Assessing the sensitivity of foraging and vigilance to internal state and environmental variables in yellow-bellied marmots (Marmota flaviventris)

摘要

Both internal and environmental factors influence the trade-offs animals make between foraging and antipredator vigilance. However, few studies examine both internal and environmental factors simultaneously, preventing us from drawing inferences about their relative importance during foraging. We capitalized on a long-term study of yellow-bellied marmots (Marmota flaviventris) to compare the relative importance of internal state-based factors versus external environmental factors in explaining variation in marmot foraging and vigilance behavior. Results indicate that while internal factors such as baseline fecal glucocorticoid metabolites, parasite infection, and body condition influence the time allocated to both foraging and vigilance, environmental factors such as group size and habitat characteristics only explain variation in the time allocated to vigilance. Thus, our findings reveal not only the importance of considering effects of both internal and environmental factors in explaining behavioral trade-offs but also the value in evaluating the subtle ways in which factors explaining vigilance and foraging differ.