Ups and Downs for Grizzly Bears

North American grizzly bears appear in the news frequently. The overall picture is one of a species in trouble, but possibly with some help on the way. Is it too little too late?

Historically the grizzly bear ranged much of the North American continent — from the mid-plains to California, and from central Mexico to Canada and Alaska. As human populations across North America began to grow, the grizzly bear populations began to decline. Between 1800 and 1975, the grizzly bear population in the continental United States dropped from an estimated 50,000 to approximately 1,000. In 1975, the grizzly bear was listed as a threatened species under the Endangered Species Act.

There are now about 58,000 grizzly bears left on the North American continent. More than half of them live in Alaska. The rest live in Canada and scattered areas in the U.S. Northwest.

Threats to grizzly bears include destruction of habitat and interference from humans who feel they need to protect livestock and human life. Grizzlies feed on green vegetation, wild fruits, insects, carrion, and small mammals. Bears along the western coast depend heavily on salmon, which are also threatened. The bears have a slow reproductive rate, which makes it hard for the population to rebound.

Here are summaries of news stories about North American grizzly bears. Each story presents its own educational problem.

1. Development is bad news for grizzlies

Grizzly bears in the Greater Yellowstone ecosystem in Idaho, Montana, and Wyoming are being threatened by rapid development in the area. Urban sprawl, logging, oil and gas drilling, SUV and RV traffic, and new roads are destroying traditional grizzly bear habitats.

Learn about the Problem

• Learn more about urban sprawl in the Riverdeep article, "Urban Sprawl Changes Landscape."

2. Salmon shortage starving Canadian grizzlies

British Columbia's grizzly bears come out of hibernation in spring, hungry for a good breakfast. But the salmon stocks on which they usually feed have declined to the point where the fish cannot satisfy the bear population's nourishment needs. The salmon shortage is a result of overfishing and logging, which fills the salmon streams with mud. Hungry bears go out in search of food, a trip that often brings them into contact with humans, with fatal consequences for the animals.

Learn about the Problem

• Learn more about how changes in the food web can affect populations in the activity Biology Gateways: Food Chains and Food Webs. (This and other activities require Logal Express. Get a free trial subscription.)
  
  
• For a discussion, additional examples, and educational links, see Teaching the News, "Warming the Food Web."

3. DNA technology helps track grizzlies

In order to aid in conservation of grizzly bears, researchers need to know how many bears exist and whether the population in a given area is increasing or shrinking. Traditional monitoring methods, such as radio telemetry, are very expensive and require trapping and sedating the bears. U.S. Geological Survey ecologist Katherine Kendall has begun to use DNA fingerprinting to identify bears by the hairs that they leave behind when scratching themselves on baited barbed wire.

Learn about the Problem

• Learn what DNA fingerprinting is, and perform a simulated identification in the Biology Gateways activity: DNA Fingerprinting.
  
  
• Read about other applications of DNA fingerprinting in Teaching the News, "MIAs Top Priority during Cohen's Vietnam Visit."

4. Final plan afoot to reintroduce grizzly bears

The U.S. Fish and Wildlife Service released a plan for reintroducing grizzly bears into wilderness areas in Idaho and Montana. Species that are reintroduced into natural habitat must be monitored, a responsibility that would be shared by federal managers and local citizen volunteers. Bears who frequent areas used by humans could be relocated or destroyed.

Learn about the Problem

• Learn about population management and introducing species into an ecosystem in the Biology Explorer activity: Maintaining System Balance.
  
  
• Read about additional animal populations that present management problems in Teaching the News, "Hunting and Restoration as Population Management Tools."
  
  
• Read articles and studies pertaining to grizzly bear recovery in the Bitterroot and Yellowstone ecosystems.

Think about the Problems

Synthesize the information presented in the articles and activities by writing a short summary of the status of North American grizzly bears. List the problems facing the bear population and possible solutions.

For the Teacher: Extending the Problem

• Students can learn more about grizzly bears and the initiatives to help them at the following sites:
  
  
  • The Bear Den
    
    
  • American Bear Association
    
    
  • U.S. Fish and Wildlife Service's Grizzly Bear Recovery
    
    
  • Sierra Club's Grizzly Bear Ecosystems Project
    
    
  • Monitoring Grizzly Bear Populations using DNA
  
  
• Divide your students into groups and have each group choose an endangered species. The students should research the species and prepare a plan for preserving the population. Use the following sites as starting points:
  
  
  • U.S. Fish and Wildlife Service's Endangered Species
    
    
  • EE-Link Endangered Species
    
    
  • American Museum of Natural History's Endangered! Exploring a World at Risk
  
  
• Cartoon classic Yogi Bear of Jellystone Park is exactly the kind of bear that ecologists do not want grizzly bears to become. If the cartoon is run on a cable channel in your area, have students watch a few episodes and make a list of Yogi's "bad habits" that North American grizzly bears are at risk of adopting.
  
  
• National Geographic.com has a multimedia-rich article where kids can see grizzly bears in action.