Eurasian beaver or European beaver (Castor fiber) is a species of
beaver which was once widespread in Eurasia. It was hunted to
near-extinction for both its fur and castoreum; and by 1900, only 1200
beavers survived in eight relict populations in Europe and Asia.
Reintroduced through much of its former range, it now occurs from
Great Britain to
China and Mongolia, although it is absent from Italy,
Portugal, the southern Balkans, and the Middle East.
1.1 Physical characteristics
2 Differences from North American beaver
Subspecies of Eurasian beaver
5.1 Continental Eurasia
5.3 Great Britain
5.3.1 Reintroduction into Scotland
6.1 Effects on fish
6.2 Effect on water quality
9 See also
11 External links
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.
Eurasian beavers are one of the largest living species of rodents and
are the largest rodent native to Eurasia. They weigh around
11–30 kg (24–66 lb). In Norway, adult males average
21.5 kg (47 lb) while females average 23.1 kg
(51 lb), while another study found adults from the same country
to average 18.4 kg (41 lb). By the average weights known,
Eurasian beaver appears to be the world's second heaviest rodent
behind the capybara, but averaging slightly larger and heavier than
the North American beaver. While the largest specimen
confirmed on record weighed 31.7 kg (70 lb), the Smithsonian
has reported that this species can exceptionally exceed 40 kg
(88 lb). Typically, the head-and-body length is 80–100 cm
(31–39 in) and the tail length is 25–50 cm
Differences from North American beaver
Eurasian beaver appears superficially similar to the
North American beaver, there are several important differences, chief
among these being that the
North American beaver
North American beaver has
40 chromosomes, while the
Eurasian beaver has 48. The two species
are not genetically compatible: After more than 27 attempts in
Russia to hybridize the two species, the result was one stillborn kit
that was bred from the pairing of a male
North American beaver
North American beaver and a
female Eurasian beaver. The difference in chromosome count makes
interspecific breeding unlikely in areas where the two species' ranges
Skulls of a European and North American beaver
Eurasian beaver has a larger, less rounded head; a longer,
narrower muzzle. The
Eurasian beaver also has longer nasal bones, with
the widest point being at the end of the snout; in the case of the
North American beaver, the widest point is at the middle of the snout.
Eurasian beaver has a triangular nasal opening, unlike those of
the North American beavers, which are square. Furthermore, the foramen
magnum is rounded in the Eurasian beaver, but triangular in the North
Eurasian beaver has a narrower, less oval-shaped tail; and shorter
shin bones, making it less capable of bipedal locomotion than the
North American species. The anal glands of the
Eurasian beaver are
larger, and thin-walled, with a large internal volume, relative to
that of the North American beaver.
The guard hairs of the
Eurasian beaver have longer hollow medullae at
their tips. There is also a difference in the frequency of fur
colours: 66% of Eurasian beavers overall have beige or pale brown fur,
20% have reddish brown, nearly 8% are brown, and only 4% have blackish
coats; among North American beavers, 50% have pale brown fur, 25% are
reddish brown, 20% are brown, and 6% are blackish.
Subspecies of Eurasian beaver
Historically, eight subspecies of Castor fiber were described, one for
each of the eight 19th– to 20th-century refugia where the species
never became extinct. The basis of the differentiation was
morphological, largely based on very small differences in cranial
morphology, but has been recently refuted based on genetic
studies. In 2005, Durka et al. showed that only two evolutionarily
significant units exist based on mitochondrial DNA studies, a western
phylogroup (C. f. gallicus, C. f. albicus, and C. f. fiber) and an
eastern phylogroup (C. f. ssp., C. f. tuvinicus, C. f. pohlei, and C.
f. birulai). In addition, Ducroz et al. found that even in the
more genetically diverse eastern phylogroup, the degree of genetic
divergence was below thresholds considered sufficient for subspecies
Eurasian beavers have one litter per year, coming into estrus for only
12 to 24 hours, between late December and May, but peaking in January.
Unlike most other rodents, beaver pairs are monogamous, staying
together for multiple breeding seasons. Gestation averages 107 days
and they average three kits per litter with a range of two to six
kits. Most beavers do not reproduce until they are three years of age,
but about 20% of two-year-old females reproduce.
Areas inhabited by beavers in Europe outside of
Russia in 2001: red
shows range of Eurasian beaver; purple shows range of introduced North
American beaver in Finland. In 2009, the
Eurasian beaver was
reintroduced into Great Britain.
Eurasian beaver is recovering from near extinction, after
depredation by humans for its fur and for castoreum, a secretion of
its scent gland believed to have medicinal properties. The
estimated population was only 1,200 by the early 20th century. In
many European nations, the beaver became extinct, but reintroduction
and protection has led to gradual recovery to about 639,000
individuals by 2003. Milishnikov found in genetic studies that
beaver likely survived east of the Urals from a 19th-century
population as low as 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 three individuals,
and that beavers are monogamous and select mates that are genetically
different from themselves. About 83% of Eurasian beavers live
in the former Soviet Union due to reintroductions, but the result is
that beavers in
Mongolia or Siberia do not appear significantly
genetically different from samples from the European part of Russia,
despite the great geographical distance.
In China, a few hundred beavers are known to live in the basin of the
Ulungur River, near the Mongolian border. The Bulgan
Reserve (Chinese: 布尔根河河狸自然保护区; 46°12′00″N
90°45′00″E / 46.20000°N 90.75000°E / 46.20000;
90.75000) was established in 1980 to protect the creatures.
In France, the
Eurasian beaver was almost wiped out, but a small
population survived on the Rhône, near Lyon, from where it has been
reintroduced to other parts of the country. The French population of
beavers was estimated to be 10,000-12,000 individuals in 2009.
In Germany, beavers had become close to extinct in the 19th century.
Smaller populations survived along the
Elbe and spread into
Brandenburg, Mecklenburg-Vorpommern, and
Saxony after being protected.
Beavers in Germany number up to 25,000 all across the country, even
appearing in many urban areas. The largest beaver populations are
found in eastern Germany (6,000, descendants of the
Elbe beavers), and
Bavaria along the
Danube and its tributaries. After a resettlement
programme started in 1966, their number in
Bavaria is estimated to be
In Switzerland, the
Eurasian beaver was extinct in the 19th
century and reintroduced since 1956.
In Iraq, Iran, Syria, and Turkey, subfossil evidence of beavers
extends down to the floodplains of the Tigris-Euphrates basin, and a
carved stone stela dating between 1,000 and 800 BC in the Tell Halaf
archaeological site along the Khabur River (a Euphrates tributary) in
Syria depicts a beaver. Although accounts of
19th-century European visitors to the
Middle East appear to confuse
beavers with otters, a 20th-century report of beavers by Hans
Kummerlöwe in the
Ceyhan River drainage of southern
the diagnostic red incisor teeth, flat, scaly tail, and presence of
gnawed willow stems. According to the Encyclopaedia Iranica, early
Avestan and Pahlavi, and later Islamic literature, all reveal
different words for otter and beaver, and castoreum was highly
valued. Johannes Ludwijk Schlimmer, a noted Dutch physician in
Iran reported beavers below the confluence of the Tigris
and the Euphrates in small numbers, along the bank of the Shatt
al-Arab in the provinces of
Shushtar and Dezful." Austen Layard,
the British explorer of Assyrian ruins, notably Babylon and Nineveh,
reported finding beavers during his visit to the Kabur River in Syria
the 1850s, but noted they were being rapidly hunted to
Beavers were reintroduced in the
Netherlands in 1988 after being
completely exterminated in the 19th century. After its reintroduction
in the Biesbosch, 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. In 2012, the population
was estimated to be about 600 animals and could easily grow to 7000 in
20 years' time. According to the
Mammal Society and the Dutch
Water Board, this will cause a threat to the river dikes. The main
problem is that beavers excavate corridors and caves in dikes, thereby
undermining the stability of the dike, just as the muskrat and the
coypu do. If problems become unmanageable, as local administrators
in Limburg fear, the beaver will be captured again.
As of 2014 population of beaver in Poland reached 100,000 animals
and was still growing. After major flooding in Poland in May and June
2010, the local authorities of Konin in central Poland held beavers
responsible for causing the flooding and demanded the culling of 150
In Romania, beavers became extinct in 1824, but were reintroduced in
1998 along the Olt River, spreading to other rivers in Covasna
County. In 2014, the animals were confirmed to have reached the
In the former Soviet Union, almost 17,000 beavers were translocated
from 1927 to 2004, of which 12,000 were to Russia, and the remainder
to the Ukraine, Belarus, the Baltic States, and Kazakhstan. They
are now common in
Estonia and Latvia.
In Spain, nongovernment sanctioned reintroduction around 2003 has
resulted in tell-tale beaver signs documented on a 60-km stretch on
the lower course of the
Aragon River and the area adjoining the Ebro
River in Aragon, Spain.
Greece beaver was first described by
Aristotle (4th century BCE)
under the name Λάταξ/Latax. He wrote that it is wider than the
otter, with strong teeth and that it gets often in the night to the
river banks to cut down trees with these teeth. Remains from late
Roman, early Byzantine periods and from the late 18th, early 19th
century, have been found in Nicopolis. Ιt remains unclear when
they vanished from
Kastoria which was possibly named after
Kastor/Castor which means beaver, but in 18th century CE the locals
were still hunting them for their fur. In 19th CE century they
were still reported from Alpheius in the
Peloponnese and from
The recently resurgent beaver population in Eurasia has resulted in
increases in human-beaver encounters. Indeed, in May 2013, a
Belarusian fisherman died after being bitten several times by a
beaver, severing an artery in his leg and causing him to bleed to
Eurasian beaver in Estonia
In Sweden, the beaver had been hunted to extinction by around
1870. Between 1922 and 1939, about 80 individuals were imported
Norway and introduced to 19 separate sites within the country.
Beavers reintroduced to central Norway's Ingdalselva River watershed
on the Agdenes peninsula,
Sør-Trøndelag County in 1968-1969, were
recently studied. The area is hilly to mountainous with many small
watersheds. Rivers are usually too steep along most of their length
for beaver colonisation, so that suitable habitat is scattered, with
rarely room for more than one territory in a habitat patch. While
widespread signs of vagrant beavers were found, spread as a breeding
animal was slowed by watershed divides in the hilly terrain.
Colonisation of all suitable sites within a watershed once the species
was established was rapid. Some spread could only be plausibly
explained by assuming travel though sheltered sea water in fjords
In Denmark, the beaver was reintroduced to the wild in western Jutland
in 1999 and in Arresø, northern Zealand, in 2009 after it was
hunted to extinction around 1000 CE. The reintroduced beavers were
caught in the river
Elbe in Germany. As of 2013[update], the Danish
population of beavers was estimated to be roughly 185 individuals.
Some Eurasian beavers are present in Finland, but most of the Finnish
population is a released population of C. canadensis, the North
American species. (These animals were imported to Finland in 1937,
when it was not yet known that C. canadensis was a different species
from the Eurasian beaver.)
Beaver dam, Scotland
The same dam four months on, showing enlargement
Beaver tracks in snow
The beaver became extinct in
Great Britain in the 16th century:
Giraldus Cambrensis reported in 1188 (Itinerarium ii.iii) that it was
to be found only in the
Wales and in one river in Scotland,
though his observations are clearly secondhand. The last reference to
England dates to 1526. About the same time, Hector
Boece wrote that they were still common in parts of Scotland,
especially around Loch Ness.
As a former British species, interest in reintroducing beavers to the
wild across Britain has been shown. It has been suggested that beaver
dams could retain water in upland areas, reducing flood volumes and
creating new habitats for wildlife. Currently, beaver populations are
found in a number of large enclosures in wildlife parks, as well as
free-living populations around the
River Tay and
Knapdale areas in
Scotland and the River Otter in Devon, in south-west England. The
Knapdale population was deliberately released, while the other
populations are of unknown origin.
In 2001, the
Kent Wildlife Trust
Kent Wildlife Trust with the Wildwood Trust and Natural
England imported two families of Eurasian beavers from
manage a wetland nature reserve. This project pioneered the use of
beavers 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 lives in a 130-acre
(0.53 km2) fenced enclosure at the wetland of Ham Fen.
Subsequently, the population has been supplemented in 2005 and 2008.
The beavers continue to help restore the wetland by rehydrating the
soils. Six Eurasian beavers were released in 2005 into a fenced
lakeside area in Gloucestershire. In 2007, a specially selected
group of four Bavarian beavers was released into a fenced enclosure in
Martin Mere nature reserve in Lancashire. The beavers
hopefully will form a permanent colony, and the younger pair will be
transferred to another location when the adults begin breeding
again. The progress of the group will be followed as part of the
Autumnwatch television series. On November 19, 2011, a pair of
beaver sisters was released into a 2.5-acre (1 ha) enclosure at
Blaeneinion, Furnace, Mid Wales. A colony of beavers is also
established in a large enclosure at Bamff, Perthshire.
A group of three beavers was spotted on the River Otter in
2013, apparently successfully bearing three kits the next
year. Following concern from local landowners and anglers, as
well as farmers worrying that the beavers could carry disease, the
government announced that it would capture the beavers and place them
in a zoo or wildlife park. A sport-fishing industry lobbyist group,
the Angling Trust, said, "it would be irresponsible even to consider
re-introducing this species into the wild without first restoring our
rivers to good health." These actions were protested by local
residents and campaign groups, with environmental journalist George
Monbiot describing the government and anglers as 'control freaks':
"I'm an angler, and the Angling Trust does not represent me on this
issue...most anglers, in my experience, have a powerful connection
with nature. The chance of seeing remarkable wild animals while
waiting quietly on the riverbank is a major part of why we do it."
On 28 January 2015, Natural
England declared that the beavers would be
allowed to remain on condition that they were free of disease and of
Eurasian descent. These conditions were found to be met on 23 March
2015, following the capture and testing of five of the beavers.
DNA testing showed that the animals were the once-native Eurasian
beaver, and none of the beavers was found to be infected with
Echinococcus multilocularis, tularaemia, or bovine TB. On 24 June
2015, video footage from local filmmaker Tom Buckley was featured on
the BBC news website showing one of the wild
Devon females with two
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, and
Forestry Commission Wales, with additional funding from Welsh Power
Ltd. The resulting reports were published in 2012 with the launch of
Beaver Project, which is a partnership led by the Wildlife
in Wales, and are downloadable from www.welshbeaverproject.org.[needs
update] A 2009 report by Natural England, the government’s
conservation body, and the People's Trust for Endangered Species
recommended that beavers be reintroduced to the wild in England.
This goal was realised in November 2016, when beavers were recognised
as a British native species.
Reintroduction into Scotland
The first sustained and significant population of wild-living beavers
in the United Kingdom became established on the river Tay catchment in
Scotland as early as 2001, and has spread widely in the catchment,
numbering from 20 to 100 individuals. 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. Proponents of the beavers argue
that no reason exists to believe that they are of "wrong" genetic
stock. One of the wild Tayside beavers was trapped by Scottish
Natural Heritage on the
River Ericht in Blairgowrie, Perthshire, in
early December 2010, and was held in captivity in the Edinburgh Zoo.
In March 2012 the Scottish Government reversed the decision to remove
beavers from the Tay, pending the outcome of studies into the
suitability of re-introduction.
In 2005, the Scottish government turned down a licence application for
unfenced reintroduction. However, in late 2007, a further application
was made by the Royal Zoological Society of Scotland, Scottish
Wildlife Trust and Forestry Commission Scotland for a release
project in Knapdale, Argyll. This application was accepted, and
the first beavers were released on 29 May 2009 after a 400-year
absence. This initial release into the wild of 11 animals
(termed the Scottish
Beaver Trial) received a setback during the first
year with the disappearance of two animals and the alleged illegal
shooting of a third. This allegation was later refuted by Simon Jones
of the Scottish
Beaver Trial, as no evidence supported the allegation
and all three missing beavers were sighted after they had left the
release loch. However, the remaining population was increased by
further releases in 2010. 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. Alongside the
trial, the separate population of beavers along the Tay was monitored
Following receipt of the results of the trial, in November 2016 the
Scottish Government announced that beavers could remain permanently,
and would be given protected status as a native species within
Scotland. Beavers will be allowed to extend their range naturally from
Knapdale and along the River Tay, however to aid this process and
improve the health and resilience of the population a further 28
beavers will be released in
Knapdale between 2017 and 2020.
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
regrow as dense shrubs which provide cover for birds and other
Beaver dams trap sediment and improve water quality, and
recharge groundwater tables and increase cover and forage for trout
and salmon. A recent study in Poland found that beavers increased
the abundance and diversity of bats, apparently because they create
gaps in forest cover, making it easier for bats to navigate.
Effects on fish
Beaver dam on Sosnovochka River in Penza Oblast, Russia
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 found that brown trout in beaver
ponds were larger than those in riffle sections, and that beaver ponds
provide habitat for larger trout in small streams during periods of
drought. 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
unimpounded stream sections in
Colorado and Alaska. In
addition, research in the Stillaguamish River basin in Washington
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. 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. Downstream migration of Atlantic salmon
smolts was similarly unaffected by beaver dams, even in periods of low
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. 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. A 2003 study showed that 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. In Norway, beaver dams are considered
beneficial for brown and sea trout populations (these are
potamodromous and anadromous forms of the same species). There, beaver
ponds produce increased food for young fish and provide refuges for
large adults heading upstream to spawn.
Effect on water quality
The misnomer ‘beaver fever’ was invented by the American press in
the 1970s after an outbreak of Giardia lamblia, which causes
giardiasis, was blamed on beavers. However, the outbreak area was also
frequented by humans, who are generally the primary source of
contamination of waters. In addition, many animals and birds carry
Giardiasis affects humans in southeastern
Norway, but a recent study found no Giardia in the beavers there.
Recent concerns point to domestic animals as a significant vector of
Giardia, with young calves in dairy herds testing as high as 100%
positive for Giardia. New Zealand has Giardia but no beavers. In a
1995 paper recommending reintroduction of beaver to Great Britain,
MacDonald stated that the only new diseases that beaver might convey
to that country's birds and mammals, are rabies and tularaemia - both
diseases that should be preventable by statutory quarantine procedures
and prophylactic treatment for tularaemia.
In addition, fecal coliform and streptococci bacteria excreted into
streams by grazing cattle have been shown to be reduced by beaver
ponds, where the bacteria are trapped in bottom sediments.
Eurasian beaver Castor fiber was once widespread in Europe and
Asia but by the beginning of the 20th century both the numbers and
range of the species had been drastically diminished, mainly due to
hunting. At this time, the global population was estimated to be
around 1,200 individuals, living in eight separate
sub-populations. In 2008, however, the ICUN granted the Eurasian
Beaver a status of least concern, with the justification that the
species had recovered sufficiently with the help of global
conservation programmes. Currently the largest numbers can be
found across Europe, where reintroductions have been successful in 25
countries and conservation efforts are ongoing, however populations in
Asia remain small and fragmented, and are under considerable
Eurasian beaver in Osmussaar, Estonia
Signs of beaver activity
Tayside mother beaver with her kit
Large beaver dam in Lithuania
Beaver lodge in Poland
Knapdale in Argyll
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