Camera trapping for conservation

Camera traps use a motion sensor to capture images of passing animals, representing verifiable and non-invasive records of the presence of a given species at a specified place and time. These simple records provide fundamental data on biodiversity that have proven invaluable to conservation. Thanks to the improved (better, smaller, and less expensive) camera technology and the concurrent development of analytical approaches, camera trapping science has grown steadily in the last 15 years and advanced our knowledge of elusive and rare fauna across the planet. Here we review the use and potential of camera trapping in conservation science. We start with an introduction to the importance and challenges of studying reclusive wildlife and discuss the technical aspects of camera traps that make them so efficient and widely used for this purpose. We then review the variety of ways camera trapping has contributed to conservation, first presenting the wildlife metrics camera traps can document and then surveying how these have been applied to conservation through studies of habitat preference, distribution models, threat assessments, monitoring, and evaluations of conservation interventions. We also present case studies showing how camera trapping can effectively contribute to link ecological monitoring to conservation, including how data and images can be used to engage the public and policymakers with conservation issues, and how this work is now being scaled up through citizen science and networks of standardized data collection coupled with cyber-infrastructures for automatized analyses. We conclude by reviewing possible technological improvements of camera traps and how they would aid conservation in the future.