two conditions.
It is known that females do not ovulate until they reach a particular nutritional level (Frisch and McArthur 1974). Since resource competition increases with group size, it could be expected that the number of females able to build up sufficient nutritional reserves, so as to start ovulation, would decrease with increasing group size. There is no systematic data on the number of females coming into sexual cycle as a function of group size. In one large group with more than 25 members, which was regularly censused, not more than 4 of the 1 2 females were ever seen with sexual swelling on the same day. Since births in the larger groups were few, it was unlikely that other females were in post-paitum amenorrhea. Moreover, although the group was seen almost every month in 1979, swellings were seen only in June and November-December (with 2 and 3-4 females respectively).
In addition, the number of adult and subadult males increase with group size (Kumar, 1987). No data was collected on the sexual behaviour of males in multi-male groups. The limited data on sexual behaviour of the subadult male of the study group indicate that mounting frequency of subadult males increased with the number of sexually active females in the group (Table 3). Even if mountings by the subadult male (and probably low ranking adult males of multi- male groups) are confined to the early follicular and luteal phases of the cycle, such mountings could significantly reduce the sexual competition between the females with overlapping sexual cycles. As a result, mountings by the adult male (or dominant male in multi-male groups), even if only confined to the late follicular phase, could be less harassed by other females which are in other phases of the cycle.
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY. 97(1), APR. 2000
49
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MACAQUES
The short birth season in the larger groups might be, therefore, a cumulative function of (a) fewer females coming into sexual cycles in each season which in itself would significantly reduce female sexual competition and (b) more adult males in the larger groups which would further reduce female sexual competition. Thus, it appears unlikely that sexual harassment could be a population regulatory factor, in the small and large groups. In the former, in spite of female sexual competition (resulting from one male and several sexually active females), postponement of conception is expected to be only within the mating season. In the larger groups, on the other hand, fewer females ovulate in the mating season. It is possible that ovulating females are still sufficiently numerous in the medium sized one male groups, so that sexual competition could be high. A few females would be forced to postpone conception to the next mating season thus leading to/reproductive suppression.
Postponement of conception within the season could serve indirectly as a population
R E FE
Abbott, D.H. (1988): Social suppression of reproduction in primates. In: Comparative Socioecology: The Behavioural Ecology and Humans and Other Animals (Eds. V. Standen and R.A. Foely), pp. 285-304. Abbot. D.H., E.B. Keverne, G.F. Moore & U. YoDYiNGYARd (1986): Social suppression of reproduction in subordinate talapoin monkeys, Miopithecus talapoin. In: Primate Ontogeny, Cognition and Reproductive Behaviour (Eds. J.G. Else and P.C. Lee), Cambridge University Press, Cambridge. Pp 329-34 1 .
Caughley, G. ( 1 975): Analysis of Vertebrate Populations. Wiley, Chichester.
Drickamer. L.C. (1974): A ten-year summary of reproductive data for free-ranging Macaca mulatto. Folia Primatologica 21: 61-80.
Dunbar, R.I.M. (1980): Determinants and evolutionary consequences of dominance among female gelada baboons. Behavioural Ecology and Sociobiology 7: 253-265.
Fooden, .1. (1975): Taxonomy and Evolution of Liontai 1 and Pigtail Macaques (Primates : Cercopithecidae).
regulatory factor. Increased mortality of infants born in late season has been reported; for example in M. mulatto (Drickammer, 1974) and in A. palliatta (Froelich et al., 1981). Since postponement of conception is expected to increase with group size within the small to medium-size range, late season births and infant mortality could be expected to increase with group size within that range.
Acknowledgements
I am grateful to Tamil Nadu Forest Department for facilities provided in the field; to Zoological Survey of India for funding in 1 977- 80, to Wenner-Gren Foundation, L.S.B. Leaky Foundations, WWF-US, WWF-India, and Cambridge Commonwealth Trust for grants in 1981-87; and to Wildlife Conservation Society, New York, for grants in 1987-89. Earlier drafts of this paper greatly benefited from comments by Drs. D.J. Olivers, E.L. Bennet, J.M.Y. Robertson, E. Barret, L. Fuller, E.B. Keverne, and G.W. Norton.
e n c e s
Bibliotheca Primatologica 10. Basel, Karger. Frisch, R.E. & E. McArthur (1974): Menstrual cycles: fatness as a determinant of minimum weight for the maintenance or onset. Science 185: 949-95 1 Froelich, J.W., Thorington, Jr., & J.S. Otis ( 1 98 1 ): The demography of howler monkeys ( Alouatta palliata) on Barro Colorado Island, Panama. International Journal of Primatology 2: 207-236.
Keverne. E.B. (1983): Endocrine determinants and constraints on sexual behaviour in monkeys. In: Mate Choice, (Ed. P. Bateson). Cambridge University Press, Cambridge, pp. 407-420.
Kumar, A. (1987): The Ecology and Population Dynamics of the Lion-tailed macaque (Macaca silenus) in South India. Ph.D. Dissertation submitted to the University of Cambridge, U.K.
Kumar, A. (1995a): The life history, ecology, distribution and conservation problems in the wild. In: The Lion- taled Macaque: Population and Habitat Viability Assessment Workshop. Zoo Outreach. Coimbatore, India. Kumar, A., S. Molurand S. Walker (Eds.). Kumar. A. ( 1995b): Birth rate and sun ival in relation to
50
JOURNAL. BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
SEXUAL HARASSMENT AMONG FEMALE LION-TAILED MACAQUES
group size in the lion-tailed macaque, Macaco silenus. Primates. 36: 1-9.
Kumar, A. & G.U. Kurup (1 985): Sexual behaviour of the Lion-tailed macaque, Macaca silenus. In: The Lion- tailed Macaque: Status and Conservation (Ed. P.G. Heltne), pp, 1 09- 1 30, Alan R. Liss, New York. Lindburg, D.G. & B.L. Lasely (1985): Strategies of optimising the reproductive potential of lion-tailed macaque colonies in captivity, lit: The Lion-tailed
Macaque: Status and Conservation (Ed. P.G. Heltne). pp. 34-56. Alan R. Liss. New York.
Mori. A. (1979): Analysis of population changes by body weight in the Koshima troop of Japanese monkeys. Primates 20: 371-397.
Wasser, S.K. (1983): Reproductive competition and cooperation among female yellow baboons. In: Social Behaviour of Female Vertebrates. (Ed. S.K. Wasser), Academic Press, New York. pp. 349-390.
JOURNAL BOMBAY NATURAL HISTORY SOCIETY. 97(1). APR. 2000
51
SEASONAL CHANGES OF TROPICAL FOREST BIRDS IN THE SOUTHERN WESTERN GHATS1
E.A. Jayson2 and D.N. Mathew3 ( With seven text-figures)
Key words: Seasonal changes, forest birds, Western Ghats, Kerala, India
A study was carried out in the tropical forests of Silent Valley and Mukkali in the Western Ghats, Kerala from May 1988 to April 1993, to elucidate the seasonal changes of bird communities in the two vegetation types. Abundance and density of birds were assessed, using variable width line transects each month. The highest populations, 609-1 ,892 /km2 were found from December- April. Total number, monthly density and species richness of birds declined during monsoon. When compared, abundance and density of birds, observed in the evergreen forests was more (929 /km2) than in moist deciduous forests (747 /km2). However, bird population showed more stability in the moist deciduous forests. Except for two summers, significantly higher bird density was obtained in the evergreen forests during summer (1,074 /km2). Bird species diversity was high during summer and low in monsoon in both the vegetation types. A direct negative relationship was also obtained between the rainfall, total number of birds, bird density and total number of bird species in the evergreen forests. Significant positive correlation was obtained between the temperature and bird community parameters in the evergreen forests, whereas rainfall and temperature showed no significant effect on the bird community in the tropical moist deciduous forests.
Introduction
Tropical forests support a stable population of birds m all seasons, whereas marked variations have been noted in temperate forests (Wright, 1970; Kricher, 1975). Seasonal variation of forest birds has been reported from several other countries (Anderson, 1972, Morrison etal. 1980, Pyke, 1984). No information, however, is available on the seasonal trends of tropical forest birds of the Western Ghats of South India. An attempt has been made to monitor the seasonal changes of bird communities in the tropical evergreen forests and the southern secondary moist mixed deciduous forest of Kerala. Birds of Kerala have been studied by Ali (1969), Ali and
'Accepted April, 1999 ;Division of Wildlife Biology Kerala Forest Research Institute Peechi 680 653, Kerala, India.
■ Department of Zoology
University of Calicut, Calicut University P.O,
Kerala, India.
Ripley (1983a) and All and Ripley (1983b) earlier. Ecological studies were carried out at Silent Valley by Balagopalan (1990) and Balasubramanian (1990). Ramakrishnan (1983) studied the ecology of birds in the Malabar forests. Daniels (1989) and Daniels et al. (1990) reported many aspects of birds of the northern Western Ghats.
StudyArea
Location and topography: The study areas, Silent Valley and Mukkali are located in Palakkad dist., Kerala State, between 1 1° 3' and 11° 13' N lat., and between 76° 25' and 76° 35' E long. They lie in the Western Ghats of south India and form part of the Nilgiri Biosphere Reserve (Fig. 1). After evaluating the entire area, two intensive study sites were selected: a tropical evergreen forest, Silent Valley, and a moist deciduous forest at Mukkali. The elevation of the study sites varied from 500 m to 1500 m above msl. The topography is undulating. According
52
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
53
Fig. 1 : Location of the study area
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
to Udvardy (1975), Silent Valley and Mukkali fall under the Malabar Rain Forest Realm. These two study sites are at a distance of about 20 km with a difference in elevation of 400 m between them.
Climate: There are two distinct seasons in the study area, monsoon starting from the end of May, up to mid-November, and the dry summer from December to April. Mukkali (4,227 mm/year) receives less rainfall compared to Silent Valley (5,096 mm/year). Heavy rainfall, 803 mm to 2,043 mm/month, was recorded at Silent Valley. From December to March, there is practically no rain. Temperature ranged froml9°C to 22°C at Silent Valley and 21°C to 27°C at Mukkali.
Vegetation: A total of 966 species of angiosperms belonging to 559 genera and 134 families were recorded from Silent Valley and adjacent areas (Manilal, 1988). Pascal (1988) described the vegetation of the area as Cullenia exarillata-Mesua ferrea-Palaquium ellipticum type. It is characterised by the abundance of these three species, which may constitute about 80% of the large trees. Degraded areas and other vegetation types like grasslands are also common here. Vegetation of Mukkali is southern secondary moist mixed deciduous forest (Champion and Seth, 1968), degraded to some extent.
Methods
After considering all the available techniques, variable width line transect method described by Burnham et al. (1981) was adopted. Whenever a bird was spotted, it was identified up to the species level and details like the number of birds, perpendicular distance from the transect, height at which it is located in the canopy and habitat features were noted. Two line transects were selected, one at Silent Valley and the other at Mukkali; each transect was 4 km in length. The first transect covered evergreen forests and
the second habitats like moist deciduous forests, rocky patches and fire burned moist deciduous forests. Census was started 30 minutes after sunrise in all the months. Transects were covered at a uniform speed. No census was done on days with very heavy rain and fog.
Two samples were collected from each area in a month. The second sample was started from the end of the first sample. A total of 1 50 samples were collected between May 1988 and 1993. No systematic data was collected on nocturnal birds. All calls were considered as single individuals. Perpendicular distances were measured approximately up to metres. To help distance assessment, known distances were measured and marked on trees using a Range Finder before the census. Abundance of birds in each month obtained from the census was used for analysis. Seasonal index of birds for each month was calculated using Time Series Analysis by the method of Simple Averages (Rao, 1983). The formula used is given below:
Monthly average
Seasonal Index = x 100
Sum of monthly averages
Analysis of variance was employed to find any significant difference existing in the total number of birds among the months. The Fourier Series Method was employed for calculating density from the ungrouped perpendicular distances from the transect. All the assumptions described by Burnham et al. ( 1 98 1 ) were followed during the census. Students ‘t’ test was applied to find out the significant difference in the number of birds between summer and monsoon. Diversity was calculated using Shannon- Wener Index (H - -X (pi In pi) with the program specdivers.bas developed by Ludwig and Reynolds (1988). Spearman Rank Correlation was used to find out the correlation between climatic parameters and bird community parameters.
54
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY. 97(1), APR. 2000
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
Table 1
SEASONAL INDEX OF BIRDS PRESENT IN EACH MONTH AT SILENT VALLEY AND MUKKALI
|
Area |
Months |
|||||||||||
|
.1 |
F |
M |
A |
M |
J |
.1 |
A |
S |
O |
N |
D |
|
|
Silent |
114 |
109 |
88 |
81 |
95 |
54 |
58 |
59 |
119 |
101 |
136 |
153 |
|
Valley Mukkali |
113 |
92 |
131 |
89 |
84 |
113 |
73 |
87 |
116 |
99 |
133 |
70 |
Results
Patterns of change
Monthly variation: During September to February, more birds were present at the Silent Valley compared to the annual average of 100 (Table 1). In Mukkali, higher number than the annual average were observed during the months of January, March, September and November. Highest Seasonal Index (133) was obtained in November. Analysis of variance showed a significant difference in the total number of birds among the months at Silent Valley (F= 6.18; P= 0.01), whereas no significant difference was obtained at Mukkali (F= 1.95; P= 0.08).
Seasonal variation in a year: The total number, monthly density and species richness of birds at Silent Valley and Mukkali declined during monsoon and increased in the dry months (Table 2). No significant difference in total number was obtained between monsoon and summer at Silent Valley and Mukkali (Silent Valley ‘t’=1.63, P=0.14; Mukkali ‘f=0.28, P=0.79). Species like
the black bulbul ( Hypsipetes madagciscariensis ), emerald dove(Chalcophaps indica) and the imperial pigeon ( Ducula badia) were practically absent during monsoon at Silent Valley.
Seasonal change over the years: Total number of birds: Data were pooled into two seasons, monsoon and summer, to find out the seasonal differences in the total number of birds over the years. Chi-square test revealed a significant difference in the number of birds between the seasons at Silent Valley (Table 3). The highest number of birds per month (91) was observed in the 1991 summer and the lowest (53) in the monsoon of 1992. At Mukkali, there was no significant difference among seasons in the total number of birds. Significant difference in the number of birds per month between Silent Valley and Mukkali was observed during three summers. During these seasons, there were more birds at Silent Valley. But during the 1992 summer and monsoon, no significant difference in the number of birds was observed, both at Silent Valley and Mukkali.
Table 2
COMM UNITY PARAMETERS OF BIRDS RECORDED DURING TWO SEASONS (1 988-1993)
|
Area |
Monsoon season |
Summer season |
|
|
No. of birds (mean) |
70.00 (±28.63) |
90.33 (±32.25) |
|
|
Silent Valley |
Density (birds/knr ) |
958. 16 (±478.58) |
1286.17 (±781 .1 8) |
|
Species richness |
28.33 (±6.87) |
43. 16 (±7.00) |
|
|
No. of birds (mean) |
60.67 (±12.61) |
56.5 (±12.91) |
|
|
Mukkali |
Density (birds/knr) |
854.33 (±400.43) |
707.00 (±285.36) |
|
Species richness |
30.67 (±9.35) |
39.17 (±10.23) |
Standard Deviation is in parenthesis
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
55
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
Table 3
MEAN NUMBER OF BIRDS RECORDED PER MONTH IN DIFFERENT SEASONS AT SILENT VALLEY AND MUKKALI
|
Seasons |
Silent Valley |
Mukkali |
Total |
X2 |
P= |
|
Monsoon 1988 |
70 |
76 |
146 |
0.25 |
NS |
|
Summer 1989 |
95 |
52 |
147 |
12.58 |
0.02 |
|
Monsoon 1990 |
74 |
48 |
122 |
5.50 |
0.02 |
|
Summer 1991 |
91 |
50 |
141 |
11.92 |
0.001 |
|
Monsoon 1992 |
53 |
67 |
120 |
1.63 |
NS |
|
Summer 1992 |
83 |
70 |
153 |
1.10 |
NS |
|
Summer 1993 Total X2 P = |
89 555 16.36 0.02 |
59 422 1 1.83 NS |
148 |
6.08 |
0.02 |
NS= Not Significant
Species Richness: There is no significant difference in bird species richness between years
in monsoon (x2=4.26; P=0.05) and summer (X2=8.92; P=0.05) at Silent Valley. But a significant difference was obtained between years in both seasons at Mukkali (Monsoon x 2 =38.97; P=0.001, Summer %2= 14.64; P=0.001).
Density: Significant difference in density was obtained between seasons in different years at Silent Valley and Mukkali. The values for summer and monsoon showed a significant difference (Silent Valley: %2=62.25, P=0.05, df=l; Mukkali: %2=39.33, P=0.05, df=l). Bird density was high during summer, both at Silent Valley and Mukkali. Except for two summers, significantly higher bird density was observed at Silent Valley in summer (Table 4).
Diversity: Variations in the diversity of birds, based on Shannon- Wener diversity index, in different seasons at Silent Valley and Mukkali are given in Table 5. Diversity index showed high values in summer (X=3.12, 11=5) and lower during monsoon (X=2.65, n=4), at Silent Valley and Mukkali (monsoon: X=2.78. n=4 and summer: X=3.14, n=5).
Table 4
SEASONAL VARIATION IN BIRD DENSITY AT SILENT VALLEY AND MUKKALI
|
Seasons |
Density/sq. km |
Mean density |
||||
|
Silent Valley |
Mukkali |
Total |
Mean |
X2 |
P = |
|
|
Monsoon |
1036 |
638 |
1674 |
837 |
94.63 |
0.00 1 |
|
1988 |
(3.23) |
(5.01) |
||||
|
Summer |
2123 |
1662 |
3785 |
1892.5 |
56.15 |
0.001 |
|
1989 |
(2.21) |
(7.72) |
||||
|
Monsoon |
685 |
401 |
1086 |
543 |
74.27 |
0.001 |
|
1990 |
(3.03) |
(7.86) |
||||
|
Summer |
741.4 |
370 |
1 1 1 1 .4 |
555.7 |
124.11 |
0.001 |
|
1991 |
(3.93) |
(14.99) |
||||
|
Monsoon |
493 |
792 |
1285 |
642.5 |
69.57 |
0.001 |
|
1992 |
(9.11) |
(3.06) |
||||
|
Summer |
823 |
757 |
1580 |
790 |
2.76 |
NS |
|
1992 |
(6.03) |
(4.34) |
||||
|
Summer |
608 |
688 |
1296 |
648.0 |
4.94 |
NS |
|
1993 |
(10.91) |
(5.61) |
||||
|
Total |
6509.40 |
5308 |
||||
|
X2 |
1976.52 |
1471.29 |
||||
|
P = |
0.001 |
0.001 |
NS= Not Significant; The values in the brackets denote coefficient of variation of the estimates.
56
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
Factors affecting the seasonal variation Rainfall: A direct relationship was obtained between rainfall and number of birds, density and total number of bird species at Silent Valley. When rainfall increased, all of these three community parameters decreased, and vice versa
(Figs. 2, 3 & 4). At Mukkali also, rainfall had its influence on bird community, but not in the same magnitude as that of Silent Valley (Figs. 5, 6 & 7).
At Silent Valley, significant negative correlation was obtained between the mean of monthly total rainfall (1988-1993) and number
Fig
J FMAMJ JASOND Months
2: Relation between rainfall and number of species at Silent Valley
1400
J FMAMJ JASOND Months
Fig. 3: Relation between rainfall and number of species at Mukkali
Species 19 Rainfall
Species
Rainfall
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
57
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
1600
1400
1200
1000 |
800 75 c
600 c 400 200 0
J FMAMJ JASOND Months
Fig. 4: Relation between rainfall and abundance of birds at Silent Valley
i ou
1400 -1200 -1000
E
800 £
75
600 1 DC
400 200 0
J FMAMJ JASOND Months
Fig. 5: Relation between rainfall and number of birds at Mukkali
Birds
91 Rainfall
Birds
Rainfall
of species in each month (r= -0.731, P= 0.01, n= 12). Significant correlation was also obtained between mean monthly rainfall and total number of birds in each month (r= -0.66, P= 0.05, n= 12). But there was no significant correlation between the density of birds in each month and rainfall (r= -0.45, P= 0.05, n= 12).
At Mukkali, no significant correlation was obtained between monthly rainfall and bird community parameters. Here, monthly rainfall showed negative correlation with the number of bird species (r= -0.41, P= 0.05, n= 12) and there was no significant correlation between monthly rainfall and the total number of birds (r= -0.21,
58
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY. 97(1), APR. 2000
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
3000
1600
J FMAMJ JASOND
Months
Fig. 6: Relation between rainfall and density of birds at Silent Valley
1400
1200
1000
£ 800 »
& 600
J FMAMJ JASOND Months
Fig. 7: Relation between rainfall and density of birds at Mukkali
Density
Rainfall
Density
Rainfall
P= 0.05, n=12) and their density (r= -0.06, P= 0.05, n= 12). This suggests that rainfall does not have any significant effect on the bird community at Mukkali.
Temperature: There was significant positive correlation between temperature and bird
community parameters at Silent Valley. Number of species increased with increase in temperature (Coefficient of correlation r= 0.57, P= 0.05, n= 12). Similarly, total number of birds (r= 0.83, P= 0.001, n= 12) and their density (r= 0.62. P= 0.05, n= 12) showed an upward trend as the
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
59
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
Table 5
SEASONAL VARIATION IN DIVERSITY (H’) AT SILENT VALLEY AND MUKKALI
|
Seasons |
Silent Valley |
Mukkali |
|
Monsoon 1988 |
2.77 |
2.50 |
|
Monsoon 1989 |
2.38 |
2.63 |
|
Monsoon 1990 |
2.70 |
2.85 |
|
Monsoon 1992 |
2.74 |
3.13 |
|
Mean |
2.65 |
2.78 |
|
Summer 1 989 |
3.20 |
2.96 |
|
Summer 1 990 |
3.01 |
2.95 |
|
Summer 1991 |
3.23 |
3.08 |
|
Summer 1 992 |
3.29 |
3.46 |
|
Summer 1993 |
2.88 |
3.25 |
|
Mean |
3.12 |
3.14 |
temperature increased during summer. At Mukkali, no such significant correlation was found (temperature and number of species r= 0.21, P= 0.05, n= 12; temperature and total number of birds r= -0.08, P= 0.05, n= 12).
Discussion
Patterns of change: During monsoon, there was reduction in the number of birds both at Silent Valley and Mukkali. Birds appeared to move locally to avoid the unfavourable climate. Local movements in search of optimum habitats are possible because of the availability of other habitats in the vicinity as the tracts where the study was conducted were fragmented forest patches. Similar trends were reported from the tropical forests of other countries also. Variation in rainfall and soil moisture makes tropical bird fauna seasonal (Greenberg and Gradwohl, 1986). According to them, this is due to the influence of rainfall on phenological patterns of trees, which in turn affect the population trends of arthropods. Karr (1976) also showed the effect of high rainfall on the seasonal patterns of birds.
Higher numbers of birds were recorded during summer in two vegetation types. A greater abundance of birds was found at Silent Valley during summer than at Mukkali. Density of birds
and their diversity indices were also higher for Silent Valley during summer, which can be attributed to the availability of more fruits at Silent Valley during summer. However, at Mukkali, the bird population showed much more stability.
Factors influencing the seasonal variations: Rainfall and temperature were the major factors influencing the abundance of birds at Silent Valley and Mukkali. Price (1979) who worked on the birds of Eastern Ghats also found a similar trend in annual cycles of bird fauna due to changes in rainfall. As mentioned earlier, a few species of birds like the yellowbrowed bulbul ( Hypsipetes indicus ) showed stability in population even in the fluctuating environment. This can be attributed to the resident nature of the species, coupled with its ability to feed on various food types like berries, drupes, nectar, spiders and insects.
Stiles (1978) had also shown that in tropical forests bird communities fluctuated in number as a response to the availability of food and climate changes. The relationship between food resources and bird diversity was also reported by Terborgh (1985). Even though tropical forest birds are considered sedentary, MacArthur (1972) has shown that seasonal movements are fundamental in many species as an adaptive strategy in varied forest habitats. This study also showed that rainfall and temperature influence the tropical evergreen forest bird community, whereas such climatic factors have little effect on birds of moist deciduous forests.
Acknowledgements
Statistical analyses were done with the help of Ms. K.A. Mercey, Asst. Prof., College of Veterinary and Animal Sciences, Mannuthy, Trichur. We thank the field staff of Silent Valley National Park for their help and the Dept, of Environment, Govt, of India for support.
60
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
SEASONAL CHANGES OF TROPICAL FOREST BIRDS
References
Ali, S. (1969): The Birds of Kerala. Oxford University Press, Bombay, pp. 444.
Ali, S. & S.D. Rjpley ( 1 983a): Handbook of the Birds of India and Pakistan. Oxford University Press, New Delhi, pp. 737.
Ali, S. & S.D. Rjpley (1983b): A Pictorial Guide to the Birds of the Indian Subcontinent, Bombay Natural History Society. Bombay, pp. 1 77.
Anderson, S.H. (1972): Seasonal variations in forest birds of Western Oregon, Northwest Science 46(3) : 1 94- 206.
Balagopalan, M. (1990): Soil and plant community relationships in wet evergreen forests of Silent Valley. In: Ecological Studies and Long-term Monitoring of Biological Process in Silent Valley National Park. KFRI Research Report, pp. 1 35-206.
Balasubramanian, K. (1990): Establishment of permanent sample plots for long-term monitoring of ecological process. In : Ecological Studies and Long-term Monitoring of Biological Processes in Silent Valley National Park. KFRI Research Report, pp. 201-231.
Burnham, K.P., D.R. Anderson & J.L. Laake (1981): Line transect estimation of bird population density using a Fourier series. In: Estimating the number of terrestrial birds. Eds. C.J. Ralph and M.J. Scott. Studies in Avian Biology No. 6. Cooper Ornithological Society.
Champion, H.G. & S.K. Seth ( 1 968): A Revised Survey of the Forest Types of India. Govt, of India. 404 p.
Daniels, R.J.R. (1989): A conservation strategy for the birds of the Uttara Kannada District. Ph.D. Thesis. Indian Institute of Science, Bangalore.
Daniels R.J.R, M. Hegde & M. Gadgil (1990): Birds of the man-made ecosystems: the plantations. Proc. Indian Acad. Sci (Anim. Sci.) 99(1): 79-89.
Greenberg, R. & J. Gradwohl (1986): Constant density and stable territoriality in some tropical insectivorous birds. Oecologia (59:61 8-625.
Karr, J.R. ( 1 976): Seasonality, resource availability and community diversity of tropical bird communities.
Amer. Nat. // 0:973-974.
Kricher, J.C. (1975): Diversity in two wintering bird communities: Possible weather effects. Auk 92 (4):! 66-111.
Ludwig, J. A. and J.F. Reynolds (1988): Statistical Ecology, John Wiley and Sons, New York.
MacArthur, R.A. (1972): Geographical Ecology. Harper and Row, New York.
Manilal, K.S. (1988): Flora of Silent Valley Tropical Rainforests of India. The Mathrubhmni (MM) Press, Calicut, pp. 398.
Morrison, M. L.. A. Kimberly & 1. C. Timossi (1980): The structure of a forest bird community during winter and summer Wilson Bull., 98(2): 214-230.
Pascal, J.P. (1 988): Wet Evergreen Forests ofthe Western Ghats of India, Ecology, Structure, Floristic Composition and Succession. Institute Francais de Pondicherry. Pondicherry. 239 p.
Price, T.D. ( 1 979): The seasonality and occurrence of birds in the Eastern Ghats of Andhra Pradesh. J. Bombay nat. Hist. Soc. 76(3):319-422.
Pyke, G.H. (1984): Seasonal patterns of abundance of insectivorous birds and flying insects. Emu 85(1): 34-39.
Ramakrishnan, P. (1983): Environmental Studies on the Birds of Malabar Forest. Ph. D. Dissertation. University of Calicut.
Rao, G.N. (1983): Statistics for Agricultural Sciences. Oxford and IBH Publ. Co. pp 280.
Stiles, F.G. (1978): Temporal organization of flowering among the Humming bird, food plants of a tropical forest. Biotropica 10: 1 94-2 10.
Terborgh, J. (1985): Habitat selection in Amazonian birds In: Habitat selection in birds. Ed. M.L. Cody, Academic Press, New York. 3 1 1 -338.
Udvardy, M.D.R. (1975): A classification of the biogeographical provinces of the world. IUCN Occasional Paper. 18 IUCN. Gland, Morges.
Wright, J.S. (1970): Competition between insectivorous lizards and birds in Central Panama. Amer. ZooL, 19:1 145-1156.
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
61
PLODIA INTERPUNCTELLA (HUBNER) (PHYCITIDAE : LEPIDOPTERA) AS A POTENTIAL PEST OF DRY FRUITS1
S.P. Rad3, H.R. Pajni andNeelima Talwar2
Key words: Plodia interpunctella , dry fruits, susceptibility, weight loss, development
period, moisture content
Relative susceptibility of 1 2 types of dry fruits viz., almond, apricot, cashewnut, chilgoza, coconut, date, fig, hazelnut, mulberry, pista, raisin and walnut and 1 0 varieties of pista procured from Iran i.e. Ebrahimi, Fandoghi, Gholam Rezaia, Jabbary, Kallenghoochi, Momtaz, O’hadi, Rezaia, Shasti and Wahedi to the attack of Plodia interpunctella (H.) has been studied for the first time. The results showed that cashewnut and pista were the most susceptible and date the least. Out of 10 pista varieties, the varieties Rezaia and Wahedi were the most resistant while the cultivars Fandoghi and Momtaz were the most susceptible. The index of susceptibility has been calculated on the basis of weight loss of fruits and development period and progeny of the pest.
Introduction
The Indian meal moth Plodia inteipunctella (Hubner) (Phycitidae : Lepidoptera) is an important pest of stored cereals, legumes and dry fruits. The damage is caused by the larvae: besides consuming the product they also spoil it with their webbings and faecal matter, making it unfit for human consumption. A large number of studies have been made on its general biology. Hoppe (1981), Mbata (1987, 1990) and Stein (1990) studied the development pattern while food preference was studied by Lecato (1976). Observations on oviposition behaviour have been made by Mullen and Arbogast (1977), Mbata (1985, 1990) and Almasi et ah, (1987). Grant (1974), Grant and Brady (1975) and Grant (1976) studied the copulation while Grant (1974), Grant and Brady (1975), Ono (1981) and Rangaswamy ( 1 985) made observations on the role of pheromones. The diapause behaviour has been studied by Bell and Walker (1973) and Bell ( 1 976a, 1 976b). However, only a few dry fruits have been tested as hosts of this pest. Myers (1928) studied the relative preference of the pest for a few dry fruits. Hamlin et al.,{ 1931 ), Simmons ( 1 93 1 ) and William ( 1 964) observed development in some dry fruits and
'Accepted February, 1998 : Department of Zoology, Panjab University,
Chandigarh 160014, India.
'Present Address: 28, Matyer Feeroze Lane,
Caroon Street, Azarbyjan Street, Tehran - Iran 1 3448.
cereals. Mullen and Arbogast (1977) studied oviposition on peanuts and dates while Mbata and Osuji ( 1 983) studied the development in whole and cracked groundnuts.
The present communication deals with the relative susceptibility and extent of damage to 12 dry fruits and 10 varieties of pista, to assess the potential of P. interpunctella (Hubner) as a pest of stored dry fruit.
Material and Methods
Adults of Plodia interpunctella (H.) used in the present study were taken from stock cultures raised in the laboratory from small samples collected from Delhi and Chandigarh. The cultures were maintained on different foods stored in an electric incubator fixed at 30 ± 1° C and 75-85% R.H. The foods used for stock cultures as well as those selected for different experiments were sterilized at 50° C for two hours in order to eliminate any parasites or other microorganisms. The twelve selected dry fruits were Prunus amygdalus Batsch almond, Primus armeniaca L. apricot, Anacardium occidental L. cashewnut, Pinus gerarcliana chilgoza, Cocos nucifera L. coconut, Phoenix dactylifera L. date, Ficus glomerata fig, Corylus spp. hazelnut, Morus nigra L. mulberry, Pistacia vera L. pista, Vitis vinifera L. raisin and Juglans regia L. walnut. The susceptibility index of different dry
62
JOURNAL . BOMBAY NATURAL HISTORY SOCIETY. 97(1) APR. 2000
PLODIA INTERPUNCTELLA ASA POTENTIAL PEST OF DRY FRUITS
fruits was studied out by keeping ten three-day old eggs mixed with 2 gm of nuts. Three replications were kept in each case.
The samples were reweighed after emergence to determine the loss of weight due to consumption by the larvae. The moisture content of the samples was also calculated at the beginning and the end of the experiment and loss/ increase in weight due to moisture variation was considered while calculating actual weight loss.
The percentage weight loss due to moisture content variations has been calculated by using the following relationship given by Jamieson (1970).
100 (M,-M.)
G = — -
100 -M,
Where M, = Initial moisture content
percentage wet basis.
M, = Final moisture content
percentage wet basis.
Knowing the value of G, the loss Or gain in weight due to variation in moisture content (d) can be calculated as under, and necessary correction in weight loss of the food made.
GxW,
d - —
100
Where W = Observed weight loss of the food.
G =* Loss or gain percentage in
weight due to moisture content variation.
The data obtained were subjected to statistical analysis.
Results and Discussion
The relative susceptibility of twelve types of dry fruits was calculated on the basis of food consumed, the number of adults emerged, duration of developmental period and weight loss of the fruits.
The results given in Table 1 showed that amount of different foods consumed by the larvae varied greatly, the largest amount being consumed in mulberry (1.816 gm) and the least in the case of coconut (0.004 gm).
Appreciable differences have also been noted in the average development period. Pista registered the shortest development period of 31.71 days, whereas, date showed the longest development period of 104.25 days. However, Hamlin et al. (1931) observed more rapid development of larvae on figs among three fruits namely raisins, prunes and figs tested by them. The progeny produced was maximum in pista, walnut, cashewnut and almond, while other fruits produced comparatively much less progeny. The
Table 1
|
WEIGHT LOSS OF 1 2 DRY FRUITS DUE TO THE ATTACK OF PLODIA INTERPUNCTELLA (H.) (based on three observations) |
|||||||
|
Food |
Initial Weight of food mean (gm) |
Final Weight of food mean (gm) |
Moisture Content M, M, |
Weight loss |
Mean % age weight loss |
Corrected mean % age weight loss |
|
|
Mulberry |
2 |
0.184 |
8.96 |
7.326 |
1.816 |
90.80 |
90.768 |
|
Fig |
2 |
0.593 |
10.32 |
9.949 |
1.407 |
70.35 |
70.345 |
|
Cashewnut |
2 |
1.149 |
4.38 |
3.307 |
0.851 |
42.55 |
42.541 |
|
Almond |
2 |
1.248 |
3.82 |
3.410 |
0.752 |
37.60 |
37.597 |
|
Walnut |
2 |
1.449 |
3.40 |
2.208 |
0.551 |
27.55 |
27.544 |
|
Pista |
2 |
1.485 |
3.34 |
2.828 |
0.515 |
25.75 |
25.748 |
|
Raisin |
2 |
1.497 |
12.12 |
6.479 |
0.503 |
25.15 |
25.120 |
|
Hazelnut |
2 |
1.550 |
3.46 |
2.387 |
0.450 |
22.50 |
22.496 |
|
Date |
2 |
1.713 |
9.26 |
7.764 |
0.287 |
14.35 |
14.346 |
|
Apricot |
2 |
1.862 |
17.54 |
14.607 |
0.138 |
6.90 |
6.896 |
|
Coconut |
2 |
1.996 |
2.98 |
2.550 |
0.004 |
0.20 |
0.200 |
|
Chilgoza |
2 |
Nil |
Nil |
Nil |
Nil |
Nil |
Nil |
JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 97(1), APR. 2000
63
PLODIA INTERPUNCTELLA ASA POTENTIAL PEST OF DRY FRUITS
larvae failed to survive on apricot, coconut and chilgoza as they do not get sufficient nutrition to reach maturity. In fact, the larvae did consume some food in the case of apricot and coconut but died before reaching the pupal stage. In the case of chilgoza, on the contrary, the larvae did not consume any food.
The relative suitability of different foods was also determined with the help of the formula Log eY/T, given by Osuji (1976), where Y is the number of progeny, T is the time taken by 50% of the adults to emerge and e is a constant with a value of 2.303 (Table 2). Pista, walnut and hazelnut, with a suitability index value of 1.743, 1.590 and 1.393, were the most suitable food while date with an index value of 0.085 was the least suitable food.
The relative susceptibility of various foods can be judged by combining the amount of food consumed with the index of suitability (Table 3). Cashewnut and pista with susceptibility index values of 49.773 and 44.878 respectively, were the most susceptible foods whereas date with the index value of 1.219 was the least susceptible food.
Table 2
RELATIVE SUITABILITY OF 12 DRY FRUITS TO THE ATTACK BY PLODIA INTERPUNCTELLA (H.)
(based on three replications of 1 0 eggs each)
|
Food |
Progeny Y |
(Average) Development period (Todays) |
Index of suitability L°SeY/T50 |
|
Pista |
24 |
31.71 |
1.743 |
|
Walnut |
25 |
36.20 |
1.590 |
|
Hazelnut |
21 |
34.71 |
1.393 |
|
Cashewnut |
25 |
49.20 |
1.170 |
|
Almond |
24 |
49.04 |
1.127 |
|
Mulberry |
14 |
81.21 |
0.397 |
|
Fig |
8 |
101.38 |
0.181 |
|
Raisin |
5 |
94.60 |
0.121 |
|
Date |
4 |
104.25 |
0.085 |
|
Apricot |
Nil |
Nil |
Nil |
|
Coconut |
Nil |
Nil |
Nil |
|
Chilgoza |
Nil |
Nil |
Nil |
Loge = 2.303 (constant)
T-0 = Time taken by 50% of the adults to emerge.
It is clear from the data in Tables 2 and 3 that the order of relative suitability and relative susceptibility of the foods was different. This is so because cashewnut undergoes maximum weight loss though the development period on this food is long. It is the duration of the
Table 3
RELATIVE SUSCEPTIBILITY OF 12 DRY FRUITS TO THE ATTACK BY PLODIA INTERPUNCTELLA (H.)
|
Food |
Suitability index value (a) |
‘ Corrected mean % age of weight loss (b) |
Susceptibility index value (axb> |
|
Cashewnut |
1.170 |
42.541 |
49.773 |
|
Pista |
1.743 |
25.748 |
44.879 |
|
Walnut |
1 .590 |
27.544 |
43.795 |
|
Almond |
1.127 |
37.597 |
42.372 |
|
Mulbeiry |
0.397 |