Environmental Temperature Modulates Onset

Individual dams and their litters were observed from Days 14-22 in a seminatural environment consisting of a nestbox attached to a larger, open field in which powdered chow was available. Ambient temperature in the field was either warm (30”C), moderate (21”C), or cold (10°C); nest temperature was always moderate. Behavior was monitored 12 hr/day by time-lapse video recording. The pups’ egressions into the field and onset of independent feeding were temperature-related: Weaning was earliest in the warmth and increasingly late with decreasing ambient temperature. Among subjects in the cold condition, there was a positive correlation between duration in the field and duration feeding. Pup growth was unaffected by the temperature regimes. Environmental temperature has emerged as a determinant for early nest egressions and weaning onset.