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Density estimation in a wolverine population using spatial capture-recapture models

July 13, 2011

Classical closed-population capture-recapture models do not accommodate the spatial information inherent in encounter history data obtained from camera-trapping studies. As a result, individual heterogeneity in encounter probability is induced, and it is not possible to estimate density objectively because trap arrays do not have a well-defined sample area. We applied newly-developed, capture-recapture models that accommodate the spatial attribute inherent in capture-recapture data to a population of wolverines (Gulo gulo) in Southeast Alaska in 2008. We used camera-trapping data collected from 37 cameras in a 2,140-km2 area of forested and open habitats largely enclosed by ocean and glacial icefields. We detected 21 unique individuals 115 times. Wolverines exhibited a strong positive trap response, with an increased tendency to revisit previously visited traps. Under the trap-response model, we estimated wolverine density at 9.7 individuals/1,000-km2(95% Bayesian CI: 5.9-15.0). Our model provides a formal statistical framework for estimating density from wolverine camera-trapping studies that accounts for a behavioral response due to baited traps. Further, our model-based estimator does not have strict requirements about the spatial configuration of traps or length of trapping sessions, providing considerable operational flexibility in the development of field studies.

Publication Year 2011
Title Density estimation in a wolverine population using spatial capture-recapture models
DOI 10.1002/jwmg.79
Authors J. Andrew Royle, Audrey J. Magoun, Beth Gardner, Patrick Valkenbury, Richard E. Lowell
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Wildlife Management
Index ID 70004542
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center