Capture history of Asiatic black bear from Himachal Pradesh, India

Robust population estimation of rare or elusive threatened species lacking
distinct identifiable features poses a challenge in the field of
conservation and management. The Asiatic black bear (Ursus thibetanus) is
one such species. Methodological frameworks—such as radiotelemetry,
genetic sampling, and camera-trapping—though crucial and advantageous,
sometimes require additional information through invasive methods for
individual identification. In this study, we estimated the population
density of Asiatic black bear in 2 protected areas in the Indian Himalayan
Region without information on individual identification. We conducted the
study through a spatial capture–recapture framework using camera traps in
the summer during May–July 2018 in Daranghati Wildlife Sanctuary (WLS) and
May–July 2019 in Rupi Bhaba WLS. Using the recently developed Spatial
Presence–Absence model, we estimated g0 (detection probability), σ (scale
or movement parameter related to home range of the species), and N
(population size) of Asiatic black bears from the camera-trap data using a
Bayesian framework. We estimated a population density of 2.5
individuals/100 km2 (95% Credible Interval = 1.42–9.63 individuals/100
km2) from Daranghati WLS and 0.3 individuals/100 km2 (95% Credible
Interval = 0.2–0.7 individuals/100 km2) from Rupi Bhaba WLS. Abundance
estimates produced by extrapolating these densities were 11 Asiatic black
bear individuals (95% Credible Interval = 4–27) from Daranghati WLS and 2
Asiatic black bear individuals (95% Credible Interval = 1–3) from Rupi
Bhaba WLS. This is the first population estimate of Asiatic black bear
from the Indian Himalaya without individual identification. We recommend
that this method, which provides minimal sampling bias and ease of
sampling, can be replicated in other mountainous landscapes for a robust
density estimation of this species.