Research overview: time-to-event and space-to-event abundance estimators

Time-to-event, space-to-event, and instantaneous-sampling estimators are recognition-free methods that infer animal abundance from how long, or across how much sampled space, one waits until an animal appears at cameras, drawing on encounter-rate theory. This overview explains the intuition that higher densities produce shorter waits and more frequent detections, and how these models exploit the timing and spatial structure of detections without requiring movement-speed calibration or individual identification. It discusses their assumptions, data requirements such as continuous monitoring or known detection-zone areas, and their growing use for unmarked cats and prey. By offering alternatives with different assumptions than the Random Encounter and distance-sampling models, these estimators expand the analyst's toolkit. The overview helps practitioners match method to the data and assumptions their study can support.