Salmon & Coastal Old Growth Forests
Research in the Flathead Valley


BLACK BEARS, SALMON & COASTAL OLD GROWTH FORESTS

Short seasonal salmon runs can be a major yearly protein source for black bears as well as a major source of nitrogen for vegetation along streams (Reimchen 2000). Black bears eat the parts of the salmon having the highest fat levels: the brain, eggs, skin and back muscles.

Black bears may consume as little as 2% of the salmon on larger rivers, but Reimchen (2000) found that at Bag Harbour, a small stream on Haida Gwaii, black bears consumed 45%-80% of the total salmon population. Although each black bear consumed an average of 15 salmon per day, 70% of the salmon were spawned out. This means that the bears did not have a substantive impact on salmon reproduction.

Bears drag salmon out of streams and often carry them as far as 100 m from the stream bank. Uneaten salmon remains and bear scats become available to provide nutrients to trees and other plants in these surrounding forests.

Research on denning habitats of Vancouver Island black bears indicates that they use old-growth structures, such as root boles of large trees, stumps, or logs for winter denning (Davis 1996). Cavities provided by these structures are dry, often secure from predators (other bears and wolves) and can be available for a long time. Third rotation forests may be missing large enough logs or stumps for denning. Large-diameter hollow trees are of particular importance for black bear winter dens, according to recent research in Oregon (Parks 1999).

Large trees serve as security trees that allow a safe retreat for cubs and mothers or young bears when they sense a threat nearby. Trees provide forage in the form of buds, leaves, sap and cambium and are also used as territorial markers, particularly by adult males.


Salmon & Coastal Old Growth Forests
Research in the Flathead Valley



BLACK BEAR RESEARCH IN THE FLATHEAD VALLEY

The most comprehensive research on black bears in the British Columbia Interior has been conducted in the Flathead Valley. This recent study was conducted in conjunction with research on grizzly bears initiated more than 20 years ago. These studies are finding that black bears select timbered areas and avoid large open areas with little tree cover (Hovey 2000). Large trees provide escape from
predators, such as grizzly bears and wolves. While grizzly bears select open burns during summer because of the high berry abundance, black bears avoiding grizzlies were rarely observed in these areas.

Summer is when bears gain most of their body fat for winter storage, with some gaining as much as 1 kg of fat per day (Hovey 2000). During the summer bears are able to more than double their weight. The high activity levels in summer reflect the increased time spent foraging.

Research in the Flathead showed that black bears usually were denned by November 10 (Hovey 2000). Pregnant females denned about a month earlier. Females and their young emerged last, as late as May 24, about a month later than males. Bears may den in a variety of structures, including tops of large diameter larch snags, cottonwood trees, under logging debris, in natural caves of rocky cliffs, under root wads, in holes they dug and even in abandoned outhouse holes.


Salmon & Coastal Old Growth Forests
Research in the Flathead Valley