Exploratory dispersal movements by young tigers in Thailand’s Western Forest Complex: the challenges of securing a territory

Habitat for tigers and many carnivores is fragmented and degraded to an extent that the existing land base supporting discrete tiger populations is often inadequate to maintain viable populations. Using fine-scale location data of dispersing tigers, we studied their exploratory movements in Thailand’s Western Forest Complex (WEFCOM), where the last remaining viable tiger population in mainland Southeast Asia resides. We mapped 21,897 locations of three satellite-collared tigers as they made 11 forays from the vicinity of their natal areas in Huai Kha Khaeng Wildlife Sanctuary to four adjacent protected areas in WEFCOM and Myanmar. Our objectives were to describe (1) the spatial and temporal movements of dispersing tigers and (2) the quality of habitat moved through during dispersal and at the time they established a territory. We used the probability of tiger occupancy at hourly locations as a measure of quality of the habitat traversed by dispersing tigers, and we compared these probabilities of use to probabilities at hourly locations of resident, breeding females. Dispersal forays lasted 3 to 52 days and ranged from 29 to 301 km. During these forays, tigers explored areas where the probability of tiger habitat use ranged from 0.212 to 0.961. One dispersing female settled in a territory with a 0.721 probability of use in the range of use in the territories of 10 breeding females (p = 0.600–0.914). This study produced the first high temporal resolution data of tiger dispersal movements in a landscape where the occurrence and probability of use by tigers is known. These data also support modeling of dispersal and landscape resistance that provides critical information for managers seeking to increase connectivity and extent of tiger habitat.