Are degraded habitats from agricultural crops associated with elevated faecal glucocorticoids in a wild population of common vole (Microtus arvalis)?

The severe impact of agriculture on species' abundance and diversity is widely recognized. However, its effects on the physiology of wild animal populations are poorly known. We analyzed faecal glucocorticoids levels in wild common voles (Microtus arvalis) living in a farmland landscape to test whether living in degraded habitats, such as crops, is correlated with increased glucocorticoids. Other factors such as sex, reproductive status, and population density were also considered. We captured voles with Sherman traps in crops and in their field margins which were comprised of semi-natural vegetation. We collected fresh faecal samples from captured individuals and quantified their levels of faecal corticosterone metabolites (FCM) in the laboratory. The quantification of FCM concentrations was performed by competitive enzyme immunoassay. Individuals captured within the crops had higher levels of FCM than those in field margins; females and breeding individuals exhibited higher FCM levels. In addition, FCM concentrations positively correlated with abundance of voles. Our results suggest that degraded habitats in agricultural landscapes are associated with increased glucocorticoid levels on common voles likely caused by a higher disturbance from agricultural practices and a lesser vegetation cover in crops compared with field margins.This research has been financed by the projects: Junta de Castilla y León (SEK02B06) and Ministerio de Educación y Ciencia (CGL2006-05047/BOS) and FEDER funds. A. Navarro-Castilla was supported by a FPU scholarship from the Ministerio de Educación y Ciencia of Spain.Peer Reviewe