Population Ecology of Grizzly Bears in the Slave Geological Province
(Revised January 1998)
Organization / Researcher: University of Saskatchewan, Francois Messier / GNWT, Ray Case
Length of Project: 5 years (1995-1999) (WKSS funding provided from 1996 to end)
Personnel involved: Local HTA members
Total Expenditures (WKSS funding only): $1,138,489
Before this project, few studies had been done on barren-ground Grizzly Bears in the central Arctic. If these bears are to withstand the environmental changes brought about by development activities, including mining, it is important to know what type of environment and how much space they need. The study originally focused on the Lac de Gras area but was expanded in 1997-98 to include areas north of Contwoyto Lake, east of Tree River and east of Bathurst Inlet; all of these areas have high potential for development.
Of 264 bears captured during the course of the study, 81 have been tracked by satellite collar (all collars were removed by the end of the study). Distances covered by bears in their home range are larger than previously reported for Grizzly Bears in other areas. Young males move over very large distances while adult males and females stay in large, but more defined areas. Individual adult males in this study covered an area averaging 6,685 square km each year (larger than the entire area of Banff National Park); female home ranges averaged 2,074 square km.
The bears appear to be in three groups; the groups are roughly centred on Bathurst Inlet, Lac de Gras and Kugluktuk. The researchers conclude that due to the high overlap and exchange rates between these population clusters, barren-ground Grizzly Bears in the study area will have to be managed as one continuous population. This is an important management consideration because the large ranges may put individual bears in contact with humans even when developments are hundreds of kilometres from the animal's core home range.
All bears moved greater distances in spring and early summer, with decreasing travel distances in autumn. The movement patterns and large home range sizes allow the bears to access certain key habitats, especially eskers (linear sand/gravel deposits left by glaciers), tall shrub riparian (birch, willow, alder up to 4m tall near running water), tussock/hummock areas and birch seep (areas of boulder fields where birch grow in seeping water). Choice of habitat is thought to be guided by availability of different foods, for example:
The nutritional component of the study found there are three (of five) "seasons" when the bears eat mainly caribou (spring, mid-summer and autumn); they concentrate on green vegetation in early summer and berries in late summer. This diet is somewhat different from Grizzly Bears in other locations.
There were some significant differences between male and female habitat selection during different seasons; females with cubs may have been avoiding adult males during much of the year by avoiding habitats preferred by males. Males are known to prey on females and their cubs.
Most bears denned in late October of each year, emerging in early May. Eskers, which previously had been regarded as the major denning habitat for barren-ground Grizzly Bears, accounted for only seven of 56 den sites studied. Most dens, about 60%, were found in heath tundra habitat or heath tundra with boulders. About 13% were located in esker habitat. Four other habitat types accounted for the remaining 15 dens. Most dens were on south facing slopes, constructed under cover of tall shrubs, and containing mats of crowberry vegetation for bedding.
Spatial Organization and Habitat Selection Patterns of Barren ground Grizzly Bears (2000)
Grizzly Bear (Ursus Arctos) Studies in the Northwest Territories: Nutritional Component