The effect of time of release on microhabitat use by the white-footed mouse

Fluorescent paint powders have frequently been used to determine the spatial activity patterns and microhabitat use of small mammals. The time of day that powdered animals were released differs among studies and data used in many studies were collected on the trails of powdered animals released in the morning outside the normal period of activity of many species of small mammals. We tested for differences in the characteristics of fluorescent powder trails of white-footed mice Peromyscus leucopus (Rafmesque, 1818) released using three protocols: night capture-night release, morning capture-morning release, and morning capture-delayed night-release. The night release and morning release protocols were established to replicate the extremes found in the literature. We added the third protocol to evaluate how capturing mice in the morning, holding them in captivity, and releasing them at night affected their use of microhabitat. There were no significant differences in the use of microhabitat between the night release and delayed night-release treatments. However, a significantly greater proportion of the trails of mice released in the morning were in areas of thick cover and under logs than the trails of mice released at night. Because mice released during the day used microhabitat differently than mice released at night, we caution against the interpretation of data on use of habitat collected using the fluorescent powder trails of animals released outside their normal period of activity.