BC Conservation Data Centre: Conservation Status Report
Bos bison athabascae
Wood Bison
| Scientific Name: | Bos bison athabascae |
|---|---|
| Scientific Name Synonyms: |
Bison bison athabascae
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| English Name: | Wood Bison |
| Provincial Status Summary | |
| Status: | S2 |
| Date Status Assigned: | May 28, 2010 |
| Date Last Reviewed: | February 15, 2015 |
| Reasons: | Four small herds occupy isolated areas of northeastern British Columbia; range expansion is limited by agricultural development. Potential threats include disease transmission and genetic contamination that may result from contact with plains or commercial bison. |
| Range | |
| Range Extent: | F = 20,000-200,000 square km |
| Range Extent Comments: | Historically, Wood Bison ranged throughout northeastern British Columbia. At present, reintroduced herds occupy the Liard River valley east of Fireside as far as Aline Lake. A separate herd occupied the Etthithun Lake areas. The Hay-Zama herd in northwestern Alberta occasionaly crosses the border into British Columbia. The total area occupied is between 3,000 and 4,000 km2. |
| Area of Occupancy (km2): | F = 126-500 |
| Area of Occupancy Comments: | There have been no detailed assessments of the area of occupancy within the range of wood bison in British Columbia. A rough estimate would be that less than 10% of the range is potential habitat. If the Hay-Zama herd is excluded, bison occupy approximately 145 2x2 km grid cells. |
| Occurrences & Population | |
| Number of Occurrences: | A = 1 - 5 |
| Comments: | There are 4 populations that occur in British Columbia. The Nordquist Flats herd and Etthithun Lake herd are entirely contained in British Columbia. The Nahanni Herd occurs mainly in the Northwest Territories, but approximately 30 animals from this herd summer and winter in British Columbia. The Hay-Zama herd occurs mainly in Alberta and wood bison from this population are known to travel into British Columbia during the growing season. |
| Number of Occurrences with Good Viability / Ecological Integrity: | B = 1 - 3 |
| Comments: | The Nahanni herd is likely the most viable of all the populations in British Columbia since it most isolated from both disease and potential mixing with plains bison. It is also the population that appears to be growing the fastest. The other introduced populations are still quite small and have low levels of genetic diversity. The Etthithun Lake and Hay-Zama herds are at greater risk of contacting commercial bison than the Nordquist and Nahanni herds. |
| Number of Occurrences Appropriately Protected & Managed: | A = None |
| Comments: | Small portions of the habitat of the Nordquist herd are protected by portions of the Portage Brule Rapids Ecological Reserve and Protected Area and the Liard River Cooridor Park. |
| Population Size: | C = 250 - 1,000 individuals |
| Comments: | There are likely around 400 bison in BC, with 80-90% of these being of breeding age. During roadside surveys of the Nordquist herd in winter 2008/2009, the highest count in single survey was 117 (9 of which were calves). This should be considered a minimum number, as greater numbers of individual age/sex cohorts were counted during previous and subsequent surveys (Thiessen 2009). During an aerial survey of the Etthithun herd in March 2009, 156 bison were counted, though 40 of these were in Alberta. Of the 116 bison that were counted in BC, 18 were calves; again, these counts should be considered minimums (Thiessen 2009). Even though the Nahanni herd was estimated at 399 non-calf bison in 2004 (Larter et al. 2007), only about 30 of these animals winter in British Columbia. Since Alberta's Hay-Zama herd only occasionally wanders into British Columbia, it does not contribute to the provincial population, although this could change in the future. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | C = Medium |
| Comments: | Bison infected with tuberculosis and brucellosis in and around WBNP threaten the health and potential of reintroduced wood bison in n. Alberta, n. British Columbia, and sw. Northwest Territories (Gates et al. 2001). In WBNT, where 49% of wood bison were seropositive for tuberculosis and 31% were seropositive for brucellosis (Joly and Messier 2004a), populations have declined 80% since 1971 to approximately 2900 animals (Mitchell and Gates 2002). The two herds most at risk of contact with diseased bison from WBNT are the Nahanni and Hay-Zama herds, because of their proximity to infected bison, and the habit of dispersing male bison to travel long distances. Hopefully interim "bison-free" buffer zones established by Alberta and the Northwest Territories will help prevent spread of these diseases to bison in British Columbia. Cross-breeding with plains bison or commercial bison is another signficant threat, the mostly likely source being escaped commerial bison. The Pink Mountain population of plains bison is also potential source of cross-breeding. This plains bison herd was estimated at 1302 animals in 2006 (Rowe 2007), but the policy of restricting each subspecies to mutually exclusive ranges to prevent hybridization (Harper et al. 2000) means this is unlikely to occur. Loss of genetic diversity is also a significant threat facing wood bison in British Columbia. All the reintroduced wood bison in British Columbia are direct descendants of the 21 animals captured in 1965 near Needle Lake in the Nyarling River area of Wood Buffalo National Park (WBNP) and relocated to Elk Island National Park (EINP) (Harper et al. 2000). This was the first genetic bottleneck. For the Nordquist population, the second genetic bottleneck occurred in 1995 when 49 animals were translocated from EINP to establish this population in the Liard River valley. Due to this series of founding events and population bottlenecks, genetic diversity is not well distributed among disease-free wood bison herds in Canada (McFarlane et al. 2006). Among non-diseased, free-roaming populations of wood bison, the Nordquist herd has the lowest current level of heterozygosity, and the poorest projected trend over the next 200 years, based on simulated population viability analysis (McFarlane et al. 2006). Further loss of genetic diversity in wood bison populations is probable due to genetic drift in British Columbia's small populations, particularly if only a few males are responsible for the majority offspring born to a population (Wilson et al. 2005). The smallest herds (e.g. Nordquist and Etthithun), have the lowest heterozygosity. Movement of animals among all herds will significantly reduce the rate at which diversity is lost (McFarlane et al. 2006). To a less extent collisions with vehicles are a threat to the Nordquist and Etthithun herds. Wolf predation may limit population growth rates in some areas. |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | HI = Increase of >10% |
| Comments: | The short-term trend is +10 to 30%. |
| Long-Term Trend: | A = Decline of >90% |
| Comments: | Wood bison once occurred over a large part of northeastern British Columbia, although they were unevenly distributed and never as numerous as plains bison. Like the plains bison, wood bison were nearly eliminated by uncontrolled hunting for the fur trade during the late 1800's and the last confirmed wood bison from the primordial population was shot at near Fort St. John in 1906. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | Although wood bison are capable of fairly rapid population growth rates in the absence of significant threats, the intrinsic lack of genetic diversity within the relatively small British Columbia populations means they are still vulnerable further loss of heterozygoticity through genetic drift. |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | Monitor the disease status of free-roaming and domestic bison (Harper et al. 2000). The majority of genetic diversity still exists in the diseased wood bison populations of WBNP (Wilson and Strobeck 1999, Wilson et al. 2005), since the genetic diversity of the salvaged disease-free bison is substantially less due to founder effects and genetic drift (McFarlane et al. 2006). Further research into ways to salvage disease-free wood bison from WBNP are needed. A recent effort to establish a second captive-breeding population at Hook Lake began in 1996 (Nishi et al. 2002b). Unfortunately, after 10 years of effort, the Hook Lake Wood Bison Recovery Project was terminated in March 2006, and the 120 animals in the herd were destroyed after tuberculosis was detected in one of the founder animals and several captive born bison. |
| Inventory Needs: | Routine inventories of populations are needed to monitor changes in population distribution, size, and demographics (Harper et al. 2000). |
| Stewardship | |
| Protection: | |
| Management: | Implement actions recommended in the BC management plan (Harper et al. 2000) the national recovery plan (Gates et al. 2001). Additional transplants, habitat enhancement, and an vigilant efforts to keep plains and wood Bison separate are of highest priority. Predator control may be necessary improve juvenile survival in some circumstances. |
| Version | |
| Author: | Harper, W., A. Teucher |
| Date: | May 18, 2010 |
| References | |
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Alberta Environment and Parks and Alberta Conservation Association. 2017. Status of American Bison in Alberta: Update 2017. Alberta Wildlife Status Report No. 38 (Update 2017). Edmonton AB. 134 pp.
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B.C. Ministry of Water, Land and Resource Stewardship. 2022. Large ungulate abundance in British Columbia. Online. Available: https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/wildlife-wildlife-habitat/ungulates/2022_provincial_ungulate_population_estimates.pdf (accessed 16 April 2024).
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Bork, A.M., C.M. Strobeck, F.C. Yeh, R.J. Hudson, and R.K. Salmon. 1991. Genetic Relationship of wood and Plains bison based on restriction length polymorphisms. Can. J. Zool. 69(1):43-48.
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COSEWIC. 2013. COSEWIC assessment and status report on the Plains Bison Bison bison bison and the Wood Bison Bison bison athabascae in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xv + 109 pp.
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Gates, C.C. et al. 2001. National Recovery Plan for the Wood Bison (Bison bison athabascae). Recovery of Natl. Endangered Wildl. Comm. Rep. No. 21. Ottawa. 50pp.
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Geist, V. 1990. Agriculture versus bison in Canada's Wood Buffalo National Park. Conservation Biology 4:345-346.
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Harper, W.L., J.P. Elliot, I. Hatter and H. Schwantje. 2000. Management plan for Wood Bison in British Columbia. Ministry of Environment, Lands and Parks Wildlife Branch, Victoria, B.C. Wildlife Bulletin No. B-102. 43pp.
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Joly, D.O., and Messier, F. 2004. Factors affecting apparent prevalence of turberculosis and brucellosis in wood bison. Journal of Animal Ecology 72:623-631.
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Larter, N.C., D.G. Allaire, and T.S. Jung. 2007. Population survey of the Nahanni Wood Bison population March 2004. Manuscript Report No. 176, Department of Environment and Natural Resources, Government of the Northwest Territories, Fort Simpson, NT. 22p.
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McFarlane, K., G.A. Wilson, and J.S. Nishi. 2006. Management strategies for the conservation of genetic diversity in wood bison. File Report No. 135, University of Alberta. Edmonton, AB.
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Mitchell, J.A. and C.C. Gates. 2002. Status of the Wood Bison (Bison bison athabascae) in Alberta. Alberta Sustainable Resource Development, Fish and Wildlife Division, and Alberta Conservation Association, Wildlife Status Report No. 39, Edmonton, AB. 32 pp.
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Nishi, J.S., C. Stephan, and B.T. Elkin. 2002b. Implications of agricultural and wildlife policy on management and eradication of bovine tuberculosis and brucellosis in free-ranging wood bison of northern Canada. Annals of the New York Academy of Sciences 696:236-244.
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Rowe, M.R. 2006. Halfway/Sikanni Plains Bison inventory. Environmental Stewardship Division, BC Ministry of Environment, Fort St. John, BC. 14pp.
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Rowe, M.R. 2007. Nordquist wood bison inventory. Peace Region Technical Report, Ministry of Environment, Fish and Wildlife Section, Fort St. John, BC. 9pp.
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Wilson, G.A. et al. 2005. Effects of a recent founding event and intrinsic population dynamics on genetic diversity in an ungulate population. Conservation Genetics 6:905-916.
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Wilson, G.A., and C. Strobeck. 1999. Genetic variation within and relatedness among wood and plains bison populations. Genome 42:438-496.
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Wood Bison Recovery Team, (WBRT). 1987. Status report on the Wood bison (Bison bison athabascae) in Canada. 86pp.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2010. Conservation Status Report: Bos bison athabascae. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jul 27, 2024).