Estimation of tiger densities in India using photographic captures and recaptures

Ecology, Dec, 1998 by K. Ullas Karanth, James D. Nichols

2) To estimate densities of wild tiger populations using photographic capture-recapture models in four ecologically distinct study sites.

3) To estimate densities of principal ungulate prey species at these four sites using line-transect sampling (Burnham et al. 1980, Buckland et al. 1993), in order to evaluate the role of prey abundance and community structure in shaping predator communities.

STUDY AREAS

Because tiger densities appear to be influenced primarily by the characteristics of their ungulate prey assemblages (Seldensticker and McDougal 1993, Karanth and Sunquist 1995), we selected four sites representing important tiger-prey communities in India. These consisted of the best preserved, representative sites within the National Parks of Pench (290 [km.sup.2]), Kanha (900 [km.sup.2]), Kaziranga (488 [km.sup.2]), and Nagarahole (644 [km.sup.2]). Ecological features of these areas, described elsewhere (Purl et al. 1983, Kothari et al. 1989), are briefly summarized.

The Pench site, located in central India (21 [degrees] 38[minutes] - 21 [degrees] 51[minutes] N, 79 [degrees] 09[minutes]-79 [degrees] 22[minutes] E), receives an average annual rainfall of 1400 mm and supports a tropical deciduous teak (Tectona grandis) forest type, classified as Tectona-Terminalia series by Purl et al. (1983) and as a tropical moist deciduous forest (TMD) tiger habitat by Wikramanayake et al. (1998). Common ungulate prey species of tigers in Pench are chital (Axis axis), sambar (Cervus unicolor), nilgat (Boselephas tragocamelus), gaur (Bos gaurus), wild pig (Sus scrofa), muntjac (Muntiacus muntjac), and four-horned antelope (Tetracerus quadricornis).

The Kanha site is also located in central India (22 [degrees] 07[minutes]-22 [degrees] 27[minutes] N, 80 [degrees] 26[minutes]-81 [degrees] 03[minutes] E), with an annual rainfall of 1500 mm. Kanha has tropical deciduous forests dominated by sal (Shorea robusta), classified as Shorea-Terminalia-Adina series by Puri et al. (1983) and classed under the tiger habitat category tropical moist deciduous forest (TMD) by Wikramanayake et al. (1998). Grassy meadows of anthropogenic origin are interspersed within the forested area. The common tiger prey species are chital, sambar, gaur, barasingha (Cervus duracell), wild pig, and muntjac.

The Nagarahole site in southwestern India (11 [degrees] 50[minutes]-12 [degrees] 15[minutes] N, 76 [degrees] 00[minutes]-76 [degrees] 15[minutes] E) gets an annual rainfall ranging from 1100 mm in the east to 1600 mm in the west. It supports tropical deciduous forests classified as Terminalia-Anogeissus-Tectona series in low-rainfall zones, and Tectona-Dillenia-Lagerstoremia series in the higher rainfall zones (Purl et al. 1983). The site is included under the tropical moist forest (TMF) tiger habitat category by Wikramanayake et al. (1998). The common ungulate prey species are chital, gaur, sambar, wild pig, and muntjac.

The Kaziranga site in northeastern India (26 [degrees] 33[minutes]-26 [degrees] 45[minutes] N, 93 [degrees] 08[minutes]-93 [degrees] 40[minutes] E) gets an annual rainfall of 3000 mm. Although placed under the TMD tiger habitat category by Wikramanayake et al. (1998), our specific study site was an alluvial floodplain grassland (AGD) interspersed with patches of tropical moist forest. The common ungulate prey species are wild buffalo (Bubalus bubalis), barasingha, hog deer (Axis porcinus), muntjac, wild pig, and gaur.