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Timber Damage by Black Bears:
Approaches to Control the Problem

Consequences of Bear Damage

When bears strip trees (figures 2a and 2b), they can harm the health of a stand or a particular species within the stand. Complete girdling is lethal. Partial girdling slows a tree’s growth and increases the likelihood of insect and disease infestations. Bears often strip the most vigorous trees. Damage frequently occurs after stand improvements, such as thinning.

Photos of trees peeled by a black bear.
Figures 2a and 2b—Douglas-fir trees peeled by a black bear
feeding on sugars in the newly formed wood beneath the bark.

While bear damage occurs nationally, damage occurs frequently in the Pacific Northwest. Whether the damage reflects improved stands with just one timber species, decreased alternative forage, behaviors that offspring have learned from their mothers, or increased bear populations is largely unknown. All of these causes probably play some role. Stand improvements have increased the palatability and nutritional content of the trees. Cubs that eat the sapwood of trees stripped by their mother will probably continue stripping trees when the cubs are adults.

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