Recovery Strategy for the Grizzly Bear (Ursus arctos), Prairie Population, in Canada
The federal Draft Policy on the Feasibility of Recovery (Government of Canada 2005) states that recovery is not feasible if the answer is no to any one of the following four questions:
Are individuals capable of reproduction currently available to improve the population growth rate or population abundance? -Unlikely.
This question is addressed in three parts: i) Are there individuals capable of reproduction? ii) Are they currently available? iii) Will they likely improve the population growth rate or size?
The Prairie population was assessed separately because of its unique state and geographic range in Canada, not because of genetic differences. Sexually-mature bears from interior North American populations (INAP) exist and could be a source for a reintroduction program on the Prairies. However, it is uncertain whether grizzly bears would be available from any of the INAP, given the likely reluctance or concern by another jurisdiction to provide grizzly bears from their populations at risk, especially if the probability of reintroduced bears dying is not acceptable (i.e.,too high). A Prairie population of grizzly bears would be unlikely to achieve population growth because of high mortality risk on agricultural (Figure 4) and private (approximately 80%; Riley et al. 2007) lands, and inadequate habitat (see Section 1.5). For example, grizzly bear source-sink dynamics were observed in the Greater Yellowstone Ecosystem; positive population growth occurred within the grizzly bear recovery zone, consisting of 98% public lands, and, negative population growth (λ = 0.878) occurred outside of the recovery zone, comprised mainly of private lands (Schwartz et al. 2006). Sink habitat for grizzly bears likely occurs in the foothills of Alberta's Rocky Mountains (Nielsen et al. 2006, M. Proctor pers. com.). For these reasons, it seems unlikely that an active reintroduction program would be feasible and successful.
The occasional grizzly bear will probably successfully disperse to the Prairies, from Canada's Northwest population or the U.S. Northern Continental Divide population, during non-drought years. However, the dispersal rate from these two source populations would likely be extremely low and insufficient to re-establish a viable population on the Prairies. Grizzly bear dispersal is usually of short distance and of long duration (see Section 1.4.4), and not successful in human-dominated landscapes (Proctor et al. 2005). Also, grizzly bear habitat on the Prairies is limited. Most grizzly bears dispersing from these two source populations would probably not travel to the habitat areas identified by the predictive model (i.e., southeastern Alberta, Cypress Hills, Grasslands National Park; Figure 6), because it would be too far and involve travel through large areas of unsuitable habitat. Two reproductive female grizzlies have been observed within the Prairie Ecozone of southwestern Alberta since 2001 (K. Morton pers. com.).
Is sufficient suitable habitat available to support a population, or could it be made available through habitat management or restoration? -No.
Populations of grizzly bears persist in areas where large expanses of relatively secure habitat are retained and where human-induced mortality is low (U.S. Fish and Wildlife Service 2007).
According to the predictive model, potentially suitable habitat is present for up to a maximum of 25 adult female grizzly bears in the Prairie Ecozone, and the largest area of continuous suitable habitat is sufficient for only 17 adult females. Small isolated populations are vulnerable to chance events (e.g., demographic stochasticity, large-scale environmental changes), and have a high probability of being extirpated or becoming extinct because of demographic processes (Lande 1988 in Proctor et al. 2005). This concern is evident in the recovery plan for the Yellowstone population of grizzly bears, where the demographic recovery criteria required that a minimum of 48 females with cubs of the year be maintained, and not drop below 48 for any two consecutive years (U.S. Fish and Wildlife Service 1993). Similarly, Proctor et al. (2005) concluded that two grizzly bear populations in southern B.C., each with a total of <100 animals and limited inter-population movements, were vulnerable. A viable and therefore recovered population is one that has high long-term prospects for survival within acceptable levels of risk (U.S. Fish and Wildlife Service 2007). An isolated population of up to 17 reproductive females is not expected to be viable. It is important to note that the threat of human-caused mortality of grizzly bears still exists in the suitable habitats modeled herein.
In addition, the habitat analysis did not account for food resources. The amount of natural food sources available would probably be inadequate for a Prairie population of grizzly bears. Without large herds of wild bison, the primary food source of prairie grizzlies (Nielson 1975, Mattson and Merrill 2002), it would not be possible to recover grizzly bears on the Prairies to densities observed prior to 1880.
There is insufficient suitable habitat available to support a Prairie population of grizzly bears. It is unlikely that sufficient habitat could be managed or restored at a scale required to support a stable Prairie population, given the current and foreseen human population growth in southwestern Canada, and the extent of agricultural land use and privately-owned land in the Prairie Ecozone.
Can significant threats to the population or its habitat be avoided or mitigated through recovery actions? -No.
The high potential for human-caused mortality and lack of suitable habitat are the primary threats to recovering the Prairie population. A population of prairie grizzlies would be highly visible to humans due to extensive access features (e.g., roads), extensive agricultural activities, and lack of secure cover for bears (e.g., tall vegetation, topographical relief). The prevalence of private lands on the Prairies would certainly aggravate an already high potential for human-caused mortality. Numerous authors discuss how these landscape features and uses increase human-caused mortality of grizzly bears (Nielson 1975, Gibeau et al. 2001, Mattson and Merrill 2002, Ross 2002, Johnson et al. 2004, Proctor et al. 2005, Schwartz et al. 2006). Even in those areas identified as potentially suitable habitat in the Prairie Ecozone, grizzly bears could still be subjected to considerable mortality risk.
Large-scale habitat loss and degradation has occurred on the Prairies since the 1880s. Major river systems have been dammed resulting in much less riparian habitat important to the prairie grizzly. Most native prairie habitats have been lost to cultivation, and rural, urban, and industrial development; loss of native prairie continues (Watmough pers. com.). Habitat degradation due to roadways and railways is ubiquitous.
It is believed that much of the Prairie Ecozone would be sink habitat for a resident population of grizzly bears. Where the occasional grizzly bear occurs, measures can be taken to ensure its survival. For example, monitoring the movements of individual grizzlies, where feasible, is a component of the Prairie Grizzly Operation Strategy developed by Alberta Fish and Wildlife (Morton and Lester 2004). The Draft Alberta Grizzly Bear Recovery Plan 2005-2010 (AGBRT 2005) states there may be opportunities for grizzly bears to expand their range to southeastern Alberta. However, this would likely be limited to only a few individuals, and occupancy on the Prairies may be temporary, restricted to non-drought years.
Do the necessary recovery techniques exist and are they demonstrated to be effective? -Yes.
Some populations of grizzly bears have expanded naturally to reoccupy former range (Pyare et al. 2004), because of an adequate source population and sufficient suitable habitat nearby. For example, an estimated 136 bears comprised the Yellowstone source population in 1975, and as already mentioned, nearby secure habitat was extensive: the Primary Conservation Area consisted of 98% public lands, measuring 9210 mi2 (23 854 km2). By 2006, the Yellowstone population recovered to >500 bears (U.S. Fish and Wildlife Service 2007). However, for reasons explained above, under the first question in Section 2.1, the recovery of a viable Prairie population, through natural dispersal processes, is unlikely.
A program to actively remove grizzly bears from source populations and reintroduce them to suitable habitat on the Prairies would be an alternative approach, however, it is problematic. It is uncertain whether grizzly bears would be available from any source populations, given the likely reluctance or concern by another jurisdiction to provide grizzly bears from their populations that might be at risk. Techniques for relocating grizzly bears exist and are proven effective, but have associated risks: approximately 30% are more likely to die (Blanchard and Knight 1995 in AGBRT 2005). A grizzly bear used to living in mountainous or barren-ground habitats, and relocated to the Prairies, would have to immediately change its foraging behaviour and adapt to its new environment to survive. This would increase the mortality risk to the grizzly bear substantially, especially given the reduced foraging opportunities in the drier and colder Prairie Ecozone. Also, as explained above, insufficient suitable habitat exists to support a viable population of resident grizzlies on the Prairies. A Prairie reintroduction program would likely be ineffective.
Critical habitat is defined in Canada's Species at Risk Act (SARA) as "the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species' critical habitat in the recovery strategy or in an action plan for the species." If recovery is not feasible, paragraph 41(2) of SARA requires a recovery strategy to include an identification of the species' critical habitat to the extent possible.
Grizzly bears were extirpated from the Prairie Ecozone approximately 125 years ago. Recovery is deemed to be not feasible due to the lack of suitable habitat to support a sustainable population of the species, the uncertainty as to whether natural food resources are presently available to support a population, and the threats to the population and habitat. Insufficient suitable habitat is available to support the survival or recovery of a Prairie population of grizzly bears and there is no intent to reintroduce the species. Therefore there is no critical habitat necessary for the survival and recovery to identify.
Although the recovery of a Prairie population is not feasible, grizzly bears from the Northwest and Northern Continental Divide populations may occasionally frequent the Prairies, at least temporarily. For example, in the Milk River and St. Mary's River drainages, a few grizzly bears have been observed recently. During 2001, a sow (adult female) grizzly with cubs was seen intermittently. During 2003-2004, two independent male grizzlies were captured, but returned to the mountains immediately after being released. During the 2008 summer, a sow grizzly and cub foraged regularly in a grassland area of southern Alberta (K. Morton pers. com., Morton and Lester 2004). Whether any grizzly bears reside year-round on the Prairies is not known; grizzlies may occupy prairie habitats only temporarily, such as during dispersal, or during seasons or years when vegetation productivity is high. Monitoring the movements of individual prairie grizzlies, where feasible, is a key component of the Prairie Grizzly Operation Strategy, developed by Alberta Fish and Wildlife (Morton and Lester 2004). Engaging in other initiatives, such as Alberta's "Bear Smart" program, could also minimize the potential for any human-grizzly bear conflicts on the Prairies, which would be beneficial. As well, the Grassland Natural Ecoregion of southern Alberta and the mixed grasslands of southwestern Saskatchewan are recognized provincially as high priority conservation areas for species at risk (R. Quinlan, pers. com., and D. Campbell, pers. com., respectively), with stewardship initiatives and conservation planning underway which will improve habitat conditions for wildlife, such as grizzly bears.
Grizzly bears require productive habitats with few people, minimal motorized access, secure cover (e.g., forest), and adequate food resources, which occur, to some degree, within the historical range of the grizzly bear (Figure 1), but mostly outside of the Prairie Ecozone. To increase the likelihood of persistent grizzly bear populations in Canada, management and conservation activities need to target the habitats best suited to grizzly bear survival.
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