Tiger populations are declining globally, and depletion of major ungulate prey is an important contributing factor. To better understand factors affecting prey distribution in Thailand's Western Forest Complex (WEFCOM), we conducted sign surveys for gaur (Bos gaurus), banteng (Bos javanicus), and sambar (Rusa unicolor) along 3517 1-km transects and used occupancy models to identify important covariates associated with habitat use by each species. Habitat use by both gaur and sambar was lowest in areas closest to human settlements, although sambar preferred lower slopes near streams whereas gaur preferred steeper slopes at higher elevations. Banteng were found in only one of 17 protected areas (Huai Kha Khaeng [HKK] Wildlife Sanctuary), where they used low elevations and low slopes. We used these modeled relationships to predict occurrence of gaur, sambar, and banteng across each square km of the 19,000 km2 WEFCOM landscape, using > 60 % occupancy probability to define suitable habitat use for each species. Based on this criterion, gaur and sambar occupied 28 and 50 % of suitable habitat in WEFCOM, and banteng occupied 57 % of suitable habitat in HKK. We used our models to assess the effectiveness of two hypothetical conservation initiatives. First, we modeled the impact of decreasing human activities around nine villages in the core of WEFCOM, which increased predicted suitable habitat in WEFCOM to 68 and 75 % for guar and sambar. We also modeled the extent of potential banteng habitat that still remains in the other 16 protected areas. This could result in a 4-fold increase in banteng suitable habitat in WEFCOM. This is the first study to use occupancy surveys to determine where large prey species can be restored to support management to increase the distribution of tigers, and potentially fill a half-full tiger landscape.
Bibliographical noteFunding Information:
We sincerely thank Thailand’s Department of National Parks, Plant, and Wildlife Conservation (DNP), for permission to conduct this research and the Wildlife Conservation Society (WCS, Thailand) and the World Wildlife Fund (WWF, Thailand) for support to conduct occupancy surveys in the western forest complex of Thailand as a part of collaborative work. This work was supported by grants from the Rhino and Tiger Conservation Fund of the U.S. Fish and Wildlife Service and the Liz Claiborne and Art Ortenberg Foundation (LCAOF) . The first author was a recipient of funding from the WCS graduate scholarship program while studying at the University of Minnesota, USA . J.L.D. Smith’s contribution to the research was supported by the USDA National Institute of Food and Agriculture .
- Detection probability
- Landscape survey
- Occupancy modeling
- Panthera tigris
- Prey restoration