Nutritional condition and net body weight for adult female mule deer (Nov 2017–Mar 2018), Wyoming, USA

Many temperate and polar animals have developed physiological and behavioral adaptations to survive the challenging conditions of winter. Some animals hibernate to reduce energetic expenditure while other animals, including ungulates, migrate to avoid cold temperatures and deep snow. Despite moving vast distances between seasonal ranges, many migratory ungulates are unable to escape the energetic challenges of winter and often rely on reserves of fat to withstand food scarcity and a negative energy balance. The mobilization of fat for ungulates often is dependent on nutritional condition, yet the fine-scale rate at which ungulates mobilize fat throughout winter remains unclear. We took advantage of three sampling periods during the winter of 2017–18 on a population of mule deer that spends the winter in the Red Desert of south-central Wyoming, USA to investigate the fine-scale expenditure of fat from mid-autumn through late winter (November–March). Although the full effects of winter on...