Northern Continental Divide Ecosystem

The grizzly bear (Ursus arctos horribilis) occupies over 6 million wilderness and non-wilderness acres in the Northern Continental Divide Ecosystem (NCDE) of western Montana. Notable regions within this ecosystem include Glacier National Park and the Bob Marshall wilderness complex. Grizzlies were listed as Threatened under the Endangered Species Act in 1975 for lack of biological information on its population status and habitat requirements. The NCDE is believed to have the largest population in the lower 48 states, although the number of bears is unknown at present. In 2004 however, fieldwork was completed that should provide an estimate of population size in the NCDE. This study used DNA extracted from hair-samples collected throughout the NCDE to estimate the number of bears.

However, information on both population size and trend are needed. Having estimates of size and trend will greatly improve our collective knowledge of grizzly bear ecology, and provide more measurable and precise information to judge the status of the grizzly population in the NCDE. Therefore, Montana Fish, Wildlife and Parks, in cooperation with other state and federal agencies, has initiated a program to monitor the population trend of grizzly bears in NCDE. The purpose of this long-term program is to monitor the vital population parameters of grizzly bears by assessing the survival and reproductive rates, and trend. This will be accomplished by radio-monitoring female grizzly bears.

• Cooperators
• Objectives
• Study Area
• Methods
• Reports
• Staff
• Core Team Members
• Acknowledgements

Cooperators

This program is a cooperative effort among the Montana Fish, Wildlife and Parks, the US Fish and Wildlife Service, the National Park Service, US Geological Service, USDA Forest Service, the Blackfeet Tribe, and the Confederated Salish and Kootenai Tribes.

Objectives

• Monitor survival and reproductive rates of female grizzly bears to determine population trend;
• monitor distribution of bears within and out-side of the recovery zone boundary;
• serve as a clearinghouse for telemetry and survival data on grizzly bears in the NCDE;
• collect and provide information on other management-oriented and pertinent aspects of grizzly bear ecology, and;
• provide annual written summaries to appropriate institutions, agencies, and the public.

Study Area

The grizzly bear historically ranged over much of North America from the plains westward to California and from central Mexico north through Canada and Alaska. Today, the grizzly is found in only about 2% of its original range in the lower 48 states.

The Northern Continental Divide Ecosystem (NCDE), in western Montana, has the largest population of grizzly bears in the lower 48 states, comprising over 6 million acreas of occupied habitat. The NCDE includes such notable areas as Glacier National Park, the Bob Marshall Wilderness complex, and the Rocky Mountain front. Female grizzly bears are being monitored in all areas of this mountaneous ecosystem.

Methods

A detailed description of study protocol can be downloaded in Reports. Generally, a sample of at least 25 radio-collared female grizzly bears will be maintained throughout the NCDE study area. Biologists will then monitor the bears radio signals from aircraft to determine whether they die, and their reproductive status.

Grizzly bears are captured using either culvert traps or Aldritch foot-hold snares. Female grizzly bears are then fitted with radio collars so that their movements can be monitored. In most cases gps collars are used and programmed to stay on the bear for 3 years, after which they are designed to automatically fall off via a release mechanism on the collar. We are also using specialized collars whose location data can periodically uplinked to a satellite and then to field computers. Using the Argos based satellite system, bears can be monitored in near-real-time. In other cases bears are monitored from fixed-wing aircraft.

Each female grizzly bear is radio-monitored as long as possible. During this period, biologists document how many litters and cubs they have. Some females will die, yielding an estimate of mortality levels and causes. Population trend will be determined by comparing the mortality rate of females to their reproductive rate. For example, a population that is growing will have a higher birth rate than death rate.

Reports

• Grizzly Bear Population Monitoring Team 2005 Annual Report ( 1.4 MB)
• Grizzly Bear Population Monitoring Team 2006 Annual Report ( 3.6 MB)
• Grizzly Bear Population Monitoring Team 2007 Annual Report ( 2.6 MB)
• Grizzly Bear Trend Monitoring Methods ( 1.24 MB)

Staff

Core Team Members

• D. Carney, Blackfeet Tribe
• T. Chilton FWP
• S. Courville, Confederated Salish and Kootenai Tribes
• J. Jonkel, FWP
• K. Kendall, USGS
• R. Mace FWP
• M. Madel, FWP
• T. Manley, FWP
• B. McLellan, British Columbia Ministry of Forests
• G. Olson, FWP
• C. Servheen, FWS
• J. Waller, NPS
• E. Wenum, FWP