Fine-scale ecological and anthropogenic variables predict the habitat
use and detectability of sloth bears in the Churia habitat of east Nepal
Abstract
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/non-detection data
and field-based covariates data were collected at the 74 randomly chosen
4-km2 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 mounds 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.