Foraging and Caching Behavior of the Plateau Mouse (Peromyscus melanophrys)

Abstract

This study explores the foraging and caching behavior of the Peromyscus melanophrys. Subjects consisted of twelve randomly selected first generation lab-raised Peromyscus melanophrys—six mature males and six mature females. Subjects were kept on a 15L:9D summer photoperiod with their environment maintained at 20-25°C. Subjects were allowed to become habituated to their surroundings in the nest box, with food and water, for several days before experimental sessions began, however, subjects were not allowed access to a runway section of their boxes until sessions began. Subjects were randomly divided into a food satiated and a food unsatiated group, with the three individuals of each sex randomly assigned to each group. The first group was the food satiated group, who had free access to food until 1.5 hours before each experimental session. The other group—the unsatiated food group—was deprived of food for 25.5 hours before each session. Each run consisted of eight experimental sessions, which included two unrecorded trial session to accustom subjects to the runways. The remaining sessions were each spaced 44 hours apart and consisted of two experiments at varying distances. Thirty rat chow blocks—10 small (1.5g), 10 intermediate (3.5g), and 10 large (5g)—were placed in bins at the end of each runway. Each session consisted of a three hour period beginning 1.5 hours after the beginning of the dark period, during which subjects accessed the runways. Researchers recorded foraging activity (any activity where the subject contacted, moved, or consumed the food provided) and caching activity (removing the food to the next box). Recorded data included the interval in which it was cached, the location of the blocks within the nest chamber at the end of the session, and the exact weight of the food blocks before and after the session to determine the amount of food consumed. Researchers observed that there is a great deal of normal variation in P. melanophrys’ foraging and caching behavior. Researchers note that there may be a range of minimum and maximum distances that an animal will travel when foraging, however that range varies from species to species and is affected by environmental conditions. Distance may play an important role in subjects’ foraging/caching strategies, with subjects hauling larger loads over longer distances. No significant differences between male and female subjects’ foraging/caching behaviors were observed, contradicting earlier research.