Estimating Patch Occupancy When Patches Are Incompletely Surveyed

Institute of Statistics Mimeo Series #2543 In this paper we describe a method for statistical modeling of the probability of patch occupancy by a species as a function of patch size and other covariates when patches may be incompletely surveyed. The model is appropriate for study designs is which each patch: is visited once; is surveyed at a set of access sites from which an observer can detect the species within a measurable portion of the patch; and is surveyed until the species is detected or until all access sites have been visited. The model explicitly accounts for incomplete patch coverage, providing unbiased estimates of patch occupancy relative to the “naive” modeling approach that ignores incomplete patch coverage. The statistical model is motivated by and illustrated with data from a study of Barred owl habitat.