Estimates of Energy and Prey Requirements of Wolverines

Wolverine (Gulo gulo) populations have decreased throughout much of their North American range and there is interest in establishing recovery programs in the Sierra Nevada of California and the Rocky Mountains of Colorado. Determining the sufficiency of prey resources is an important consideration for initiating wolverine recovery, yet there are limited data on resource availability and needs. Our goal is to estimate prey requirements based on wolverine caloric needs and the caloric content of prey likely to be available. We achieve this goal by modifying existing models to account for wolverine biology. Models show a male wolverine requires 5096 kJ/day (2925-7462 kJ) and a female wolverine requires 3645 kJ/day (2158-5439 kJ). This translates to an annual energy budget for males of 1.9 million kJ/yr that could be met by consuming the equivalent of approximately 8 mule deer/yr (Odocoileus hemionus) and 1.4 million kJ/yr for females that could be met by consuming the equivalent of less than 6 mule deer/yr. In light of published records of prey availability, these results suggest populations of wolverines could be sustained where recovery programs are being considered in Colorado and California. We suggest incorporating energetic needs of focal species, such as those calculated here for wolverines, into the assessment of resource availability before implementing recovery programs. Further, these estimates can be applied to management and conservation of wolverines throughout their range