title: Examining Temporal Sample Scale and Model Choice with Spatial Capture-Recapture Models in the Common Leopard Panthera pardus.
abstract: Many large carnivores occupy a wide geographic distribution, and face threats from habitat loss and fragmentation, poaching, prey depletion, and human wildlife-conflicts. Conservation requires robust techniques for estimating population densities and trends, but the elusive nature and low densities of many large carnivores make them difficult to detect. Spatial capture-recapture (SCR) models provide a means for handling imperfect detectability, while linking population estimates to individual movement patterns to provide more accurate estimates than standard approaches. Within this framework, we investigate the effect of different sample interval lengths on density estimates, using simulations and a common leopard (Panthera pardus) model system. We apply Bayesian SCR methods to 89 simulated datasets and camera-trapping data from 22 leopards captured 82 times during winter 2010-2011 in Royal Manas National Park, Bhutan. We show that sample interval length from daily, weekly, monthly or quarterly periods did not appreciably affect median abundance or density, but did influence precision. We observed the largest gains in precision when moving from quarterly to shorter intervals. We therefore recommend daily sampling intervals for monitoring rare or elusive species where practicable, but note that monthly or quarterly sample periods can have similar informative value. We further develop a novel application of Bayes factors to select models where multiple ecological factors are integrated into density estimation. Our simulations demonstrate that these methods can help identify the "true" explanatory mechanisms underlying the data. Using this method, we found strong evidence for sex-specific movement distributions in leopards, suggesting that sexual patterns of space-use influence density. This model estimated a density of 10.0 leopards/100 km2 (95% credibility interval: 6.25-15.93), comparable to contemporary estimates in Asia. These SCR methods provide a guide to monitor and observe the effect of management interventions on leopards and other species of conservation interest.
authors.affiliation: Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, Montana, United States of America.
authors.forename: Joshua F
authors.initials: JF
authors.lastname: Goldberg
authors.affiliation: Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, Montana, United States of America.|Ugyen Wangchuck Institute for Conservation and Environment, Department of Forests and Park Services, Ministry of Agriculture and Forests, Lamai Goempa, Bumthang, Bhutan.
authors.forename: Tshering
authors.initials: T
authors.lastname: Tempa
authors.affiliation: Ugyen Wangchuck Institute for Conservation and Environment, Department of Forests and Park Services, Ministry of Agriculture and Forests, Lamai Goempa, Bumthang, Bhutan.
authors.forename: Nawang
authors.initials: N
authors.lastname: Norbu
authors.affiliation: Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, Montana, United States of America.
authors.forename: Mark
authors.initials: M
authors.lastname: Hebblewhite
authors.affiliation: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: L Scott
authors.initials: LS
authors.lastname: Mills
authors.affiliation: Bhutan Foundation, Washington, D.C., United States of America.
authors.forename: Tshewang R
authors.initials: TR
authors.lastname: Wangchuk
authors.affiliation: Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, Montana, United States of America.
authors.forename: Paul
authors.initials: P
authors.lastname: Lukacs
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D017753:Ecosystem; D005260:Female; D008297:Male; D008954:Models, Biological; D046009:Panthera / Q000502:physiology*; D011156:Population Density