Seasonal variation in group size of Cantabrian chamois in relation to escape terrain and food

The herd size of Cantabrian chamois Rupicapra pyrenaica parva (Cabrera, 1910) varied seasonally in relation to escape terrain and food availability in our study area (Asturias, north of Spain). The median group size of females without kids was 1 (mean ± SD = 1.62 ± 1.00), females with kids was 4 (5.59 ± 5.42), males was 1 (1.73 ± 1.78), and mixed group size was 7 (8.91 ± 7.91). The female-kid group size depended more on escape terrain availability than on food quality. Throughout the early weeks of the life of kids, the mothers remained in difficult access areas (cliffs and steep slopes), and showed a weak tendency to aggregate. These areas provided a wide visual range and hiding places for offspring and their use may be an anti-predation strategy. When the kids were able to run quickly, the mothers used subalpine meadows. These areas were very open and exposed kids to predation and human disturbance, however the forage has high nutritive value, and may compensate for the cost of breeding and suckling by the mothers. Aggregation may be selected as an anti-predation strategy in subalpine meadows, allowing a reduction in time spent vigilant by each individual in the group, and increased time available for other activities. The largest male groups were located in pastures with abundant but poor quality forage. Our results suggest that group size in Cantabrian chamois is very flexible, changing seasonally and in response to resource availability.