III - Reproduction of the Bank Vole ( Evotomys glareolus, schreber ). I - The oestrous cycle of the female

Abstract

The Bank Vole is one of the commonest and most widely distributed of British mammals, sometimes increasing in numbers to such an extent as to constitute a serious agricultural pest. The details of its reproductive processes therefore are of some economic importance to agriculture and forestry. Remarkably little information is available regarding the reproductive processes of the species. Marshall (1922) states that it “ is almost certainly polyoestrous, since it can become pregnant immediately after parturition at certain times of the year ” ; a conclusion which is fully substantiated. The results of the earlier observations on the breeding habits are summarized by Barrett-Hamilton (1911). Recently Baker (1930) has provided some further information on this species, and Svihla (1929) has recorded some interesting observations on the breeding in captivity of the allied American species Evotomys gapperi . The oestrous cycle of the Bank Vole described in this paper is that of a wild species, uninfluenced by captivity or domestication. Comparison with the oestrous cycle of the white mouse which is essentially similar in its main features should throw some light on the modifications resulting from domestication.