Social Variety in the Yellow-bellied Marmot : a Population-behavioural System

Rates of amicable and agonistic behaviour are not correlated either within or between two colonies of Marmota flaviventris nor is there any consistent pattern of rates being higher in one colony than in the other . Rates of social behaviour are related to population density, the age-sex structure of the population, the individual behavioural characteristics of the residents and potential recruits, the way in which space is shared, and the number of years residents have lived together . The social and population biology of the yellow-bellied marmot (Marmota flaviventris) have been intensively studied (Armitage 1962, 1965, 1973, 1974; Downhower & Armitage 1971 ; Armitage & Downhower 1974). These studies revealed considerable variation in social behaviour which has been incorporated into a model of population regulation (Armitage 1975) . Furthermore, each marmot has a behavioural profile which affects not only its relationship with other marmots but also the spatial distribution and population dynamics of marmots (Svendsen 1974) . Barash (1973a, 1974) suggested that social behaviour of marmots is closely related to those ecological variables correlated with length of growing season . Yellow-bellied marmots living at 3850 m were smaller and more sociable than those living at 2650 m. However, Armitage, Downhower & Svendsen (1976) found no difference in body weights of marmots living at 2900 and 3400 m when weights were compared at the same time in the annual cycle . Furthermore, my studies reveal wide variation in behaviour from year to year in the same colony and in the same year among colonies at the same elevation. The purpose of this paper is to describe the nature of this behavioural variety .