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Aspects of the ecology of black and grizzly bears in coastal British Columbia

University of British Columbia

This study was conducted to identify aspects of the ecology of the grizzly bear (Ursus aretos) and black bear (Orsus americanus) in coastal British Columbia for both research and management purposes. Information on the feeding ecology and habitat use of black and grizzly bears was collected during field studies conducted in 1976 and 1977. Trails were cut into the study area and systematically travelled to collect scats and other sign. Bears were trapped and subsequently monitored with telemetry. The study of black and grizzly bear movements was constrained by the logistic difficulties of the coast. Five grizzlies were located a total of 36 times and four black bears a total of 42 times. Extensive overlap in the use of space occurred. Movement between watersheds in coastal British Columbia occurs, but the extent of travel is unknown. Marking behaviour of bears on trees and on the ground was described. No reliable method was found to distinguish individual bears from other bears using their tracks. Two criteria were found which separate the tracks of grizzlies from those of black bears. The toes in grizzly tracks are either very close together or joined, whereas the toes in black bear tracks are separate. A less reliable criteria is that the fifth toe in a grizzly track does not register below the midline of the other four toes, whereas in a black bear it does.. Scats collected from May through September averaged 88 percent vegetable matter and 12 percent salmon (Qncorhynchus sp.) and insects. The bears in the study area consumed 21 different recognizable foods. The bulk of the diet came from eight of these foods: sedge (Carex sp.), ladyfern (Athyrium filix-femina), spiny wood fern (Dryopteris austriaca), huckleberry (Vaccinium sp.), salmonberry (Rubus spectabilis), devil's club (Oglopanax horridum), insects, and salmon. The spring and early summer diet consisted of sedge, herbs and ferns, and the current year growth of shrubs. Fruits and salmon were used extensively in August and September. As the green bear foods mature, the levels of crude protein, crude fat, soluble carbohydrates, and moisture content decreased, while crude fibre increased and gross energy and total ash remained constant.. For salmonberry, devil's club, and huckleberry, the fibre:protein ratio was lower in the part of the plant which the animal consumed than in that which it did not consume. As the berries matured, the levels of crude protein and crude fibre decreased, and the levels of crude fat, soluble carbohydrate, and moisture content increased. A simple model was presented which discusses the energetic importance of salmon and berries to the coastal grizzly bear. The vegetation in the study area was grouped into types and the bear foods in these types were described. The implications of the results of this study to the future management of bears on the coast of British Columbia were discussed.

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2010-03-03

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http://hdl.handle.net/2429/21401

Forestry

University of British Columbia

Graduate