Grizzly Bear

By: David Ferris 3 White

Background

The North American grizzly bear is listed as threatened in in the United States, but is put on the endangered list in Canada. Though it is actually disputed whether or not the animal should actually be on the endangered list. In 2006, the U.S. Fish and Wildlife Service proposed to remove the species from its endangered species list, but was met with heavy lawsuits from several environmental organizations. Eventually, U.S. District Judge Molloy reinstated their protected status because of the decline of the whitebark pine tree, whose nuts are an important source of food for the grizzlies.

Why is the Grizzly Bear Endangered?

Grizzly bears are endangered for a number of reasons. One reason is that the bears are hunted as big game all over North America. Farmers also illegally hunt the bears because they see them as a threat to their livestock, and do not want the bears to kill their animals, which is how they make their living. Poachers also hunt the bears because their hides, teeth, claws, and internal organs, such as the gall bladder, fetch a very high price in the Asian medical markets. The gall bladder is ground up into powder and used to cure digestive problems, inflammation, and purify blood. Bear bile is also extremely high priced, and is supposedly a cure for AIDS. Ninety-five percent of grizzly bears who live past two years old will be shot by humans, but if they were free to live their full lifespan, they would live for about twenty-five years.

Ecological Importance

Grizzly bears play a very important ecological role in the ecosystem. One role is the mutualistic relationship that the bears have with fruit-bearing plants. The bears eat the plants and then the seeds are excreted and distributed all around the bears habitat, because of this the seeds are now germinable and ready to grow again.

Another ecological role bears play is that they stir up soil. When bears forage for food, they dig into the soil and mix the soil up. Studies show that when the bears dig up soil, it actually increases plant diversity in that area. When bears dig up the soil, it also causes nitrogen from the lower soil levels to be brought up, which plays a vital role in the nitrogen cycle, which can help cleanse our air. Bears can also increase nitrogen when they bring salmon carcasses back behind the river bed.

Grizzly bears can be categorized as a keystone species in Yellowstone National Park, that is they directly influence the ecosystem. They keep the prey population under control and help prevent overgrazing. A study done in Yellowstone found that with the removal of wolves and the grizzly bear the herbivorous prey increased, changing the density and structure of the surrounding plants, which decreased the population of migratory birds.

Economical Importance

As mentioned above, the grizzlies dig up the soil and bring salmon carcasses up from the river bed which in turn produce nitrogen. Without this, the air around their habitats would become more dirty and less fresh. This would drive down tourism into the national parks, causing the parks to lose revenue.

Grizzlies also are a keystone species in Yellowstone, so if they did not keep the prey population under control, the herbivorous prey would increase, causing the plant population to significantly decrease, which would also drive down tourism at the national parks, which would be bad for the national parks.