Exploring the influence of density-dependence and weather on the spatial and temporal variation in common vole (Microtus arvalis) abundance in Castilla y León, NW Spain.

BACKGROUND

The common vole invaded the agroecosystems of northwestern Spain, where outbreaks cause important crop damage and management costs. Little is yet known about the factors causing or modulating vole fluctuations. Here we used 11 years of vole abundance monitoring data in 40 sites to study density-dependence and weather influence on vole dynamics. Our objective was to identify the structure of population dynamics and determine if there is direct or delayed density-dependence. An evaluation of climatic variables followed, to define if they influenced vole population peaks.

RESULTS

First and second-order outbreak dynamics were detected in 7 and 33 study sites, respectively, together with variability in periodicity in the second order (2-3 to 4-5-year cycles). Vole population growth was explained by previous year abundances (mainly summer and spring numbers) in 21 of the sites (52.5%), by weather variables in 11 sites (27.5%; precipitation or temperature in 6 and 5 sites, respectively), and by a combination of previous abundances and weather variables in 8 sites (20%).

CONCLUSIONS

We detected variability in vole spatiotemporal abundance dynamics, which differs in cyclicity and period. We also found regional variation in the relative importance of previous abundances and weather as modulating factors of vole fluctuations. Most vole populations were cyclical, with variable periodicity across the region. Our study is a first step towards the development of predictive modelling, by disclosing relevant factors that might trigger vole outbreaks. It improves decision-making processes within integrated management dealing with mitigation of agricultural impacts caused by voles. This article is protected by copyright. All rights reserved.

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