Black bear habitat use in burned and unburned areas, central Arizona

摘要

Vegetation characteristics selected by black bears (Ursus americanus) likely change after wildfire, but those characteristics are unknown. In April 1996 a wildfire destroyed >90% of the vegetation in 237 km(2) around Four Peaks, southern Mazatzal Mountains, Arizona. Within the burn perimeter, 2 islands of unburned vegetation (16 and 10.8 km(2)) remained. We documented habitat use of black bears by recording locations of 27 transmittered bears (10 F, 17 M) on Four Peaks (burned) and a similar unburned area 27 km north (Mount Ord). We hypothesized that black bears inhabiting burned sites would utilize the unburned patches more than would be expected by chance. We found that black bears in unburned sites selected areas with greater shrub density (shrubs >1.2 m tall/0.04 ha), higher horizontal cover, and more percent vegetation cover from 0.91 m to >4.6 m than at random sites. In burned sites blacks bears selected the same vegetation characteristics along with greater coniferous- and deciduous-tree density and steeper slopes than at random sites. Vegetation within unburned islands at Four Peaks was similar to areas selected on Mount Ord. Shrub density correctly predicted 76% of black bear midday locations via logistic regression. On burned Four Peaks, bears selected midday sites (bedding or feeding) within the unburned vegetation islands. Females used unburned islands more than males during morning hours. Strong selection for high shrub densities by black bears suggests that preservation of sufficient shrub patches ought to be a priority in fire management plans.