Non-lethal effects of avian predators on root voles (Microtus oeconomus).

Abstract

Abstract Anti-predation behaviour in many rodents has mainly been studied under laboratory conditions, and less in naturally conditions in the field. Here we studied the results of an experiment specifically designed for testing the effect of avian predators on root vole Microtus oeconomus sub-populations. We compare the frequency of risk-prone behaviour in six protected versus six unprotected sub-populations, and study possible costs connected to such risky behaviour. More specifically, we predicted that root vole are able to detect the current risk of predation by avian, and therefore we assume that the degree of risk prone behaviour in root voles will be higher in areas protected from avian predators compare with unprotected areas. Additionally, we also investigate the possibility that the preceding mortality rate of the sub-populations is the specific cue used for detecting the current predation level and risk of being killed by a predator. In accordance with our hypothesis, the results showed that adults root voles performed less out-of-patch excursions when inhabiting areas with high levels of predation. Juveniles, on the other hand, did not differ between high and low predation levels. The frequencies of adult out-of-patch excursions were also positively correlated with the preceding mortality rate of the sub-population, we therefore suggest that mortality rate may be the cue used by the individuals as a demographical indicator of the current risk of predation.