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Little is known about interactions between the critically endangered Sumatran tiger Panthera tigris sumatrae and its prey because of the difficulties associated with detecting these species. In this study, we quantify temporal overlap between the Sumatran tiger and five of its presumed prey species from four study areas comprising disturbed lowland to primary submontane forest. Data from 126 camera traps over 8984 camera days were used to estimate species activity patterns and, in turn, their overlap through the coefficient D (ranging from 0 to 1, i.e. no overlap to complete overlap). A newly developed statistical technique was applied to determine confidence intervals associated with respective overlap, which is important, as such measures of precision are usually not estimated in these types of study. Strong temporal overlap was found between tiger and muntjac Muntiacus muntjac (D = 0.80, 95%CI= 0.71-0.84) and tiger and sambar Cervus unicolor (D =0.81, 0.55-0.85), with the latter illustrating the importance of measuring precision. According to the foraging theory, Sumatran tigers should focus on expending lower levels of energy searching for and then capturing larger bodied prey that present the least risk. Hence, surprisingly, there was little overlap between the crepuscular tiger and the largest-bodied prey species available, the nocturnal tapir Tapirus indicus (0.52, 0.44-0.60), suggesting that it is not a principal prey species. This study provides the first insights into Sumatran tiger-prey temporal interactions. The ability to estimate overlap statistics with measures of precision has obvious and wide benefits for other predator-prey and interspecific competition studies.

Aim  This study determines whether the establishment of tropical protected areas (PAs) has led to a reduction in deforestation within their boundaries or whether deforestation has been displaced to adjacent unprotected areas: a process termed neighbourhood leakage. Location  Sumatra, Indonesia. Methods  We processed and analysed 98 corresponding LANDSAT satellite images with a c. 800 m2 resolution to map deforestation from 1990 to 2000 across 440,000 km2 on the main island of Sumatra and the smaller island of Siberut. We compared deforestation rates across three categories of land: (1) within PAs; (2) in adjacent unprotected land lying with 10 km of PA boundaries; and (3) within the wider unprotected landscape. We used the statistical method of propensity score matching to predict the deforestation that would have been observed had there been no PAs and to control for the generally remote locations in which Sumatran PAs were established. Results  During the period 1990–2000 deforestation rates were found to be lower inside PAs than in adjacent unprotected areas or in the wider landscape. Deforestation rates were also found to be lower in adjacent unprotected areas than in the wider landscape. Main conclusions  Sumatran PAs have lower deforestation rates than unprotected areas. Furthermore, a reduction in deforestation rates inside Sumatran PAs has promoted protection, rather than deforestation, in adjacent unprotected land lying within 10 km of PA boundaries. Despite this positive evaluation, deforestation and logging have not halted within the boundaries of Sumatran PAs. Therefore the long‐term viability of Sumatran forests remains open to question.

Summary1. Conservation managers require accurate and timely information on the occurrence, size and viability of populations, but this is often difficult for cryptic species living at low densities over large areas. This study aimed to provide such information for tigers in the 36 400-km 2 Kerinci Seblat (KS) region, Sumatra, by identifying and assessing subpopulation viability under different management strategies. 2. Tiger occurrence was mapped within a geographical information system (GIS) using repeat detection-non-detection surveys to incorporate a function of detection probability into a logistic regression model. The landscape variables that influenced tiger occupancy were then used to construct a spatially explicit habitat model to identify core areas. 3. The number of tigers within each core area was estimated by calculating the area of different forest types and their respective tiger densities as determined through camera trapping. The viability of each subpopulation was then assessed under different management scenarios using a population viability analysis (PVA). 4. Tiger occurrence was negatively correlated with distance to public roads. Four core tiger areas were identified, all predominantly located within KS National Park, estimated to support subpopulations of 21, 105, 16 and three adult tigers, respectively. PVA showed that the three larger subpopulations could be demographically viable if well protected. However, if poaching removed ≥ 3 tigers per year, then only the largest subpopulation would not reach extinction within 50 years. Connectivity to this large subpopulation would ensure survival of the smaller subpopulations, through providing a source of tigers to offset poaching losses. 5. Synthesis and applications. Our key management recommendations for tigers in the Kerinci Seblat region of Sumatra stress the importance of maintaining connectivity between the smaller areas and the larger area, and minimizing poaching within these smaller areas. More widely, our research has shown the feasibility of using detectionnon-detection surveys combined with spatial modelling to provide timely information for conservation management.

Threatened species become increasingly difficult to detect as their populations decline. Managers of such cryptic threatened species face several dilemmas: if they are not sure the species is present, should they continue to manage for that species or invest the limited resources in surveying? We find optimal solutions to this problem using a Partially Observable Markov Decision Process and rules of thumb derived from an analytical approximation. We discover that managing a protected area for a cryptic threatened species can be optimal even if we are not sure the species is present. The more threatened and valuable the species is, relative to the costs of management, the more likely we are to manage this species without determining its continued persistence by using surveys. If a species remains unseen, our belief in the persistence of the species declines to a point where the optimal strategy is to shift resources from saving the species to surveying for it. Finally, when surveys lead to a sufficiently low belief that the species is extant, we surrender resources to other conservation actions. We illustrate our findings with a case study using parameters based on the critically endangered Sumatran tiger (Panthera tigris sumatrae), and we generate rules of thumb on how to allocate conservation effort for any cryptic species. Using Partially Observable Markov Decision Processes in conservation science, we determine the conditions under which it is better to abandon management for that species because our belief that it continues to exist is too low. . Even the persistence of large mammals, like the Sumatran rhinoceros, Dicerorhinus sumatrensis, can be uncertain in particular locations (8). Managers of cryptic threatened species are prone to 2 sorts of error. First, it is possible, if not likely, that some reserves are being managed to conserve a species that has already disappeared or become functionally extinct (e.g., the Ivory-billed woodpecker, Campephilus principalis) (9, 10). The second possible error is that managers could give up on a species too soon, failing to invest in sufficient surveying to be sufficiently sure further management is unwarranted. Managers of protected areas need to know how long they should continue investing in conservation management without strong evidence that the species is still present and when to shift their resources from saving a species to looking for that species, that is, surveying. Ultimately, if their belief in the persistence of the species continues to decline, when should managers surrender resources to another conservation problem?The problem of how best to allocate conservation resources can be couched in terms of a trade-off between managing, surveying, or doing nothing (surrendering and redistributing resources to other problems). Whether to invest scarce management resources and time in surveying may be a difficult decision for managers to make, although some may argue that expenditure on determining the presence of a potentially viable population is a prerequis...

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BackgroundPlasmodium knowlesi is a zoonotic pathogen, transmitted among macaques and to humans by anopheline mosquitoes. Information on P. knowlesi malaria is lacking in most regions so the first step to understand the geographical distribution of disease risk is to define the distributions of the reservoir and vector species.MethodsWe used macaque and mosquito species presence data, background data that captured sampling bias in the presence data, a boosted regression tree model and environmental datasets, including annual data for land classes, to predict the distributions of each vector and host species. We then compared the predicted distribution of each species with cover of each land class.ResultsFine-scale distribution maps were generated for three macaque host species (Macaca fascicularis, M. nemestrina and M. leonina) and two mosquito vector complexes (the Dirus Complex and the Leucosphyrus Complex). The Leucosphyrus Complex was predicted to occur in areas with disturbed, but not intact, forest cover (> 60 % tree cover) whereas the Dirus Complex was predicted to occur in areas with 10–100 % tree cover as well as vegetation mosaics and cropland. Of the macaque species, M. nemestrina was mainly predicted to occur in forested areas whereas M. fascicularis was predicted to occur in vegetation mosaics, cropland, wetland and urban areas in addition to forested areas.ConclusionsThe predicted M. fascicularis distribution encompassed a wide range of habitats where humans are found. This is of most significance in the northern part of its range where members of the Dirus Complex are the main P. knowlesi vectors because these mosquitoes were also predicted to occur in a wider range of habitats. Our results support the hypothesis that conversion of intact forest into disturbed forest (for example plantations or timber concessions), or the creation of vegetation mosaics, will increase the probability that members of the Leucosphyrus Complex occur at these locations, as well as bringing humans into these areas. An explicit analysis of disease risk itself using infection data is required to explore this further. The species distributions generated here can now be included in future analyses of P. knowlesi infection risk.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1527-0) contains supplementary material, which is available to authorized users.

Crop raiding can reduce farmers' tolerance towards wildlife. Despite higher human population densities in rural areas, and more rapid conversion of forest to farmland, much less is known about crop raiding in Asia than in Africa. Over 14 months, we identified perceived and actual crop pests, and their patterns of crop raiding from farmland in and around Kerinci Seblat National Park, Sumatra. Farmers named either the wild boar Sus scrofa (80%) or the pig-tailed macaque Macaca nemestrina (20%) as the two most destructive crop pests. From 5125 crop raids by 11 species of mammal, most raids were indeed made by the wild boar (56%) and the pig-tailed macaque (19%). For all species combined, temporal crop raiding peaks were positively correlated with periods of high rainfall. Spatially, most crop raids occurred nearest to the forest edge and the local guarding strategies used were ineffective. However, raids by wild boars were more extensive than raids by pig-tailed macaques, which caused much greater crop damage (73%) than wild boars (26%), contrary to farmers' perceptions. Our research suggests that alternative mitigation strategies need to be trialed over dry and rainy seasons to identify the most effective strategies and that guarding effort should be increased during the rainy seasons and tailored towards specific crop raiding species based on their unique spatial patterns.