Are mature female voles more susceptible than immature ones to avian predation?

Abstract

It is well known that a number of activities related to reproduction can increase the predation risk for individuals. Both in the aviary and in the field, we studied whether maturity of female field voles (Microtus agrestis) affected their behaviour and consequently their risk of predation by Tengmalm's owls (Aegolius funereus). In an aviary, we recorded the behaviour of mature and immature voles in control (owl absent) and predator (owl present) treatments, but did not find obvious differences in behaviour or vulnerability between mature and immature female voles. In the field, we compared maturity status of female field voles snap-trapped in owl territories with those caught by breeding owls in 1992 and 1994. In accordance with the results from an aviary experiment, there were no obvious differences in vulnerability to Tengmalm's owls between mature and immature individuals. This suggests that mature and immature female field voles are equally exposed to avian predation.