Density 



Grizzly bears are long-lived animals that range over extensive geographic areas. These traits make it 

 difficult to census and assess population levels. Furthermore, capture and marking of grizzlies is 

 expensive and dangerous for both researchers and bears. In combination, these factors result in limited 

 sample sizes for statistical analyses. Tlius, population estimates and dynamics calculations are often 

 contested. Generally, researchers do not contest the fact that grizzlies have low reproductive rates and 

 that grizzly populations are very susceptible to human impacts. Also recognized is that bear numbers are 

 very sensitive to changes in female survival rates. 



As with all other bear populations in the world, it is not possible to determine definitively the actual 

 numbers of bears in western Montana. Any figure will, therefore, be a result of some form of estimation. 

 Density estimates have been, and continue to be, a widely accepted method for estimating grizzly bear 

 populations. This may be changing however. In the past, grizzly bear management programs in the 

 NCDE were based on densitv estimates (Table 3). These estimates were developed and validated using 

 the best available information. All esHmates were developed using very conservative approaches to 

 ensure that the management program in no way negatively impacted the grizzly population. Currently 

 there is a major new effort underway to develop a point population estimate using DNA samples from 

 hair. Results of this effort should be available in 2006 and will allow us to evaluate past density estimates 

 as well as provide a more precise population estimate in the ecosystem. 



Table 3. Minimum density estimates for grizzly bears in the NCDE from previous programmatic EISs. 



Area 



Size 

 (mi=) 



Density 

 (mi-/bear) 



Number of Bears 



14-22 

 33-46 



198-264 

 11-21 

 9-12 



125-162 

 36-45 

 26-39 

 23-42 

 17-34 



Total 



Total excluding GNP 



9,633 

 8,050 



14-20 

 19-27 



492-687 

 294-423 



Status in the NCDE 



The Northern Continental Divide recovery zone encompasses about 9,600 mi= of northwestern Montana 

 and is one of five areas in the contiguous 48 states where grizzly bears still persist (see Figure 2). 

 Moreover, the area is contiguous to Canadian grizzly bear populations and interchange of bears has been 

 documented. Recent data suggests that bears in the NCDE occupy approximately 37,460 km= (14,500 mi-) 

 of habitat that includes Glacier National Park, parts of the Flathead and Blackfeet Indian Reservations, 

 parts of five national forests (Flathead, Helena, Kootenai, Lewis and Clark, and Lolo), Bureau of Land 

 Management lands, and a significant amount of state and private lands. Encompassed within this region 



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