Bioenergetics of Bodily Maintenance, Thermoregulation, and Behavior in a Wild Rodent

AbstractEnergy is a central resource for life, but animals' energy budgets are limited by their ability to collect, process, and redistribute energetic assets to diverse functions, including behavior. Yet none of the existing bioenergetic models unequivocally explain behavioral variation, suggesting that they are not mutually exclusive or that they are incomplete and overlook important processes. To describe a means by which an endotherm regulates its metabolism and behavior in varying environments, we simultaneously analyzed several components of energetic budgets. To accurately assess the costs of body maintenance, thermoregulation, locomotory movement, and shyness of wild mice, we measured resting metabolism at different temperatures and repeatedly quantified basal metabolic rate (BMR) and behavior. At the among-individual level, we found no significant associations between personality traits and metabolic rates. At the within-individual level, we found that when including the most accurate estimates of BMR, higher BMR was associated with reduced shyness. The among-individual trends of the associations between thermoregulatory cost and behavior were stronger than those between BMR and behavior. Our results suggest that temperature affects shyness and that behavior and BMR may covary over time within individuals, reinforcing context dependence of energetic regulation of behavioral responses.