Including biotic interactions with ungulate prey and humans improves habitat conservation modeling for endangered Amur tigers in the Russian Far East

Wild tiger numbers continue to decline despite decades of conservation action. Identification, conservation and restoration of tiger habitat will be a key component of recovering tiger numbers across Asia. To identify suitable habitat for tigers in the Russian Far East, we adopted a niche-based tiger habitat modeling approach, including biotic interactions with ungulate prey species, human activities and environmental variables to identify mechanisms driving selection and distribution of tiger habitat. We conducted >28,000 km of winter snow tracking surveys in 2004/2005 over 266,000 km2 of potential tiger habitat in 970 sampling units (∼171 km2) to record the presence of tracks of tigers and their ungulate prey. We adopted a used-unused design to estimate Resource Selection Probability Functions (RSPF) for tigers, red deer, roe deer, sika deer, wild boar, musk deer and moose. Tiger habitat was best predicted by a niche-based RSPF model based on biotic interactions with red deer, sika deer and wild boar, as well as avoidance of areas of high human activity and road density. We identified 155,000 km2 of occupied tiger habitat in the RFE in 17 main habitat patches. Degradation of tiger habitat was most extreme in the southern areas of the Russian Far East, where at least 42% of potential historic tiger habitat has been destroyed. To improve and restore tiger habitat, aggressive conservation efforts to reduce human impacts and increase ungulate densities, tiger reproduction and adult survival will be needed across all tiger habitat identified by our tiger habitat model.