Survivorship and Reproductive Success of Released Laboratory-bred and Native Golden Mice within a Forest-edge Habitat

Abstract

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 laboratorybred 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.