Tigers Need Cover: Multi-Scale Occupancy Study of the Big Cat in Sumatran Forest and Plantation Landscapes

The critically endangered Sumatran tiger (Panthera tigris sumatrae Pocock, 1929) is generally known as a forest-dependent animal. With large-scale conversion of forests into plantations, however, it is crucial for restoration efforts to understand to what extent tigers use modified habitats. We investigated tiger-habitat relationships at 2 spatial scales: occupancy across the landscape and habitat use within the home range. Across major landcover types in central Sumatra, we conducted systematic detection, non-detection sign surveys in 47, 17×17 km grid cells. Within each cell, we surveyed 40, 1-km transects and recorded tiger detections and habitat variables in 100 m segments totaling 1,857 km surveyed. We found that tigers strongly preferred forest and used plantations of acacia and oilpalm, far less than their availability. Tiger probability of occupancy covaried positively and strongly with altitude, positively with forest area, and negatively with distance-to-forest centroids. At the fine scale, probability of habitat use by tigers across landcover types covaried positively and strongly with understory cover and altitude, and negatively and strongly with human settlement. Within forest areas, tigers strongly preferred sites that are farther from water bodies, higher in altitude, farther from edge, and closer to centroid of large forest block; and strongly preferred sites with thicker understory cover, lower level of disturbance, higher altitude, and steeper slope. These results indicate that to thrive, tigers depend on the existence of large contiguous forest blocks, and that with adjustments in plantation management, tigers could use mosaics of plantations (as additional roaming zones), riparian forests (as corridors) and smaller forest patches (as stepping stones), potentially maintaining a metapopulation structure in fragmented landscapes. This study highlights the importance of a multi-spatial scale analysis and provides crucial information relevant to restoring tigers and other wildlife in forest and plantation landscapes through improvement in habitat extent, quality, and connectivity

Addressing human-tiger conflict using socio-ecological information on tolerance and risk

Tigers are critically endangered due to deforestation and persecution. Yet in places, Sumatran tigers (Panthera tigris sumatrae) continue to coexist with people, offering insights for managing wildlife elsewhere. Here, we couple spatial models of encounter risk with information on tolerance from 2,386 Sumatrans to reveal drivers of human-tiger conflict. Risk of encountering tigers was greater around populated villages that neighbored forest or rivers connecting tiger habitat; geographic profiles refined these predictions to three core areas. People’s tolerance for tigers was related to underlying attitudes, emotions, norms and spiritual beliefs. Combining this information into socio-ecological models yielded predictions of tolerance that were 32 times better than models based on social predictors alone. Pre-emptive intervention based on these socio-ecological predictions could have averted up to 51% of attacks on livestock and people, saving 15 tigers from the wild. Our work provides further evidence of the benefits of interdisciplinary research on conservation conflicts

Examining the shifting patterns of poaching from a long-term law enforcement intervention in Sumatra

Current levels of illegal wildlife trade for many in-demand species are unsustainable and place them at a heightened risk of extinction. While several Asian protected areas standout for their remarkable successes in tackling poaching, the threat continues nonetheless. We analyse a decade of law enforcement data from a Sumatran protected area to investigate tiger and prey poaching trends, the arrests and subsequent prosecution of those involved. Some 3882 snare traps were destroyed, but a recent spike in tiger poaching revealed that twice the number of snares were annually encountered in 2013 and 2014 than the eight preceding years. We detected a change in the techniques employed for poaching tigers from 2011 onwards, with more frequent encounters of snare trap clusters that contained six or more tiger traps set in a single location. Comparing monthly patterns of poaching within years revealed an increase in deer, but not tiger, poaching during the month of Ramadan. This result confirmed long-held views by the ranger teams that local demand for meat increases in the build up to Idul Fitri, a main Islamic holiday. Finally, from 24 law enforcement operations conducted, 40 tiger poachers/traders were arrested with > 90% being prosecuted. However, the fines and prison sentences issued were much lower than the maximum available, and the highest sentence was for firearms possession and not illegal activities towards wildlife. Our site-based study demonstrates what can be achieved, but also identifies areas for strengthening the sub-national and national law enforcement response to an escalating tiger poaching trend