Beaver and Salmon

3,183 views

Published on

Presentation by R. Castor for Oregon State University class FW323, Salmon Management. 2012.

Published in: Spiritual
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
3,183
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
4
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • This presentation is about the link between beavers and salmon - specifically the ways in which beavers affect salmon. We will talk about the history of Beavers in North America and in Europe, and briefly about the history of salmon in North America and Europe. I will then explore studies showing that beaver may be beneficial to salmon, as well as address concerns and other studies showing that beaver may harm salmon. Beavers are currently being used to modify habitat for salmon and trout, and we will list potential ongoing uses of beaver in watershed recovery as well. This photograph shows a Sockeye Salmon attempting to jump over a beaver dam in Alaska[A].
  • There are two extant species of beaver - the North American Beaver, Castor canadensis, and the Eurasian Beaver, Castor fiber. The mountain beaver, Aplodontia rufa, is another species of rodent. It is not a Castor beaver, and is the only animal in the Aplodontia genus. It is more closely related to squirrels and is a more ancient mammal than our more modern (recently evolved) Castor beavers. Aplodontia is not considered a beaver for the purposes of this presentation, as it does not build dams and create wetlands as the Castor beavers do.
  • Beavers (the Eurasian and North American together) are the second largest living rodents. Beavers are herbivorous, eating strictly plant matter. They do not eat fish, fish eggs, aquatic insects, etc. Beavers also do not eat wood. They eat leaves, twigs, bark and the cambium layer beneath the bark. They are second only to humans in their ability to modify the landscape. Beavers are semi-aquatic and clumsy on land. In order to avoid predation, they create a series of ponds and wetlands by damming streams. They build lodges in these manufactured ponds where they are safe from terrestrial predation. Photo [B]
  • The Eurasian Beaver was hunted nearly to extinction. The estimated population was only 1,200 by the early 1900s (Halley 2003). Beaver were extinct in many countries, but reintroduction and protection led to a recovery of approximately 639,000 individuals by 2003 (Komarov 2004). Genetic studies show that beaver may have survived from a nineteenth century population as low of 300 animals, and that they have the ability to “maintain sufficient genetic diversity to recover from a population as low as 3 individuals (Milishnikov 2004). While the introductions have been far from uncontroversial, beaver have been reintroduced to most of northern Europe. The two species of beaver cannot reproduce. This photo shows a Eurasian Beaver in Estonia [C].
  • Castor canadensis is the National Animal of Canada, the state animal of Oregon, and the mascot of Oregon State University. Beaver were once ubiquitous in North America, and perhaps in the Northern Hemisphere. They ranged from the artic tundra to the deserts of northern Mexico, and from the Atlantic to the Pacific Oceans. (Morgan 1868; Naiman 1988). Crossing most of North America in 1784, explorer David Thompson wrote that “this Continent… from the Atlantic to the Pacific Ocean, may be said to have been in the possession of two distinct races of Being, Man and Beaver” (Tyrell 1916). This is perhaps also a comparison from the only two animals known to so dramatically change and even manufacture their environment to suit their needs. The historic population of Canada canadensis in North America is thought to have been up to 200 million (Sun, 2003).
  • From 1630 to 1640 80,000 beaver were taken annually from the Hudson River and western New York (Hays 1871). The eastern population was decimated by 1650 (Brown 2007). Once eastern beaver populations were decimated, trappers moved west. Some claim that the westward expansion and exploration of our continent was driven by the desire for beaver fur. Even before the California Gold Rush, an earlier California Fur Rush was responsible for the first American settlements in California. The Mountain Men era in the Northwest, from 1806-1838, when the West was explored from Canada to Mexico and Missouri to California, the beaver was trapped nearly to extinction (Brown 2007). In his book, Salmon Without Rivers, Lichatowich claims that the Hudson’s Bay Company (HBC), which managed to actually preserve beaver populations through harvest regulations in western Canada, carried out a “Scorched Earth” policy in what would eventually become Oregon, Washington, California, and Idaho. Seeing that this area was likely to become part of the US, the HBC set out to eliminate the beaver precisely because it would make it harder for the US to settle an area devoid of their most valuable trading commodity (Lichatowich 1999). In 1826 - 1834 the HBC harvested 3,000 beaver per year in the Columbia River area. By 1850 that figure was down to 438 beaver. The beaver were nearly extinct in North America by 1900 (Lichatowich 1999). Photo [D]
  • With protection in the late 19th and early 20th centuries the current beaver population has rebounded to an estimated 10 to 15 million; however this is still a fraction of the originally estimated 100 to 200 million North American beaver before the days of the fur trade (Sun 2001; Outwater 1997) In 1900 the Lacey Act becomes the first Federal law protecting game, prohibiting the interstate shipment of illegally taken wildlife and importation of species. Enforcement of the Act becomes the responsibility of the Biological Survey (DFW 2012). This law is passed after a popular movement in the late 1800’s of growing public concern over wildlife. Sportsmen's clubs were established and pushed for state laws regulating wildlife hunting and fishing. These first conservations efforts resulted in an end to commercial harvest of wildlife, except fisheries. But of course the real end to the beaver trade happened when the fashion changed by 1830 to favor imported Chinese silk over beaver fun in hats. While the laws did have some influence, it was really trade with China that saved the beaver from extinction. (Brown 2007) In 1903 the first Federal Bird Reservation is established by President Theodore Roosevelt on Pelican Island, Florida, and placed under the jurisdiction of the Biological Survey. Pelican Island and other early Federal wildlife reservations are re- designated as "national wildlife refuges" in 1942 (DFW 2009). After he became President in 1901, Roosevelt used his authority to protect wildlife and public lands by creating the U.S. Forest Service and establishing 51 Federal Bird Reservations, 4 National Game Preserves, 150 National Forests, 5 National Parks, and enabling the 1906 American Antiquities Act which he used to proclaim 18 National Monuments. During his presidency,Theodore Roosevelt protected approximately 230,000,000 acres of public land (NPS 2012). Roosevelt was a conservationist, not a preservationist, and created public lands for multiple uses instead of the single use of wildlife preservation. This legacy is why we have the majority of hunting, grazing, and timber harvest occurring on public lands today. In 1937 The Federal Aid in Wildlife Restoration Act (commonly referred to as the Pittman-Robertson Act) is passed by Congress to provide funding for the selection and improvement of wildlife habitat, improving wildlife management research and distributing information (DFW 2009). This law codified what conservationists and sportsmen all over the country were clamoring for - an end to commercial wildlife In 1973 the all-encompassing Endangered Species Act (ESA) is passed by Congress to protect endangered plants and animals. Building upon legislation passed in 1966 and 1969, the new law expands and strengthens efforts to protect species domestically and internationally. The Fish and Wildlife Service and the National Marine Fisheries Service assume responsibility for administering the Act (DFW 2009). The ESA has far-reaching implications for wildlife conservation in the United States. Beaver were no longer threatened by 1973, and so have never been listed on the ESA as far as I could determine. Salmon, as we know, have many Evolutionary Significant Units (ESUs) listed both Federally and at the state level as endangered and threatened. This has led to agencies being required by law to protect listed salmon ESUs, and much more money and effort has gone into conservation of salmon in the past 40 years, some of it a direct result of the ESA of 1973. This has led to research using beaver to restore wetlands, and also to increase smolt production among various species of salmonids. The next slides will explore this ongoing restoration work and studies showing its efficacy. Oregon State Law establishes wildlife as state property. Conservationists rebuke US environmental laws and policies for diverging from the English model of establishing wildlife as state property. In the United States, wildlife has been considered a public good, belonging to all people. Sanctuaries, refuges, parks and National Forests were designed originally to give everyone access to these public goods, and to protect the environments where they thrived. This was instead of requiring land owners to preserve any of their own resources. When wildlife becomes state property, as it has always been in English law, it becomes the government's responsibility to preserve and sustain these populations. The public then must be granted permission by the State in order to take wildlife. This Oregon law protects beavers and other wildlife from fashion and the free-market anarchy of consumerism, which once drove the beaver to near extinction in the Northern Hemisphere. Surprisingly, fisheries laws have never caught up with laws protecting terrestrial and avian wildlife. However, fish are included in this Oregon State Law, and belong to the state. Oregon Law also prohibits the selling of wildlife or wildlife parts, except for as allowed by state law. State law still allows for selling of some animals, mostly fish. Fish are the only wildlife still being massively hunted for commercial trade. All terrestrial and avian wildlife was protected from commercial hunting at the turn of the last century. The Oregon DFW (ODFW) is responsible for enforcing and helping to write state law regarding salmon and wildlife regulations. The ODFW in involved in managing fish and wildlife throughout the state, in all freshwater ecosystems. They would be managing multiple life stages of these anadromous fish. Photo [E]
  • The beaver is a keystone species, increasing biodiversity in its territory through creation of beaver ponds and wetlands (Wright 2002). As wetlands are formed and riparian habitats enlarged, aquatic plants colonize newly available watery habitat. Insect, invertebrate, fish, mammal, and bird diversity are also expanded (Rosell 2005).
  • The presence of beaver dams was shown to both the number and size of fish in a study of brook trout (Salvelinus fontinalis), rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) in Sagehen Creek, a tributary of Little Truckee River in the northern Sierra Nevada (Gard 1961). In British Columbia, Swales and Leving’s study of the Coldwater River showed that off-channel beaver ponds were preferentially populated by Coho salmon over other salmonids and provided over wintering protection, protection from high summer snowmelt flows and summer Coho rearing habitat (Swales 1989). Research in the Stillaguamish River basin in Washington state, found that extensive loss of beaver ponds resulted in an 89% reduction in Coho salmon ( Oncorhynchus kisutch ) smolt summer production and an 86% loss of critical winter habitat carrying capacity. This study also found that beaver ponds increased salmon smolt production eighty times greater than the placement of large woody debris (Pollock 2004). This shows that the use of beaver to restore wetlands is more effective and obviously cheaper than using backhoes and helicopters to put in LWD by hand.
  • Water quality and water flow are important for salmon. Water must be clean and clear, and flow all year long, in order for salmon to flourish in a stream. By creating wetlands, beaver have been shown to mitigate droughts and floods, keeping water-levels more even. Beaver ponds are even more effective than non-beaver created wetlands in all the prized wetland functions, including storage of water during droughts, mitigation of floods, increased biodiversity, increased productivity of aquatic environment, increased groundwater tables, removal of sediment and pollutants from water, and reduction of harmful bacteria, including those harmful for humans (Science, 2008).
  • Beaver fell trees and are considered nuisance animals for the damage they cause to trees and shrubs. However, long-term studies show that beaver increase tree and shrub growth. Studies of the Bridge Creek watershed in E. Oregon reveal increased growth of all riparian plants where beavers are present. Pollack report that in Bridge Creek, a high-desert stream, the area of riparian vegetation increased by seven times due to beaver activity changing the water table. Some portions of the studied reach were abandoned periodically after being heavily used by beaver. Over a number of years these heavily used areas grew denser and more diverse stands of woody plants than prior to beaver activity. (Pollock 2007) Trees are of course necessary for salmon and trout survival. They help regulate the water table and decrease sedimentation due to run-off. Trees also provide shade which keeps the water cool and increase dissolved oxygen content. Riparian vegetation provides input of woody debris and nitrogen-rich leaf-litter, which is the basis of the aquatic food chain. Photo [F]
  • In the 1930s, the U.S. Government put 600 beaver to work alongside the Civilian Conservation Corps in projects to stop soil erosion by streams in Oregon, Washington, Wyoming, and Utah. At the time it was estimated that each beaver, whose initial cost was about $5, completed work worth $300 (Ruedemann 1938). In a pilot study in Washington state, the Lands Council is reintroducing beavers to evaluate their projections that if 10,000 miles of suitable habitat were repopulated then 650 trillion gallons of spring runoff would be held back for release in the arid fall season (Groc 2010). This project was developed in response to a 2003 Washington Department of Ecology proposal to spend as much as ten billion dollars on construction of several dams on Columbia River tributaries to retain storm season runoff.
  • Michael Pollock has been studying Bridge Creek, which drains into Oregon’s John Day River, for over 17 years. Wedging posts deep into the stream-bed speeds up the dam-building process and encourages beaver activity in specific locations. This research team also brought in fresh branches for beavers to eat and build with, to further encourage activity where it was needed most. The Bridge Creek watershed is an Extensively Managed Watershed (EMW), a specific designation for the Department of Fish and Wildlife and the National Oceanic and Atmospheric Administration (NOAA) (Jahn 2010). The NOAA is involved in many stages of salmon restoration, though their involvement in freshwater habitats has been recent, in the past decade. The NOAA’s involvement in using beavers to restore wetlands involves them now in the important freshwater stages of salmon lifecycles, from egg to fry to parr to smolt. Photo [G]
  • “ Photo 1. A typical incised reach of Bridge Creek at high flow during spring runoff. Incision depth in this reach is 1.5-2 m. Note the high suspended sediment load. Photo 2. View of an aggraded reach upstream of a 1.5 m high beaver dam on Bridge Creek, Oregon. The pond has almost completely backfilled with (approximately 7500 m 3 ) of sediment. Willows, cattails and other riparian vegetation have colonized the new surface. Additionally, willows have recently replaced sagebrush on the adjacent terrace where water tables have risen to within 0.5 m of the surface. The dam is just beyond the patch of open water in the upper left of photograph. “(Pollock 2011). Photos [H]
  • Plant biologist Gregory Hood began project while studying sweet gale, a wetland plant, in tidal marshes. He was surprised to find a network of beaver dams in the salt water. When he found no record of beavers living in salt water, he began a serious investigation. His report is available and very informative. Consider that the entire Puget Sound could once have been inhabited by beavers. The salt flats of the northern Washington coast were drained very early on in the development of the state, and only about 6% of these coastal wetland remain. Hood also made the point that it is dangerous to undertake extensive restoration efforts when there is so little we do not know about the past. Since we have no baseline, we cannot know exactly how much woody debris was in the stream, or how it got there, or how much it helped the salmon. It appears now, thanks to his research, that beavers greatly modified the landscape all along our tidelands, and played an essential role in creating salmon habitat. Hood’s findings point again towards the cost-effectiveness and general efficiency of using beavers to restore salmon habitat. (Hood, 2009) Photo [I]
  • Photo [J]
  • Contrary to popular belief, most beaver dams are not a problem for trout and salmon migration, although fish may be restricted seasonally during periods of low stream flows (Pollock 2003). Studies show rainbow, brown and brook trout crossing up to 14 consecutive beaver dams(Gard 1961). Pollock found that adults and juveniles of many fish species, including coho, steelhead, sea run cutthroat, Dolly Varden, and sockeye salmon are crossing beaver dams (Pollock 2003). Downstream migration of Atlantic salmon smolts has been shown to be unaffected by beaver dams even during drought conditions of low flow. There still seems to be a plethora of bad press for beavers out there though. Numerous news sources in the UK are reporting negative stories about beaver and salmon. There are also hundreds of beaver dams being removed every year in the US because they are believed to block salmon. Some areas are being monitored through state and tribal departments of fisheries, which are recommending beaver dam removal in order to preserve fish stocks. While I found numerous sources still citing beaver dams as the cause of local salmon problems, most of the the scientific literature seems to point to beaver dams not being a problem to fish. I believe longer term studies are needed, especially in those areas where locals claim beaver dams are adversely affecting salmonids. Perhaps some low-flow years there is a legitimate problem.
  • According to the Wild Earth Guardians, “ B eaver trapping is still widespread on many public and private lands in the West, where private individuals trap to provide pelts in the international fur market. At the same time a federal agency within the Department of Agriculture (DOA) has killed more than 100,000 beavers over the last five years. This agency rarely considers non-lethal approaches that would promote co-existence with beavers. Furthermore, widespread stream habitat degradation due to excessive grazing by domestic and native ungulates continues to be a limiting factor to the expansion of beaver populations. Interestingly, the loss of beaver is both a symptom and cause of stream degradation. Overgrazing of vegetation prevents their recovery and re-population while suitable streams without beaver function at levels much lower than their optimum. Habitat restoration and beaver reintroduction are key to the recovery and resilience of the streams” (Wild, no date). The DOA is therefore having a great effect on salmon smolts and parr throughout the salmon’s freshwater habitat, especially in the arid west west where the department is involved with conflicts between humans and wildlife. Photo [K]
  • According to the Wildlife Habitat Society, “Overgrazing in riparian areas can lead to a loss of bank-stabilizing plants, formation of an over-widened channel, and increased sedimentation in the stream channel. Pictured – Squaw Creek in Freemont County, WY” (Wildlife, no date). In order to restore salmon populations we must first restore beaver populations. Beaver can restore whole watersheds in the American arid west. Many groups are attempting to do just that, to get government funding for reestablishing healthy beaver populations on headwaters in the dry western interior. They are focusing on public lands. I believe this restoration work, beginning with beaver to restore the watersheds, and moving toward removal of dams on the Columbia River, is vital to restoring salmon populations, and whole ecosystems. Photo [L]
  • Beaver and Salmon

    1. 1. Beavers and Salmon QuickTime™ and a decompressor are needed to see this picture. Rachel Castor November 10, 2012
    2. 2. The Beavers• European Beaver - Castor fiber – Found in Europe and Asia – Unable to reproduce with C. canadensis• American Beaver - Castor canadensis – Found in North America – Introduced into South America, become invasive• Not the Mountain Beaver - Aplodontia rufa
    3. 3. American Beaver: Castor QuickTime™ and a decompressor are needed to see this picture. canadensis• Second largest extant rodent species (after capybara)• Herbivorous (does NOT eat fish, insects, etc)• Clumsy on land with rear feet webbed• Creates its own habitat by damming running water• Lives in constructed lodge or in burrows on bank
    4. 4. Eurasian Beaver: QuickTime™ and a decompressor are needed to see this picture.Castor fibre • Hunted to near extinction in Europe • Extinct in UK by 1600 AD • Extinct in Denmark by 1000 AD • 8 populations survived and were used to repopulate other European countries, where it has been used to restore wetlands.
    5. 5. History of Beaver in N.America• Ubiquitous – arctic tundra to the deserts of northern Mexico – from the Atlantic to the Pacific Oceans.• Explorer David Thompson (crossed North America in 1784) – "this Continent...from the Atlantic to the Pacific Ocean, may be said to have been in the possession of two distinct races of Beings, Man and the Beaver."• Historic Population = 100 to 200 million pre- fur trade
    6. 6. History of Beaver in N.America• Trapped for – Fur - Clothing and hats – Castoreum musk - for perfumes and medicinal uses• 1630 to 1640: 80,000 beaver taken per year from the Hudson River and western New York.• 19th century California Fur Rush• Hudson Bay Company (HBC) Scorched Earth policy• 1826-1834 HBC took 3,000 beaver per year PNW• 1850 - only 438 beaver taken as population decreased• Nearly extinct by 1900 QuickTime™ and a decompressor are needed to see this picture.
    7. 7. Protection• Population rebounded to an estimated 10 to 15 million• Originally estimated 100 to 200 million before fur trade• 1900 The Lacey Act• 1903 Roosevelt establishes first Federal Bird Reservation. QuickTime™ and a Goes onto establish Wildlife Refuges, National Parks, and decompressor are needed to see this picture. National Forests, protecting 230, 000,000 acres• 1937 The Federal Aid in Wildlife Restoration Act (Pittman- Robertson Act)• 1973 The Endangered Species Act State Laws governing wildlife proliferated in 1990’s• OR 498.002 Wildlife is state property• OR 498.022 Selling of wildlife & furs is prohibited
    8. 8. Keystone Species• The beaver is a keystone species, increasing biodiversity in its territory through creation of beaver ponds and wetlands.• Aquatic plants colonize newly available watery habitat.• Insect, invertebrate, fish, mammal, and bird diversity are also expanded.
    9. 9. Beavers and Fish: modern studies• Is the decline of salmonids related to the decline in beaver populations?• Sagehen Creek Study, CA – Beaver dams increase # and size of trout• Coldwater River Study, BC – Beaver ponds preferred by Coho for rearing habitat – Over wintering and flood protection• Stillaguamish River Study, WA – Loss of beaver ponds = 89% reduction in Coho smolt production – Beaver pond increase smolt production 80x > Large Woody Debris
    10. 10. Stream Flow and Water Quality• Beaver ponds increase stream flow in dry seasons by storing run-off in rainy season.• Increases groundwater tables• Remove sediment and pollutants• Harmful bacteria reduced in beaver ponds• Increased wetland functions
    11. 11. • Beaver and Trees Beavers once thought to cause deforestation.• Still killed and relocated for causing damage to trees• Forests damaged in South America where beaver are introduced, invasive species and where wetlands do not form or function as they do in the Northwest• Studies show beaver activity increases woody plant cover• Trees provide shade and woody debris necessary for salmon survival QuickTime™ and a decompressor are needed to see this picture.
    12. 12. Stream Restoration• Conservation Corps 1930’s – Beaver stop soil erosion in streams – Oregon, Washington, Wyoming, Utah – Each $5 beaver completed $300 of work• Instead of Dams – WA Lands Council pilot study – In response to DOE plan to build $10,000,000,000 worth of dams for flood control
    13. 13. Support structures installed along Bridge Creek to encourage increased beaver activity in the John Day River drainage of E.Oregon. QuickTime™ and a decompressorare needed to see this picture.
    14. 14. Bridge Creek, OR QuickTime™ and a decompressorare needed to see this picture. Typical reach without beaver activity QuickTime™ and a decompressor Reach with beaver dam are needed to see this picture. activity - notice large riparian zone
    15. 15. ESTUARY RESTORATION QuickTime™ and a decompressor are needed to see this picture.“Recently, beaver have been discovered living in brackish waterin estuarine tidal marshes, where Chinook salmon (Oncorhynchustshawytscha) densities were five times higher in beaver pondsthan in neighboring areas.” (Mapes 2009)
    16. 16. Do Dams Block Salmonids? QuickTime™ and a decompressor are needed to see this picture.
    17. 17. Salmon Move Through Beaver Dams• Restrict salmon during seasonaldrought•Trout shown to cross 14consecutively•Coho jump up to 2m•Anadromous trout and salmon QuickTime™ and a decompressor are needed to see this picture.found above beaver dams•Downstream migration unaffectedby beaver dams
    18. 18. Modern Threats to Beaver• Trapping for International Fur Market• Pest Status – DOA Killed 100,000 beaver in past 5 years• Habitat Degradation – Excessive Grazing in arid West QuickTime™ and a decompressor are needed to see this picture.
    19. 19. Overgrazing :cause of beaver and salmon declines QuickTime™ and a decompressor are needed to see this picture.
    20. 20. • Sources Morgan, L. H. 1868. The American Beaver and his works. J. B. Lippincott. Rochester, NY. Available: http://books.google.com/? id=gY4-AAAAcAAJ&printsec=frontcover&dq=lewis+h.+morgan+1868+%22american+beaver%22#v=onepage&q=gila&f=false. (November 12, 2012).• Naiman, R. J.; C. A. Johnston, and J. C. Kelley. 1988. Alteration of North American streams by beaver. BioScience: 38:11 753–762. Available: http://www.landscouncil.org/documents/Beaver_Project/Articles/Naiman_et_al_1988_alter_n_american_streams_by_beaver.pdf. (November 12, 2012).• NPS (National Parks Service). 2012. Theodore Roosevelt and conservation. Available: http://www.nps.gov/thro/historyculture/theodore-roosevelt-and-conservation.htm. (November 12, 2012).• Oregon State Law. Available: http://www.leg.state.or.us/ors/498.html. (November 12, 2012).• Outwater, A. 1997. Water: A natural history. Basic Books, New York. Available: http://books.google.ca/books? id=3_oRrNgE_mkC&dq=water+alice+outwater&printsec=frontcover&hl=en#v=onepage&q&f=false. (November 12, 2012).• Pollock, M. M., M. Heim, D. Werner. 2003. Hydrologic and geomorphic effects of beaver dams and their influence on fishes. American Fisheries Society Symposium 37. Available: http://www.albergstein.com/cao/Best%20Available%20Science/Fish/Beaver %20dam%20effects%20paper%20final.pdf. (November 12, 2012).• Pollock, M. M., G. R. Pess, T. J. Beechie. 2004. The importance of beaver ponds to coho salmon production in the Stillaguamish River Basin, Washington, USA". North American Journal of Fisheries Management: 749–760. Available: xhttp://duff.ess.washington.edu/grg/publications/pdfs/Pollock.pdf. (November 12, 2012).• Pollock, M. M, T. J. Beechie, C. E. Jordan. 2007. Geomorphic changes upstream of beaver dams in Bridge Creek, an incised stream channel in the interior Columbia River basin, eastern Oregon. Earth Surface Processes and Landforms. Available: http://dx.doi.org/10.1002%2Fesp.1553%2Fpdf. (November 12, 2012).• Pollock, M.M., J.M. Wheaton, N. Bouwes, and C.E. Jordan. 2011. Working with beaver to restore salmon habitat in the Bridge Creek Intensively Monitored Watershed: Design rationale and hypotheses, Interim Report. NOAA Northwest Fisheries Science Center. Seattle, WA. Available: http://etal.usu.edu/BridgeCreek/NOAA/BDSS_Tech_Memo_6.07.11.pdf. (November 10, 2012).• Rosell, F., O. Bozser, P. Collen, H. Parker. 2005. Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems". Mammal Review: 248–276. Available: http://duff.ess.washington.edu/grg/publications/pdfs/Pollock.pdf. (November 12, 2012).• Ruedemann, R.; W. J. Schoonmaker. 1938. Beaver-dams as geologic agents". Science: 88:2292 523–525. Available: http://adsabs.harvard.edu/abs/1938Sci....88..523R/ (November 12, 2012).• Science Daily. 2008. Busy beavers can help ease drought". Science Daily. Available: http://www.sciencedaily.com/releases/2008/02/080220130511.htm. (November 12, 2012).
    21. 21. • Sources Brown, R. D. 2007. The History of wildlife conservation and research in the United States – and implications for the future. North Carolina State University College of Natural Resources Paper. Raleigh, NC. Available: http://www.google.ca/url? sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCIQFjAA&url=http%3A%2F%2Fcnr.ncsu.edu%2Ffer%2Fdirect %2Fdocuments%2FArticle- HistoryofWildlifeResearch.pdf&ei=CJWhUImtM4L3igKvmoC4Dw&usg=AFQjCNH7CX_44u76cpFXNCQHC_PvGA4eqQ. (November 12, 2012).• Demmer, R., R. L. Beschta. 2009. Recent history (1988–2004) of beaver dams along Bridge Creek in Central Oregon. Northwest Science 82 (4): 309–318. Available: doi:10.3955/0029-344X-82.4.309. (November 12, 2012)• DFW (Department of Fish and Wildlife). 2009. Conservation history: origins of the U.S. Fish and Wildlife Service. Available: http://training.fws.gov/History/TimelinesOrigins.html. (November 12, 2012).• Gard, R. 1961. Effects of beaver on trout in Sagehen Creek, California. Journal of Wildlife Management 25 (3): 221–242. Available: http://dx.doi.org/10.2307%2F3797848. (November 12, 2012).• Groc, I. 2010. Beavers sign up to fight effects of climate change. Discover, April 2010. Available: http://discovermagazine.com/2010/apr/19-beavers-sign-up-fight-effects-climate-change. (November 12, 2012).• Halley, D. J. & F. Rosell. 2003. Population and distribution of European beavers (Castor fiber). Lutra: 91–101. Available: http://teora.hit.no/dspace/handle/2282/534. (November 12, 2012).• Hays, W. J. 1871. Notes on the range of some of the animals in America at the time of arrival of the whitemen. The American Naturalist 5 (7): 25–30. Available: http://www.jstor.org/stable/2447602. (November 12, 2012).• Hood, W. G. 2009. An Overlooked ecological web: sweetgale, beaver, salmon, and large woody debris in the Skagit River tidal marshes. Skagit River Cooperative. Available: http://www.nisquallydeltarestoration.org/pdf/hood-%20skagit%20rvr%20tidal %20marshes.htm. (November 12, 2012).• Jahn, E., and N. Fisher. 2010. Beaver assisted restoration. Oregon Field Guide. Oregon Public Broadcasting. Available http://www.opb.org/programs/ofg/segments/view/1758. (November 10, 2012).• Komarov, S. 2004. Why beavers survived in the 19th Century. Innovations Report. Available: http://www.innovations- report.com/html/reports/environment_sciences/report-34906.html. (November 11, 2012).• Lichatowich, J.A. 1999. Salmon without rivers: A history of the pacific salmon crisis. Island Press, Washington, D.C. 317 pgs.• Mapes, L. V. 2009. Scientist discovers beavers building prime salmon habitat in Skagit Delta. The Seattle Times. Available: http://seattletimes.com/html/localnews/2009231736_beavers18m.html. (November 12, 2012).• Milishnikov, A. N. 2004. Population-genetic structure of beaver (Castor fiber L., 1758) Communities and Estimation of Effective Reproductive Size Ne of an Elementary Population. Russian Journal of Genetics: 40:7 pp772–781. Available: http://www.springerlink.com/content/m51734p93337273j/. (November 12, 2012).
    22. 22. • Sources Sun, L., D. M Ver-Schwarze. 2003. The Beaver: Natural history of a wetlands engineer. Cornell University Press. Ithaca, NY. Available: http://books.google.ca/books? id=eqIenKko3lAC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false. (November 12, 2012).• Swales, C., D. Levings. 1989. Role of off-channel ponds in the life cycle of Coho Salmon (Oncorhynchus kisutch) and other juvenile salmonids in the Coldwater River, British Columbia". Canadian Journal Fisheries Aquatic Sciences 46: 232–242. Available: http://www.nrcresearchpress.com/doi/pdf/10.1139/f89-032. (November 12, 2012).• Tyrell, J. B. 1916. David Thompsons narrative of his explorations of Western America 1784-1812. Greenwood Press. New York. Available: http://www.archive.org/details/davidthompsonsna00thom. (November 12, 2012).• Wild Earth Guardians. No date. Beavers: climate heroes. Available: http://www.wildearthguardians.org/site/PageServer? pagename=priorities_wild_places_jemez_mountains_beavers . (November 12, 2012).• Wildlife Habitat Initiative. No date. Effect of livestock exclusion in Eastern Oregon. Available: http://wildfish.montana.edu/cases/gallery1.asp?ProjectID=67. (November 12, 2012).• Wright, J. P., C. G. Jones, and A. S. Flecker. 2002. An ecosystem engineer, the beaver, increases species richness at the landscape scale. Oecologia 132 (1): 96–101. Available: http://www.springerlink.com/content/0637gf0979lru90j/. (November 12, 2012).
    23. 23. Photo Credits• [A] Ramstad, Kristina. 1997. Sockeye salmon jumping over beaver dam. Lake Aleknagik, AK. Wikipedia Commons. Link• [B] Robertson, D. Gordon E. 2010. “Canadian Beaver (Castor canadensis). Gatineau Park, Quebec, Canada. Wikipedia Commons. Link• [C] Začek, Sven. 2006. European beaver (Castor fiber). Tartu County, Estonia. Wikipedia Commons. Link• [D] Harding, Arthur Robert. 1907. Steel Traps. A.R. Harding Publishing Co, Columbus, OH. Gutenberg Book Project. Link• [E] Mark, William-Mathieu. 1992. Beaver pelt, wood and twine. Canadian Museum of Civilization. Gastineau, Quebec. Link• [F] Wheaton, Joe. Beaver dam on Bridge Creek. Eastern Oregon. Link• [G] Wheaton, Joe. A series of beaver dam support structures in Bridge Creek. Eastern Oregon. Link• [H] Pollock, M.M., J.M. Wheaton, N. Bouwes, and C.E. Jordan. 2011. Working with Beaver to Restore Salmon Habitat in the Bridge Creek Intensively Monitored Watershed: Design Rationale and Hypotheses, Interim Report. NOAA Northwest Fisheries Science Center: Seattle, WA. Link• [I] Berner, Allen. 2009. The Seattle Times. Seattle, WA. Link• [J] Juliux. 2007. European Beaver (Castor fiber) dam. Inkūnai, Anykščiai district, Lithuania. Link• [K]Wild Earth Guardians. Beavers: Climate Heroes. Public Domain. Link• [L]Wildlife Habitat Initiative. Squaw Creek in Freemont County, WY. Freemont County, WY. Link

    ×