Home range, movements, and denning chronology of the Grizzly Bear (Ursus arctos) in west-central Alberta

Abstract

An understanding of the natural history of the Grizzly Bear (Ursus arctos) is important for recovery planning. We present data on home range size, movements and denning chronology collected using Global Positioning System (GPS) collars on Grizzly Bears in west-central Alberta. Mean annual kernel estimates for adult (1034 ± 656 (SD) km²) and subadult (1298 ± 1207 km²) males were larger than those for females with cubs of the year (213 ± 212 km²) and lone adult females (337 ± 176 km²) but not different from sub-adult females, females with yearlings, or females with ≥ 2-yr old cubs (P > 0.05). Mean rates of movement among female age–reproductive classes were different from each other (Z₉ < 2.70, P > 0.05) but not different from sub-adult males (Z₉ < 2.70, P > 0.05). Rates of movement of adult males were significantly different only from those of females with cubs of the year (Z₉ = 3.94, P = 0.001). The greatest amount of movement occurred in June and the least in October. Bears traveled fastest in the morning and evening and slowest at night. Pregnant females had the longest denning period (175 days, ± 16 days SD). No difference was detected in denning duration among the remaining five age–sex–reproductive classes (P > 0.05). GPS collars provided large location datasets from which accurate home range estimates, hourly movement rates, and precise denning dates were determined. Examining similarities and differences in the basic biology of Grizzly Bears from various locations will improve our understanding of the plasticity of this species and the potential impacts of habitat and climate change.