Document Details
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Title |
Khutzeymateen Valley grizzly bear study: final report | ||||||||||
Author |
MacHutchon, A.G. | ||||||||||
Date |
1993 | ||||||||||
Abstract |
The Khutzeymateen Valley Grizzly Bear Study was conducted between 1989 and 1991 as a component of the Khutzeymateen Project. A wide range of information on grizzly bears (Ursus arctos) in the Khutzeymateen study area was collected to estimate population density and determine habitat value. Meeting these objectives was important for evaluating the impact of proposed land use scenarios on grizzly bears and their habitat. Grizzly bears were radio-collared and monitored over the 3 years of study. Basic life history information on movements, food habits, reproduction, mortality, and denning was collected. Three main seasons of activity were identified. Trapping, incidental observations, detection at remote camera sites, and aerial surveys were methods used to determine population characteristics. Aerial and ground telemetry locations were used to determine habitat use and evaluate what habitats were selected and preferred by grizzly bears on a seasonal basis. Habitat use was examined at two levels of resolution: Bear Habitat Units (BHUs) and Bear Habitat Types (BHTs). Both BHUs and BHTs were seasonally rated from very high to nil for grizzly bears based on the above analyses, as well as: the prominence values of major grizzly bear foods within habitats; a qualitative assessment of relative habitat capability in adjacent watersheds; and a qualitative interpretation of patch use. Sixty-four grizzly bears (including young) that used the Khutzeymateen study area were identified during the 3 years of study. However, nine of these bears were known or suspected to have died by 1991. Fifty-one grizzly bears were identified during 1991 and within each season 30-40 different bears were identified. Based on these numbers, seasonal density estimates were determined, and ranged from 4.7 to 14.8 km2 per bear. Grizzly bears using the Khutzeymateen study area spent most of their active period on lower slopes or valley bottoms, particularly the valley bottoms of the lower Khutzeymateen and Kateen rivers and lower Carm Creek. During all seasons, grizzly bears actively selected habitats for feeding and bedding and within each season they preferred certain habitats. Generally, the preferred and most heavily used habitats in all seasons were those on lower slopes and valley bottoms. These included both non-forested and forested habitats. Forested habitats such as floodplain old growth and skunk cabbage old growth were consistently preferred in all seasons, as were non-forested wetlands and estuaries. Sidehill old growth with high moisture and nutrient regimes and a diverse, abundant understory was used in all seasons and was preferred for feeding over drier sidehill old growth. The lower slopes of both types of sidehill old growth were frequently used for bedding, particularly when adjacent to well-used feeding areas. The productive lower slopes and valley bottoms in the Khutzeymateen study area are some of the best bear habitat. They are also among the best timber growing sites. This puts conventional timber extraction and the maintenance of grizzly bear numbers and habitat in direct conflict. There is concern that conventional timber extraction would have a major effect on the capability of the Khutzeymateen study area to support and sustain the current grizzly bear population. | ||||||||||
Report Number |
WHR31 | ||||||||||
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