Evaluating methods for detecting and monitoring pangolin (Pholidata: Manidae) populations

The behaviours, ecologies and morphologies of pangolins make them challenging to survey and monitor, and non-targeted wildlife surveys have not produced robust status assessments, especially where population densities are low because of overexploitation. To inform the development of feasible survey and monitoring techniques for pangolins, we conducted a systematic review of all traceable efforts used to survey and monitor pangolins to date: 87 articles were included in the review. Pitfalls of current approaches are discussed and recommendations made on suitable methods. Recommendations include the use of mark-recapture for burrow-dwelling species, community interviews, sign-based surveys in arid and open habitats, detection dog teams, and targeted camera-trapping. Occupancy sampling using camera-traps could be used to monitor some pangolin populations, particularly ground-dwelling species, but the rarity of all species makes it uncertain whether this would provide enough data for monitoring; combinations of methods used within an occupancy sampling framework are likely to be the most effective. There will be many circumstances where direct monitoring of a population at a site, to a level that will generate precise data, is not financially viable nor the best use of conservation resources. In many sites, particularly in Asia, pangolins are too rare as a result of overexploitation, and/or occur in inaccessible areas where significant resources will be needed to implement a targeted monitoring programme. Under such circumstances, the use of proxy variables, including status of other hunting-sensitive species that are easier to record, in combination with enforcement or patrol data and/or community interviews, is likely to be the most cost-effective method for assessing the impact of conservation interventions on pangolin status. The publication of incidental observations and survey ‘by-catch’ would significantly improve understanding of pangolin status and ecology, and therefore how best to identify, conserve and monitor priority populations.