History of wolves in Yellowstone
The history of wolves in Yellowstone includes the
Beginning in the 1940s, park managers, biologists, conservationists, and environmentalists began what would ultimately turn into a campaign to
Extirpation (1872–1926).
In 1872, when
Shortly after the U.S. Army took over administration of the park on August 1, 1890, Captain Moose Harris, the first military superintendent, allowed public hunting of any wildlife and left all predator control to the park's administration.[4] Official records show, however, that the U.S. Army did not begin to implement a policy of killing wolves until 1914.[5]
In 1885, Congress created the Division of Economic Ornithology and Mammalogy with the express purpose of conducting scientific research for the protection of wildlife. The agency soon became the U.S. Biological Survey, which was in turn the forerunner of the
It is generally accepted that sustainable gray wolf packs had been extirpated from Yellowstone National Park by 1926,[3] although the National Park Service maintained its policies of predator control in the park until 1933.[5] However, a 1975–1977 National Park Service-sponsored study revealed that during the period from 1927 to 1977, there were several hundred probable sightings of wolves in the park.[6] Between 1977 and the reintroduction of wolves in 1995, there were additional reliable sightings of wolves in the park, most believed to be singles or pairs transiting the region rather than permanently inhabiting the park.[7]
Official records of wolves killed
Prior to the National Park Service assuming control of the park in 1916, the U.S. Army killed 14 wolves during their tenure (1886–1916),[5] most in the years 1914–15.[3] In 1940, Adolph Murie, a noted wildlife biologist published his Fauna Series No. 4— Fauna of the National Parks of the United States-Ecology of the Coyote in the Yellowstone National Park. In this report, Murie tallied the number of wolves killed as reported annually by park administrators between 1915 and 1935:[8]
From the Superintendent's Annual Report: | |
---|---|
Year | Number killed |
1915 | 7 |
1916 | 14 |
1917 | 4 |
1918 | 36 |
1919 | 6 |
1920 | 28 |
1921 | 12 |
1922 | 24 |
1923 | 8 |
1924–1935 | 0 |
Updated research in the 1980s verified that the last official killing of wolves in the park took place in 1926 when two pups found near
Absence (1926–1995)
Ecological impacts
Once the wolves were gone,
Reintroduction initiatives
The campaign to restore the gray wolf in Yellowstone had its roots in a number of seminal studies related to the predator-prey ecology of the park. In 1940, Adolph Murie published Ecology of the Coyote in the Yellowstone National Park. That study and his 1940–41 work The Wolves of Mount McKinley was instrumental in building a scientific foundation for wolf conservation.[13] In 1944, noted wildlife biologist Aldo Leopold, once an avid predator control advocate, made the following comments in his review of The Wolves of North America, Young and Goldman, 1944:
There still remains, even in the United States, some areas of considerable size in which we feel that both red and gray [wolves] may be allowed to continue their existence with little molestation. ... Where are these areas? Probably every reasonable ecologist will agree that some of them should lie in the larger national parks and wilderness areas: for instance Yellowstone and its adjacent national forests. ... Why, in the necessary process of extirpating wolves from livestock ranges of Wyoming and Montana, were not some of the uninjured animals used to restock Yellowstone?
— Aldo Leopold, 1944[14]
By the 1960s, cultural and scientific understanding of ecosystems was changing attitudes toward the wolf and other large predators. In part, this included the emergence of Robert Paine's concept of the keystone species. In the early 1960s, Douglas Pimlott, a noted Canadian wildlife biologist was calling for the restorations of wolves in the northern rockies.
In 1970, American wolf expert,
Therefore I recommend restoring this native predator by introducing wolves to Yellowstone
— John Weaver, National Park Service, 1978[6]
The gray wolf was one of the first species to be listed as endangered (1967) under the
The Northern Rocky Mountain Wolf Recovery Plan represents a "road map" to recovery 'of the gray wolf in' the Rocky Mountains. The primary goal of the plan is to remove the Northern Rocky Mountain wolf from the endangered and threatened species list by securing and maintaining a minimum of 10 breeding pairs of wolves in each of the three recovery areas for a minimum of three successive years.
— Northern Rocky Mountain Wolf Recovery Plan, USFWS, August 1987[17]
In 1991, Congress directed the U.S. Fish and Wildlife Service to develop an
- Reintroduction of Experimental Populations (incorporating most of the state implemented nonessential reintroduction alternative with parts of the 1987 Recovery Plan).
- Natural Recovery (with limited land-use restrictions in anticipation of some illegal killing of wolves).
- No wolf (as proposed in alternative scoping).
- Wolf Management Committee (as proposed by Congress).
- Reintroduction of Non-experimental Wolves (incorporating the accelerated wolf recovery alternative but with fewer land-use restrictions)
Alternative 1 was the recommended and ultimately adopted alternative:
Reintroduction of Experimental Populations Alternative – The purpose of this alternative is to accomplish wolf recovery by reintroducing wolves designated as nonessential experimental populations to Yellowstone National Park and central Idaho and by implementing provisions within Section 10(j) of the ESA to conduct special management to address local concerns. The states and tribes would be encouraged to implement the special rules for wolf management outside national parks and national wildlife refuges under cooperative agreement with the FWS.
— EIS-The Reintroduction of Wolves to Yellowstone National Park and Central Idaho, 1994[18]: 2.1–2.11
The final EIS opened the way for re-introduction, but not without opposition. The
Reintroduction (1995–present)
Initial releases 1995–96
In January 1995, U.S. and Canadian wildlife officials captured 14 wolves from multiple packs east of Jasper National Park, near Hinton, Alberta, Canada. These wolves arrived in Yellowstone in two shipments—January 12, 1995 (8 wolves) and January 20, 1995 (6 wolves). They were released into three acclimation pens—Crystal Creek, Rose Creek and Soda Butte Creek in the Lamar Valley in Northeast East Yellowstone National Park. In March 1995, the pens were opened and between March 21 and March 31, 1995, all 14 wolves were loose in Yellowstone.[20]
Seventeen additional wolves captured in Canada arrived in Yellowstone in January 1996 and were released into the park in April 1996 from the Chief Joseph, Lone Star, Druid Peak and Nez Perce pens. The reintroductions were planned on taking 3-5 years but these were the last wolves released into the park as officials believed that the natural reproduction and survival were sufficient.[20][21][22]
Annual wolf status since reintroduction
Wolf population declines, when they occur, result from "intraspecific strife," food stress, mange, canine distemper, legal hunting of wolves in areas outside the park (for sport or for livestock protection) and in one case in 2009, lethal removal by park officials of a human-habituated wolf.[23]
*1995-99 Data reflects status of the wolf in the Greater Yellowstone Ecosystem. Since 2000 monitoring has focused on packs operating within park boundaries. Wolves continue to spread to surrounding areas, and the last official report by the park for the Greater Yellowstone Area counted 272 wolves in 2002.
Annual status of Wolves in Yellowstone (as of December)[24] | ||||
---|---|---|---|---|
Year | Total number of packs | Total number of wolves | Number of pups surviving | |
1995* | 3 | 21 | 9 | |
1996* | 9 | 51 | 14 | |
1997* | 9 | 86 | 49 | |
1998* | 11 | 112 | 36 | |
1999* | 11 | 118 | 38 | |
2000 | 8 | 119 | 55-60 | |
2001 | 10 | 132 | 43 | |
2002 | 14 | 148 | 58 | |
2003 | 13–14 | 174 | 59 | |
2004 | 16 | 171 | 59 | |
2005[25] | 13 | 118 | 22 | |
2006 | 13 | 136 | 60 | |
2007 | 11 | 171 | 64 | |
2008[26] | 12 | 124 | 22 | |
2009[23] | 14 | 96 | 23 | |
2010[27] | 11 | 97 | 38 | |
2011[28] | 10 | 98 | 34 | |
2012[29] | 10 | 83 | 20 | |
2013[30] | 10 | 95 | 41 | |
2014[31] | 11 | 104 | 40 | |
2015[32] | 10 | 98 | 35 | |
2016[33] | 11 | 108 | 36 | |
2017[34] | 11 | 97 | 21 | |
2018[35] | 9 | 80 | 24 | |
2019[36] | 8 | 94 | 42 | |
2020[37] | 9 | 123 | 54 | |
2021[38] | 8 | 97 | 47 | |
2022[39] | 10 | 108 | 40 |
Ecological impacts after re-introduction
Scientists have been researching and studying the impacts on the Yellowstone ecosystem since re-introduction in 1995.
As the wolf population in the park has grown, the elk population, their favored prey, has declined. Prior to reintroduction, the EIS predicted that wolves would kill an average 12 elk per wolf annually. This estimate proved too low as wolves are now killing an average of 22 elk per wolf annually.[40] This decline in elk has resulted in changes in flora, most specifically willows, cottonwoods and aspens along the fringes of heavily timbered areas. Although wolf kills are directly attributable to declines in elk numbers, some research has shown that elk behavior has been significantly altered by wolf predation. The constant presence of wolves have pushed elk into less favorable habitats, raised their stress level, lowered their nutrition and their overall birth rate.[41]
The wolves became significant predators of coyotes after their reintroduction. Since then, in 1995 and 1996, the local coyote population went through a dramatic restructuring. Until the wolves returned, Yellowstone National Park had one of the densest and most stable coyote populations in America due to a lack of human impacts. Two years after the wolf reintroductions, the pre-wolf population of coyotes had been reduced to 50% through both competitive exclusion and intraguild predation. Coyote numbers were 39% lower in the areas of Yellowstone where wolves were reintroduced. In one study, about 16% of radio-collared coyotes were preyed upon by wolves. Yellowstone coyotes have had to shift their territories as a result, moving from open meadows to steep terrain. Carcasses in the open no longer attract coyotes; when a coyote is chased on flat terrain, it is often killed. They feel more secure on steep terrain where they will often lead a pursuing wolf downhill. As the wolf comes after it, the coyote will turn around and run uphill. Wolves, being heavier, cannot stop and the coyote gains a large lead. Though physical confrontations between the two species are usually dominated by the larger wolves, coyotes have been known to attack wolves if they outnumber them. Both species will kill each other's pups given the opportunity.[42][43]
Coyotes, in their turn, naturally suppress foxes, so the diminished coyote population has led to a rise in foxes, and "That in turn shifts the odds of survival for coyote prey such as hares and young deer, as well as for the small rodents and ground-nesting birds the foxes stalk. These changes affect how often certain roots, buds, seeds and insects get eaten, which alters the balance of local plant communities, and so on down the food chain all the way to fungi and microbes."[44]
The presence of wolves has also coincided with a dramatic rise in the park's beaver population; where there was just one beaver colony in Yellowstone in 2001, there were nine beaver colonies in the park by 2011. The presence of wolves seems to have encouraged elk to browse more widely, diminishing their pressure on stands of willow, a plant that beavers need to survive the winter.[45] The renewed presence of beavers in the ecosystem has substantial effects on the local watershed because the existence of beaver dams "even[s] out the seasonal pulses of runoff; store[s] water for recharging the water table; and provide[s] cold, shaded water for fish."[46] Beaver dams also counter erosion and create "new pond and marsh habitats for moose, otters, mink, wading birds, waterfowl, fish, amphibians and more."[44]
Similarly, after the wolves' reintroduction, their increased predation of elk benefited Yellowstone's grizzly bear population, as it led to a significant increase in the growth of berries in the national park, an important food source for the grizzly bears.[47]
Wolf kills are scavenged by and thus feed a wide array of animals, including, but not limited to, ravens, wolverines, bald eagles, golden eagles, grizzly bears, black bears, jays, magpies, martens and coyotes.[44]
Meanwhile, wolf packs often claim kills made by cougars, which has driven that species back out of valley hunting grounds to their more traditional mountainside territory.[44]
The top-down effect of the reintroduction of an apex predator like the wolf on other flora and fauna in an ecosystem is an example of a trophic cascade.
2009 removal from Endangered Species List
Because gray wolf populations in Montana, Wyoming and Idaho had recovered sufficiently to meet the goals of the Wolf Recovery Plan, on May 4, 2008, the
The wolves in Yellowstone and the Greater Yellowstone Ecosystem fall within this population. In response to the change in status, state wildlife authorities in Idaho and Montana enacted quota-based hunting seasons on wolves as part of their approved state Wolf Management Plans. Environmental groups objected to the delisting and the hunting seasons, but despite legal attempts to stop them (Defenders of Wildlife et al. v Ken Salazar et al.), the wolf hunts, which commenced in Montana in September 2009 were allowed to proceed.[citation needed]
Although wolves within the park boundaries were still fully protected, wolves that ventured outside the boundaries of the park in Idaho or Montana could now be legally hunted. During these hunts, Montana hunters legally killed a number of wolves in the
Reactions
Hunting opportunities
This section needs to be updated.(March 2024) |
From 2000–2004, the Montana Fish, Wildlife and Parks reduced antlerless permits by 51% from 2,882 to 1,400. They proposed only 100 permits for 2006 which was a 96% decrease from the 2,660 permits issued in 1995. Initially, the effects of wolf predation on elk during the first five years of the recovery were not detected, as elk numbers were identical to those of 1980–1994. From the winter of 1995 to the winter of 2004 however, the elk greatly decreased in number, dropping from 16,791 to 8,335 as the number of wolves on the northern range increased from 21 to 106, though predation from bears, increased human harvests, more severe winter and droughts were also factors. Since 2000, 45% of known deaths and 75% of predation-caused deaths of radio collared cow-elk have been confirmed to be attributable to wolves. Human caused deaths in the same period accounted for 8–30% of known deaths. Yellowstone elk comprise up to 92% of the winter diet of wolves, the overall kill rates of Yellowstone wolves on elk in winter being estimated at 22 ungulates per wolf annually. This is higher than the 12 ungulates per wolf rate predicted in the
Subspecies
Historically, the wolf populations originally native to Yellowstone were classed under the subspecies
In popular culture
- The podcast Criminal covered the killing of Wolf 10 (a male) in their episode, "Wolf 10."[52] Their sister podcast, This is Love, produced an episode about the reintroduction of wolves to Yellowstone, and focused on the stories of Wolves 8 (male), 21 (male), and 42 (female).[53]
See also
- O-Six, dominant breeding female ("alpha female") of the Lamar Canyon pack, whose death by hunting just outside Yellowstone received extensive media coverage and was the subject of a bestselling book by Nate Blakelee.
- OR-7, first confirmed wild wolf in western Oregon since 1947 and the first in California since 1924
- Repopulation of wolves in California began in 2011
- Repopulation of wolves in Colorado includes the natural expansion and proposed reintroduction
- Repopulation of wolves in the Midwestern states of Michigan, Minnesota, and Wisconsin occurred naturally
- List of gray wolf populations by country
- Wolf distribution (species distribution)
- Yellowstone (British TV series)
References
- ^ "Wolf Restoration". NPS.
- ^ This article incorporates public domain material from Wolf Restoration - Yellowstone National Park. U.S. National Park Service. Retrieved May 18, 2023.
- ^ ISBN 0-87081-391-9.
- ISBN 0-395-84174-7.
- ^ ISBN 0-87113-025-4.
- ^ ISBN 1-881019-13-6.
- ISBN 1-881019-13-6.
- ^ Murie, Adolph (1940). Fauna of the National Parks of the United States-Ecology of the Coyote in the Yellowstone National Park (Report). U.S. Department of the Interior.
- ISBN 1-56044-352-9.
- ISBN 1-881019-13-6.
- PMID 18459344.
- ^ Stolzenburg, William (2008). Where the Wild Things Were. Jeffers Literary Press.
- ISBN 1-56044-352-9.
- ISBN 1-881019-13-6.
- ^ ISBN 1-56044-352-9.
- ^ a b "Species Profile-Gray Wolf". U.S. Fish and Wildlife Service. Retrieved December 5, 2009.
- ^ Northern Rocky Mountain Wolf Recovery Plan (PDF) (Report). Denver, CO: U.S. Fish and Wildlife Service. 1987.
- ^ a b The Reintroduction of Gray Wolves to Yellowstone National Park and Central Idaho-Final Environmental Impact Statement (PDF) (Report). Denver, CO: U.S. Fish and Wildlife Service. 1994. Archived from the original (PDF) on May 1, 2012. Retrieved December 5, 2009.
- ISBN 1-56044-352-9.
- ^ a b Phillips, Michael K; Smith Douglas W. (1997). Yellowstone Wolf Project-Biennial Report 1995–96 (PDF) (Report). National Park Service.
- ^ Smith, Douglas W. (1998). Yellowstone Wolf Project—Annual Report 1997 (PDF) (Report). National Park Service.
- ISBN 978-1-4443-1202-7.
- ^ a b "Yellowstone Wolf Project, Annual Report 2009" (PDF). Retrieved February 5, 2018.
- ^ Annual Wolf Project Reports, Yellowstone National Park, 1995–2021
- ^ "wolf2005.indd" (PDF). Retrieved February 5, 2018.
- ^ Smith, D.W., D.R. Stahler, E. Albers, M. Metz, L. Williamson, N. Ehlers, K. Cassidy, J. Irving, R. Raymond, E. Almberg, and R. McIntyre (2009). Yellowstone Wolf Project—2008 Annual Report (PDF) (Report). Yellowstone Center for Resources, Yellowstone National Park, National Park Service. pp. vi.
{{cite report}}
: CS1 maint: multiple names: authors list (link) - ^ Grey Wolves NPS.gov: Wolves of Yellowstone, Retrieved October 28, 2011
- ^ Yellowstone Wolf Project. Annual Report 2011 National Park Service. Retrieved January 30, 2023
- ^ "Yellowstone Wolf Project, Annual Report 2012" (PDF). Retrieved February 5, 2018.
- ^ "Yellowstone Wolf Project, Annual Report 2013" (PDF). Retrieved February 5, 2018.
- ^ "Yellowstone Wolf Project, Annual Report 2014" (PDF). Retrieved February 7, 2019.
- ^ "Yellowstone Wolf Project, Annual Report 2015" (PDF). Retrieved February 7, 2019.
- ^ "Wolves in Yellowstone National Park". National Park Service. Retrieved December 13, 2017.
- ^ "Yellowstone Wolf Project, Annual Report 2017" (PDF). Retrieved February 7, 2019.
- ^ "Yellowstone Wolf Project, Annual Report 2018" (PDF). Retrieved May 1, 2021.
- ^ "Yellowstone Wolf Project, Annual Report 2019" (PDF). Retrieved May 1, 2021.
- ^ "Yellowstone Wolf Project, Annual Report 2020" (PDF). Retrieved March 29, 2022.
- ^ Park, Mailing Address: PO Box 168 Yellowstone National; Us, WY 82190-0168 Phone: 307-344-7381 Contact. "Yellowstone Wolf Project Reports - Yellowstone National Park (U.S. National Park Service)". www.nps.gov. Retrieved September 2, 2023.
{{cite web}}
: CS1 maint: numeric names: authors list (link) - ^ Cassidy, K.A., D.W. Smith, D.R. Stahler, E. Stahler, M. Metz, J. SunderRaj, T. Rabe, W. Binder, M. Jackson, M. Packila, B. Cassidy, J. Rabe, N. Tatton, C. Meyer, A. Bott, C. Ho, C. Lacey, and D. Sanborn. 2023. Yellowstone National Park Wolf Project Annual Report 2022. National Park Service, Yellowstone Center for Resources, Yellowstone National Park, WY, USA, YCR-2023-04.
- ^ White, P.J.; Smith, Douglas W. (Winter 2005). "Wolf EIS Predictions and Ten-Year Appraisals" (PDF). Yellowstone Science. 13 (1): 34–41.
- ^ Ellig, Tracy (July 15, 2009). "Greater Yellowstone elk suffer worse nutrition and lower birth rates due to wolves". Montana State University News Service. Archived from the original on September 23, 2009. Retrieved December 8, 2009.
- ^ "Weaving A New Web: Wolves Change An Ecosystem" Archived 2009-01-24 at the Wayback Machine, Zoogoer magazine, May/June 1998, Smithsonian National Zoo
- ^ "Coyotes Cower in Wolf Territory". Livescience. September 11, 2007. Retrieved March 20, 2008.
- ^ a b c d Douglas H. Chadwick (June–July 2011). "Keystone Species: How Predators Create Abundance and Stability". Mother Earth News.
- ^ "Beyond the Headlines". Living on Earth. March 20, 2015. Retrieved March 22, 2015.
- ^ YELLOWSTONE NATIONAL PARK WOLF REINTRODUCTION IS CHANGING THE FACE OF THE GREATER YELLOWSTONE ECOSYSTEM, YellowstonePark.com, BY STAFF, JUNE 21, 2011, visited 10/28/2011 Archived October 21, 2011, at the Wayback Machine
- ^ Barber, Elizabeth (July 29, 2013). "Why the return of the wolf is good news for the bear". Christian Science Monitor. Retrieved July 30, 2017.
- ^ "Three Yellowstone Wolves Killed During Montana's Hunting Season". National Parks Traveler. Retrieved December 31, 2021.
- ^ Yellowstone National Park's gray wolves impact elk Archived 2009-08-10 at the Wayback Machine
- ^ "Top Yellowstone Expert Takes on the Wolf Critics". Archived from the original on August 12, 2015. Retrieved July 20, 2015.
- ^ "Wolf -Bison Interactions in Yellowstone National Park". University of Nebraska.
- ^ "Wolf 10". Criminal. April 3, 2020.
- ^ "The Wolves". This is Love. April 1, 2020.
Further reading
- Urbigkit, Cat (2008). Yellowstone Wolves: A Chronicle of the Animal, the People, and the Politics. Blacksburg, VI: McDonald & Woodward Publishing. ISBN 978-0-939923-70-0.
- Bartlett, Richard A. (1974). Nature's Yellowstone. Albuquerque, NM: University of New Mexico Press. ISBN 9780826302571.
- Haines, Aubrey L. (1977). The Yellowstone Story—A History of Our First National Park. Yellowstone National Park, WY: Yellowstone Library and Museum Association.
- Chase, Alston (1986). Playing God in Yellowstone—The Destruction of America's First National Park. Boston, MA: The Atlantic Monthly Press. ISBN 0-87113-025-4.
- Bartlett, Richard (1985). Yellowstone: A Wilderness Besieged. Tucson, AZ: University of Arizona Press. ISBN 0-8165-1098-9.
- Northern Rocky Mountain Wolf Recovery Plan (PDF) (Report). Denver, CO: U.S. Fish and Wildlife Service. 1987.
- The Reintroduction of Gray Wolves to Yellowstone National Park and Central Idaho-Final Environmental Impact Statement (PDF) (Report). Denver, CO: U.S. Fish and Wildlife Service. 1994. Archived from the original (PDF) on May 1, 2012. Retrieved December 5, 2009.
- Fischer, Hank (1995). Wolf Wars—The Remarkable Inside Story of the Restoration of Wolves to Yellowstone. Helena, MT: Falcon Press Publishing Co. Inc. ISBN 1-56044-352-9.
- Schullery, Paul, ed. (1996). The Yellowstone Wolf—A Guide and Sourcebook. Worland, WY: High Plains Publishing. ISBN 1-881019-13-6.
- Kay, Charles E. (January 1996). Wolf Recovery, Political Ecology and Endangered Species (Report). The Independent Institute.
- Schullery, Paul (1997). Searching for Yellowstone: Ecology and Wonder in the Last Wilderness. Boston: Houghton Mifflin Co. ISBN 0-395-84174-7.
- McNamee, Thomas (1997). The Return of the Wolf to Yellowstone. New York: Henry Holt and Company, Inc. ISBN 0-8050-3101-4.
- Jones, Karen R. (2002). Wolf Mountains-A History of Wolves along the Great Divide. Calgary, Ontario: University of Calgary Press. ISBN 1-55238-072-6.
- Smith, Douglas O. (September 2003). Management of Habituated Wolves in Yellowstone National Park (PDF) (Report). National Park Service.
- Rydell, Kiki Leigh; Culpin, Mary Shivers (2006). Managing the "Matchless Wonders—A History of Administrative Development in Yellowstone National Park 1872–1965 (Report). Yellowstone Center for Resources.
- Bangs, Ed; Barbee, Bob; Petersen, Rolf O. (Winter 2005). "Perspectives on Wolf Restoration" (PDF). Yellowstone Science. 13 (1): 4–6.
- Smith, Douglas W. (Winter 2005). "Ten Years of Yellowstone Wolves, 1995–2005" (PDF). Yellowstone Science. 13 (1): 7–32.
- White, P.J.; Smith, Douglas W. (Winter 2005). "Wolf EIS Predictions and Ten-Year Appraisals" (PDF). Yellowstone Science. 13 (1): 34–41.
- "Technical Publications on Wolves, 1995–2004" (PDF). Yellowstone Science. 13 (1): 42–43. Winter 2005.
- Duffield, John, Chris Neher, and David Patterson (September 2006). Wolves and People in Yellowstone: Impacts on the Regional Economy (PDF) (Report). Yellowstone Park Foundation. Archived from the original (PDF) on August 5, 2010. Retrieved December 8, 2009.
{{cite report}}
: CS1 maint: multiple names: authors list (link) - Smith, D.W., D.R. Stahler, E. Albers, M. Metz, L. Williamson, N. Ehlers, K. Cassidy, J. Irving, R. Raymond, E. Almberg, and R. McIntyre (2009). Yellowstone Wolf Project - 2008 Annual Report (PDF) (Report). Yellowstone Center for Resources, Yellowstone National Park, National Park Service.
{{cite report}}
: CS1 maint: multiple names: authors list (link)