Estimating site occupancy and detection probability parameters for meso- and large mammals in a coastal eosystem

Journal of Wildlife Management
By: , and 



Large-scale, multispecies monitoring programs are widely used to assess changes in wildlife populations but they often assume constant detectability when documenting species occurrence. This assumption is rarely met in practice because animal populations vary across time and space. As a result, detectability of a species can be influenced by a number of physical, biological, or anthropogenic factors (e.g., weather, seasonality, topography, biological rhythms, sampling methods). To evaluate some of these influences, we estimated site occupancy rates using species-specific detection probabilities for meso- and large terrestrial mammal species on Cape Cod, Massachusetts, USA. We used model selection to assess the influence of different sampling methods and major environmental factors on our ability to detect individual species. Remote cameras detected the most species (9), followed by cubby boxes (7) and hair traps (4) over a 13-month period. Estimated site occupancy rates were similar among sampling methods for most species when detection probabilities exceeded 0.15, but we question estimates obtained from methods with detection probabilities between 0.05 and 0.15, and we consider methods with lower probabilities unacceptable for occupancy estimation and inference. Estimated detection probabilities can be used to accommodate variation in sampling methods, which allows for comparison of monitoring programs using different protocols. Vegetation and seasonality produced species-specific differences in detectability and occupancy, but differences were not consistent within or among species, which suggests that our results should be considered in the context of local habitat features and life history traits for the target species. We believe that site occupancy is a useful state variable and suggest that monitoring programs for mammals using occupancy data consider detectability prior to making inferences about species distributions or population change.

Publication type Article
Publication Subtype Journal Article
Title Estimating site occupancy and detection probability parameters for meso- and large mammals in a coastal eosystem
Series title Journal of Wildlife Management
DOI 10.2193/0022-541X(2006)70[1625:ESOADP]2.0.CO;2
Volume 70
Issue 6
Year Published 2006
Language English
Publisher The Wildlife Society
Contributing office(s) Patuxent Wildlife Research Center
Description 9 p.
First page 1625
Last page 1633
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