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HABITAT AND POPULATION EVALUATION FOR LARGE PREY SPECIES IN MIXED DECIDUOUS FOREST OF SOUTHERN INDIA
Surendra Varma
Asian Elephant Research and Conservation Centre (A division of Asian Nature Conservation foundation ANCF), C/o Centre for Ecological Sciences, Indian Institute of Sciences, Bangalore. 560 012 Email: varma@ces.iisc.ernet.in
Evaluating habitat and prey population densities are important management and conservation issues, with a global relevance. However, less or no studies have been focused on understanding the status of habitat and numbers of prey species. The effect of this phenomenon (not evaluating habitat or number) on prey species or game management and conservation could be severe and may lead to greater challenges in conserving some of the crucial prey species.
The habitat and population evaluation of large prey species at the Bandipur Tiger Reserve, southern India was assessed through both GIS and line transect method (Burnham et. al., 1980 and Varman & Sukumar, 1995) in 4 different seasons from August 2000 to June 2001. The habitat was evaluated through satellite im-
ageries (LANDSAT-TM), which was then supported by ground truthing using GPS (Global Positioning System).
In total, 17 transects (total of 60 km, with varying length of 2.5 to 4 km) were laid across the reserve for habitat evaluation, habitat usage in response to habitat availability and the population number of prey species. Transect length in each habitat types were in proportion to the vegetation type areas in the reserve (Table 1). Four seasons were defined as first wet, second wet, dry and pre-monsoon for survey. Each transect was surveyed by one volunteer and a forest staff for six times; three times each morning and evening during every season, to obtain a sufficient sample size for analysis.
Specific habitat evaluation (vegetation survey) was carried out between regular intervals on the line. For this exercise, the four nearest tree species from the centre of the line (in all four directions) were identified and information such as ground cover and canopy cover were collected in percentage ratings. Habitat assessment exercise was carried out independently from the animal counts. The density of animals was determined using the program DISTANCE4.0 beta 1.
The computer program software Statistica 5.5 was used for carrying out statistical tests data processing, Shapiro Wilk's W test was used to test the normality and Spearman Rank Correlation was used for testing the correlation between canopy and ground cover.
Results:
Habitat evaluation
Habitat type
The results of habitat evaluation shows that total of 6 habitat types are available for the prey species and among them the degraded dry deciduous forest appeared to be the dominating type (26%), followed by plantation and associated forests (21 %), scrub (19 %) and dry deciduous forest (15%). The distance covered for each habitat during the survey for all the seasons corresponded with their proportionate areas (Table 1).
Canopy and ground cover:
Mean canopy cover of the habitat was 40 % (SE = 3.4, CV % 8.7), that ranged from 0 to 90 % and 25 % dominated (47%) followed by 50 % (21%). The mean ground cover was 63% (SE = 3.9, CV % 6.2) ranging from 15 to 100 % and 50 % ground cover dominated (25%) followed by 90 and 100 % (15 %). The Shapiro - Wilk's W test for normality suggests that the distribution of canopy and ground cover was not normal (p < 0.001), a nonparametric correlation was carried out and it was found that there was no significant correlation between canopy and ground cover (r = 0.172, p = 0.215, Figure 2).
Figure 2:
Canopy cover VS Ground cover
120 100 8i 80 ä 60 i 40 20 0
♦ • ♦. i
Prey species abundance
Total number of species and frequency of sightings of prey species
The carried out surveys covering 4 seasons (wet season 1, wet season 2, dry and pre monsoon - starting from August 2000 to June 2001) show a total of 23 mammalian species for the park (Table 2). Both direct and indirect methods are useful for assessing the number of species, but direct method gives more relevant results, as decay rate of signs for some species are very slow and extensive effort is needed for identification for some species. Based on the results from direct methods, spotted deer the major prey species for both wild dog and common leopard appeared to be the more frequently sighted mammal for the entire park. Other prey species such as Sambar, Hanuman Langur, Gaur and Wild boar also occur in high frequency.
Among 23 species encountered, density and population estimates are presented only for five species of prey species as other species had very low sample size to analyze the data. Based on these results the seasonal encounter rate for three prey species, overall sample size, and density for the four species and habitat wise density for 5 species of prey were also estimated.
Population density of prey species The results of densities (Table 2) for different species show that the spotted deer is the most abundant prey species followed by Gaur and Sambar. As there
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are no studies or survey on the numbers of different species of animals available for the park at this stage, no inferences on the results could be made. However, a comparison of the density results with Mudumalai , which has similar habitat type for prey species such as Spotted deer, Sambar and Gaur (20, 7.80 and 7.67 animals km2 respectively) show that the results are not comparable as the differences in the density estimates for these two reserves are very high.
Sample size and density of four prey species.
Species Sample Size Density CV %
Spotted deer 198 48.4 40
Sambar 229 12..5 24
Gaur 79 17..3 39
Langur 158 8.3 25
Seasonal habitat usage pattern of prey species
Considering the encounter rates of different species for different seasons, not much variation could be noticed across all seasons for Spotted deer and Sambar (Table 3). A similar pattern could also be observed for langur.
Habitat usage pattern in relation to habitat type and total habitat available
The results of habitat utilization for prey species indicate that spotted deer densities are more in degradetion of dry deciduous forests, followed by in planta-
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tions and associated forests, dry deciduous and moist deciduous forests. Sambar utilizes more of deciduous forest followed by moist deciduous, degraded dry deciduous and savanna forests. Gaur shows its association more towards moist deciduous forests.
MGS; Malabar Giant Squirrel. Dry Deciduous (DD), Degraded Dry Deciduous (DDD), Moist Deciduous (MD), Plantation & Associated Forests (PAF), Savanna (SAV), Scrub (SCR). D = Density, Se= Standard Error. Density is expressed in Km2- Inadequate sample sizes for density calculations.
Habitat usage in relation to its availability:
Pattern of density in relation to the area available for each habitat type suggest that, habitat was not utilized in relation to its availability, but most of the prey species have specific preference to the habitat. For spotter deer, expect for degraded dry deciduous (DDD) and dry deciduous forests (DD), the habitat usage pattern was not in relation to the habitat size and they may have preference to plantation and plantation associated forest (PAF) and moist deciduous forest (MD) also. Sambar shows preference to DD followed by PAF and MD and Gaur was for MD followed by DDD and PAF.
REFERENCES:
Burnham, K. P., Anderson, D. R. and Laake, J. L., 1980. Estimation of density from line transect sampling of biological populations. Wildlife Monographs. 72. 202pp.
Table 3
Seasonal encounter rate for three prey species
Seasons Spotted deer Sambar Langur
N n/l Se N n/l Se N n/l Se
Wet I 42 0.14 0.04 40 0.13 0.04 25 0.08 0.03
Wet II 65 0.25 0.05 73 0.24 0.06 42 0.13 0.03
Dry 65 0.25 0.05 81 0.25 0.07 45 0.14 0.05
P-M 36 0.12 0.05 31 0.10 0.05 44 0.15 0.04
N: Sample size, n/l: encounter rate, Se: Standard error
Habitat wise density for five prey species
Table 4
Habitat type Chi tal Sambar Langur Gaur MGS
D Se D Se D Se D Se D Se
DD 19.3 6.4 52.3 18.9 14.1 10.2 9.8 3.2 17.1 17
DDD 104. 6 43 4.4 1.7 8.4 3.3 21.8 14.4 - -
MD 13.0 7.2 8.7 5.0 4.6 4.0 34.4 23.3 2.7 0.8
PAF 18.4 7.0 9.9 3.2 14.5 5.5 2.3 2.2 0.14 2.5
SAV - - 4.4 3.4 3.8 1.3 - - - -
SCR - - - - 0.7 0.6 - - - -
Dattaraja, H.S., Suresh, H.S., Robert, J. and R. Sukumar. Plant diversity studies in Nilgiri Biosphere Reserve. Proceedings of Biosphere Reserve meeting, Pant Institute, Almora, UP.
Easa, P.S. 1986. Prey and predator studies in Eravikulam NP, Kerala Forest Research Institute, Peechi, Kerala.
Karanth, K.U. and M.E. Sunquist. 1995. Prey selection by tiger, leopard and dhole in tropical forests. J. Anim. Ecol. 64: 439 - 450.
Parthasarathy, N., Changes in forest composition and structure in three sites of tropical evergreen forest around Sengaltheri, Western Ghats, 2001, Current Science, 80, 389-393.
StatSoft, Inc. (2001) STATISTICA for Windows (data analysis software system). StatSoft, Inc. Tulsa
Varman, K. S. and Sukumar, R., 1995. The line transect method for estimating densities of large mammals in a tropical deciduous forest: An evaluation of methods and field experiments; J. Biosci.20 273-287.
Varman, K.S. and Sukumar, R. 1993. Ecology of Sambar in Mudumalai Sanctuary, Southern India. Elsevier Science Publishers B. V.
Table 2
Frequency of sightings (%) of mammals reported during the survey of park
Name Scientific name S.no Direct % Indirect % Mean
Spotted deer Axis axis 1 20.11 7.66 13.88
Sambar Cervus unicolor 2 17.78 6.92 12.35
Elephant Elephas maximus 3 14.39 66.47 40.43
Hanuman langur Semnopithecus entelJus 4 10.46 0.49 5.47
Indian giant squirrel Ratufa indica 5 10.37 0.08 5.22
Gaur Bos gaurus 6 7.51 6.92 7.21
Wild boar Sus scrofa 7 3.84 1.48 2.66
Sloth bear Melursus ursinus 8 3.84 2.80 3.32
Indian Muntjac Mintiacus muntjak 9 2.77 0.99 1.88
Indian hare Lepus nigicollis 10 2.41 2.64 2.52
Grey mongoose Herpestes edwardsii 11 1.79 0.08 0.93
Bonnet macaque Macaca radiata 12 1.34 0.08 0.71
Stripe necked mongoose Herpestes vitticollis 13 0.71 0.00 0.36
Four horned antelope Tetracerus quadricornis 14 0.63 0.33 0.48
Indian porcupine Hystrix indica 15 0.63 0.66 0.64
Wild dog Cuon alpinus 16 0.54 0.66 0.60
Tiger Panthera tigris 17 0.36 0.99 0.67
Mouse deer Moschiola meminna 18 0.18 0.00 0.09
Ihree striped palm squirrel Funambulus palmarum 19 0.18 0.00 0.09
Common Leopard Panthera pardus 20 0.09 0.25 0.17
Ruddy mongoose Herpestes smithii 21 0.09 0.00 0.04
Striped hyena Hyaena hyaena 22 0.00 0.08 0.04
Jungle cat Felis chaus 23 0.00 0.16 0.08
ОЦЕНКА МЕСТООБИТАНИЙ И ПОПУЛЯЦИИ КРУПНЫХ МЛЕКОПИТАЮЩИХ-ФИТОФАГОВ В СМЕШАННЫХ ЛИСТВЕННЫХ ЛЕСАХ ЮЖНОЙ ИНДИИ
С. Варма
Центр изучения и охраны азиатских слонов
Центр Экологических Наук Института Наук Индии, Бангалор
Проведена оценка местообитания и популяционных характеристик для крупных травоядных млекопитающих в смешанных лиственных лесах Южной Индии. На территории парка присутствуют шесть типов местообитаний, и среди них деградирующий сухой лиственный лес является доминирующим
(26%). Наибольшей плотности достигает популяция аксиса - основного объекта охоты красных волков и леопарда, затем следуют замбар и гаур. Аксис чаще встречается в деградирующих сухих лиственных лесах, замбар обитает на большей части лиственных лесов, а гаур - во влажных лиственных лесах. Показатель плотности по отношению к доступному ареалу местообитания для каждого вида сообщества показывает, что большинство растительноядных млекопитающих отдают специфическое предпочтение местообитаниям, без какой-либо связи с их доступностью.
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