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Marking Trees and Poles

marking_major-bite_red-pine_800x600.jpgBlack bears of all ages and both sexes rub their scent on marking trees, including wooden sign posts and utility poles, but the majority of this marking is by mature males during the mating season (May and June in Minnesota).  They rub their shoulders, neck and crown and may also claw and bite the tree.  Claw marks are usually superficial, but incisor bites are deep enough that pieces of bark and wood are sometimes pulled out.  Bites leave nearly horizontal marks that look like a dot and a dash where the upper and lower canine teeth came together.

Marking trees are generally along trails.  Favorite trees have little ground vegetation to prevent a bear from approaching them, and they often lean slightly toward the trail.  Look for hair caught in the bark or wood 2 to 5 feet high and look for bites 5½ to 6½ feet high. 

The hair often bleaches to brown or blond after a few months but can still be distinguished as bear hair from its length and appearance.  Guard hairs are typically coarse and 3-4 inches long and have a narrow base that may be wavy.  Bears are shedding their winter fur when much of the marking is done in spring or early summer, so the bark may also catch underfur, which is thin, wavy and shorter. 

Utility poles are favorite marking ‘trees.'  These are typically in ideal locations along travel corridors, but preservatives might be a factor, too.  An easy way to tell if bears live in an area is to check the utility poles, especially those on upland ridges where bears are likely to cross a road.  Bite marks on utility poles are generally at the same height as on trees, but bears sometimes bite low on poles.

Bear-marked Trees and Poles:
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This utility pole has been heavily marked by black bears.  Bears seem to prefer poles and trees that lean  slightly and they rub into the lean.
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This utility pole has been bitten repeatedly by a male during mating season.  He both stood to back-rub and bite, and sat to head-rub and bite this pole. 
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Black bear fur caught on a utility pole the bear rubbed.  Hair can often be found on poles and trees where bears have rubbed.  Hair bleaches where it is exposed to sunlight. 
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This well-bitten utility pole marks a spot where bears regularly cross a road. 
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 This utility pole is along a power corridor.  There is a pool of mud around a nearby utility pole and that is likely the source of the mud rubbed on this pole.
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This simple bite was made by a black bear as it rubbed and bit this birch tree.  Bears stand to twist their head and bite with the upper and lower canine teeth on one side of their mouth. 
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This white birch bite tree was found along a bear trail paralleling a stream.  The red staining on the bark indicates the bite was fresh in the spring when the sap was flowing. 
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This white birch was bitten 3 years in a row in the spring—likely by a male bear—with each bite higher than the year before.  If the tree was bitten by the same male each time it might indicate a growth in stature.
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This white birch is located on the side of an ATV trail which bears use as well.  The bite on the left is very fresh while the darkened bite on the right is at least a year old. 
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This young white pine along a wooded trail has been heavily bitten over the course of several years. 
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This red pine is located along a well-used bear trail.  Fresh bites were found in April—likely made by an adult male.
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This red pine is located along a well-used bear trail and has been used repeatedly by bears as a marking tree.  The intensity of the marking has effected the tree's growth.
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This picture of a bear back-rub marking the red pine (see previous slide) was taken by a passive infrared trail camera. 
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Bear hair is caught in the bark of this red pine marking tree. 
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This hemlock, located at the edge of a stream, is coated with mud where a black bear has rubbed.  The lower muddy area is from rubbing its back and the upper area is from looking up and rubbing the top of its head. 
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This large cedar, located along a logging road, has been bitten repeatedly by bears over several years. 
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Bears are attracted to cedar and go out of their way to bite and rub cedar posts. 
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This is a closeup of the marking on the cedar post in the previous picture. 
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The slight lean to this white birch may have invited bear marking activity.  Bears seem to prefer trees and poles that lean. 
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This is a closeup of the white birch in the previous picture.  Notice the rather superficial claw marks.  The heavy marking is done with the teeth not the claws. 
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A recent bear bite on this spruce removed a wood chip. 
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Bear bites on marking trees such as this balsam fir are visible for many years. 
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If a marking tree dies, bears often move their marking activity to a nearby tree. 
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Marking trees along well-used corridors are often within sight of one another as in this picture.  The tree to the right in the background is also marked. 
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Bear bites on trees are long-lasting and allow for the identification of bear travel corridors even in winter.
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This red maple located along a bear trail has been bitten repeatedly over the years.