Fine-scale ecological and anthropogenic variables predict the habitat use and detectability of sloth bears in the Churia habitat of east Nepal

Once widespread throughout the tropical forests of the Indian
Subcontinent, the sloth bears have suffered a rapid range collapse and
local extirpations in the recent decades. A significant portion of their
current distribution range is situated outside of the protected areas
(PAs). These unprotected sloth bear populations are under tremendous human
pressures, but little is known about the patterns and determinants of
their occurrence in most of these regions. The situation is more prevalent
in Nepal where virtually no systematic information is available for sloth
bears living outside of the PAs. We undertook a sign survey-based
single-season occupancy study intending to overcome this information gap
for the sloth bear populations residing in the Trijuga forest of southeast
Nepal. Sloth bear sign detection histories and field-based covariates data
were collected between 2nd October to 3rd December 2020 at the 74 randomly
chosen 4-km^2 grid cells using a varying number of 400m long
transects in each grid cell. From our results, the model-averaged estimate
of site use probability (ψ ± SE) was estimated to be 0.432 ± 0.039, which
is a 13% increase from the naïve estimate (0.297) not accounting for
imperfect detections of sloth bear signs. The presence of termite mound
and the distance to the nearest water source were the most important
variables affecting the habitat use probability of sloth bears. The
average site-level detectability (p ± SE) of sloth bear signs was
estimated to be 0.195 ± 0.003 and was significantly determined by the
index of human disturbances. We recommend considering the importance of
fine-scale ecological and anthropogenic factors in predicting the sloth
bear-habitat relationships across their range in the Churia habitat of
Nepal, and more specifically in the unprotected areas.