Fecal corticosterone metabolite levels in two closely related rodent species in a sub-Mediterranean environment

Glucocorticoids regulate many physiological functions and play an
important role in coping with challenging stimuli. The non-invasive
assessment of glucocorticoids is increasingly used as a tool to evaluate
individual and population health status in wild animals. Given the crucial
role of rodents in forest ecosystems, it may be useful to study the
glucocorticoid profile of these species to find possible links with the
environmental characteristics in which they live and facilitate the
development of biodiversity management plans. We studied two closely
related species that are the main representatives of the ground-dwelling
rodent communities in sub-Mediterranean forested areas: Apodemus
sylvaticus and A. flavicollis. Fecal corticosterone metabolite (FCM)
levels of animals captured in a Mediterranean agroforestry system were
assessed. We found that A. sylvaticus males excreted lower FCM levels than
females, while A. flavicollis males showed higher FCM levels than females.
Males of the two species excreted similar FCM levels, while higher FCM
levels were recorded in A. sylvaticus females than in their A. flavicollis
counterparts. The FCM levels in both species were similar between breeding
conditions, seasons, and habitat types. The results of our exploratory
investigation suggest that traditional silviculture may not trigger the
activity of the hypothalamus-pituitary-adrenal axis. Further studies are
required for a more detailed examination of how environmental factors
affect FCM levels. Long-term studies may disclose possible effects of
interannual environmental factor variability in ground-dwelling rodents.