Population Status of a Cryptic Top Predator: An Island-Wide Assessment of Tigers in Sumatran Rainforests

Large carnivores living in tropical rainforests are under immense pressure from the rapid conversion of their habitat. In response, millions of dollars are spent on conserving these species. However, the cost-effectiveness of such investments is poorly understood and this is largely because the requisite population estimates are difficult to achieve at appropriate spatial scales for these secretive species. Here, we apply a robust detection/non-detection sampling technique to produce the first reliable population metric (occupancy) for a critically endangered large carnivore; the Sumatran tiger (Panthera tigris sumatrae). From 2007–2009, seven landscapes were surveyed through 13,511 km of transects in 394 grid cells (17×17 km). Tiger sign was detected in 206 cells, producing a naive estimate of 0.52. However, after controlling for an unequal detection probability (where p = 0.13±0.017; ±S.E.), the estimated tiger occupancy was 0.72±0.048. Whilst the Sumatra-wide survey results gives cause for optimism, a significant negative correlation between occupancy and recent deforestation was found. For example, the Northern Riau landscape had an average deforestation rate of 9.8%/yr and by far the lowest occupancy (0.33±0.055). Our results highlight the key tiger areas in need of protection and have led to one area (Leuser-Ulu Masen) being upgraded as a ‘global priority’ for wild tiger conservation. However, Sumatra has one of the highest global deforestation rates and the two largest tiger landscapes identified in this study will become highly fragmented if their respective proposed roads networks are approved. Thus, it is vital that the Indonesian government tackles these threats, e.g. through improved land-use planning, if it is to succeed in meeting its ambitious National Tiger Recovery Plan targets of doubling the number of Sumatran tigers by 2022

Assessing the distribution and habitat use of four felid species in Bukit Barisan Selatan National Park, Sumatra, Indonesia

There have been few targeted studies of small felids in Sumatra and there is little information on their ecology. As a result there are no specific management plans for the species on Sumatra. We examined data from a long-term camera trapping effort, and used Maximum Entropy Modeling to assess the habitat use and distribution of Sunda clouded leopards (Neofelis diardi), Asiatic golden cats (Pardofelis temminckii), leopard cats (Prionailurus bengalensis), and marbled cats (Pardofelis marmorata) in Bukit Barisan Selatan National Park. Over a period of 34,166 trap nights there were low photo rates (photo events/100 trap nights) for all species; 0.30 for golden cats, 0.15 for clouded leopards, 0.10 for marbled cats, and 0.08 for leopard cats. There is overlap in the predicted distributions of clouded leopards, golden cats, and marbled cats; indicating areas of high conservation importance for these species within the park. The predicted distribution of leopard cats was discrete from the other species which is important to consider in the development of conservation strategies. This study provides important documentation of small felid distribution in Sumatra, information for the development of management strategies within the park, and a basis upon which to develop future research for the species

Safeguarding Asian tapir habitat in Sumatra, Indonesia

The Asian tapir Tapirus indicus is the only tapir species in Southeast Asia. It is declining across its range and is categorized as Endangered on the IUCN Red List. The forests of Sumatra are critical to Asian tapir conservation as they contain some of the last remaining populations of the species, yet conservation efforts are hindered by a lack of information on habitat suitability. We collated camera-trap data from nine landscapes across 69,500 km2 of Sumatran rainforest to help predict suitable habitat for Asian tapirs on the island. Predictions from Bayesian occupancy models demonstrated that tapir occupancy was greatest in forests below 600 m elevation and exclusively in forests with high aboveground biomass. Forests around the Barisan Mountains on the west of Sumatra provide the most suitable habitat for the species. Only 36% of the most critical habitat (i.e. the top 20th percentile of predicted occupancy) for tapirs is formally protected for conservation, with much of the remainder found in forests allocated to watershed protection (35%) or logging (23%). We highlight several key areas in Sumatra where tapir conservation could be bolstered, such as by leveraging existing conservation efforts for other charismatic flagships species on the island

Cryptic mammals caught on camera: assessing the utility of range wide camera trap data for conserving the endangered Asian tapir

The loss and fragmentation of substantial areas of forest habitat, in combination with rampant hunting, has pushed many of Southeast Asia's megafauna species to the verge of extinction. However, the extent of these declines is rarely quantified, thereby weakening lessons learned and species-based management. This need not be the case as a proliferation of camera trap surveys for large-bodied mammals across Southeast Asia, which use a standardized sampling technique, presents a rich yet under-utilized wildlife data set. Furthermore, advances in statistical techniques for assessing species distribution provide new opportunities for conducting comparative regional analyses. Here, we focus on one of Southeast Asia's least known species of megafauna, the Endangered Asian tapir (Tapirus indicus), to investigate the performance of a camera trap-based spatial modeling approach in conducting a range-wide species assessment. Detection data were collectively collated from 52,904 trap days and 1,128 camera traps located across 19 study areas drawn from the Asian tapir's entire range. Considerable variation in tapir occurrence was found between study areas in: Malaysia (0.52–0.77); Sumatra, Indonesia (0.12–0.90); Thailand (0.00–0.65); and, Myanmar (0.00–0.26), with generally good levels of estimate precision. Although tapirs were widespread (recorded in 17 of the 19 study areas), their occurrence was significantly and negatively correlated with human disturbance. Thus, this study extends the previously known applicability of camera traps to include a threatened and cryptic species by identifying where and how tapirs persist (including new records of occurrence), where future surveys should be conducted and providing a benchmark for measuring future conservation management efforts

Summary of Sumatra-wide field survey effort for each landscape.

<p>*I = global priority; II = regional priority; III = long-term priority.</p>1<p>Kerinci Seblat National Park and Batang Hari Protection Forest and their surrounding forests.</p>2<p>Bukit Barisan Selatan National Park and Bukit Balai Rejang Selatan.</p>3<p>Pasir Pangaraian, Giam Siak, Duri, Balaraja, Tapung.</p>4<p>Tesso Nilo, Bukit Bungkuk, Bukit Rimbang-Baling, Bukit Batabuh, Bukit Tigapuluh, Kerumutan.</p>5<p>Dangku, Bukit Duabelas, Berbak.</p

Estimated Sumatran tiger site occupancy and sites with actual indirect tiger sign detections (black dots).

<p>Estimated Sumatran tiger site occupancy and sites with actual indirect tiger sign detections (black dots).</p

Sumatran tiger site occupancy () and density () estimates for the best model, averaged for each study area.

<p>The two right-most columns show the estimates conditional to the data observed. Standard errors are shown in brackets.</p