Breeding of captive bank voles (Clethrionomys glareolus) related to dynamics of source populations

Proportionately fewer female bank voles from cyclic or dense populations bred than did females from sparse or non-cyclic populations when brought into a laboratory and kept as monogamous pairs for at least 1 year. Similarly, fewer litters were produced by females from cyclic or dense populations. Breeding frequency and litter production did not differ in the second laboratory generation. Large variance in litter numbers indicated further changes in reproduction in response to the laboratory environment. Certain differences between origins still persisted after long-term laboratory breeding. The regional variations between field-born animals are most parsimoniously explained by differences in sensitivity to density.