Body weight and horn development in Alpine chamois, Rupicapra rupicapra (Bovidae, Caprinae)

With the aim of describing the trend in somatic development, especially the attainment of asymptotic body mass of Alpine chamois, Rupicapra rupicapra rupicapra, we recorded measurements (eviscerated body weight, length and height of horns) of 548 chamois harvested in 6 different valleys of the Piedmont region (Western Italian Alps), from 1984 to 1996. In male Alpine chamois, asymptotic mass was reached at 4.5-5.5 years of age, and after 4.5 years of age, the horns did not grow significantly between one year and the next. Females reached maximum body weight at about 3.5 years of age. Male chamois showed rapid early somatic development with consequent early development of sexual dimorphism. The mean body weights of males and females differed significantly from 3.5 years of age onwards, while horn size differed at as early as 1.5 years of age. Highest degree of sexual dimorphism in body weight (31.3 %) was found at 7.5 years of age. Male chamois reach asymptotic body mass in correspondence with first reproduction, while females mature before achieving asymptotic growth.