By Jack Sherritt ’22
When you think of bears you typically think of bears as large, passive, lonely animals when angry are very ferocious. They usually communicate by growls, huffs, or barks. Bears also mark trees by clawing or biting. However, in this study it shows communication with chemical signaling. Bears do chemical signaling by rubbing mostly on trees, but also on fence posts and some power poles. The goal of this study was to determine if the bears rubbing was to show dominance or to greatly advertise themselves to females for breeding. The test was conducted in southeast British Columbia on brown bears for over ten years. They purposely picked a place where food was spread out so bears are forced to travel around possibly giving themselves more chances to rub on new things. They set up specific bait sites to make it easier to collect hair from the different bears. There are about 350 bears in the area of study. The test is comparing males and females depending on the season.
Bears are not territorial animals. They have home ranges that they travel and these ranges overlap with other bears home ranges. Since they do not have set territories, it was initially thought that the rubbing was for mate attraction. It was thought that if they don’t compete for territory, dominance shouldn’t matter too much. Yet, mate attraction and dominance does have somewhat of a correlation in the breeding season. The reason that males rub in the mating season is to show their dominance and availability for mates. How dominance is shown is that the more rubbing in an area you have rubbed, the less likely another male will compete in that area. This means that bears must constantly rub on trees so they can show dominance throughout the breeding season to give them the best chance to find a mate. However, in the non breeding season, the amount of rubbing that males do decreases. They rub on objects 41% less in the non breeding season. Females on the other hand were found to rub around the same amount in both the breeding and non breeding season. They were also found to rub significantly less than males in both seasons.
Bears use this rubbing technique to both show dominance and attract a mate. Males have almost no need to be dominant in the non breeding season since they don’t have territories to guard. They could use rubbing as a signal for a frequent food spot it visits to possibly fend off other bears so there is more for himself. They could also use it in the non breeding season to attract males for the next years breeding season. Rubbing isn’t just native to this group, there are other groups that do it even though they don’t have many things to rub on. Another group in the Arctic of Canada don’t have many things to rub on, but if they are presented something to rub on, they do it. This makes it look like a natural behavior. This behavior is seen in multiple areas with brown bears. It gives the more “dominant” males an advantage and isn’t seen as much in females. Females could rub more if they have cubs in an effort to keep other bears away or even other animals. This chemical signal is probably sensed by other animals as well, leading to bears solarity. This study showed that rubbing is mainly done by males, done mostly during breeding season to attract a female.
