Date of Award
Doctor of Philosophy
Gordon M. Burghardt
William S. Verplanck, Michael R. Pelton, Robert Wahler
This study describes the relationship of the human observer to observed black bears (Ursus americanus) , and describes social investigation and autogrooming behavior in black bears and relates these to aspects of chemical communication. The subjects were two pairs of captive black bears kept at separate locations--a male-female pair and a female-female pair, all of approximately the same age. They were sexually immature during most of the study. Both pairs were usually observed on the same days, for comparison. Observations were typically one hour long and behavior was recorded on paper every 30 seconds using a time-sampling technique. One hundred and forty-six hours of systematic observation were completed over a two-year period.
For non-human species there has been little, if any, quantitative research done on the problem of the reactivity of the observed to the observer or to the presence of humans. In the present study the effect was measured by pooling the 146 hours of data for all categories of behavior and groupings of categories by activity level for each of the 30 2-minute divisions within hour-long observation sessions. A linear regression analysis was performed on the rates for behaviors from the first 2-minute period through the last. At one location, Tremont, measures of certain categories of behavior and groupings of categories by activity level were highly correlated with time period within the observation session hour. Many of the correlations were steeply positively or negatively sloped. Behaviors which indicated resting or "relaxed" behavior increased from beginning to end of observations while behaviors requiring more energy decreased. The large changes in rates of some behaviors are interpreted as habituation to the presence of the observer. At the other location, Goldrush, there was far more stimulation from sources other than the observer and the bears were less responsive to the observer's presence.
Between bears, especially the females at Tremont, direct social investigation (less appropriately referred to as allogrooming) , which consisted solely of social sniffing and social licking, decreased to very low rates as they got older. The head/neck region was investigated most by two of the females. The male investigated his female cagemate's perianal/genital region, which is the site of socially attractive pheromone-producing glands in most species of Carnivora, might have been expected to be investigated at higher rates. The low rates may have been related to the absence or inactivity of such glands in the perianal/genital region and on the rest of the body surface.
Autogrooming, including rubbing (thought by some to function additionally in marking), was observed in order to determine its functions. Black bears have a varied repertoire of autogrooming behavior which is made possible by their postural flexibility and the dexterity of the plantigrade front paw. The various methods of autogrooming are each most effective at reaching certain parts of the body. The dorsal areas of the body were most easily groomed by rubbing against objects. Rates of scratching during quarterly periods of the year were related to rates of rubbing, especially during periods when the skin was known to be irritated by infection. It was concluded that rubbing is a significant form of grooming that relieves skin irritation, although other evidence was presented to suggest that rubbing may also function as a relatively unstereotyped form of marking that does not involve specialized skin glands.
Jordan, Robert Herbert, "An Observational Study of the American Black Bear (Ursus americanus). " PhD diss., University of Tennessee, 1979.