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Encounter rates of carnivores with prey are dependent on spatial and temporal overlap, and are often highest with their preferred prey. The Critically Endangered Sumatran tiger Panthera tigris sumatrae is dependent on prey populations, but little is known about its prey preferences. We collected camera-trap data for 7 years (2010–2016) in Bukit Barisan Selatan National Park, Sumatra, to investigate spatial and temporal overlap of tigers with potential prey species. We also developed a novel method to predict predator–prey encounter rates and potential prey preferences from camera-trap data. We documented at least 10 individual tigers, with an overall detection rate of 0.24 detections/100 trap nights. Tigers exhibited a diurnal activity pattern and had highest temporal overlap with wild boar Sus scrofa and pig-tailed macaques Macaca nemestrina, but highest spatial overlap with wild boar and sambar deer Rusa unicolor. We created a spatial and temporal composite score and three additional composite scores with adjustments for the spatial overlap and preferred prey mass. Wild boars ranked highest for all composite scores, followed by sambar deer, and both are known as preferred tiger prey in other areas. Spatial and temporal overlaps are often considered as separate indices, but a composite score may facilitate better predictions of encounter rates and potential prey preferences. Our findings suggest that prey management efforts in this area should focus on wild boar and sambar deer, to ensure a robust prey base for this Critically Endangered tiger population.

SummaryDestruction of tropical rainforests reduces many unprotected habitats to small fragments of remnant forests within agricultural matrices. To date, these remnant forest fragments have been largely disregarded as wildlife habitat, and little is known about mammalian use of these areas in Sumatra. Here, we conducted camera trap surveys (2285 trap-nights) within Bukit Barisan Selatan National Park and five surrounding remnant forest fragments during 2010–2013 and used species composition metrics to compare use. We found 28 mammal species in the protected forest and 21 in the fragments. The fragments harboured a subset of species found in the protected forest and several species not observed in the protected forest. Critically endangered species such as Sunda pangolin (Manis javanica) and Sumatran tiger (Panthera tigris sumatrae) were found in the forest fragments, along with species of conservation concern such as marbled cat (Pardofelis marmorata) and Asiatic golden cat (Pardofelis temminckii). The biodiversity found within the fragments suggests that these small patches of remnant forest may have conservation value to certain mammal species and indicates the importance of further research into the role these habitats may play in landscape-level, multispecies conservation planning.

Reliable information on wildlife populations and the threats they face is crucial for assessing the performance of conservation strategies. As part of its efforts to improve the effectiveness of Bukit Barisan Selatan National Park in Sumatra, Indonesia, and aid the recovery of flagship species, the Park's management authority designated a 1,000 km2 forest block an Intensive Protection Zone. To set a baseline from which to evaluate the performance of this zone, we investigated the density of tigers Panthera tigris sumatrae, and spatio-temporal interactions between tigers, their principle prey and threats. The estimated density of tigers was 2.8 per 100 km2, whereas in 2002 camera-trapping failed to record any tigers in the Intensive Protection Zone. We found the study area contained a rich prey base, with muntjac deer Muntiacus muntjak, macaques Macaca nemestrina and wild pigs Sus scrofa occupying 85–98% of the area, and sambar Rusa unicolor 61%. Despite these promising findings we also recorded a relatively high number of people entering the Park illegally, with 77 incidents over 6 months, of which 20% involved armed poachers. The poachers operated mainly at night and were concentrated in two locations. Law enforcement patrol teams were active during the day, and therefore had little overlap with the poachers. Prioritizing these at-risk areas for increased protection by rangers would further secure the Intensive Protection Zone, and expanding ranger activity across the Park would support efforts to remove the Park from UNESCO's List of World Heritage In Danger.

Information on spatial and temporal variation in abundance is crucial for effective management of wildlife. Yet abundance estimates for the Critically Endangered Sumatran tiger Panthera tigris sumatrae are lacking from Riau, the province historically believed to hold the largest percentage of this subspecies. Recently, this area has had one of the highest global rates of deforestation. Using camera traps we investigated tiger abundance across peatland, flat lowland, and hilly lowland forest types in the province, and over time, in the newly established Tesso Nilo National Park, central Sumatra. We estimated densities using spatially explicit capture–recapture, calculated with DENSITY, and traditional capture–recapture models, calculated with CAPTURE. With spatially explicit capture–recapture the lowest tiger density (0.34 ± SE 0.24 per 100 km2) was estimated in the hilly lowland forest of Rimbang Baling and the highest (0.87 ± SE 0.33 per 100 km2) in the flat lowland forest of the Park. Repeated surveys in the Park documented densities of 0.63 ± SE 0.28 in 2005 to 0.87 ± SE 0.33 per 100 km2 in 2008. Compared to traditional capture–recapture the spatially explicit capture–recapture approach resulted in estimates 50% lower. Estimates of tiger density from this study were lower than most previous estimates in other parts of Sumatra. High levels of human activity in the area appear to limit tigers. The results of this study, which covered areas and habitat types not previously surveyed, are important for overall population estimates across the island, provide insight into the response of carnivores to habitat loss, and are relevant to the interventions needed to save the tiger.

Increasing demand for cooking oil and biofuels has made palm oil, > 80% of which is grown in South-east Asia, the dominant globally traded vegetable oil. However, this region is host to some of the world’s most biodiverse and threatened tropical forests. Strategic engagement with commercial operations is increasingly recognized to be an essential part of the solution for raising funds for conservation initiatives, raising consumer consciousness and potentially stemming environmental degradation. Linking market incentives towards conservation is also of critical importance because it is becoming widely recognized that conservation needs to begin to address the wider countryside (outside protected areas) where human–wildlife interactions are frequent and impacts are large. Using the Sumatran tiger Panthera tigris sumatrae as both a threatened species in its own right and emblematic for wider species diversity, we show that western consumers are willing to pay a significant premium for products using palm oil grown in a manner that reduces impacts on such species. Results suggest that the price premium associated with a ‘tiger-friendly’ accreditation may provide a useful additional tool to raise conservation funds and, within the right institutional context, serve as an inducement to address the problem of habitat and species loss.

The 1,080 km2 Batang Gadis National Park in the North Sumatra province of Indonesia was established in December 2004 by the regional government of Mandailing Natal district. The Park has the potential to make an important contribution to tiger conservation but lacks scientific data on the occurrence of the species. This study aimed to assess the tiger population of the Park, using camera trapping conducted between December 2005 and July 2006. We recorded a mean tiger density of 1.8 tigers per 100 km2 (95% CI 1.8–6.4) and, based on this, estimated the tiger population in and adjacent to the Park to be 29–103 adults. We found that tiger presence was negatively correlated with altitude and positively correlated with distance from forest edge to the interior, and < 18% of the total suitable habitat occupied by tigers was of high quality. This study indicates that Batang Gadis National Park potentially serves as a natural corridor betwen the Angkola and Barumun-Rokan ecosystems, areas totalling c. 6,500 km2, and that this landscape could serve as a stronghold for tiger populations in northern Sumatra.

The Sumatran tiger is the only one of three original subspecies of tigers that survives in Indonesia today. Its wild population, estimated to be 400–650 animals, has progressively diminished because of habitat destruction, poaching and the removal of tigers involved in conflicts with local farmers. This paper presents previously undocumented information on the market in tiger products. It shows that, while no documentation of intentional tiger poaching to meet an international demand for tiger bones was recorded, the domestic demand for tiger bones, teeth and claws is still a potential threat to the future survival of this subspecies. In addition to continuing work to protect the integrity of tiger habitat in Sumatra, enforcement actions are required to prevent the domestic market for tiger parts increasing the threats to this subspecies and to ensure its conservation.