We investigated season-of-release effects on survivorship and reproductive success of laboratory-bred compared with a native population of golden mice [Ochrotomys nuttalli (Harlan)] within a deciduous forest habitat. We released two sets of 32 adult pairs of laboratory-bred golden mice into eight experimental transects established in forest-edge habitat. Releases were conducted in early spring (7 Mar. 2009) and late autumn (2 Nov. 2009). Population abundance of laboratory-bred and native golden mice was severely reduced in late spring and summer following the spring release due to black rat snake [Elaphe obsoleta (Stejneger and Barbour)] predation. Laboratory-bred golden mice, however, maintained a stable population density of 15–18 individuals following the late autumn release as snake predation diminished during winter months. The native population of golden mice maintained an abundance of 25–28 individuals through mid-Mar. The laboratory-bred and native populations exhibited similar reproductive success following autumn release, even crossbreeding during winter.

The season-of-release was the most important factor regarding survivorship and reproductive success of released laboratory-bred golden mice and the native population in identical forest-edge habitat.