Close
Menu

Grizzly Bear Population Monitoring

Northern Continental Divide Ecosystem

Grizzly Bear Monitoring Team

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. It is estimated from a 2004 DNA study that there are over 700 bears in the ecosystem.

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, initiated a program in 2004 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.

Grizzly Bear photo

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

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

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.

We are studying grizzly bears in the NCDE Northern Continental Divide Ecosystem (NCDE) of western Montana and into the Canadian provinces of British Columbia and Alberta. Our primary emphasis is placed within the 23,136 km2 federal recovery zone in the United States (Fig. 1), although bears traveled beyond this zone. We also capture and monitor bears up to 16 km north of the United States into Canada, which enlarged the study area to approximately 24,000 km2. There are 2 national parks in the study area: Glacier National Park in Montana (4,081 km2) and Waterton Lakes National Park (505 km2) in Alberta, Canada. Portions of the Blackfeet Indian Reservation and the Confederated Salish and Kootenai Reservation occur within our study area. Notable roadless regions outside the national parks include the Bob Marshall, Great Bear, Scapegoat, and Mission Mountain federal wilderness areas in the US. Nonwilderness areas of the NCDE are characterized by multiple-use lands under public, state, corporate, and tribal ownership. Approximately 17% of the NCDE was private land.

The study area consisted of rugged mountain topography shaped by glaciation. West of the Continental Divide, lower elevation habitats were dominated by Douglas fir (Pseudotsuga menziesii), lodgepole pine (Pinus contorta), subalpine fir (Pinus albicaulis), and spruce (Picea spp.). Mountains abruptly transition to short-grass prairie and limber pine (Pinus flexilis) savanna habitats along the eastern edge of the Rocky Mountains. Nonforested alpine habitats generally occurred above 2,000 m. Primary fruit-bearing shrubs important to the diet of grizzly bears during summer and fall include huckleberry (Vaccinium spp.), soapberry (Sheperdia spp.), mountain ash (Sorbus spp.), hawthorn (Crataegus douglasii), and serviceberry (Amanchier alnifolia).

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 be uplinked weekly to a satellite and then to computers. Using the Argos based satellite system, bears can be monitored much more closely. In other cases bears are monitored from 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.

Rick Mace

Richard Mace, Research Biologist. Montana Fish Wildlife and Parks.
Contact Rick!

Rick Mace has worked as a Research Biologist for Montana Fish, Wildlife, & Parks (MTFWP) for 28 years. Dr. Mace's research has ranged from osprey to bears, but he now focuses primarily on grizzly and black bears in northwest Montana. Currently, he supervises the Northern Continental Divide Grizzly Bear Population Trend Monitoring Program. He also works on brown bears and Dall sheep with the National Park Service in Denali Park and Preserve, Alaska. Rick received an M.S. is from the University of Montana, and a PhD in Wildlife Ecology from Sweden.

Lori Roberts

Lori Roberts, Database Manager/Trapper. Montana Fish Wildlife and Parks.
Contact Lori!

Lori Roberts has worked with Montana Fish, Wildlife, and Parks since 2007. Before beginning work with Montana FWP, Lori worked for five years in Yellowstone National Park as part of the Yellowstone Bear Management Team. Lori began her work with MT FWP working as a technician for Bear Management Conflict Specialists in Region 4 and Region 1 and has dealt with grizzly bear, black bear, and mountain lion conflicts. Moving from bear management to research, Lori became a member of the Northern Continental Divide Monitoring Team three years ago. She now assists with Monitoring Team field work and operations and manages the Northern Continental Divide Ecosystem grizzly bear database.

Seleted Publications

Aune, K. E., R. D. Mace, and D.W. Carney. 1994. The reproductive biology of female grizzly bears in the Northern Continental Divide Ecosystem with supplemental data from the Yellowstone Ecosystem. Ursus. 9:451-458 (PDF icon and link 430 KB)

Bestin, J.A. and R.D. Mace. What can harvest data tell us about Montana’s black bear bears? Ursus. In press.

Brannon, R, A. Dood, and R. D. Mace. 1988. Grizzly bear mortality in the Northern Continental Divide Ecosystem, Montana. Wildl. Soc. Bull. 16:262-269. (PDF icon and link 344 KB)

Dood, A. R., R. D. Brannon, and R. D. Mace. 1987. Management of grizzly bears in the Northern Continental Divide Ecosystem, Montana. Trans. 51th. N.A. Wildl. And Nat. Res. Conf. (PDF icon and link 522 KB)

Harris, R. B., C. C. Schwartz, R. D, Mace and M. A. Haroldson. 2011. Study design and sampling intensity for demographic analyses of bear populations. Ursus 22:24-36. (PDF icon and link 603 KB)

Owen, P. and R. D. Mace. 2007. Grizzly bear population ecology in Denali Park and Preserve. Alaska Park Science Symposium (PDF icon and link 111 KB)

McLellan, B. N., F. Hovey, R. D. Mace, J. G. Woods, D.W. Carney, M. L. Gibeau, W. L. Wakkinen, W.F. Kasworm. 1999. Rates and causes of grizzly bear mortality in the interior mountains of British Columbia, Alberta, Montana, Washington, and Idaho. J. Wildl. Manage. 63:911-920. (PDF icon and link 2 MB)

Mace, R. D.1985. Analysis of grizzly bear habitat in the Bob Marshall Wilderness, Montana. Pages 136-149 in G. P. Contreras and K. E. Evans, compilers. Proc. Grizzly Bear Habitat Symposium. U.S. For. Serv. Gen. Tech. Rep. INT-207.

Mace, R. D. and G. N. Bissell. 1985. Grizzly bear food resources in the flood plains and avalanche chutes of the Bob Marshall Wilderness, Montana. Pages 78-91 in G. P. Contreras and K. E. Evans, compilers. Proc. Grizzly Bear Habitat Symposium. U.S. For. Serv. Gen. Tech. Rep. INT-207.

Mace, R. D. and C. J. Jonkel. 1986. Local food habits of the grizzly bear in Montana. Ursus. 6:105-110. (PDF icon and link 224 KB)

Mace, R. D. K. Aune, W. Kasworm, R. Klaver, and J. Claar. 1987. Incidence of human conflicts by research grizzly bears. Wildl. Soc. Bull. 15:170-173 (PDF icon and link 159 KB)

Mace, R. D. ,S. C. Minta, T. L. Manley, and K. E. Aune. 1994. Estimating grizzly bear population size using camera sightings. Wildl. Soc. Bull. 22:73-84. (PDF icon and link 461 KB)

Mace, R. D., T. Manley, and K. E. Aune. 1994. Factors affecting the photographic detection rate of grizzly bears in the Swan Mountains, Montana. Ursus. 9:245-251 (PDF icon and link 329 KB)

Mace, R. D. and J. S. Waller. 1996. Grizzly bear distribution and human conflicts in Jewel Basin Hiking Area, Swan Mountains, Montana. Wildl. Soc. Bull. 24:461-467. (PDF icon and link 9.3 MB)

Mace, R. D.,J. S. Waller, T. L. Manley, L. J. Lyon, and H. Zuuring. 1996. Relationships among grizzly bears, roads, and habitat in the Swan Mountains, Montana. J. Appl. Ecol. 33:1395-1404 (PDF icon and link 1 MB)

Mace, R. D. and J. S. Waller. 1997a. Spatial and temporal interaction of male and female grizzly bears in northwestern Montana. J. Wildl. Manage. 61:39-52. (PDF icon and link 668 KB)

Mace, R. D. and J. S. Waller. 1997b. Demography and population trend of grizzly bears in the Swan Mountains, Montana. Conserv. Biol. 12:1005-1016. (PDF icon and link 738 KB)

Mace, R. D. J. S. Waller, T. L. Manley, K. Ake, and W. T. Wittinger. 1997. Landscape evaluation of grizzly bear habitat in western Montana. Conserv. Biol. 13:367-377. (PDF icon and link 714 KB)

Mace, R. D. 2004. Integrating science and road access management: lesions learned from the Northern Continental Divide Ecosystem Experience. Ursus 129-136 (PDF icon and link 303 KB)

Mace, R. D., D. W, Carney, T. Chilton-Radandt, S.A. Courville, M.A. Haroldson, R.B. Harris, J. Jonkel, M. Madel, T.L Manley, C.C. Schwartz, C. Servheen, J.S. Waller, and E. Wenum. Grizzly bear population vital rates and trend in the Northern Continental Divide Ecosystem, Montana. Journal of Wildlife Management. 76:119-128 (PDF icon and link 198 KB)

Manley, T. L., k. Ake, and R. D. Mace, 1992. Mapping grizzly bear habitat using Landsat TM satellite imagery. In: Greer, J. D. (Ed.), Remote Sensing and Natural Resource Management. American Society of Photogrammetry and Remote Sensing, Bethesda, Maryland, USA, pp. 231–240.

Neilson, S. E., S. Herrero, M.S. Boyce, R. D. Mace, B. Benn, M. L. Gibeau, and S. Jevons. 2004. Modeling the spatial distribution of human-caused grizzly bear mortalities in the Central Rockies Ecosystem of Canada. Biological Conservation. 120:101-113. (PDF icon and link 515 KB)

Phillips, L. M., R. D. Mace, and T. Meier. 2010. Assessing impacts of traffic on large mammals in Denali National Park and Preserve. ParkScience. 27(2):42-47. (PDF icon and link 328 KB)

Proctor, M. P., D. Paetkau, B. Mclellan, G. Stenhouse, K. Kendall, R. Mace, W. Kasworm, C. Servheen, C. Lausen, M. Gibeau, W. Wakkinen, M. Haroldson, G. Mowat, C. Apps, L. Ciarniello, R. Barclay, M. Boyce, C. Strobeck, C. Schwartz. 2011. Population Fragmentation and Inter-ecosystem Movements of Grizzly Bears in Western Canada and the Northern USA. Wildlife Monographs. In review.

Riley, S. J., K. Aune, R. D. Mace, and M. J. Madel. 1994. Translocation of nuisance grizzly bears in northwestern Montana. Ursus. 9:567-573 (PDF icon and link 328 KB)

Schwartz, C. C, K. A. Keating, H. V. Reynolds, III, V. G. Barnes, Jr.,R. A. Sellers, J. E. Swenson, S. D. Miller, B. N. McLellan, J. Keay, R. McCann, M. Gibeau, W. F. Wakkinen,R. D. Mace, W. Kasworm, R. Smith, and S. Herrero. 2003. Reproductive maturation and senescence in the female brown bear. Ursus 14(2):109–119. (PDF icon and link 452 KB)

Short Bull, R. A., S. A. Cushman, R. D. Mace, T. Chilton, K. C. Kendall, E. L. Landguth, M.K. Schwartz, K. McKelvey, F.W. Allendorf, and G. Luikart. 2011. Why replication is important in landscape genetics: American black bear in the Rocky Mountains. Molecular Ecology. 20:1092-1107.

Waller, J. S. and R. D. Mace. 1997. Grizzly bear habitat selection in the Swan Mountains, Montana. J. Wildl. Manage. 61:1032-1039. (PDF icon and link 1 MB)

Selected Unpublished Material

R. D. Mace and J. S. Waller.1997. Final Report: Grizzly Bear Ecology in the Swan Mountains, Montana. Montana Fish, Wildlife and Parks. Helena, MT. Unpublished data. (PDF icon and link 9 MB)

Mace, R. D. 2005. Northern Continental Divide Ecosystem Grizzly Bear Monitoring Team Annual Report - 2005. Montana Fish, Wildlife and Parks, 490 N. Meridian Road, Kalispell, MT 59901. Unpublished data. (PDF icon and link 1.8 MB)

Mace, R. and T. Chilton. 2006. Northern Continental Divide Ecosystem Grizzly Bear Monitoring Team Annual Report - 2006. Montana Fish, Wildlife & Parks, 490 N. Meridian Road, Kalispell, MT 59901. 53 pp. Unpublished data. (PDF icon and link 3.4 MB)

Mace, R. and T. Chilton. 2008. Northern Continental Divide Ecosystem Grizzly Bear Monitoring Team Annual Report - 2007. Montana Fish, Wildlife and Parks, 490 N. Meridian Road, Kalispell, MT 59901. Unpublished data. (PDF icon and link 2.6 MB)

Mace, R. D. and T. Chilton. 2009. Northern Continental Divide Ecosystem Grizzly Bear Monitoring Team Annual Report - 2008. Montana Fish, Wildlife & Parks, 490 N. Meridian Road, Kalispell, MT 59901. Unpublished data. (PDF icon and link 982 KB)

Mace, R. D. and L. Roberts. 2011. Northern Continental Divide Ecosystem Grizzly Bear Monitoring Team Annual Report, 2009-2010. Montana Fish, Wildlife and Parks, 490 N. Meridian Road, Kalispell, MT 59901. Unpublished data. (PDF icon and link 2.3 MB)

Mace, R. D. and T. Chilton-Radandt. 2011. Black Bear Harvest Research and Management in Montana. 2011. Final Report. Montana Fish, Wildlife and Parks. Helena, MT. (PDF icon and link 6.7 MB)