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The survival of grizzly bear populations depends on two factors: minimizing human-caused mortalities and protecting essential habitat. In 2004, the death rate of Yellowstone grizzlies was higher than the population can sustain. We know that 19 bears were killed in the Greater Yellowstone Ecosystem -- most as a result of conflict with humans -- and the U.S. Fish and Wildlife Service estimates that at least one other grizzly was killed illegally for each bear killed within the bounds of the law.

How Bears are Killed

In the area around Yellowstone, most bears die at the hands of humans. As described below, grizzly bears are killed primarily as a result of conflicts with big game hunters, or by game managers who kill bears deemed dangerous to people because they have become habituated to garbage and other human attractants.

  1. Hunter-Caused Mortality: In 2004, hunters killed 10 grizzly bears in and around Yellowstone National Park. These bears were killed as a result of:
    • Self-defense: A hunter can legally kill a grizzly if he feels the bear is attacking him. Eight grizzlies were killed in "self-defense" in 2004.

    • Mistaken Identity: Black bear hunters, often at bait sites in Wyoming, kill grizzlies because they cannot tell them apart from black bears. Two grizzlies were killed because of mistaken identity in 2004.

    • Poaching: Deliberate illegal killing of grizzly bears, while relatively rare near Yellowstone, is very common near Glacier National Park.

    Since 1990, the highest number of grizzlies killed by hunters have occurred in the backcountry around the southeast corner of Yellowstone National Park and in the vicinity of Cody, Wyoming.

  2. Management Action: Game managers killed seven grizzly bears in 2004, because of:
    • Food Conditioning/Habituation: Grizzlies are killed by game managers when they demonstrate repeated signs of pursuing food or garbage from human sources or other attractants such as grain and birdseed. These bear deaths can be avoided if people keep food and other attractants out of the grizzlies' reach. Six food-conditioned grizzlies were killed in 2004.

    • Livestock Depredation: If a grizzly bear repeatedly kills domestic livestock, managers will kill the bear. One grizzly was killed for livestock depredation in 2004.

    Since 1990, grizzlies have been killed by game managers primarily around the "gateway communities" of Yellowstone National Park. These are Big Sky, Montana; West Yellowstone, Montana; Dubois, Wyoming; and Cody, Wyoming.

Why Bear Mortality is a Problem

Given the small size of remaining populations, the death of even a few bears, especially females, can threaten recovery of the entire population. Grizzly mortalities are particularly problematic because:

  1. Grizzly bears have a very slow reproductive rate.
    • The average female grizzly bear does not have her first litter of cubs until she is five years old.

    • Litters range from only one to three cubs, and many cubs die before they reach adulthood.

    • The average female bear produces only one litter every three years.

  2. The Yellowstone population is small -- only 500 to 600 bears in the ecosystem.
    • Today, the Yellowstone grizzly bear population is isolated from other populations, making Yellowstone grizzlies vulnerable to genetic problems. Excessive mortalities increase the risk to the population in the future.

    • With so few bears in the population, it will take only a few years of high bear mortality to reverse the trajectory of the population from an increase to a decline.

    • Because grizzly bears reproduce at such a low rate, the population may not recover from a few years of excessive mortality, especially if many females are killed. Scientists project that a population decline of as little as 3 percent per year could make Yellowstone grizzlies functionally extinct within a few decades.

last revised 2/14/2006

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