Environmental stressors in a mountain-dwelling herbivore

The interplay between social and ecological stressors may affect phenotype of individuals, e.g. behaviour and physiology. I evaluated the role of etho-ecological stressors (i: age and seasonality; ii: food depletion; iii: weather) on female social behaviour (activity, herding, aggression, vigilance) and endocrine levels (faecal cortisol and testosterone), in a mountain-dwelling herbivore, the Apennine chamois Rupicapra pyrenaica ornata, throughout July-October (a key period for the biological cycle of mountain herbivores due to nursing/weaning/early growth of offspring). i) Aggression, vigilance and stress peaked during nursing, despite food abundance. Stress peaked in the expected breeder age class. Costs of motherhood were determinants of behavioural/physiological stress. ii) Aggression, vigilance and stress peaked in poor areas, where nutritional quality of pasture has been reduced by climatic/vegetation changes, as well as food exploitation by a competitor (reintroduced red deer Cervus elaphus), over the last decades. Food depletion led to cascading effects on physiology and behaviour. iii) Temperature had a direct, negative effect on activity, suggesting heat avoidance because of thermoregulation. Harsh weather i.e. higher temperature/lower rainfall during the growing season of vegetation promoted feeding interference to access depleted pasture. Social behaviour and endocrine response were driven by the interaction between several environmental stressors, such as costs related to maternal cares, resource availability and weather parameters. Current environmental changes may be detrimental to viability of wild mountain herbivores, affecting their social behaviour and stress.