Growth and Dispersal Timing in Male Red-Backed Voles Clethrionomys Rufocanus Bedfordiae

Abstract

Experimental populations of the red-backed vole (Clethrionomys rufocanus bedfordiae), with males of different body weight distributions, were introduced into field enclosures, and then the growth of males, reproductive condition, and home ranges were examined. I compared the growth rates and body weights between males that disappeared during the trapping periods (dispersers), and those that established home ranges throughout the periods (residents). The growth rate of dispersers and residents varied among individuals and among the enclosures. The dates of disappearance of males were compared with the dates of the females whose home ranges overlapped with or adjoined them. The males tended to disappear around the dates of estrus. Resident males overlapped with estrous females more frequently than dispersers. Dispersers tend to be smaller than the males that were competing with them for an estrous female, but statistically significant differences in mean body weight between residents and dispersers could not be found in two of the three enclosures examined.