We studied the influence of snow cover and habitat heterogeneity on altitudinal distribution, grouping patterns, and habitat selection in the isard or Pyrenean chamois (Rupicapra pyrenaica) in a protected area from the beginning of May to mid-June 1992. Data were recorded from a single vantage point that allowed visual observations to be made over a wide range of elevations. Variations occurred in the spatial extension of groups, with no sightings above 1900 m when snow was abundant at high altitude and only a few sightings below 1700 m when small patches remained at high altitude. During a late heavy snowfall, however, most sightings were made at the middle altitudinal range, where adjoining habitats of steep terrain provided areas of reduced snow depth. The frequency of observations of solitary animals increased slightly and was higher in closed than in open habitats. Both a significant habitat effect and a significant interaction between habitat and time period of observations were found for groups of the average size, ≥ 2 individuals. Montane pastures at low altitude were first selected. Then, when snow melted, this habitat was vacated for 1800- to 2000-m subalpine pastures. Regardless of the time period, the areas dominated by rhododendrons and rocks or scree were systematically avoided. We suggest that in order to gain a better understanding of habitat selection by large ungulates, especially in mountainous areas, short-term variations in environmental heterogeneity be considered.
Habitat Effect on Urban Roof Vegetation