Description
Summary:International audience Common voles in western France exhibit threeyearpopulation cycles with winter crashes after largeoutbreaks. During the winter of 2011–2012, we monitoredsurvival, reproduction, recruitment and population growthrate of common voles at different densities (from low tooutbreak densities) in natura to better understand densitydependence of demographic parameters. Between Octoberand April, the number of animals decreased irrespective ofinitial density. However, the decline was more pronouncedwhen October density was higher (loss of &54 % ofindividuals at low density and 95 % at high density). Usingcapture-mark-recapture models with Pradel’s temporalsymmetry approach, we found a negative effect of densityon recruitment and reproduction. In contrast, density had aslightly positive effect on survival indicating that mortalitydid not drive the steeper declines in animal numbers at highdensity. We discuss these results in a population cycleframework, and suggest that crashes after outbreaks couldreflect negative effects of density dependence on reproductionrather than changes in mortality rates.