Sex differences in patch-leaving foraging decisions in rats

The ubiquity, importance, and sophistication of foraging behavior makes it an ideal platform for studying naturalistic decision making in animals. We developed a spatial patch-foraging task for rats, in which subjects chose how long to remain in one foraging patch as the rate of food earnings steadily decreased. The cost of seeking out a new location was varied across sessions. The behavioral task was designed to mimic the structure of natural foraging problems, where distinct spatial locations are associated with different reward statistics, and decisions require navigation and movement through space. Male and female Long-Evans rats generally followed the predictions of theoretical models of foraging, albeit with a consistent tendency to persist with patches for too long compared to behavioral strategies that maximize food intake rate. The tendency to choose overly-long patch residence times was stronger in male rats. We also observed sex differences in locomotion as rats performed the task, but these differences in movement only partially accounted for the differences in patch residence durations observed between male and female rats. Together, these results suggest a nuanced relationship between movement, sex, and foraging decisions. Significance statement Foraging behavior offers a naturalistic way of studying temporal investment amongst different choice options, a translationally-important form of decision making. Previous laboratory investigations have relied on foraging tasks that require little movement from subjects, which could affect the strategies that animals use and the neural mechanisms that support them. We developed a spatial foraging task for rats. Behavior generally matched the predictions of theoretical models, although rats remained in patches for longer than prescribed. Male rats exhibited a stronger tendency to overharvest patches than female rats. Sex differences in movement did not account for sex differences in foraging. These data highlight the interplay between movement and decision making, and demonstrate the utility of spatial tasks for studies of foraging.