transects, Karanth (unpublished data) recorded few sightings of sloth bears despite considerable

effort. A detection function fitted to such limited data is likely to be highly unreliable. Similarly,

mark-recapture sampling requires large sample sizes and live trapping of sloth bears is not likely

to generate the requisite number of recaptures. Sampling using noninvasive DNA extracted from

hair or scat samples may be used as an alternative to live trapping, but it is very expensive.

Additionally, all these methods presently have technical problems that make them less reliable as

well (Mills et al., 2000).

 By sampling a site repeatedly for the presence-absence of a species, Royle & Nichols

(2003) constructed a model that may be used to determine the abundance of a species. This is a

simple model that makes use of a logical assumption that the detectability of a species is solely

dependent on the abundance at that site for a given animal-specific detection probability. In this

chapter, I investigate the applicability of this model for repeated presence-absence data of sloth

bears obtained using camera traps in Bandipur and Nagarahole National Parks. For reasons

discussed in chapter 2 of this thesis, I preferred to use the Bayesian approach in estimating sloth

bear abundance.

 Study Design

Study Area

 The study area comprises two protected areas, Nagarahole and Bandipur, that are

geographically separated by the Kabini reservoir (Figure 3-1).

Nagarahole

 Nagarahole was originally established in 1955 as a Game Reserve of 288 km2. In 1974, it

was expanded to become the Nagarahole National Park (Area: 644 km2), now officially renamed

"Rajiv Gandhi National Park, Nagarahole" but commonly referred to as Nagarahole. The reserve

is located in Kodagu and Mysore districts (760 00' 760 15' E 110 15' 120 15' N) at altitudes