Behavioral and environnemental factors in the spatial distribution and population dynamics of a yellow-bellied marmot population [Facteurs comportementaux et de milieu de la répartion spatiale et dynamique des populations d'une population de marmottes à ventre jaune].

Résumé

Behavioral and environmental factors in the spatial distribution and population dynamics of a yellow-bellied marmot (Marmota flaviventris) population were studied in 197l and 1972 in Gunnison Co., Colorado. Yellow-bellied marmots are generally considered to be colonial; however, this, is not their only option, depending upon the marmots' behavioral profile and the size and composition of the habitat. Of the adult-yearling group 75% lived as members of colonies, 16% lived at satellite sites, and 8% were transients. Satellite sites differed from colonies mainly in size and topographic diversity; they may be considered minihabitats, with the most limited resource being burrow sites. Marmots can be classified, by means of mirror-image stimulation (MIS), as aggressive, social, and avoider. Aggressive females tended to occupy small harems at large sites, or to live as solitary individuals regardless of the size of the site. Social females occured primarily at large sites, in harems. Avoider females lived in peripheral burrows at colonies, or in satellite sites. All behavioral types reproduced successfully, but reproductive fitness was correlated with social stucture. Aggressive females were most fit in small harems or at satellite sites, whereas social females were most fit in large social groups. Avoiders were least fit in all social situations. Data presently available fails to show that the behavioral profile of the female is reflected in the social tendencies of her young general, social behavior is a major factor affecting the distribution and dynamics of populations of yellow-bellied marmots, but dispersion is also related to ther distribution of suitable habitat.