WINTER BODY-FAT, FOOD-CONSUMPTION AND NONSHIVERING THERMOGENESIS OF REPRESENTATIVE SPONTANEOUS AND FACULTATIVE HIBERNATORS - THE WHITE-TAILED PRAIRIE DOG AND BLACK-TAILED PRAIRIE DOG

1. White-tailed prairie dogs are spontaneous hibernators while black-t ailed prairie dogs do not hibernate unless severely deprived of food a nd water at low ambient temperatures. 2. Contrary to what has been tho ught about spontaneous and facultative hibernators, both of these spec ies in this study had similar body fat content when trapped in the fie ld. Also, both species had an identical nonshivering thermogenic respo nse when tested at mid-winter. 3. White-tailed prairie dogs became spo ntaneously anorexic during late fall and underwent bouts of torpor whi le the black-tailed prairie dogs continued to eat throughout the winte r and only rarely entered torpor. 4. In spite of their different therm oregulatory and eating behaviors, both species exhibited the same body weight profiles through the fall, winter and spring. 5. It is conclud ed that the lack of spontaneous hibernation in the black-tailed prairi e dog may be a derived characteristic, divergent from the condition in the ancestral stock. However, the genetically controlled 'sliding' bo dy weight set-point remains similar to that of the hibernating white-t ailed prairie dog, a representative of the presumed ancestral conditio n. (C) 1997 Elsevier Science Ltd.