Chitty's Hypothesis and Behaviour in Subarctic Red-Backed Voles Clethrionomys Gapperi

Abstract

Behavioural relations in Clethrionomys gapperi were studied in peak and decline years as a partial test of Chitty's polymorphic behaviour hypothesis. Behaviour was related to sex, age, and sexual maturity, and was consistent with a dominance hierarchy that favoured mature females over immatures of both sexes and mature males. Dominant voles selectively occupied preferred habitat, but they did not consistently differ from subordinate voles in individual attributes. This social structure appeared to be an adaptation to suboptimal subarctic conditions that favoured selection for maximal reproductive output. Behavioural changes associated with declining population density were contrary to Chitty's original prediction. High density selected for docile as opposed to aggressive types in some population categories. These results suggest a need for further study of behaviour, seasonal generations, and dispersal in microtine populations.