Density estimation in live-trapping studies

Murray Efford introduced spatially explicit density estimation, addressing the long-standing problem that traditional capture-recapture estimates abundance without a well-defined area, forcing ad hoc buffer corrections. He proposed modeling the detection process as a function of distance between an animal's home-range center and each trap, using simulation and inverse prediction to estimate density directly. This conceptual leap eliminated the arbitrary effective-sampling-area step and properly accounted for animals near survey edges. Although developed for live-trapping grids, the spatial detection model became the theoretical foundation of spatially explicit capture-recapture, transforming camera-trap density estimation. Efford's insight underpins the secr software and nearly all modern SECR analyses of felid densities, making it one of the most consequential methodological contributions to the field.