Research overview: the Royle-Nichols abundance-induced heterogeneity model

The Royle-Nichols model leverages a simple insight: sites holding more individuals are more likely to produce a detection, so variation in detection across sites encodes information about local abundance. This overview explains how the model links per-individual detection probability to site abundance, allowing relative abundance to be inferred from repeated detection-nondetection data without identifying individuals. It situates the approach between basic occupancy modeling, which estimates only presence, and full N-mixture or capture-recapture methods, and discusses its assumptions, including how individuals contribute independently to detection. For camera-trap studies of cats that cannot be told apart, the model offers a way to map relative abundance from occupancy-style data. The overview covers its uses, limitations, and place within the broader family of unmarked-abundance methods.