The weather dictates the rhythms: Alpine chamois activity is well adapted to ecological conditions

Activity rhythms play an important role in the ecological relations of a species and form part of its evolutionary adaptation. Such rhythms are strongly synchronised with the annual cyclic changes by environmental stimuli, the so-called Zeitgebers. Animals' reliance on environmental stimuli is highly species-specific and allows behavioural adjustments to be made in preparation for the conditions expected in each season. We investigated daily and annual activity rhythms of Alpine chamois (Rupicapra rupicapra) by analysing high-resolution data of animals monitored with GPS collars. This first detailed field study of chamois activity showed that this species exhibited clear daily and annual activity rhythms entrained to the light-dark cycle. Chamois were more active during spring-summer and less active during winter, likely in response to the variation in the availability of food resources: both sexes appeared to maximise energy intake during the season offering the highest amount of food resources to compensate for poor food supply during winter. Daily activity was influenced by the climatic factors considered. We showed a negative correlation between daily activity and adverse climatic conditions (i.e. precipitation and, during winter, snow depth). As activity was strongly influenced by the interplay between temperature and wind throughout the year and by radiation and wind in winter, we conjectured that it was critically dependent upon animals' thermal balance. In conclusion, our study highlighted that chamois is well adapted to the Alpine environment and seasonality but also raised questions about its ability to adapt to future climate change.