Seasonal changes in lipids, diet, and body composition of free-ranging black-tailed prairie dogs (Cynomys ludovicianus)

Black-tailed prairie dogs (Cynomys ludovicianus) enter torpor intermittentl y during winter in the field but do not hibernate continuously from fall to spring. Previous studies have established that hibernators rely primarily on stored lipids during winter and that the storage of n-6 PUFAs in white a dipose tissue (WAT) is required to maintain low body temperatures during th is continuous torpor. Adult (>1 year) black-tailed prairie dogs were livetr apped in the fall, winter, spring, and summer (n = 10-12). To determine whe ther free-ranging black-tailed prairie dogs rely heavily on stored proteins during winter, we investigated seasonal changes in body composition of the prairie dogs with dual- energy X-ray absorptiometry scans. We also examine d seasonal changes in lipid composition of the WAT and diet using gas-liqui d chromatography to determine whether black-tailed prairie dogs lack the li pids necessary for hibernation. Seasonal changes in fat, lean, and total bo dy mass indicate that black-tailed prairie dogs relied heavily on stored li pids during the winter and appeared to rely on proteins primarily during pe riods that coincided with reproductive activity. Seasonal changes in dietar y and WAT lipids indicate that WAT n-6 PUFAs are used during winter and sto red during summer, while WAT n-3 PUFAs are stored during winter and used du ring summer. These patterns of lipid use are different than those reported in free-ranging hibernators and may explain why black-tailed prairie dogs e xperience shallow and infrequent torpor bouts.