Space use and interaction in a colony of alpine marmots Marmota marmota L.) [Utilisation de l'espace et interactions dans une colonie de marmotes alpines].

Résumé

The alpine marmot Marmota marmota L.) is a territorial species which lives in family groups made of a monogamous pair and offspring, social hibernation is a prominent behavioural trait. Colonies are generally made up of several territories and each group actively defends his boundaries against intruder neighbours. The size of territories do not consistently change according to the size of the group. Space use is differentiated in the colony in that individuals belonging to the same family group use the same spotting points, summer burrows and hibernating burrows, which are considered the limiting resource to population expansion. Social bonds are also differentiated because amicable interactions most frequently happen within a familiar group and agonistic interactions are observed mostly between neighbours and at the boundaries of territories. In this paper the type and function of social interaction in keeping social bonds in the colony are further investigated. Data were collected during a field study which took place in 1985, 1986, 1987, 1988 during the months of July, August and September at the Gran Paradiso National Park, Valle d'Aosta, Italy. The study area was located at 2300 m. asl, above timberline. 438 hr of observations, concentrated in the early morning (06.00-11.00 hr) and late afternoon (17.00- 20.00 hr), were done on thirty-three animals, belonging to five different family groups.The animals were live trapped and marked for individual recognition. Focal animal sampling was used to record marking patterns, spatial location of behavioural acts and behavioural profiles. Focal sampling periods lasted 15min, animals to be sampled were chosen at random. Observations were recorded on a portable tape recorder and later transcribed. For further delails see Lenti (1985) and Lenti, Boero, & Boerro (1989). Social patterns were previously described in Lenti (1983b). Results show that both amicable and agonistic interaction can be further subdivided in many subcategories which serve a highly differentiated social communication. In the monogamous pair social grooming seems to be more reciprocated than in other age and sex classes, social play bouts can be observed across different age and sex class of siblings until two or three years of age, use of particularly reqested spotting points show a clear dominance hierarchy within a family group.