Do alternative strategies of space use occur in male Alpine chamois?

Abstract

Twenty-one adult male chamois were radio-tracked from February 2000 to November 2002, in Gran Paradiso National Park, Graie Alps, Italy. The median size of annual home ranges was 70 ha (Kernel 95%). Home range size in the warm months was significantly much larger than in the cold period. In the summer, all males moved to greater altitudes (about 2200 m a.s.l.), whereas they lived at ca 1950 m a.s.l. in the winter. Two strategies of space use were detected: 76.2% of male chamois were residents (i.e., overlapping or contiguous summer and winter home ranges), whereas the others were seasonal migrants (i.e. well separate summer and winter home ranges). In the warm months, the home ranges of migrants were significantly much larger and at higher altitudes than those of residents. Resident males may gain a reproductive advantage over migrants in years with a snow cover during the rut (i.e. when females descend to low altitudes, where resident males live), whereas migrants could be favoured in ruts with little or no snow (i.e. when females stay at high altitudes during the rut). Thus, both male spatial strategies can persist in the same population.