One herd, different movements: spatial behaviour of female forest chamois in a changing meteorological perspective

Mountain herbivores are a multispecies group of animals with behavioural adaptations to the severe living conditions at high elevations. Because of their marked seasonality, mountain ecosystems are particularly sensitive to the impact of long-term meteorological changes. These changes can significantly influence the abundance, distribution, and ultimately the survival of plant and animal species. We focused on the spatial behaviour of a herd of 21 radio-tagged female chamois, Rupicapra rupicapra, from December 1998 through November 2001. We investigated home range size, habitat selection and elevational distribution of female chamois. Our findings revealed distinct seasonal patterns in home range size, with smaller ranges observed during the warmer months (May-October), as well as high interindividual variability in female spatial behaviour, with more than 80% variability in home range size explained by the individual identity. Home range size also decreased with increasing elevations, but only during the warmer months. Sparse larch forests were selected as preferred habitats, shrublands and other coniferous forests were avoided, and grasslands were used proportionally to availability. Chamois were counted yearly in 2000–2001 and from 2020 to 2023 using the same methodology, with a mean temperature increase of ∼2 °C. Counts revealed an upward shift of up to ∼90 m in the summer locations of most females, although a minority of groups remained stationary or even moved downwards. Although predation and interspecific competition may have played ancillary roles, alteration in vegetation distribution, and in turn, local food availability, was probably the major factor triggering chamois movements. Contrary to predictions, despite belonging to the same female herd, some individuals showed different spatial behaviour responses, which could be adaptive to ensure survival in case of a changing environmental context, as natural selection can only take place if there is individual variation.