FIELD GUIDE TO INSECTS AND DISEASES OF ARIZONA AND NEW MEXICO FORESTS
Black Bear
Ursus americanus Pallas
Figure 300. Figure 300. Black bears rip strips of bark from trees and feed on the cambium.

Black bears rip wide strips of bark from trees, often starting at about 1 m from ground line. They forage on the cambial zone in the lower bole by removing or peeling the bark with their claws and scraping the vascular tissue with their incisors. Trees are often girdled and die from one stripping, but sometimes survive. The wound left in partially girdled trees can lead to extensive decay. Bears also break branches on oak trees to access acorns.

In the White Mountains and Pinaleño Mountains of eastern Arizona, black bear strip the bark of southwestern white pine and subalpine fir greater than 25 cm in diameter. This activity is so widespread in some areas that it is difficult to find a large undamaged southwestern white pine or subalpine fir.

References:  47, 50, 94