GRIZZLY AGGRESSIVENESS: HONED BY EVOLUTION

The potential aggressiveness of the female grizzly helps ensure the survival of her young. A female with older offspring is shown here. Photo by Janine Cairns-Michael.

So why is the grizzly a more bellicose bear? It is instructive to look back in time and examine the “neighborhood” that the grizzly bear species “grew-up” in. The fossil record indicates that the first grizzlies were found in North America towards the end of the Pleistocene epoch (geologists tell us this epoch ended about 11,550 years ago, spanned about 1.8 million years and covered the earth’s most recent period of repeated glaciations). The receding glaciers left luxuriant grasslands in their wake that were home to numerous herbivores, like bison, mammoth and yak. Where there are herbivores, there will also be great predators to cull the herds. Such was the case in the Pleistocene and the grizzly was one of these predators. But this was a rougher neighborhood than the modern day grizzly inhabits. There were massive saber-toothed cats, dire wolves and a behemoth of a bear known as the giant short-faced bear (Arctodus simus) – this was a massive creature that is proposed to reach a weight of 2,000 pounds.

While the grizzly foraged in the open grasslands, usually adjacent to forested areas, the black bear was (and still is) a resident of the woodlands - a habitat that is critical for the survival of their young. A black bear cub can climb trees days after leaving the maternal den. By scurrying up trees, neonates are able to elude most predators. In many cases, the mother black bear will climb up the tree behind her young or may remain at the base of the tree to dissuade a potential threat from pursuing her offspring any further. Because of their arboreal abilities, momma black bears rarely have to fight off the enemies of their cubs.

Now consider the grizzly. This species is not an adept climber. Even if they were, spending time in the open grassland habitats preclude the likelihood they are going to be able to out climb an adversary. Therefore, in order for the grizzly to survive and protect its vulnerable young in this more exposed Pleistocene ecosystem, it was the female’s aggressiveness that determined whether her offspring survived or not. Those mother grizzlies that turned into a raging ball of fury when their young were threatened passed more of their genes (including their aggressive inclinations) into the next generation. If she had a disposition more like that of a black bear sow, her young would not last long on this hostile, unforgiving community.

Natural selection has apparently honed the female grizzly into a more volatile creature – unfortunately, when it comes to getting along with H. sapiens their defensiveness is a big strike against them. While a black bear sow with young of the year is more likely to run for cover when encountering a human hiker, a mother grizzly is more predisposed to initiate a preemptive strike (that is, take out the potential threat before that threat can harm her cubs).

Male grizzlies can also be aggressive toward people, but usually only when they are taken by surprise. If a grizzly (boar or sow) knows your coming, more often than not, they will vacate the area in order to avoid contact with their most formidable rival - man. But if the boar is suddenly face-to-face with a human, it may do as the female with cubs does; that is, take out the menace to prevent harm to itself. That said, in most cases, a surprised bear will simply bluff charge, hoping that intimidation will be enough to prevent the threat from attacking or run away. On rare occasions, usually when the person behaves inappropriately, the bear may make contact.

Many grizzly attacks can also be attributed to defense of a food source. The script for these episodes usually goes as follows: unknowing human stumbles onto a food cache (usually the carcass of a large animal), grizzly that is resting nearby guarding its prize, or feeding on it, attempts to drive off potential competitor (said human). Bear bites and slaps unsuspecting interloper around a few times and returns to its post. A subsequent assault may occur if the human does not behave appropriately (e.g., gets up attempts to flee, fights with the bear). In most cases, the curl up and “kiss your ass goodbye maneuver” (that is, play dead) is the most appropriate defensive strategy in these situations.

It was one of a family of grizzlies that were defending their food that mauled a jogger, 54-year old Dennis VanDenbos, around Jackson Hole last summer (2007). Janine and I encountered this ursid family unit (a sow with three larger offspring) in the willows along the road early one morning last spring. The family had been hanging around in this area, to the delight of many tourists, for a long time and had not been implicated in any aggression towards human observers. But this morning, the 350-pound sow, along with her cubs, were feeding on an elk carcass, when the unsuspecting Mr. VanDenbos stumbled across the bruin bunch and their freshly-killed ungulate prize. When confronted by the bears, VanDenbos yelled at the bears and when that didn’t work, he hit the ground and played dead. One of the bears ran forward and bit and clawed the man (for more on this story click here).

It may be surprising to some readers that grizzly attacks rarely have a predatory component. Of all the serious human-grizzly conflicts that have occurred in Alaska, only 1 % of these attacks ended in the victim being fed upon. In fact, the majority of attacks (about 88 %) were of short duration, lasting no longer than 60 seconds. The typical encounter is typically fast and furious.

While black bear attacks may be less frequent than those inflicted by grizzlies, bear biologist Dr. Stephen Herero has documented U. americanus assaults are often motivated by predation. If the black bear presses home an attack, it is more likely an attempt to eat you than defend progeny or a resource. In fact, Dr. Herero recommends fighting, tooth and nail, against a marauding black bear, not playing possum. In the last couple years, there were two cases of black bears preying on humans: one case in Utah (click here for more) when a black bear killed a 11-year old boy (2007), and one case in Tennessee, where this species killed a 6-year old (2006) (click here for more).

So how dangerous are bears, especially grizzlies? We will investigate this in the next ursid post.

Copyright (2008) Scott W. Michael

TWO BEARS - A DIFFERENCE IN DISPOSITION

A large boar in its prime, like this one along the Katmai coast, is an impressive animal. Photo by Scott Michael.

Another reason for the disparity between the number of black and grizzly bears in North America has to do with their habitat preferences and behavior, which is a function of their long evolutionary history. For centuries, frontiersmen that roamed the wilderness recognized that the grizzly is a much more dangerous beast than the black bear. In 1703 Baron Lahontan, in his book Memoir of A Fur Trader in Canada, made the observation “The reddish bears are mischievous creatures, for they fall fiercely upon the huntsmen, whereas the black one fly away.” In the journals of Lewis and Clark the grizzly is referred to as “a creature of extraordinary ferocity” and they noted that it would rather attack man than avoid him (ironically, the more detailed observations they include in their journals do not support this claim).

Theodore Roosevelt listed the Alaskan brown bear and then the grizzly as the most dangerous wild animals to man (note: these are one in the same species). He stated, “The king of the game beasts of temperate North America, because the most dangerous to hunters, is the grizzly bear.” In contrast, the back bear has never had such a dubious reputation. In his book Grizzly Country, Andy Russell says the following about the two species, “To compare him [the grizzly] with his lesser cousin, the black bear, is like standing a case of dynamite besides a sack of goose feathers.”

This is not to say that black bears do not attack people, but they do so much less frequently than grizzlies (In fact, in 2007 several people were killed by black bears in the Lower 48 States). Consider Dr. Stephen Herrero’s study that looked at injuries inflicted on humans by bears between 1960 and 1998 in Alberta, Canada. Of 42 serious or fatal attacks on humans in this region, 69 % were caused by grizzlies, while only 31 % were inflicted by the black bear. Then take into account that the latter is 38 times more common than U. arctos - it is very clear that the grizzly is by far the more dangerous of the two species (Herrero estimated that at this time, there were about 1,000 U. arctos in Alberta province and from 38,000 to 39,000 U. americanus). We will discuss the disposition of the grizzly in much more detail in future blogs (you might be surprised at some of my conclusions on just how dangerous grizzly bears are to humans!).

Copyright (2008) Scott W. Michael

HUMAN SPRAWL AND THE GREAT BEAR

The black bear has had a far easier time dealing with human encroachment. Photo by Scott Michael.

One reason that grizzly numbers plummeted as Europeans subdued the North American continent is because this bear requires large tracts of wilderness in order to survive. Human development in grizzly habitat has continued to have a negative impact on the great bear. Much of grizzly country includes picturesque landscapes where people want to visit or settle. More campgrounds, hotels, hiking trails, restaurants, swimming pools, tennis courts, stores, golf courses, ski areas, housing developments, etc. are popping up within or at the periphery of prime bear habitat. More development, either residential or business, also means more roads – this equates to more bear-people encounters and more bears being struck by automobiles.

Many people that set-up residence in bear country are unwilling to put up with the potential danger or property destruction that are inherent in sharing the “wilderness” with these large carnivores. In fact, most premature bear deaths result from “defense of life and property” (a.k.a. DLP) kills and automobile collisions. Between 1992 and 2000, 74 grizzlies were killed by humans in the Great Yellowstone Ecosystem (Gunther et al. 2004). Forty-three percent were killed in DLP incidents, while 28 % were destroyed by park managers because of conflict between these grizzlies and humans (most of these “bad” bears were killing livestock, raiding orchards or bee hives). During this study, no humans were killed by grizzlies in the area, but 38 people were injured (most of these were hunters [54%], followed by hikers [31%]).

Black bears have better adapted to the encroachment of human habitation. Ursus americanus is a stealthy bruin that will spend the daytime hours in the woods, only foraging in people-infested areas when darkness falls. Unlike their grizzled kin, they do not require the large wilderness areas to survive. More on the differences between black bears and grizzlies in tomorrow's post...

Copyright (2008) Scott W. Michael

THE MALIGN MONARCH OF NORTH AMERICA

Ursus arctos along the Katmai coast. Photo by Scott Michael.

The grizzly has been a subject of lore and legend for centuries. When Lewis and Clark made their way across the North American continent, it was the grizzly that made the biggest impression on this band of explorers. Of course, the Native Americans had already developed a special relationship with the grizzly. They revered the great bear and some tribes attributed physical and mystical powers to the beast. For example, In the Koyukon tribe, women were not allowed to touch the meat or hide of the grizzly as its spirit was too powerful for a female to handle. European hunters, trappers and pioneers also encountered the grizzly as they dispersed and settled across the North American wilderness. It wasn’t long before man and bear were butting heads.

California is one of many sad examples demonstrating the outcome of this conflict between man and U. arctos. It is hard to imagine that California was once a haven for the grizzly bear. There are accounts from as early as the 1500’s to as late as the 1900’s that tell of “troupes” or “regiments” of grizzly bears feeding on whale carcasses that were cast-up on California beaches. When Scotsman John Muir explored Yosemite National Park, there were both black and grizzly bears. In his writings he shares many of his observations on Yosemite’s U. arctos. He described his first encounter with a grizzly (which he refers to as the Sierra bear) as follows:

“In my first interview with the Sierra bear we were frightened and embarrassed, both of us, but the bear was better than mine. When I discovered him, he was standing in a narrow strip of meadow, and I was concealed behind a tree on the side of it. After studying his appearance as he stood at rest, I rushed toward him to frighten him, that I might study his gait in running. But, contrary to all I had heard about the shyness of the bears he did not run at all; and when I stopped short within a few steps from him, as he held his ground in a fighting attitude, my mistake was monstrously plain. I was then put on my good behavior, and never afterward forgot the right manners of the wilderness." Our National Parks (1901)

The last grizzly bear was reportedly killed in California in 1922 – it was shot by a rancher. Isn’t it ironic that the prominent symbol on the State flag of California no longer lives there because of the man-grizzly rivalry?

So why was the grizzly eradicated from the California landscape, as well as over most of their North American range, while the black bear was not? Black bears have done much better, not only in California, but all across North America. There are currently an estimated 800,000 black bears in the lower 48 and only about 1,000 grizzlies (no one really knows for sure how many of either species live on this continent, but these are the expert’s best guesses). In the 1900’s it has been estimated that there were over 100,000 U. arctos in North America. (We will look at why the black bear has been able to co-exist with Homo sapiens in more detail in a future post.)

Copyright (2008) Scott W. Michael