Ma. Eifler et Na. Slade, ACTIVITY PATTERNS IN RELATION TO BODY-MASS AND AMBIENT-TEMPERATURE AMONG OVERWINTERING COTTON RATS (SIGMODON HISPIDUS), Canadian journal of zoology, 76(4), 1998, pp. 668-672
We examined mass-specific activity patterns among overwintering cotton
rats (Sigmodon hispidus) in northeastern Kansas. We livetrapped anima
ls for a 24-h period, checking traps every 2 h. Trapping occurred ever
y 2 weeks for 5 months. We estimated probability of capture for each m
ass class, time class, and date, then tested for differences in probab
ility of capture (i.e., activity levels) using a General Linear Model
with temperature as a covariate. Large cotton rats were significantly
less active than small and intermediate-sized cotton rats. Activity of
small cotton rats increased with decreasing temperature, whereas larg
er cotton rats were less responsive to temperature. Finally, activity
levels of large and small cotton rats did not vary significantly with
time of day, but intermediate-sized cotton rats were significantly les
s likely to be captured during the night than at dusk.