Research overview: edge effects and the effective sampling area

A persistent problem in camera-trap density estimation is that animals near the edge of a camera array spend only part of their range within it, so naive abundance divided by the array area overestimates density, the edge effect. This overview surveys how the field has grappled with defining the effective sampling area, from buffer corrections to spatially explicit capture-recapture, which resolves the issue by modeling animal activity centers and detection as a function of distance, naturally accounting for partial exposure of edge animals. It discusses how array size relative to home-range size governs the severity of edge effects and why small arrays produce especially biased density estimates. The overview clarifies a subtle but fundamental source of error and explains why spatial models are now preferred for translating captures into density.