SUMMARY 1. The wood mouse (Peromyscus leucopus) population in a 17-acre area of bottomland forest was live-trapped, marked and released over a 7-night period. Following the live-trapping a central 1-acre plot was snap-trapped for 35 consecutive nights. All adult animals taken in the central snap-trapped plot had previously been taken, marked, and released in the live-trapped 17-acre area. 2. Animals taken first in the central acre were those whose normal ranges overlapped or closely approached this area. After these were removed from the area the animals captured in the central acre were in general those whose normal ranges were at succeedingly greater distances. Ingress was from all directions. 3. Most of the animals taken in the central area were those with previously established nearby home ranges, not merely vagrant animals. 4. Thirty-six of the invading animals were adult males, 18 were adult females, and 22 were young juveniles recently emerged from nests. Numbers of male and female adults had been shown in the live-trapping to be approximately equal.
