Bear update: berries and bear cubs By Michael Allen Black Bear Researcher The black bear summer foraging period traditionally starts around mid to late June when berries ripen in the Whistler Valley. This year, because of a cool and cloudy spring, berries remain green and hard and about half the size of ripened berries. So what do bears eat if their major food resource is late or failed and how does this affect all the new-born bear cubs this year? Bears will turn to their supplements, or food they will rely on to get them through the summer and fall. Because most berries, such as huckleberries, Saskatoon, Sitka mountain ash, and elderberries, depend on sunshine for ripening, these berries will be delayed in the valley until mid to late July and on the ski hills until August. Bears have to search for shade-tolerant berries (growing under the cover or shade of another tree or shrub) which do not require a lot of sunshine. Black twinberries and salmon berries are beginning to ripen at the south end of Whistler Valley. Salmon berries are more abundant along creeks and moist and disturbed areas. Red-osier dogwood, the white berries that grow from the tall, (1-2 meter high) shrubs which form hedges around the valley's parks, trails, and residential areas are flowering now and will be available to bears in August. Another food source for bears is insects. Bears eat ants and their larvae, especially the larger carpenter ants found in logs and stumps and under rocks. Wasps, their larvae and honeycombs are consumed from subterranean nests in logs and in the forest litter between tree roots. Bears feed opportunistically on carrion, (dead animals) and small rodents. Adult bears will occasionally prey on black-tail deer fawns and small mammals. There are no salmon in the Whistler area but some adult bears, if experienced, may travel hundreds of kilometres in the fall to the salmon-abundant watersheds in Pemberton and Squamish. The main supplement to a delayed or failed huckleberry crop is for bears to continue grazing on new green herbaceous vegetation. They can do this on Blackcomb and Whistler Mountains because snow is constantly releasing new growth sites of easily digested grasses, clover, sedge, and horsetail. Bears follow the elevational green — up from the valley in April and May, to the alpine in August and September. On Blackcomb a Bear Management Plan has been implemented which identifies sensitive bear feeding sites on open ski trails and manages these resources seasonally. Ski trails are usually mowed with a tractor in July and August to stimulate new growth and enhance slope stability. Because bears need to continue grazing, specific trails will be left to accommodate bear grazing. Currently, 1.5 square kilometres of Blackcomb ski trail spring grazing habitat is supporting eight bears, including two bear families. The mothers spend up to 15 hours a day grazing. As a result of the delayed or possibly failed huckleberry crop, new bear families will be stressed through summer. I have identified seven families with 14 new-born cubs this spring between Function Junction and Blackcomb Mountain. This high cub production in a relatively small area is due to mothers having access to an excellent berry crop in 1995. Cubs are born in January and cared for from 3-4 months at the den until they are strong enough to escape danger by climbing trees. Generally, the larger the litter, the smaller the cubs. Litter sizes range from one to four, with an average of two cubs per litter every second year. In some cases, mothers who occupied territories around dumps or habitats of productive berry shrubs have both larger litters and cubs than mothers in less productive habitats. The quantity and quality of food resources consumed in the first year of a bear's life has the strongest influence on the bear's survival. Because of the highly productive berry crop in 1995 most pregnant bears entered dens fat and healthy. As a result, a large number of cubs have been produced in 1996, but with no main berry crop to feed them. Cub survival into the fall and ultimately through the denning period will depend on the mother's ability to find berries or another stable food resource. We can increase bear survival by not disturbing bears while they're grazing on the ski slopes, by exercising a higher tolerance for bears passing through our residential areas, and by ensuring that bears do not have access to our garbage. Michael Allen can be heard on Mountain FM’s Mountain Monitor program the fourth Tuesday of each month. Listen July 23 at noon. photo caption: Mother with 3 cubs in early May. The small size of the cubs restricts the family's movements for up to 5 months.
