Research overview: heterogeneity in capture probability and model selection

Animals differ in how likely they are to be photographed, due to home-range placement, behavior, sex, age, or trail use, and this heterogeneity in capture probability, if unmodeled, biases abundance estimates downward. This overview surveys how capture-recapture models accommodate heterogeneity, from the classic model set allowing time, behavioral, and individual variation, to modern approaches incorporating covariates and finite mixtures. It discusses model-selection challenges, the difficulty of distinguishing heterogeneity from other effects with sparse felid data, and the consequences of choosing the wrong model. The overview connects heterogeneity to study design, since better array coverage reduces it, and to spatially explicit methods that absorb much spatial heterogeneity through the detection function. Recognizing and properly modeling unequal catchability remains central to producing unbiased abundance and density estimates from camera-trap captures.