Pangolins in global camera trap data: Implications for ecological monitoring

Despite being heavily exploited, pangolins (Pholidota: Manidae) have been subject to
limited research, resulting in a lack of reliable population estimates and standardised
survey methods for the eight extant species. Camera trapping represents a unique opportunity
for broad-scale collaborative species monitoring due to its largely nondiscriminatory
nature, which creates considerable volumes of data on a relatively wide
range of species. This has the potential to shed light on the ecology of rare, cryptic and
understudied taxa, with implications for conservation decision-making. We undertook a
global analysis of available pangolin data from camera trapping studies across their range
in Africa and Asia. Our aims were (1) to assess the utility of existing camera trapping efforts
as a method for monitoring pangolin populations, and (2) to gain insights into the distribution
and ecology of pangolins. We analysed data collated from 103 camera trap surveys
undertaken across 22 countries that fell within the range of seven of the eight
pangolin species, which yielded more than half a million trap nights and 888 pangolin
encounters. We ran occupancy analyses on three species (Sunda pangolin Manis javanica,
white-bellied pangolin Phataginus tricuspis and giant pangolin Smutsia gigantea). Detection
probabilities varied with forest cover and levels of human influence for P. tricuspis, but were low (<0.05) for all species. Occupancy was associated with distance from rivers for M.
javanica and S. gigantea, elevation for P. tricuspis and S. gigantea, forest cover for P. tricuspis
and protected area status for M. javanica and P. tricuspis.We conclude that camera traps are
suitable for the detection of pangolins and large-scale assessment of their distributions.
However, the trapping effort required to monitor populations at any given study site using
existing methods appears prohibitively high. This may change in the future should
anticipated technological and methodological advances in camera trapping facilitate
greater sampling efforts and/or higher probabilities of detection. In particular, targeted
camera placement for pangolins is likely to make pangolin monitoring more feasible with
moderate sampling efforts.