An Analysis of Trees Marked by Black Bears in the Great Smoky Mountains National Park

With the study area for the Great Smoky Mountains National Park, 691 black bear (Ursus americanus) mark trees were located. Mark trees along 135 km of preselected index trails were tagged, physiognomic parameters around the trees measured, and characteristics of the tree and mark recorded. Trees along the index trails were reobserved periodically from April to December, 1976-1977, to monitor fresh marking. Additional mark trees located away from manmade trails were characterized and classified as to their position on the slope. Multivariate analyses on an around mark tree were attempted to further delineate the relationship between environmental parameters and marking.

All mark trees were found near some type of trail. Marks on trees generally face the trail and up the slope. Eight coniferous and 26 hardwood species were marked. The choice of species apparently reflects their availability in areas of high bear use. Most mark trees were located along abandoned trails and ridge tops. Most fresh marking occurred during May, June, and July, but some fresh marks were observed during all portions of the year in which the bears were active. Thirty-one percent and 23% of the mark trees along index routes were marked fresh during 1976 and 1977, respectively.

The incidence of fresh marking from year to year or location to location may be useful as an index to population density. The form and function of bear marking was discussed and hypotheses were proposed. None of the discussed functions could be disproved and the data indicated that marking by bears has more than one function. A comparison of bear marking with scent gland marking in other animals demonstrated a close resemblance of their respective characteristics. Stepwise regression and discriminant function analysis indicated that physiognomic parameters affect both the time of year trees were marked and which trees were marked to a measurable extent. This study establishes baseline data for further investigations into the role of marking in the natural history of the black bear.