Dispersal of yearling yellow-bellied marmots (Marmota flaviventris) [Dispersion des jeunes d’un-an chez la marmotte à ventre jaune].

Résumé

Sur le terrain de l'organisation sociale de M. flaviventris, au voisinage de Gothie, Colorado, en 1962. On note des différences sexuelles de la dispersion qu'un modèle pemet de lier à une tactique maternelle de reproduction et à une réponse des jeunes de l'année dans le sens d'une maximisation de leur propre fitness. Field studies of the social organization of yellow-bellied marmots (Marmota flaviventris) in the vicinity of Gothic, Colorado, were initiated in1962. Data collected during the subsequent 14 years are sufficient to analyse the behaviours that correlate with the time yearling male and yearling female marmots leave their natal home sites. Dispersal of yearling male yellow-bellied marmots was delayed when there were many yearling males in a harem, when yearling males were underweight, and when the rates of amicable interaction between yearling males and adults were high. Dispersal of yearling females was delayed when adults behaved amicably toward them and when the rates of adult aggression were low. Dispersal of yearling females was independent of the number of females in a harem. These observations are in accord with a model of dispersal that relates sexual differences in dispersal to maternal reproductive tactics, and to responses of yearling that would maximize their own fitness.