Confrontations between American black bears and grizzly bears are fairly rare. If a black bear encounters a grizzly the black bear typically runs away or climbs a tree, but more than often they can smell each other long before they get too close. Occasionally black bears will attempt to defend themselves against small subadult brown bears and yearlings or even larger bears if there is no acceptable escape route. In areas where they are sympatric or overlap in range, the bears utilize different resources or are active at different times. In the 1970′s acclaimed bear researcher and expert on bear attacks, Dr. Stephen Herrero, a Professor Emeritus at the University of Calgary, compared aspects of ecology, evolution and behavior between black and grizzly bears. Dr. Herrero, the source for much of our current knowledge of the interactions between wild black bears and brown bears, and bears and humans for that matter, suggested that black bears had evolved to exploit forested habitats whereas grizzly bears utilized non-forested areas where they could exploit different food resources and habitat types.
In a correspondence with Dr. Herrero, he added that “In the forest, trees provided safety for climbing black bears and favored a less aggressive bear. However, in the open, brown bears had to use agression to defend themselves.” To learn more about bear behavior, I reccomend reading Bear Attacks: Their Causes and Avoidance by Stephen Herrero.
As mentioned these two distinct bear species are active at different times throughout the day. For example, in a 2008 study documenting the presence or absence of grizzly bears in the Wind River Reservation of Wyoming, the Wyoming Department of Game and Fish detected, with remote cameras, bear activity during diurnal (day) and crepuscular (dusk) periods with grizzlies being more crepuscular and black bears more active during the day. Other studies have shown that in areas where their range overlaps that grizzlies are more active at night while black bears are active during the day. This is true in Yellowstone, for example.
If a black bear is unlucky it may be killed and even consumed or partially consumed by a grizzly bear. In 2002, Gunther et al. discovered a probable case of grizzly bear predation on an American black bear in Yellowstone National Park.
This past weekend at the Alaska Wildlife Conservation Center our female black bear, Uli, who shares an enclosure with Kuma, awoke from hibernation to find two Kodiak bear cubs in an adjacent enclosure. Kuma, terrified of the smell of grizzly bear was so agitated by their presence in early winter that he could barely den down at all for a winter’s sleep. My first observation of their inter-specific interaction left me relieved and yet it gave me some ideas for how to better habituate the bears to the being neighbors. Taquka was clearly interested in this adult black bear who is at least twice his size. It appeared as though the male cub was testing her by approaching the fence, but I think he was just very curious and if anything wanted to play with her. Uli on the other hand was patroling the perimeter of the fence investigating new sights and smells of the early Spring in southcentral Alaska. She was not particularly amused by the antics of the 13 month old Kodiak cub and charged the fence if he came too close. Another sign of agitation was her persistent lip smacking behavior and high pitched vocalizations. There was nothing subtle in her attempt to communicate to the cub that he was intruding on her percieved space. Uli from a sitting position clawed at the ice, demonstrating just how powerful a bear can be and what kind of damage bear claws can inflict.
I decided that if I mediated the encounters to some degree and introduced the cubs to the black bear sow more gradually with food as somewhat of a distraction that perhaps we could expedite the introduction period and ensure that there was no need to relocate any of the bears to another enclosure. Our director, mike miller, an astute observer and a person with great animal sense was very confident that things would not escalate. He was right. On Sunday I took a bucket of Eukaneuba puppy chow and a container of blueberries out to the cubs, but instead of initiating a training and conditioning session at the front of the exhibit near the patrons, I escorted the cubs over to the side nearest Uli and Kuma. Uli was already walking the perimeter and as soon as she saw me she approached the fence and faced the cubs who were trailing me by a few meters. Taquka was a willful participant and Shaggy (Shaguyik) was just taking it all in as I began to work with them calling out behavioral cues or “commands” as part of our center’s behavioral enrichment program. As they responded to my requests I tossed some blue berries, one at a time to each cub and a few to Uli.
Although Shaggy is much more food motivated than the other cub, he is the dominant of the two. She seemed more or less indifferent to the presence of the larger black bear on the other side of the deer fencing, but none-the-less, she waited her turn as I tried to focus mostly on interactions between the male cub and the black bear. Eventually I asked both cubs to “station” where they were and like obedient pupils they both sat down. Uli was also sitting and I proceeded to feed everybody a handful of puppy chow. As onlookers and staff watched quietly I continued with the informal introduction, but gradually placed blueberries and puppy chow closer to the fence line, drawing all three bears toward each other. This tactic utilized to encourage cooperative feeding, although modified for the circumstance, is what captive wildlife managers use in zoos and other facilities to make sure that everyone gets fed. In this case, I was trying to divert some of their attention to food while they were in proximity to each other, knowing that they could not contact each other. The cubs, as expected, would occasionally squabble over food and the most important thing was for me to get out of the way as the two 100 lb fur balls went after each other.
After observing these inter-species behaviors I talked to Dr. Grey Stafford, one of the cohosts of my radio program, Zoo Talkin’ Radio, and the Director of Conservation at the Wildlife Word Zoo and Aquarium. Grey said that “Teaching animals to remain calm in a group setting (i.e., desensitization), whether physically or just visually in contact with one another, can be achieved with deliberate application of positive reinforcement, such as the high value food items Jordan describes. The key is to recognize the underlying and dynamic relationships (i.e., rank) among the various animals (or species) and to quickly provide access to reinforcement for calm, approach-type behaviors accordingly– in the order of lowest to highest ranked individuals. In any group encounter, reinforcing that situation’s highest ranked individual last, teaches it to remain calm and that delivery of reinforcement to other, lower ranked individuals is also a cue that reinforcement is forthcoming (for approaching, remaining calm while others receive reinforcement etc.). Consistent and expeditious delivery of reinforcement in the order of lowest to highest rank also teaches timid members of the group to exhibit more confident types of behavior such as approach others, station for longer duration, eat in the presence of more aggressive animals, and so on. ” He went on to say that “Since the context (e.g., environmental, internal, temporal, seasonal etc.) in which these encounters occur may alter an individual’s apparent ranking from one occasion to the next, it is vital that trainers continuously assess (i.e., best behavioral guess based on observable behaviors) the ever-changing relationships and social rank of each individual in relation to the others in a group, and thus, adjust the order of reinforcement delivery accordingly.” For more information on training wildlife and companion animals, I refer you to Zoomility by Grey Stafford.