Year of Award


Document Type


Degree Type

Doctor of Philosophy (PhD)

Degree Name

Fish and Wildlife Biology

Department or School/College

College of Forestry and Conservation

Committee Co-chair

Mark Hebblewhite, L. Scott Mills

Commitee Members

Paul Lukacs, Michael S. Mitchell, Hugh Robinson


University of Montana


Large carnivores are endangered across the globe. Loss of habitat and habitat fragmentation, prey depletion, and direct poaching for the illegal wildlife trade are the major causes driving them towards extinction. Although tigers (Panthera tigris) once roamed across Asia, they are now restricted to 7 % of their historical range and experiencing rapid population declines. This warrants a concerted, multipronged strategy that will halt further declines of tigers in the wild. One approach put forth by some scientists is to focus conservation on 6% of the presently occupied tiger habitat identified as tiger sources sites. Other scientists argued for a broader strategy to enhance tiger populations outside of tiger sources sites. Bhutan, for example, was not included in this 6% solution. Here we evaluate whether Bhutan is a potential tiger source site using spatially-explicit mark recapture models to estimate tiger density and spatial distribution in Bhutan. We used large scale remote-camera trapping across n=1,129 sites in 2014 – 2015 to survey all potential tiger range in Bhutan. We estimated 90 (95% CI 80 – 103) individual tigers with 45 females (95% CI 49 – 80) and with a mean density of 0.23 (0.21 – 0.27) adult tigers per 100 km2. Thus, Bhutan has significantly higher numbers of tigers than almost all identified source sites (mean=54) in the 6% solution. We used N-mixture models to estimate spatial distribution and relative abundance of primary prey species of tigers in Bhutan, and the effects of anthropogenic disturbance on tigers and their prey. Gaur (Bos gaurus) and sambar (Rusa unicolor) are concentrated in the southern part of Bhutan and were strong determinants of tiger occupancy. Wild pigs (Sus scrofa) and muntjac (Muntiacus muntjak) are wildly distributed across Bhutan, but did not affect tiger occupancy. In contrast to many other tiger ranges, anthropogenic disturbance did not show consistent negative impacts on tigers and their prey. We show how important the landscape of Bhutan and adjacent northeast India is to regional tiger conservation. With low human density and large swaths of forest cover, this landscape is a promising stronghold for tigers in future.



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