Introduction to Grizzly Bear Population Data

Before the grizzly bear population in the GYE can be considered for delisting, it must meet the following THREE Demographic Recovery Criteria:

1. Demographic Recovery Criterion 1 "Because 48 adult females with cubs of the year is equivalent to a population of approximately 500 total individuals (IGBC, p. 43), we are establishing a target number of 48 adult females of the year. This target number shall not go below 48 for any two consecutive years. For genetic reasons (Miller and Waits 2003, p. 4338) it is desirable that the total population of grizzly bears in the GYE be maintained above 400 bears. To assure that this goal is met and in order to adopt a conservative approach, the total population will be maintained at or above 500 grizzly bears. The estimate of 48 adult females with cubs of the year will be calculated by the IGBST based on model averaging described in the Supplement to the Reassessing Methods Document (IGBST 2006, pp.2- 10)."

2. Demographic Recovery Criterion 2 "Sixteen of 18 bear management units within the Recovery Zone must be occupied by females with young, with no two adjacent bear management units unoccupied, during a 6- year sum of observations. This criterion is important as it ensures that reproductive females occupy the majority of the Recovery Zone and are not concentrated in one portion of the ecosystem."

3. Demographic Recovery Criterion 3 "For independent females (at least 2 years old), the current annual mortality limit, not to be exceeded in 2 consecutive years and including all sources of mortality, is 9 percent of the total number of independent females. For independent males (at least 2 years old), the current annual mortality limit not to be exceeded in 3 consecutive years and including all sources of mortality, is 15 percent of the total number of independent males. For dependent young (less than 2 years old), the current annual mortality limit, not to be exceeded in 3 consecutive years and including only known and probable human caused mortalities, is 9 percent of the total number of dependent young."

Datasets

Additional Resources

Articles, Readings, and Websites

Media

  • Grizzly Bear Corridors (Map)
  • Grizzly Bear Range (Map)
    • Alternate text: Map showing North America with two differently shaded areas.
      Shade #1 shows the historic range of Grizzly bears: Covers from the top NW 1/3 of Mexico, ¾ of western Texas, nearly all of the great plains, both of the Dakotas, nearly ½ of Canada (western and northern), and all of Alaska. On the western side it covers the top of Baha all the way to the top of Alaska.Shade #2 shows the current Grizzly bear range: Covers a couple of spots in the Rocky Mountains (near Yellowstone National Park and near Glacier National Park and nowhere else in the lower 48 states or Mexico), it follows the Mountain range into Canada till about ½ way through the lower Province of Alberta, and covers approximately 7/8th of British Columbia. All of the Yukon and Alaska are covered, 2/3rds of the Northwest Territories and all ¾ of Nanavut (NE not covered).
      In summary the historic range of grizzlies covered approximately ½ of North America whereas their current range has shrunk to about 1/3 of Canada and all of Alaska.
  • Greater Yellowstone Ecosystem and Bear Management Units (Maps)