Using a novel method of potential available energy to determine masting condition influence on sex-specific habitat selection by Asiatic black bears

Habitat selection is assumed to accrue fitness benefits. Where resource availability is variable, individuals should respond by changing habitat selection to increase resource availability. However, direct links between observed changes in habitat selection and energetic benefits of this behavior are rarely detected. We used a novel method whereby we converted interannual production levels of three hard-mast-producing Fagaceae species into a comparative energetic productivity score to investigate potential energetic benefits of Asiatic black bear habitat selection. We captured and fitted GPS collars on 19 bears between 2006 and 2010 in the Ashio-Nikko Mountains, Japan. We also collected data on hard-mast production and integrated these data with fine-scale vegetation maps. Then we mapped the potential available mast energetic production for each vegetation type to evaluate their potential energetic benefit for bears. Habitat use differed between poor and good mast years. Bears mostly used Japanese oak in good mast years, and there were sexual differences in September of poor mast years; females used mostly Japanese oak, whereas males used Konara oak. In those years, bears may have benefitted energetically by changing habitat use; however, the mean potential available energy to bears never exceeded that in good mast years, even if they used different habitats.