Dramatic population declines threaten the Endangered Indochinese tiger Panthera tigris corbetti with extinction. Thailand now plays a critical role in its conservation, as there are few known breeding populations in other range countries. Thailand's Dong Phayayen-Khao Yai Forest Complex is recognized as an important tiger recovery site, but it remains poorly studied. Here, we present results from the first camera-trap study focused on tigers and implemented across all protected areas in this landscape. Our goal was to assess tiger and prey populations across the five protected areas of this forest complex, reviewing discernible patterns in rates of detection. We conducted camera-trap surveys opportunistically during 2008–2017. We recorded 1,726 detections of tigers in 79,909 camera-trap nights. Among these were at least 16 adults and six cubs/juveniles from four breeding females. Detection rates of both tigers and potential prey species varied considerably between protected areas over the study period. Our findings suggest heterogeneity in tiger distribution across this relatively continuous landscape, potentially influenced by distribution of key prey species. This study indicates that the Dong Phayayen-Khao Yai Forest Complex is one of the few remaining breeding locations of the Indochinese tiger. Despite limitations posed by our study design, our findings have catalysed increased research and conservation interest in this globally important population at a critical time for tiger conservation in South-east Asia.

The wild buffaloes, gaur Bos gaurus and banteng Bos javanicus, are among the most threatened mammals in Vietnam but little information is available on their status and distribution. Over 2004–2007 I undertook surveys in three Vietnamese distribution strongholds of the Vulnerable gaur and Endangered banteng: Ea So Nature Reserve and Yok Don and Cat Tien National Parks. A total of 22 herds with 121 gaur and seven herds with 49 banteng were observed. Herd sizes of both species were generally lower than those recorded in Thailand and Malaysia. Most of the herds were observed in remote areas, showing that the species are probably staying away from areas with human activity. No banteng were found in Cat Tien National Park. Of the other wild buffalo species the Critically Endangered kouprey Bos sauveli and Endangered water buffalo Bubalus arnee were not observed in the three protected areas but the Near Threatened serow Capricornis milneedwardsii was occasionally observed in all three areas. Illegal hunting, habitat degradation and disturbance appear to be the most significant threats to gaur and banteng in the areas surveyed. It is essential to have effective law enforcement to eliminate human impacts on these two species, and an adequate conservation strategy to secure their long-term survival.