Are Motorways Potential Stressors of Roadside Wood Mice (Apodemus sylvaticus) Populations?

Abstract

Linear infrastructures represent one of the most important human impacts on natural habitats and exert several effects on mammal populations. Motorways are recognized as a major cause of habitat fragmentation and degradation and of biodiversity loss. However, it is unknown whether motorways lead to increased physiological stress reactions in wild animal populations. We analysed faecal corticosterone metabolites (FCM) in wild populations of wood mice (Apodemus sylvaticus) living in a well-preserved Mediterranean agro-pastoral woodland at different distances (verge, 500 m and 1000 m) from the AP-51 motorway in Spain. Wood mice were captured with Sherman live traps, and fresh faecal samples from 424 individuals were collected and analyzed in the laboratory. The quantification of FCM was performed by a 5α-pregnane-3β,11β, 21-triol-20-one enzyme immunoassay. Results showed that females had higher FCM levels than males, and these levels were higher in breeding females. In addition, FCM levels were positively correlated with body weight of individuals. Wood mice captured where cattle were present showed higher FCM levels than individuals living where cattle were not detected. FCM levels were higher in non-breeding individuals living close to the motorway compared with FCM levels in those individuals captured further from the motorway. This is the first study showing evidence of the motorways' impact on physiological stress reactions in wild wood mice populations. Understanding how free-living animals are influenced by human interventions could help to understand other subtle changes observed in wild animal populations. Since mice are used world-wide as research models these results could open new perspectives testing human influence on the natural environment and trade-offs of species in degraded ecosystems.

Edge effects on small mammals: Differences between arboreal and ground‐dwelling species living near roads in Brazilian fragmented landscapes

“…diet) that trigger distinctive edge effects. It is also important to consider that even though generalist species may not show obvious behavioural changes at road edges, there may be stress reactions resulting from trade-offs that species make in a degraded ecosystem (Navarro-Castilla et al 2014). Further research will involve coordinating a network of experiments on species with different ecological requirements across ecosystems and landscape extents.…”

Exhausting all avenues: why impacts of air pollution should be part of road ecology

“…Elevated levels of this hormone (corticosterone metabolite) have been documented in wild populations of wood mice ( Apodemus sylvaticus ) living in close proximity to roads (Navarro‐Castilla et al . ).…”

“…Due to its cytotoxic effects (increased cell death and intensified oxidative stress; Lodovici and Bigagli ; Navarro‐Castilla et al . ; Khanal et al . ) and genotoxic effects (increased chromosomal abnormalities and elevated micronuclei frequencies; Spósito et al .…”

“…J Biotic responses to VRBAP Due to its cytotoxic effects (increased cell death and intensified oxidative stress; Lodovici and Bigagli 2011;Navarro-Castilla et al 2014;Khanal et al 2015) and genotoxic effects (increased chromosomal abnormalities and elevated micronuclei frequencies; Spósito et al 2015;Steiner et al 2016), VRBAP poses a serious threat to biota. Ultimately, these harmful effects culminate in negative fitness consequences such as developmental abnormalities, impaired organism functioning, and the inhibition of certain behaviors (eg species interactions) (Wik and Dave 2009; Girling et al 2013;Vujic et al 2015).…”

“…Gaseous pollutants can also increase the production of stress hormones such as adrenocorticotropic hormone (Choi et al 2011), which helps regulate flight-or-fight responses. Elevated levels of this hormone (corticosterone metabolite) have been documented in wild populations of wood mice (Apodemus sylvaticus) living in close proximity to roads (Navarro-Castilla et al 2014).…”