Abstract
BackgroundCyclic rodent population dynamics are subjected to both intrinsic regulatory processes such as density-dependence and extrinsic environmental forcing. Among extrinsic factors, seasonal environmental variation is understood to facilitate cycles. In rodents, these processes have been studied mostly independently and their relative importance for population dynamics is poorly known.ResultsWe performed a detailed analysis of common vole (Microtus arvalis) reproduction in a cyclic population using a spatially extensive data set over 17 years in central-western France. Environmental seasonality was the main source of explained variation in common vole reproduction. Additionally, inter-annual variation in the environment explained a smaller part of the variance in reproduction in spring and summer than in winter, whereas the effect of density was only found in autumn and winter. In particular, we detected a strong impact of plant productivity on fecundity during the breeding season, with low vegetation productivity being able to bring vole reproduction nearly to a halt. In contrast, vole reproduction during autumn and winter was mainly shaped by intrinsic factors, with only the longer and heavier females being able to reproduce. The effect of population density on reproduction was negative, mediated by direct negative effects on the proportion of breeders in autumn and winter during outbreak years and by a delayed negative effect on litter size the following year.ConclusionsDuring the main breeding season, variability of female vole reproduction is predominantly shaped by food resources, suggesting that only highly productive environment may induce vole outbreaks. During fall and winter, variability of female vole reproduction is mainly controlled by intrinsic factors, with high population density suppressing reproduction. This suggests, in this cyclic population, that negative direct density dependence on reproduction could explain winter declines after outbreaks.
Highlights
Cyclic rodent population dynamics are subjected to both intrinsic regulatory processes such as density-dependence and extrinsic environmental forcing
Were calculated in the set of models having a ΔAIC (AIC AIC of the best model) < 4 in order to compare the relative importance of the different selected variables. At this stage of the procedure, we introduced in the model all candidate variables that, based on literature survey, could be expected to influence common vole reproduction
We showed that NDVI anomalies have a large impact on both the breeding probability and litter size, though only during the main breeding season, which can be as unproductive as autumn and winter when the plant productivity anomaly is very low (Figure 5d)
Summary
Cyclic rodent population dynamics are subjected to both intrinsic regulatory processes such as density-dependence and extrinsic environmental forcing. Seasonal environmental variation is understood to facilitate cycles. In rodents, these processes have been studied mostly independently and their relative importance for population dynamics is poorly known. At temperate and arctic latitudes in particular, seasonal fluctuations in climate and day length constrain the primary production of ecosystems. This seasonality of Centre d’Etudes Biologiques de Chizé (CEBC-CNRS), Beauvoir sur Niort. Population dynamics of herbivores is severely impacted by food availability [4,5,6] This is true for rodents, which are small species with high fecundity, and are highly sensitive to changes in food availability, notably through the regulation of reproduction
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
