Northern Continental Divide Ecosystem (NCDE)

 

Centered around Glacier National Park and the Bob Marshall, Great Bear, and Scapegoat Wilderness Areas, the NCDE has the second largest grizzly bear population and recovery area in the lower 48 states—about 12,900 square miles in central and western Montana. It is also one of the most ecologically diverse of the remaining grizzly bear ecosystems, including wet forested lands west of Glacier Park and much drier habitat to the east, including prairie grasslands. 

 

The NCDE includes federal, state, tribal and private lands and lies adjacent to southwest Alberta, where grizzly bears are designated as threatened under the province’s Wildlife Act, and southeast British Columbia, where bears are not protected other than through limitations on the sport hunt. The Alberta portion of the population is thought to be a mortality sink due to poor wildlife management and high mortality rates. 

 

Using a DNA-based survey method, which is considered to be the most accurate of any for the purpose, Kendall estimated that there were 765 grizzly bears in the NCDE in 2009, up from around 300-500 bears at the time of listing under the ESA. Recent population growth is estimated at 3% per year.  However estimation of trend in such a remote and largely forested ecosystem is difficult, and the methods used to reach this conclusion have been disputed.

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Grizzly bears are well distributed throughout the NCDE and the population has expanded east along the Rocky Mountain Front as well as to the south and west during recent years, with some bears showing up well outside the designated recovery area. While continued expansion bodes well for connectivity to Yellowstone, it will likely stop or be reversed if NCDE grizzly bears are delisted and sport hunting is allowed, which would target bears on the periphery.

 

On the west side, two grizzly bears have been known to move from the Whitefish Range to the Cabinet-Yaak ecosystem during the past few years, whereas on the east side, a male grizzly bear was documented during 2009 approximately 80 miles east of the recovery zone boundary on the Great Plains. Since 2002, several grizzly bears with cubs have additionally been documented using habitat west of Highway 93, including the Salish Mountains south of Eureka, Montana, as well as the upper Ninemile drainage west of Missoula, Montana.

 

The most common causes of grizzly bear mortality continue to be management actions in response to the habituation of bears to human-related attractants such as garbage, poaching, accidental mortality from being misidentified as black bear, and collisions with vehicles.

 

Habitat threats include oil and gas development on the east side of the ecosystem, excessive road-building and human access on the west side, and private lands development in the Flathead area. Off road vehicles, which have effects on grizzly bears similar to those of vehicles on roads, are also increasing in numbers in the NCDE. (see roads kill). And increased habitat fragmentation along major highways threatens connectivity within and between ecosystems. Restrictions on road densities adopted on the Flathead National Forest (“Amendment 19”) and construction of wildlife underpasses and overpasses on Highway 93 have improved survival rates and connectivity for grizzly bears and other wildlife on the west side of the NCDE. The government now proposes to remove road density standards in its Conservation Strategy, as part of its package to delist, which is expected in 2017.

 

Greater Yellowstone Ecosystem (GYE)

 

Centered on Yellowstone National Park and surrounding National Forest wilderness areas, the Greater Yellowstone Ecosystem (GYE) harbors grizzly bears in 19,500 square miles of forested and mountainous habitat in northwest Wyoming, eastern Idaho, and southwestern Montana. Compared to other populations in the lower 48 states, Yellowstone grizzly bears are unique in their reliance on meat (especially elk and bison), native trout, whitebark pine, and a number of other foods that are used nowhere else. (see uniqueness of GYE bears). 

 

The most recent population estimate published in a peer-reviewed journal for grizzly bears in the GYE is around 690 bears, up from a population of perhaps 300-350 bears at the time of listing. Claims are commonly made that the grizzly bear population increased by around 4% per year from 1983 to 2001, although recent research has suggested that methods for estimating trend are unreliable and biased high.  Even taking current methods at face value, population growth appears to have stalled around 2002, with the possibility of declines since 2008, which is especially likely given the optimistic bias of current methods. (see agency spin).

 

In contrast to the NCDE, where DNA-based survey methods have been used, in the GYE population size is estimated using an indirect measure based on counts of females with cubs. This method is sensitive to changes in observer effort, changes in foraging behavior, and associated changes in intrinsic sightability of bears; population trend estimates were likely inflated as a result of quadrupling observer effort since the mid-1990s. The collapse of whitebark pine and subsequent increase in meat-eating among grizzly bears—with attendant increases in human conflicts and mortalities—are likely contributing to the population’s recent stasis or decline.   (see agency spin).

 

Despite approximately 20 years of population growth from the mid-1980s to around 2001, accompanied by some expansion in distribution, the GYE population has remained isolated from all other grizzly bears. This isolation is not surprising given that the nearest grizzly bear recovery area is 240 miles away, in central Idaho where restoration of grizzlies has not yet occurred, and is confirmed by a lack of genetic interchange with any other grizzly bear population during the last 100 years. As a result, GYE grizzly bears have the lowest genetic heterozygosity of any continental population yet investigated. The Service determined that the Yellowstone population faces higher extinction risks because it is not as genetically diverse as the nearby NCDE population, and recommended augmentation of the GYE population by one reproductive individual from another population once every 10 years if natural connectivity is not established. Suitable habitat sufficient to support an additional several hundred grizzly bears has been identified in the southeast, southwest, west, northwest, which increases prospects for eventual connectivity, especially to the west and north.

 

Major causes of mortality in the GYE are currently related to big game hunting, livestock operations, and human attractants such as garbage. As Yellowstone Park improved its management of garbage and attractants after the population was listed (see YNP success story), mortalities have shifted to private and National Forest lands outside the Park.  Habitat threats include excessive human development, climate change, and sheep grazing, which effectively blocks grizzly bear dispersal through the most promising linkage to central Idaho through the Centennial Range to the west. Domestic sheep grazing has been a chronic cause of grizzly bear mortality, including in the Centennials.

 

In 2016, the government proposed to delist grizzly bears, which will push Yellowstone’s bears back to the brink of extinction (see debunking delisting). A final decision is expected in 2017.

 

Cabinet-Yaak Ecosystem (CYE)

 

This ecosystem encompasses over 6,758 km2 of forested and mountainous habitat in northwestern Montana and northeastern Idaho. Because of the relatively small size of the Cabinet-Yaak ecosystem, which extends into British Columbia, the grizzly bear population here depends on connectivity both to Canada’s grizzly bears and to the NCDE and Selkirk ecosystems in order to achieve any prospects for long-term viability.  Unfortunately, interchange with grizzly bears in the NCDE or elsewhere in Canada is rare.

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The CYE population is on the brink of extirpation. Currently, there are a minimum of 37 grizzly bears in the CYE,[xv] about the same as 40 years ago when the grizzly bear was protected under the ESA. The most recent DNA-based population estimate is about 45 grizzly bears, with almost no apparent interchange between the Cabinet Mountains and the Yaak.  The most recent US Fish & Wildlife Service (FWS) analysis of population trend shows that CYE population is at best stable, and likely declining. Human-caused deaths in the CYE appear to be limiting recovery, manifested in a doubling of mortality during the last decade.  

 

With high levels of fragmentation and mortality, the Canadian portion of the population is thought to be a mortality sink for the CYE. A 2001 report found that while there are still a few genetic linkages between the Yaak and Canadian Purcell Mountains, Highway 3 acts as a significant barrier to bear movement between the U.S. and Canada, with no females known to have crossed the highway. The availability of human attractants on the periphery of this ecosystem also aggravates the problem of isolation. Making matters worse, there are very few bears moving between the Cabinet Mountains and the Yaak portion of the ecosystem.

 

Despite these dire conditions, suitable habitat sufficient to support an additional 100 or so bears has been identified in this ecosystem. This habitat is threatened by two hard rock mines, which would, if built, permanently sever the Cabinet Yaak from the Yaak portion of ecosystem. These mines, which together would likely extirpate the grizzly bears of the CYE, are vigorously opposed by conservationists.  

 

Since the early 1990’s there have been 17 grizzly bears moved from the NCDE to augment the Cabinet-Yaak population. Many of the grizzly bears in the CYE descended from one of the translocated females. This is the only population where programmatic augmentation has occurred. Without these translocated grizzly bears, the population would likely have been extirpated during the last several decades. 

 

Selkirk Ecosystem (SE)

 

This ecosystem encompasses approximately 2,200 square miles, of forested and mountainous habitat in northwestern Idaho and northeastern Washington and adjacent land in British Columbia. The SE is the smallest recovery area and is not large enough on its own to fully recover grizzly bears without connectivity with the Canadian population further north as well as with grizzly bear populations to the east in the United States. 

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Currently, there are approximately 30-50 grizzly bears in the SE, about the same as when this population was listed in 1975. None of the 1993 recovery plan criteria (population size, distribution of females with cubs, mortality) have been met. Human-caused mortality has increased in the SE, particularly during the last decade. There has been less of an effort to estimate size of the grizzly bear population in the SE compared to any other occupied ecosystems of the lower 48 states. Although the Service claims that the population is increasing slightly, the trend analysis is inconclusive.

 

As with the CYE population, the ecosystem’s small size, fragmented habitat, high levels of mortality, and lack of secure core habitat are major problems for grizzly bears.  The genetic and demographic isolation of the U.S. grizzly bear population in the southern Selkirks from the Canadian population in the central Selkirks poses a serious threat to the long-term persistence of this population. The transnational movement of grizzly bears within the SE is impeded, if not prevented, by Highway 3. Movement of grizzly bears between the SE and the CYE is additionally blocked by Interstate Highway 95. To the west, movement of bears is also inhibited by the extensive agricultural lands in eastern Washington. 

 

Bitterroot Ecosystem (BE)

 

This ecosystem encompasses approximately 20,000 square miles of forested and mountainous habitat in Idaho centered in the Selway-Bitterroot and the River of No Return Wilderness Areas on both sides of the Salmon River.  Grizzly bears are thought to be extirpated from this ecosystem, although occasional sightings suggest that a few grizzly bears have dispersed into the BE recovery area from the north.  The last verified death of a grizzly bear in this ecosystem occurred in 1932 and the last tracks were observed in 1946.

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A habitat and population evaluation was completed for this area in 1991, in which the authors determined that sufficient amounts of quality habitat existed to support a viable grizzly bear population. Several independent publications have since confirmed the adequacy of habitat to support a robust population of grizzly bears, with estimates of potential population sizes ranging from 300 to over 600 bears, depending on the extent of the area considered. In 1996, the Service supplemented the recovery plan with specific recovery actions for the BE.

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In 2000, the Service signed the Record of Decision on the Final EIS that proposed reintroduction of grizzly bears in the BE under Section 10(j).  The Preferred Alternative set forth a program to reintroduce a minimum of 25 grizzly bears of both sexes over a 5-year period.  The Service anticipated that a grizzly bear population could reach the tentative recovery goal of 280 grizzly bears occupying all suitable habitat within 50 years (assuming an optimal 4% growth rate); but more realistically this process would probably take closer to 110 years (2% growth rate).  Other experts maintain that a population of 400-700 bears could be sustained if the definition of “suitable” were biophysical rather than political.

 

Unfortunately, no reintroduction activities in the BE ever occurred.  Following the change of Presidential administrations in 2001, the Service published a notice of intent to reevaluate this record of decision in the FEIS and published a proposed rule to remove the existing nonessential experimental rule. This regulation and the associated nonessential experimental rule putatively remain in effect as the proposed reevaluation and associated removal were never finalized. Thus, even though the final regulations remain in effect, they were never implemented. 

 

North Cascades Ecosystem (NCE)

 

The North Cascades Ecosystem includes almost 10,000 square miles of prime grizzly bear habitat in western Washington. The government has determined that the NCE is the largest recovery area of the remaining occupied grizzly bear populations. Yet today, it harbor only a few grizzly bears. Scientists and the USFWS have concluded that natural recovery is highly unlikely in the NCE, and that reintroductions will be necessary.  There have been no confirmed breeding female bears in the NCE during the history of the species’ protection under the ESA.  A recent genetic survey estimated one female grizzly bear may be present and another study put the population estimate at six individual bears. In 2010 a hiker took a photograph of a grizzly bear south of North Cascades national park—the first time that a grizzly bear was documented in the US portion of the recovery zone since 1996.

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The NCE is contiguous to an area in Canada where the most recent estimate indicates only 6 grizzly bears remain. In 2004, a recovery plan was finalized by the government of British Columbia, which would have involved augmentations and reintroduction from other areas within the Province. However, the plan was never implemented. About 30% of the NCE recovery area lies in British Columbia, where grizzly bears are sport hunted in virtually all the Province. 

 

None of the 1993 grizzly bear recovery criteria have been met in the North Cascades. A chapter on the potential for grizzly bear recovery in the NCE was completed in 1997. As with the Bitterroot ecosystem, the Service found that the North Cascades evaluation area offers sufficient amounts of quality habitat to warrant grizzly bear recovery in the area. Recent research has suggested that this recovery area could support a population of over 700 grizzly bears. Substantial outreach to the public potentially affected by grizzly recovery has also been done—in fact some of the best conducted in any of the grizzly bear ecosystems. This outreach revealed significant public support for grizzly bear recovery.

 

In 2017, the National Park Service and FWS released an Environmental Impact Statement to augment the population of grizzlies in the North Cascades. The preferred alternative aims for a goal of 280 or so grizzly bears in the ecosystem, even though more could be supported. 

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For more on this proposal, see the blog post:  

Restoring the Grizzly in the North Cascades

 

San Juan Ecosystem (SJE)

 

This ecosystem encompasses approximately potentially 9,140 square miles of forested and mountainous habitat in southwest Colorado and northern New Mexico. The SJE is different from the other remaining recovery areas because it contains Gambel oak and pinyon pine. Acorns and pinyon seeds were once a key staple for grizzly bears throughout the southwest.

 

The San Juan population was historically contiguous with other bear populations in the Rocky Mountains. Isolation of this population probably occurred during the 1920s and 1930s, when the last known grizzlies were killed in surrounding regions.

 

At the time of listing, the status of grizzly bears was unknown in this ecosystem, but an adult female was killed there in 1979 by an archery hunter on the headwaters of the Navajo River. Field research during 1979-80, which entailed trapping in a portion of the San Juan ecosystem where the bear was shot, failed to determine the continued existence of grizzly bears in this area. Extensive investigative work by citizen scientists has not yet provided conclusive evidence that grizzly bears continue to survive there.

 

The 1993 recovery plan stated that “as budgets allow” the Service would “conduct evaluations of habitat suitability for currently unoccupied, historic habitat in Colorado.”  This evaluation has not been done. However, an assessment reported in 1989 indicated that the SJE contains substantial tracts of suitable habitat.

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