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Bear Update: Dry fall boosts valley bear activity



Black Bear Researcher

Draught conditions that stretched from early August through early November, followed by a mild, wet mid-November, influences local bear biology in four ways: 1) reduces fall weight gain by yielding smaller size (berries) and abundance of huckleberries, 2) reduces survival rate by forcing bears to search for food closer to people, increasing human-bear conflicts, 3) reinforces human food feeding behaviours, increasing bear’s knowledge of potential human food locations to return during natural food shortages, and 4) prolongs den entrance, increasing potential conflicts with people as well as stress and weight loss during movement to den through snow.

Influences of temperature and precipitation play a major role in bear biology. Below are seasonal descriptions of bear activity from changes in weather.

July-August Berry Ripening — Dry and Hot

When valley bears are feeding on ripening huckleberries in early July, ski area bears continue grazing on grasses and clover waiting the ripening of higher elevation berries. The late, cooler spring gave way to late summer during July when sunshine and higher temperatures gave a boost to the struggling berry crop. But, Mother Nature pushed the limit and extended her influence into a bone-dry August. Prolonged draughts reduce berry size and began drying up valley berries earlier than normal.

For ski area bears, smaller berry size increases the time it takes for bears to find and consume berries. Bears also have to consume more berries because of the smaller contribution of pulp/juiciness per berry. Concentrations of berries in dense patches during late August will keep bears feeding in small areas. This August bears were rotating through numerous shrub fields due to a wide dispersal of berries. For bear families, this feeding strategy can be harmful in that cubs will be exposed to more threats (other bears).

September Berry Feeding — Dry and Warm

The peak berry feeding period for ski area bears is September, and for valley bears August and September. Valley bears typically have a longer berry feeding season than ski area bears.

This year in the ski area, berries began shrivelling during early September. Because of their small size the berries tend to dry out faster. Berry feeding was concentrated for a short period (late August to mid-September) in large shrub fields (i.e., Greenacres, Raven ski trails). From mid-September on bears began to disperse, feeding throughout shrub fields inside and outside of the ski area boundary.

Reduced berry crop in the fall yields the greatest impact on mothers with COY (cubs-of-the-year/January birth) and sub-adult bears. These bear class are generally restricted to smaller movements due to burdens of cub rearing and inexperience, respectively. Adult males that do not have the role of cub rearing may travel extensively to search for alternative food sources during natural food shortages. Yearling to 2-year-old sub-adult bears do not have the experience and dominance to search wide ranging areas and fear of conflicting with larger, dominant bears or bear families. As a result they tend to move near people and garbage sources.