LARGE ANIMAL ATTACKS - Medicine for Mountaineering and Other Wilderness Activities - page 459

Brown bears, also known as grizzly bears, and Kodiak bears, which are considered the
same species, are larger and more aggressive than black bears. Attacks on humans, a num-
ber of which are fatal, are periodically reported from areas inside and surrounding Yellow-
stone and Glacier National Parks and from the northern Rocky Mountains in the contin-
ental United States, Alaska, and Canada. Unlike most black bears, brown bears do behave
aggressively when they perceive a human threat. Sows with cubs are very aggressive and
are responsible for 80 percent of brown bear attacks.
A possible reason for the aggressive behavior of sows with cubs is that sows stay with
their cubs for three years and will not mate during that time. Male grizzlies sometimes will
kill cubssotheycanmate withthemother.Therefore, themother hastobeveryaggressive
in caring for her young.
Herrero, recording only reports that he considered highly reliable, found that brown
bears had inflicted 165 injuries in 143 incidents from the time records began in 1872
through 1979. He estimated that the true number of incidents and injuries was probably
twice those numbers. Of the injuries, 50 percent were considered major. He calculated that
during the 1970s brown bears inflicted one injury for each 1.3 million visitors in Glacier
National Park and one injury foreach 1.5million visitors in Yellowstone. Injury rates were
higher for backcountry visitors and ranged from one injury for each 2620 backcountry-use
days in Glacier and Mount Revelstoke National Parks in Canada to one injury for each
59,300 backcountry-use days in Yellowstone.
Approximatelyhalfthebrownbearincidentshaveinvolvedhikerswhosurprisedabear.
In 83 percent of the thirty-five incidents in which the distance from the hiker to the bear
was known, the bear was fifty-five or fewer yards away.
Avoiding Encounters with Brown Bears
Brown bears usually try to avoid interacting with humans. Hikers in the wilderness are
advised to make noise by shouting, talking loudly, or singing as they hike to avoid surpris-
ing brown bears. The effectiveness of bear bells is unproven. Police whistles, which are
usuallylouderthanahumanvoice,orhigh-frequencywhistleshavenotbeenproveneffect-
ive, probably because they are not loud enough. The bear has to hear the noise while still
farenoughawaynottofeelthreatened.Runningwaterorastrongwindrendernoisemakers
less effective.
One effective mechanism is an air horn powered by a canister of gas. Salmon tagging
crews in Alaska who sounded such horns periodically, particularly when near dense brush,
neverencounteredbears.Whentheyassumedbearswerenotpresentbecausetheyhadnev-
er seen them and stopped sounding the horns, they came upon a number of bears.
Particular vigilance must be exercised when traveling into the wind because bears may
not smell approaching humans even though they have a keen sense of smell.