The monitoring and management of species depends on reliable population estimates, and this can be both difficult and very costly for cryptic large vertebrates that live in forested habitats. Recently developed camera trapping techniques have already been shown to be an effective means of making mark-recapture estimates of individually identifiable animals (e.g. tigers). Camera traps also provide a new method for surveying animal abundance. Through computer simulations, and an analysis of the rates of camera trap capture from 19 studies of tigers across the species' range, we show that the number of camera days/tiger photograph correlates with independent estimates of tiger density. This statistic does not rely on individual identity and is particularly useful for estimating the population density of species that are not individually identifiable. Finally, we used the comparison between observed trapping rates and the computer simulations to estimate the minimum effort required to determine that tigers, or other species, do not exist in an area, a measure that is critical for conservation planning.

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.

Summary1. The United Nations recently listed illegal wildlife trade as a serious crime because of the escalating demand for highly prized species, such as tiger and rhinoceros, and the failure to effectively control the trade. In turn, this places greater urgency on reducing supply by securing source populations of these species. Yet, whether law enforcement strategies designed to mitigate poaching are succeeding remains poorly understood, despite the millions of dollars invested annually in this mainstay conservation strategy. 2. Here, we assess the performance of one of Asia's longest running law enforcement programmes, from Kerinci Seblat National Park in Sumatra, by investigating whether forest ranger patrols reduced the occurrence of snare traps set for tiger and its ungulate prey base; local informant reports on poaching influenced ranger patrol success; and the resulting population trends of target species changed in response to these conservation actions. 3. A total of 4433 snare traps were removed during 642 foot patrols conducted from 2000 to 2010. Controlling for the influence of varying detection probabilities, as well as accessibility and other possible determinants of illegal hunting, revealed that sites with a greater frequency of patrols, rather than the combined distance walked, had a lower occurrence of snare traps in succeeding years. 4. Patrols conducted on the basis of local informant 'tip-offs' were significantly more likely to detect snare traps than routine patrols, with reports increasing detections by over 40%. 5. There were no significant changes in the occupancy status of the tiger prey base from 2004 to 2011, suggesting that it remained stable during this period. The relatively good condition of prey and predator populations in Kerinci Seblat National Park was further supported by the results of an independent survey conducted in 2008-2009 which revealed a widespread tiger occurrence. 6. Synthesis and applications. Our results not only demonstrate the effectiveness of the Kerinci Seblat law enforcement strategy in protecting wildlife, but highlight the benefits from cultivating a network of reliable informants. The study also represents a critical step in helping these urgently needed conservation assessments to become common place in the fight to save flagship species.

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.