Castor fiber

Superregnum: Eukaryota
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Ordo: Rodentia
Subordo: Castorimorpha
Familia: Castoridae
Genus: Castor
Species: Castor fiber
Subspecies: C. f. albicus - C. f. belorussicus - C. f. birulai - C. f. fiber - C. f. galliae - C. f. orientoeuropaeus - C. f. pohlei - C. f. tuvinicus - C. f. vistulanus

Name

Castor fiber Linnaeus, 1758

References

* Castor fiber in Mammal Species of the World.
Mammal Species of the World: A Taxonomic and Geographic Reference, 2 Volume Set edited by Don E. Wilson, DeeAnn M. Reeder
* Taxonomic subtree for Castor fiber on taxon.molgen.mpg.de
* IUCN link: Castor fiber Linnaeus, 1758 (Least Concern)

Vernacular names
English: European Beaver
Français: Castor Européen
‪Norsk (bokmål)‬: Eurasisk bever
Polski: Bóbr europejski
Русский: Бобр речной, Бобр обыкновенный

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The Eurasian beaver or European beaver (Castor fiber) is a species of beaver, which was once widespread in Eurasia, where it has been hunted both for fur and for castoreum, a secretion of its scent gland believed to have medicinal properties. It still occurs as far as China and Mongolia.[2][4]

Physiology

Physical characteristics

The fur colour of Eurasian beavers varies geographically. Light, chestnut-rust is the dominant colour in Belarus. In Russia, the beavers of the Sozh River basin are predominantly blackish brown, while beavers in the Voronezh Reserve are equally distributed between brown and blackish-brown.[2]

Eurasian beavers on average weigh 18 kg, the largest specimen on record having weighed 31.7 kg.[2]

Differences from North American beaver

Although superficially similar to the North American beaver, there are several important differences. Eurasian beavers tend to be bigger, with larger, less rounded heads, longer, narrower muzzles, thinner, shorter, and lighter underfur, narrower, less oval-shaped tails, and have shorter shin bones, making them less capable of bipedal locomotion than the North American species. Eurasian beavers have longer nasal bones than their American cousins, with the widest point being at the end of the snout for the former, and in the middle for the latter. The nasal opening for the Eurasian species is triangular, unlike that of the North American race which is square. The foramen magnum is rounded in the Eurasian beaver, and triangular in the North American. The anal glands of the Eurasian beaver are larger and thin-walled with a large internal volume compared to that of the North American breed. Finally, the guard hairs of the Eurasian beaver have a longer hollow medulla at their tips. Fur colour is also different. Overall, 66% of Eurasian beavers have pale brown or beige fur, 20% have reddish brown, nearly 8% are brown and only 4% have blackish coats. In North American beavers, 50% have pale brown fur, 25% are reddish brown, one fifth are brown, and 6% are blackish.[2]

The two species are not genetically compatible. North American beavers have 40 chromosomes, while Eurasian beavers have 48. Also, more than 27 attempts were made in Russia to hybridize the two species, with one breeding between a male North American beaver and a female Eurasian resulting in one stillborn kit. These factors make interspecific breeding unlikely in areas where the two species' ranges overlap.[2]

Range

The Eurasian (or European) beaver is recovering from near extinction, after depradation by humans for its fur and castoreum decimated populations to an estimated 1,200 by the early 20th century.[5] In many European nations, the beaver went extinct but reintroduction and protection has led to gradual recovery to approximately 639,000 individuals by 2003.[6] Milishnikov found in genetic studies that beaver likely survived east of the Urals from a nineteenth century population as low of 300 animals, and that factors contributing to their survival include their ability to maintain sufficient genetic diversity to recover from a population as low as 3 individuals, and that beavers are monogamous and select mates that are genetically different from themselves.[7][8] 83% of Eurasian beavers live in the former Soviet Union thanks to reintroductions, however the result is that beaver in Mongolia or Siberia do not appear significantly genetically different from samples from the European part of Russia, despite the great geographical distance.[9]

Mainland Europe

In Romania, beavers became extinct in 1824, being reintroduced in 1998, along the Olt River, spreading to other rivers in Covasna County.[10]

Beavers have been re-introduced in Bavaria and the Netherlands and are tending to spread to new locations.[11] After being reintroduced in the Biesbosch in 1988, the Dutch population has spread considerably (supported by additional reintroductions), and can now be found in the Biesbosch and surrounding areas, along the Meuse in Limburg, and in the Gelderse Poort and Oostvaardersplassen.
A Eurasian beaver in Estonia

Scandinavia

In Sweden the beaver had been hunted to extinction by the end of the nineteenth century. Between 1922 and 1939 approximately eighty individuals were imported from Norway and introduced to nineteen separate sites within the country.

Norwegian beavers also played an important role in reintroducing the locally extinct animal to Finland, but there the population also includes a substantial number of C. canadensis of Canadian origin. (The North American Beavers were imported to Finland in 1937, when it was not yet known that C. canadensis was a different species from the Eurasian beaver.)

In Denmark, the beaver was reintroduced to the wild in western Jutland in 1999[12] and in Arresø, northern Zealand, in 2009[13] after it was hunted to extinction c. 1000 AD. The reintroduced beavers were caught in the river Elben in Germany. As of 2009[update], the Danish population of beavers was estimated to be 100—120 individuals.[14]

Great Britain
Tayside mother beaver with her kit. Courtesy of Ray Scott 2010.

The beaver became extinct in Great Britain in the sixteenth century: Giraldus Cambrensis reported in 1188 (Itinerarium ii.iii) that it was to be found only in the Teifi in Wales and in one river in Scotland, though his observations are clearly secondhand. The last reference to beavers in England dates to 1526.[15]

In 2001 the Kent Wildlife Trust with the Wildwood Trust and Natural England imported two families of Eurasian beaver from Norway to manage a wetland nature reserve. This project pioneered the use of beaver as a wildlife conservation tool in the UK. The success of this project has provided the inspiration behind other projects in Gloucestershire and Argyll. The Kent beaver colony live in a 130-acre (0.53 km2) fenced enclosure at the wetland of Ham Fen. Subsequently the population of beaver has been supplemented in 2005 and 2008. The beaver continue to help restore the wetland by rehydrating the soils.[16] Six Eurasian Beavers were released in 2005 into a fenced lakeside area in Gloucestershire.[17] In 2007 a specially-selected group of four Bavarian beavers were released into a fenced enclosure in the Martin Mere nature reserve in Lancashire.[18] It is hoped that the beavers will form a permanent colony, and the younger pair will be transferred to another location when the adults begin breeding again.[19] The progress of the group will be followed as part of the BBC's Autumnwatch television series. A colony of beavers is established in a large enclosure at Bamff, Perthshire.[20]

The first sustained and significant population of wild-living beavers in the United Kingdom became established on the Tay watershed in Scotland as early as 2001 and has spread widely in the watershed, numbering from 20 to 100 individuals.[21] Because these are likely escapees from any of several nearby sites with captive beavers, or were illegally released, they were targeted for removal by Scottish Natural Heritage in late 2010.[22] Proponents of the beavers argue that they have not been proven to be of "wrong" genetic stock and there is scientific evidence to support that they may represent a rather ideal mix of western European populations, since any single relic population in western Europe is relatively genetically depauperate.[21] The first of the wild Tayside beavers was trapped by Scottish Natural Heritage on the River Ericht in Blairgowrie, Perthshire in early December, 2010 and is being held in captivity in the Edinburgh Zoo. A Facebook group, Save the Free Beavers of the Tay, has nicknamed the captured wild beaver "Eric" and opposes the ongoing effort to trap Eric's relations.[23]

In 2005, the Scottish Government turned down a licence application for unfenced reintroduction. However, in late 2007 a further application was made for a release project in Knapdale, Argyll.[24] This application was accepted, and the first beavers were released on the 29th May 2009.[25][26] This initial release into the wild of 11 animals received a setback during the first year with the disappearance of two animals and the illegal shooting of a third. However, the remaining population was increased in 2010 by further releases.[27] In August 2010, at least two kits, estimated to be eight weeks old and belonging to different family groups, were seen in Knapdale Forest in Argyll.[28]

The Scottish charity Trees for Life plans to reintroduce beavers in the Scottish Highlands.[29][30]

With the exception of the Knapdale and Tayside animals, all the beavers in the United Kingdom today are in semi-enclosed sites and not fully released into the wild. A 2009 report by Natural England, the Government’s conservation body, and the People's Trust for Endangered Species recommended that beaver be reintroduced to the wild in England.[31]

A study has been undertaken on the feasibility and desirability of a reintroduction of beavers to Wales by a partnership including the Wildlife Trusts, Countryside Council for Wales, Peoples Trust for Endangered Species, Environment Agency Wales, Wild Europe, Forestry Commission Wales, with additional funding from Welsh Power Ltd. The resulting reports are due to be published in 2010.

Ecology

Beaver are a keystone species helping support the ecosystem of which they are a part. They create wetlands which increase biodiversity and provide habitat for many rare species such as water voles, otters and water shrews. They coppice waterside trees and shrubs so that they re-grow as dense shrubs which provide cover for birds and other animals. Beaver dams trap sediment and improve water quality; recharge groundwater tables and increase cover and forage for trout and salmon.[31] A recent study in Poland, found that beavers increased abundance and diversity of bats apparently because they create gaps in forest cover making it easier for bats to navigate in.[32]

Beaver Impacts on Fishes

Beaver ponds have been shown to have a beneficial effect on trout and salmon populations, in fact many authors believe that the decline of salmonid fishes is related to the decline in beaver populations. A study of small streams in Sweden that found that brown trout were larger in beaver ponds compared with those in riffle sections, and that beaver ponds provide habitat for larger trout in small streams during periods of drought.[33] These findings are similar to several studies of beaver effects on fish in North America. Brook trout, coho and sockeye salmon were significantly larger in beaver ponds than those in un-impounded stream sections in Colorado and Alaska.[34][35] In addition, research in the Stillaguamish River basin in Washington state, found that extensive loss of beaver ponds resulted in an 89% reduction in coho salmon smolt summer production and an almost equally detrimental 86% reduction in critical winter habitat carrying capacity.[36] Migration of adult Atlantic salmon (Salmo salar) may be limited by beaver dams during periods of low stream flows, but the presence of juveniles upstream from the dams suggests that the dams are penetrated by parr.[37] Downstream migration of Atlantic salmon smolts was similarly unaffected by beaver dams, even in periods of low flows.[37] Two year old Atlantic salmon parr in beaver ponds in eastern Canada showed faster summer growth in length and mass and were in better condition than parr upstream or downstream from the pond.[38] The importance of winter habitat to salmonids afforded by beaver ponds may be especially important (and underappreciated) in streams without deep pools or where ice cover makes contact with the bottom of shallow streams.[37] A 2003 study of Atlantic salmon and Sea trout (S. trutta morpha trutta) spawning in the Numedalslågen River and 51 of its tributaries in southeastern Norway were unhindered by beaver.[39]

In Poland in May and June 2010 after major flooding, the Polish government and local authorities held beavers responsible for causing the flooding and demanded the culling of 150 beavers.[40]

References

1. ^ Batbold, J., Batsaikhan, N., Shar, S., Amori, G., Hutterer, R., Kryštufek, B., Yigit, N., Mitsain, G. & Muñoz, L. J. P. (2008). Castor fiber. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 6 January 2009.
2. ^ a b c d e f g h i j k Kitchener, Andrew (2001). Beavers. p. 144. ISBN 187358055X.
3. ^ a b Genetic Divergence and Similarity of Introduced Populations of European Beaver (Castor fiber L., 1758) from Kirov and Novosibirsk Oblasts of Russia, Journa Russian Journal of Genetics, Publisher MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC. ISSN 1022-7954 (Print) 1608-3369 (Online), Issue Volume 37, Number 1 / January, 2001
4. ^ Helgen, Kristofer M. (16 November 2005). "Family Castoridae (pp. 842–843)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=12600005.
5. ^ Nolet, B.A. & Rosell, F. (1998). "Come back of the beaver Castor fiber: an overview of old and new conservation problems". Biological Conservation: 165–173.
6. ^ Halley, D. & Rosell, F. (2003). "Population and distribution of European beavers (Castor fiber)". Lutra: 91–101. http://teora.hit.no/dspace/handle/2282/534. Retrieved Feb. 28, 2010.
7. ^ Sergey Komarov. "Why Beavers Survived in the 19th Century". Innovations Report. http://www.innovations-report.com/html/reports/environment_sciences/report-34906.html. Retrieved 2010-09-08.
8. ^ A. N. Milishnikov (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: 772–781. http://www.springerlink.com/content/m51734p93337273j/. Retrieved 2010-09-08.
9. ^ Jean-Francois Ducroza, Michael Stubbeb, Alexander P. Saveljevc, Dietrich Heideckeb, Rivčan Samjaad, Alius Ulevičiuse, Annegret Stubbeb, and Walter Durka (2005). "Genetic Variation and Population Structure of the Eurasian Beaver Castor Fiber in Eastern Europe and Asia". Journal of Mammalogy: 1059–1067. http://www.bioone.org/doi/abs/10.1644/1545-1542%282005%2986%5B1059%3AGVAPSO%5D2.0.CO%3B2. Retrieved 2010-09-08.
10. ^ "DISPĂRUŢI DE LA 1824: Castorii repopulează apele din Covasna". Evenimentul Zilei. http://www.evz.ro/articole/detalii-articol/838371/DISPARUTI-DE-LA-1824-Castorii-repopuleaza-apele-din-Covasna/. Retrieved February 3, 2008.
11. ^ "Europäischer Biber". WWF Österreich. http://www.wwf.at/Projekte/artenschutz/project141. Retrieved August 24, 2006. [dead link]
12. ^ "Bæverne i Klosterheden - Bævere i Danmark - Skov- og Naturstyrelsen". Skovognatur.dk. 2008-12-19. http://www.skovognatur.dk/DyrOgPlanter/Artsleksikon/Pattedyr/Gnavere/Baever/baeverne_klosterheden.htm. Retrieved 2010-03-15.
13. ^ "Udsætning af bævere i Arresø og søens opland - Skov- og Naturstyrelsen". Skovognatur.dk. 2010-01-04. http://www.skovognatur.dk/DyrOgPlanter/Artsleksikon/Pattedyr/Gnavere/Baever/Baeverudsaetning.htm. Retrieved 2010-03-15.
14. ^ "Bæver - Skov- og Naturstyrelsen". Skovognatur.dk. 2009-10-21. http://www.skovognatur.dk/DyrOgPlanter/Artsleksikon/Pattedyr/Gnavere/Baever/. Retrieved 2010-03-15.
15. ^ Martin, Horace T. (1892). Castorologia: Or The History and Traditions of the Canadian Beaver. W. Drysdale. p. 26. ISBN 0665079397. http://books.google.com/books?id=SRgPAAAAYAAJ.
16. ^ "Born to be Wild! Beavers breed at Kent reserve". http://www.kentwildlifetrust.org.uk/about-kent-wildlife-trust/news/born-to-be-wild/. Retrieved Feb. 28, 2010.
17. ^ "Beavers in 'wild' after centuries". BBC News. 2005-10-28. http://news.bbc.co.uk/1/hi/england/gloucestershire/4380276.stm.
18. ^ "Beavers are back after 500 years". BBC News. 2007 July. http://news.bbc.co.uk/1/hi/england/lancashire/6291260.stm.
19. ^ "Meet the Beavers". Wildfowl & Wetlands Trust. http://www.wwt.org.uk/text/673/beavers.html. Retrieved November 8, 2007. [dead link]
20. ^ "Vines, Gail, "The beaver: destructive pest or climate saviour?", 22 August 2007, ''New Scientist'' '''2618''': 42-45. Article on beaver reintroduction". Newscientist.com. http://www.newscientist.com/channel/life/mg19526181.600-the-beaver-destructive-pest-or-climate-saviour.html. Retrieved 2010-03-15.
21. ^ a b Duncan J. Halley (2011-1). "Sourcing Eurasian beaver Castor fiber stock for reintroductions in Great Britain and Western Europe". Mammal Review. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2907.2010.00167.x/pdf. Retrieved 2011-01-05.
22. ^ "Feral beavers in Tayside 'will be trapped'". BBC News. 2010-11-26. http://www.bbc.co.uk/news/uk-scotland-glasgow-west-11845803. Retrieved 2011-01-05.
23. ^ Mike Farrell (2010-12-15). "First 'free' River Tay beaver trapped". STV. http://news.stv.tv/scotland/tayside/215903-first-free-river-tay-beaver-trapped/. Retrieved 2011-01-10.
24. ^ Watson, Jeremy. "Beavers dip a toe in the water for Scots return". http://news.scotsman.com/scotland.cfm?id=1560972007. Retrieved 2007-12-11.
25. ^ "UK | Scotland | Glasgow, Lanarkshire and West | Beavers to return after 400 years". BBC News. 2008-05-25. http://news.bbc.co.uk/1/hi/scotland/glasgow_and_west/7419183.stm. Retrieved 2010-03-15.
26. ^ "UK | Scotland | Glasgow, Lanarkshire and West | Beavers return after 400-year gap". BBC News. 2009-05-29. http://news.bbc.co.uk/1/hi/scotland/glasgow_and_west/8072443.stm. Retrieved 2010-03-15.
27. ^ "New breeding beaver pair released in Scotland". BBC News. 10 May 2010. http://news.bbc.co.uk/1/hi/scotland/glasgow_and_west/8671122.stm. Retrieved 10 May 2010.
28. ^ "'First' newborn beavers spotted in the Argyll Forest". BBC News. 13 August 2010. http://www.bbc.co.uk/news/uk-scotland-10951209. Retrieved 15 August 2010.
29. ^ "Forest restoration project begins". BBC News. 3 November 2009. http://news.bbc.co.uk/2/hi/uk_news/scotland/highlands_and_islands/8340505.stm. Retrieved 1 December 2009.
30. ^ "Viva la beaver: Britain's population is beginning to thrive again". The Independent. 10 July 2008. http://www.independent.co.uk/environment/nature/viva-la-beaver-britains-population-is-beginning-to-thrive-again-863791.html. Retrieved 1 December 2009.
31. ^ a b J. Gurnell, et al REINTRODUCING BEAVERS TO ENGLAND Digest of a report The feasibility and acceptability of reintroducing the European beaver to England. (Report). Retrieved Feb. 28, 2010.
32. ^ Ella Davies (2011-01-17). "European beavers construct ideal habitats for bats". http://news.bbc.co.uk/earth/hi/earth_news/newsid_9353000/9353551.stm. Retrieved 2011-01-17.
33. ^ Hägglund, Å. & Sjöberg, G. (1999). "Effects of beaver dams on the fish fauna of forest streams". Forest Ecology and Management: 259–266. Retrieved Feb. 28, 2010.
34. ^ Rutherford, W.H. (1955). "Wildlife and environmental relationships of beavers in Colorado forests". Journal of Forestry: 803–806. http://www.ingentaconnect.com/content/saf/jof/1955/00000053/00000011/art00003;jsessionid=2k4r9ihuef8i6.alice. Retrieved Feb. 28, 2010.
35. ^ Murphy, M.L., Heifetz, J., Thedinga, J.F., Johnson, S.W. & Koski, K.V. (1989). "Habitat utilisation by juvenile Pacific salmon (Onchorynchus) in the glacial Taku River, southeast Alaska". Canadian Journal of Fisheries and Aquatic Science: 1677–1685.
36. ^ M. M. Pollock, 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. http://duff.ess.washington.edu/grg/publications/pdfs/Pollock.pdf. Retrieved Feb. 28, 2010.
37. ^ a b c Collen P, Gibson RJ (2001). "The general ecology of beavers (Castor spp.), as related to their influence on stream ecosystems and riparian habitats, and the subsequent effects on fish – a review". Reviews in Fish Biology and Fisheries: 439–461. http://www.springerlink.com/content/v48769740n817601/fulltext.pdf. Retrieved Mar. 2, 2010.
38. ^ D. B. Sigourney, B. H. Letcher, R. A. Cunjak (2006). "Influence of Beaver Activity on Summer Growth and Condition of Age-2 Atlantic Salmon Parr". Transactions of the American Fisheries Society: 1068–1075. http://afsjournals.org/doi/abs/10.1577/T05-159.1. Retrieved Mar. 1, 2010.
39. ^ Howard Park, Ostein Cock Ronning (2007-07). "Low Potential for Restraint of Anadramous Salmonid Reproduction by Beaver Castor Fiber in the Numedalslågen River Catchment, Norway". River Research and Applications. http://onlinelibrary.wiley.com/doi/10.1002/rra.1008/pdf. Retrieved 2011-01-04.
40. ^ Polish authority wants to cull 150 beavers after flooding.