Using first-passage time to link behaviour and habitat in foraging paths of a terrestrial predator, the racoon

An understanding of how animals alter their behaviour in relation to environmental conditions is a key element in the study of animal movement, foraging ecology and habitat use, and can provide valuable information for practical conservation and management applications. To exploit resources in heterogeneous landscapes optimally, foragers should intensively search in profitable patches while minimizing foraging activities in low-quality areas. We used first-passage time (FPT) analysis to identify and characterize area-restricted search (ARS) behaviour along the nightly movement paths of racoons. While FPT analysis has been successfully applied to a variety of pelagic species, our goal was to determine the ability of FPT to detect habitat characteristics associated with changes in searching behaviour for a terrestrial predator. Racoons, Procyon lotor, were tracked via radiotelemetry during their nightly movements. We found evidence of ARS behaviour in 55 of 58 paths, with racoons concentrating intensive searching bouts in areas with an average radius of 42.6 m (range 20–100 m). To test whether our detection of ARS represented an actual change in behaviour, we tracked five racoons in relation to an artificial food patch. We detected ARS behaviour during 9 of 10 occasions in which a tracked animal encountered the food patch. Racoons showed ARS behaviour in areas with abundant shallow water, and they moved quickly through openings and dry areas with sparse ground-level vegetation. Application of this method should prove useful for studies of habitat use and foraging ecology of terrestrial predators by providing links between animal movements and the environment.

► Evidence of area-restricted searching was found in the nightly foraging paths of racoons. ► Racoons concentrated intensive searching behaviour in shallowly flooded forest areas. ► Racoons moved quickly through dry areas with sparse understory vegetation and forest openings. ► This represents the first reported use of first-passage time analysis on the foraging path of a terrestrial predator. ► First-passage time is a potentially useful tool in the study of terrestrial predator foraging behaviour.