BREEDING SUPPRESSION IN VOLES UNDER PREDATION RISK OF SMALL MUSTELIDS- LABORATORY OR METHODOLOGICAL ARTIFACT

Many prey animals have life-history strategies that seem to have evolv ed to avoid predation from specialist predators. During the past few y ears, the hypothesis of breeding suppression (BSH) of voles as an adap tation to avoid small mustelid predation has prompted several empirica l and theoretical studies. However, the validity of empirical work as well as justification of the conclusions in these studies have been cr iticised. Here we report results of an experiment in which we studied the breeding suppression of bank voles, Clethrionomys glareolus, in fo ur replicated enclosures. We found no effects of simulated least wease l, Mustela nivalis nivalis. predation risk on the reproductive output of Female voles. In contrast to earlier laboratory studies, the weight s of females did not differ between treatment groups after the experim ent. We reanalysed results of our earlier laboratory studies in light of these results and criticism of the BSH. At present there is no dire ct evidence for breeding suppression of voles in field populations. Fu rthermore, the underlying assumptions of the BSH have not been tested experimentally. Thus the most parsimonious explanation for breeding su ppression is that it may be a methodological or laboratory artifact.