Grizzly Bears

The grizzly bear symbolizes wilderness in North America (Figure 57-8). In certain respects, “grizzlies” define the “wild” in wilderness. They range from Alaska down through western Canada and into the lower 48 states in remnant populations located in relatively undeveloped federal lands, primarily in the northern Rocky Mountains.

FIGURE 57-8 Grizzly bear encounters have become popular events for wildlife photographers.

(Courtesy Timothy Floyd.)

Attacks by grizzly bears are relatively rare and sporadic. A total of 162 bear-inflicted injuries (including deaths) were reported from 1900 through 1985 in Canadian and North American national parks.^28,29 In the Canadian province of Alberta, there were 29 documented serious or fatal injuries caused by grizzly bears during the period of 1960 through 1998.³¹ From 1980 to 1994, 21 grizzly bear attacks, including two deaths, occurred in Yellowstone National Park.²⁷ During the following decade, one or two people were injured by grizzly bears in Yellowstone each year, with no recorded deaths. In Alaska, the number of people injured by grizzly bears has increased in recent times, most likely as a result of increased recreational use of grizzly habitat.^41,50

Calculation of an accurate injury rate remains elusive. Earlier records were incomplete, and it has always been difficult to define and quantify those at risk. Injury rates are based on total visitation days to the national parks in Canada and the northern United States.²⁹ The average number of grizzly bear–inflicted injuries is 1 in 2,260,276 visitors to these parks combined, with a high of 1 in 317,700 visitors in Kluane National Park and a low of 1 per 6,693,859 visitors in Banff. During this same period, the grizzly bear–inflicted injury rate for Yellowstone National Park was 1 in 1,543,287 visitors, and for Glacier National Park it was 1 in 848,180 visitors.

Not every visitor to a national park is exposed to the same risk of being attacked by a grizzly bear. To obtain an injury rate that more accurately reflects the risk for visitors with higher and more uniform exposure, the incidents among registered backcountry users have been reported. However, this method provides an inaccurate injury index because some parks do not register backcountry use and others generally underestimate it. Also, significant and perhaps most backcountry use (and therefore exposure) is by unregistered day hikers.

The number of bear attacks (both black and grizzly) increases in months when more people seek recreation in grizzly country. For national parks, the incidence of bear attacks increases during the peak tourist season, July and August. For surrounding national forests, another peak occurs during hunting season, September to November. With more people seeking recreation in bear country, greater opportunity exists for human–bear encounters.

Native peoples and grizzly bears occupied the same land for thousands of years in North America in what was probably a neutral coexistence, as neither had a profound influence on the other. However, the European expansion into the West after Lewis and Clark’s expedition in the early 1800s tipped the scales heavily in favor of humans, both in sheer numbers and in technology, such as guns, traps, and poisons. Bears were killed in large numbers, out of fear and hatred and to protect life and property. Most of their original habitat was occupied by either people or livestock or was dramatically altered by ranching and agricultural development.

Selection pressures that began with European expansion into the grizzly bears’ habitat have probably been altering their behavior. Since that early period and even today in protected areas such as national parks, aggressive bears have been removed at a higher rate than nonaggressive bears. Bears that were curious about humans and human developments and those that did not readily flee the presence of humans were also removed at a higher rate. Therefore, bears that avoided humans survived at a higher rate than other bears and probably passed that trait on to their offspring through genes and learning.

A built-in safety factor exists for people entering grizzly country, because the vast majority of bears now avoid a confrontation if given the opportunity, which probably explains why grizzly bear attacks on humans are so rare. Unfortunately, the available information on grizzly attacks does not always yield an accurate account of the cause-and-effect relationship. The specific sequence of events is not always known and is subjectively reconstructed, although case histories reveal certain patterns.

A sudden and close encounter with a grizzly bear is the primary event leading to human injury. From 1980 to 1994, of 21 people injured by grizzlies in Yellowstone National Park,²⁷ 18 resulted from people surprising a grizzly at close quarters. These attacks were often brief, and the bear generally left the area soon after the attack. Although injuries were typically described as a mauling, they were generally much less severe than the bear had the potential to inflict (Figure 57-9), and victims were rarely killed. This suggests that the bear’s behavior in response to a close encounter was to remove a perceived threat.

FIGURE 57-9 When surprised at close quarters, grizzly bears, who have the potential to do much more harm, often inflict relatively minor injuries and then flee. This victim of a bear attack stumbled upon a surprised bear who was trapped by fire lines.

(Courtesy Luanne Freer.)

A close encounter with a female with cubs is considered more dangerous, as she is considered to be more aggressive in defense of her young (Figure 57-10). Evidence to support this hypothesis is strong. Females with young represent about 20% of a bear population but account for more than 80% of the bears that injure humans. Another explanation, however, is that females with young are more likely to be active during daylight hours when humans are active, whereas males are active primarily in the predawn hours and after dusk.²⁰

FIGURE 57-10 Brown bear sows with cubs are notoriously aggressive in protection of their young.

(Courtesy Luanne Freer.)

Grizzly bear attacks sometimes occur near a carcass on which the bear has been feeding. The bears may be more aggressive under these circumstances in defense of the carcass. Grizzly bears of all ages and either gender, however, may readily exit when they sense people approaching.²⁰ When a grizzly bear injures someone near a carcass, the precipitating event may simply be a close encounter with a preoccupied bear.

Another class of attacks results from provocation, most often when a grizzly bear is wounded with a gun. Once the bear is injured, its behavioral response is no longer to remove a threat but to fight for its life. These attacks tend to be more prolonged and aggressive, resulting in more severe injuries than those resulting from a close encounter. Provoked bear attacks can result from direct harassment by aggressive photographers (Figure 57-11). Although such incidences are rare, these attacks tend to resemble the response of an injured bear rather than one responding to a close encounter. The injuries tend to be more severe, and a disproportionate number of photographers are killed. Up to 1985, at least 10 photographers were injured, 1 fatally, and from 1986 to 1992, at least 4 were injured, 2 fatally.²⁸

FIGURE 57-11 Photographers dangerously close to bears in the wild.

(Courtesy Luanne Freer.)

Most people attacked by grizzly bears are injured but not killed; the intent of the bear is simply to remove a perceived threat, not to prey on the individual (Figure 57-12). From 1900 to 1979, 19 human deaths resulted from grizzly attacks documented in the national parks in North America, and 22 deaths occurred in Alaska outside the parks.^28,37 A Wikipedia file tracking human deaths in North America from grizzly bear attacks cites 12 deaths in the 10-year period from May 2000 through May 2010; all of these citations are verifiable, but it is possible that this list is not a complete one.⁵⁸ Some were victims of defensive attacks; however, some deaths were probably the result of predatory attacks. It is important to ask why grizzlies do not prey on humans more often. As a potential prey species, humans are predictable and abundant, easy to catch and kill, and easy for a grizzly to consume.

FIGURE 57-12 Hunter attacked by grizzly bear.

(Courtesy Luanne Freer.)

Historic evidence suggests that grizzly bears did not routinely prey on humans except in unusual circumstances. In 1860, a smallpox epidemic struck a small band of Stonie Indians (Assiniboin tribe) camped in the Yarrow Creek drainage in Alberta, Canada.⁵¹ Grizzlies began scavenging on the dead left on the ground as the tribe moved to the next drainage. Grizzlies followed them to their next encampment and began preying on survivors. For years, the Indians avoided this area for fear of being eaten by grizzlies that had “learned” to prey on humans.

Since about 1900, when reasonably accurate records were first kept, predatory attacks on humans by grizzly bears generally have been rare, sporadic, and isolated events.⁵ However, a disturbing trend has begun in recent times. Between 1967 and 1986, 12 deaths were inflicted by grizzly bears in Banff, Glacier, and Yellowstone National Parks. In each case, the bear was conditioned to humans’ food (regularly seeking out and obtaining it) or habituated to human presence (not readily fleeing). Nine of the victims were partially consumed, and eight deaths were classified as predatory events.²⁸ During this same period, however, many bears with these same behavioral traits did not prey on humans. Conditioned and habituated behavior may predispose some grizzlies to prey on humans under certain but still not understood circumstances. The relationship between conditioning and habituation appears strong but is not conclusive. The bear involved was not always known, and the terms conditioned and habituation are both borrowed from learning theory and have never been precisely defined by wildlife biologists. This potential relationship, however, has significantly influenced grizzly bear management. Currently, the primary thrust is to prevent bears from obtaining human foods and from routinely being around people and human developments.

Grizzly bears may also mistakenly perceive a person as one of their normal prey species. Five such incidents have been documented. Two victims were killed by grizzly bears while making prey calls to lure in other predators. Two victims were attacked while field-dressing a game animal, and the fifth was attacked while carrying the hide of a deer draped over his shoulder. Clearly, persons should not look, smell, or sound like a prey species when in grizzly country.

Black Bears

Black bears are the most numerous and widely distributed of all North American bears (Figure 57-13). They occur in more than 30 of the lower 48 states, from Maine to Florida and from California to Washington. Recently, a black bear was recovered in Nebraska, where none had been seen in more than 100 years, adding to the growing numbers of large carnivores reoccupying previously native territory in the Great Plains.³² They also occur throughout Canada and Alaska, extending up to the tree line below the Arctic Circle. They are well adapted to an arboreal habitat and prefer to eat vegetation, carrion, and mast (nuts, acorns), with small mammals and insects accounting for less than 5% of the diet.¹⁶ Black bears have been filmed fishing in southeast Alaska⁴ and observed by the author doing the same in Yellowstone National Park, evidence of their ability to adapt to available food sources.^18,19

FIGURE 57-13 Black bear.

(Courtesy Timothy Floyd.)

Between 1960 and 1980, more than 500 people were injured by black bears, but at least 90% of these episodes resulted in minor scratches or bites inflicted by bears that were either conditioned to human foods or habituated to human presence.²⁸ The number of victims of black bear attacks has declined significantly during the past 25 years, in large part because of the aggressive bear management in and around national parks that discourages the feeding of black bears and removes those bears that seek out human foods. Injuries as a result of close encounters are extremely rare, and in contrast to female grizzly (brown) bears, female black bears display little aggression in defense of their young and rarely cause injury. They have short, sharp radial claws better adapted for climbing trees than for attacking humans. They often retreat rather than attack, even in defense; thus, hunters using dogs can “tree” black bears.¹⁶

Whereas grizzly (brown) bears sometimes prey on humans at night, black bears occasionally prey on humans during the daytime. In North America, from 1900 through the present, at least 45 people were killed by black bears, with predation considered the motivation in many cases. In many instances, attacks occurred in remote areas outside park boundaries; experts conclude that neither conditioning nor habituation was a major factor.

In recent years, black bears attempted to prey or preyed on humans; some attacks occurred at night while the victims were asleep. In one case, the bear broke into a camper and pulled the victim out, and in another case the bear entered a wooden teepee (“wickiup”) and dragged the victim out by her foot.⁴⁶ In most attacks, the black bears were driven away by aggressive actions by the victims and their companions, such as yelling and throwing objects.