Despite conservation efforts, large mammals such as tigers (Panthera tigris) and their main prey, gaur (Bos gaurus), banteng (Bos javanicus), and sambar (Rusa unicolor), are highly threatened and declining across their entire range. The only large viable source population of tigers in mainland Southeast Asia occurs in Thailand's Western Forest Complex (WEFCOM), an approximately 19,000 km2 landscape of 17 contiguous protected areas. We used an occupancy modeling framework, which accounts for imperfect detection, to identify the factors that affect tiger distribution at the approximate scale of a female tiger's home range, 64 km2, and site use at a scale of 1-km2. At the larger scale, we estimated the proportion of sites at WEFCOM that were occupied by tigers; at the finer scale, we identified the key variables that influence site-use and developed a predictive distribution map. At both scales, we examined key anthropogenic and ecological factors that help explain tiger distribution and habitat use, including probabilities of gaur, banteng, and sambar occurrence from a companion study. Occupancy estimated at the 64-km2 scale was primarily influenced by the combined presence of all three large prey species, and 37% or 5,858 km2of the landscape was predicted to be occupied by tigers. In contrast, site use estimated at the scale of 1 km2 was most strongly influenced by the presence of sambar. By modeling occupancy while accounting for imperfect probability of detection, we established reliable benchmark data on the distribution of tigers in WEFCOM. This study also identified factors that limit tiger distributions; which managers can then target to expand tiger distribution and guide recovery elsewhere in Southeast Asia.
Bibliographical noteFunding Information:
We sincerely thank Government of Thailand; DNP, WCS, and WWF for support in conducting this survey. The Rhino and Tiger Conservation Fund of the U.S. Fish and Wildlife Service and the Liz Claiborne and Art Ortenberg Foundation (LCAOF) provided financial support. The second author is the recipient of the WCS graduate scholarship for study at the University of Minnesota and Conservation Biology summer grant while this manuscript was prepared, USA. J. Fieberg, T.W. Arnold, J.L.D. Smith's contribution to the research was supported by the USDA National Institute of Food and Agriculture. We thank K. Ulas Karanth and WCS India team for training and designed occupancy field methodology. Any use of trade, product of firm names is for descriptive purposes and does not imply endorsement by the U.S. Government.
© 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
- Panthera tigris
- Western Forest Complex
- large landscape survey
- multiple scale occupancy