Native or naturalized? : validating alpine chamois habitat models with archaeozoological data

Conservation of mammal species often requires the application of predictive habitat models. While empirical models can indicate the potential suitability and distribution of recent habitat, they may fail to depict native habitat and distribution. Therefore, we advocate validating such models with archaeozoological data. To demonstrate the power of archaeozoological data in investigating native distribution patterns, we use the alpine chamois (Rupicapra rupicapra) as a model species. After experiencing a severe historical population bottleneck due to overexploitation, chamois populations recovered markedly during the last century. Fostered by humans and having profited from translocations, this alpine ungulate greatly expanded its range and began to invade forested areas both within and outside the Alps, where damage to vegetation was soon obvious. Consequently, a controversy arose concerning the natural distribution and habitat of chamois. To study the native habitat and distribution of alpine chamois in Switzerland, we focus on the Late Mesolithic and Neolithic period (6000-2200 BC). This period best Suits our purpose because pristine forests then dominated the landscape and human influence was as yet minimal. We describe two opposing habitat models: the alpine model assumes that chamois had survived only in alpine areas, whereas the forest model assumes that they also roamed in steep, entirely forested areas. We validate these models with archaeozoological data. Because the probability of chamois bone occurrence in prehistoric settlements is expected to decrease with increasing distance from chamois habitat, the models differ in their geographical predictions of chamois bone records. Applying logistic regression models, only settlement proximity to chamois forest habitat explains recoveries of fossil chamois bones. The resulting function of catchment distances (i.e., the likelihood of hunting chamois depending on the distance between a settlement and the nearest chamois habitat) matches the spatial behavior of extant hunters within pristine forests. We conclude that Holocene chamois range in Switzerland naturally included steep and entirely forested regions, like the Jura Mountains. The recent invasion of these areas by chamois thus constitutes repatriation of native habitat. Accordingly, we propose a shift in perspective toward landscape integration of chamois.