A Quantitative Study of Nest Exiting during Weaning in Peromyscus leucopus

Abstract

This is the first report on nest exiting by rodents during weaning in which the behavior was monitored continuously while the animals were allowed full freedom of movement and social interaction. Peromyscus leucopus usually first left the nest box in brief exits at age 15– 18 days. Total time out of the box daily increased rapidly after first exit, reaching a quasiasymptotic value averaging >5 h by 24–26 days. At ages 18–23 days, young reared at 15–19°C averaged >40% more time per day out of the nest box than ones reared at 5–11°C.