title: An empirical evaluation of camera trapping and spatially explicit capture-recapture models for estimating chimpanzee density.
abstract: Empirical validations of survey methods for estimating animal densities are rare, despite the fact that only an application to a population of known density can demonstrate their reliability under field conditions and constraints. Here, we present a field validation of camera trapping in combination with spatially explicit capture-recapture (SECR) methods for enumerating chimpanzee populations. We used 83 camera traps to sample a habituated community of western chimpanzees (Pan troglodytes verus) of known community and territory size in Taï National Park, Ivory Coast, and estimated community size and density using spatially explicit capture-recapture models. We aimed to: (1) validate camera trapping as a means to collect capture-recapture data for chimpanzees; (2) validate SECR methods to estimate chimpanzee density from camera trap data; (3) compare the efficacy of targeting locations frequently visited by chimpanzees versus deploying cameras according to a systematic design; (4) evaluate the performance of SECR estimators with reduced sampling effort; and (5) identify sources of heterogeneity in detection probabilities. Ten months of camera trapping provided abundant capture-recapture data. All weaned individuals were detected, most of them multiple times, at both an array of targeted locations, and a systematic grid of cameras positioned randomly within the study area, though detection probabilities were higher at targeted locations. SECR abundance estimates were accurate and precise, and analyses of subsets of the data indicated that the majority of individuals in a community could be detected with as few as five traps deployed within their territory. Our results highlight the potential of camera trapping for cost-effective monitoring of chimpanzee populations.
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.|Centre for Forest Research, Département des Sciences biologiques, Université du Québec à Montréal, Montréal, Québec, Canada.
authors.forename: Marie-Lyne
authors.identifier: 0000-0003-1659-8177
authors.initials: ML
authors.lastname: Després-Einspenner
authors.affiliation: Centre for Research Into Ecological and Environmental Modelling, The Observatory, University of St Andrews, Fife, UK.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Howe
authors.affiliation: Centre for Forest Research, Département des Sciences biologiques, Université du Québec à Montréal, Montréal, Québec, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Drapeau
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.|German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
authors.forename: Hjalmar S
authors.initials: HS
authors.lastname: Kühl
mesh_terms: D000818:Animals; D007560:Cote d'Ivoire; D004777:Environment; D004784:Environmental Monitoring / Q000379:methods*; D002679:Pan troglodytes; D010781:Photography; D011156:Population Density; D015203:Reproducibility of Results
keywords: camera trapping; chimpanzee; density; monitoring; spatially explicit capture-recapture; survey design