The use of foraging areas by yellow-bellied marmots [Utilisation des zones d’affouragement chez les marmottes à ventre jaune].

Résumé

La fréquence pour une aire d’approvisionnement donnée est chez M. flaviventris positivement corrélée avec la biomasse de végétaux et négativement corrélée avec la végétation dense et haute. On interprète ces résultats comme un comportemant adaptatif intégrant les demandes simultanées d’ingestion de nourriture et d’évitement de la prédation. This study examines the use of foraging areas by a colony of yellow-bellied marmots (Marmota flaviventris) in the White Mountains of California. Usage indices that represent the amount of time 26 marmots fed in each of foraging areas were obtained through scan-sampling of the colony’s movements and correlated with habitat variables using univariate and multivariate techniques. Marmots preferred to forage in certain areas others: of the 11 areas five were preferred (used more often than expected based on relative size), three were less preferred and the remainder were used in proportion to their availability. Preference for foraging areas was positively correlated with food plant biomass and negatively correlated with dense, high vegetation. I interpret these results as adaptive behavior integrating the simultaneous demands of food ingestion and predator avoidance. Age class similarity in foraging patterns was greatest between yearlings and adults and least between juveniles and yearlings. The behavior of juveniles reflected most clearly the relationships between foraging area preferences and .habitat characteristics, whereas yearlings appeared to use foraging areas largely in response to variables not measured in the study. Age specific variations in foraging patterns may reflect the risks associated with predation and inadequate nutrition, which vary with age.