Empirical comparison of density estimators for large carnivores

摘要: Summary 1. Population density is a critical ecological parameter informing effective wildlife management and conservation decisions. Density often estimated by dividing capture–recapture (C–R) estimates of abundance ( ^ N) size the study area, but this relies on assumption geographic closure – situation rarely achieved in studies large carnivores. For geographically open populations N overestimated relative to area because animals with only part their home range are available for capture. This bias (‘edge effect’) more severe when such as carnivores widely. To compensate edge effect, boundary strip around trap array commonly included estimating A). Various methods width proposed, ⁄ A carnivore generally mistrusted unless concurrent telemetry data define A. Remote sampling cameras or hair snags may reduce costs duration, yet without inflated remain problematic. 2. We evaluated recently developed spatially explicit (SECR) models using from common carnivore, American black bear Ursus americanus, obtained remote 11 populations. These permit direct estimation population C–R assuming closure. compared derived approach those conventional approaches that estimate 3. Spatially were 20–200% lower than densities .A ICc supported individual heterogeneity capture probabilities sizes. Variable could not be accounted 4. Synthesis applications. conclude higher SECR consistent positive due effects former. Inflated lead decisions placing threatened endangered at greater risk. Such avoided violation cannot minimized design.