The Eurasian beaver has been the successful subject of a century of official and unapproved species reintroduction programs in Europe and Asia. Beavers had been driven to the point of near extinction in Eurasia by humans trapping and hunting them for their meat, fur and castoreum. The reintroductions and conservation led in 2008, to the IUCN assessing the Eurasian beaver as being of "least concern" on its red list.
Disappearance from Eurasia The Eurasian beaver was hunted and trapped to the point of near extinction. Fossil evidence shows that the Eurasian beaver lived from Western Europe to the Chinese-Mongolian border. By the beginning of the 20th century, only about 1,200 Eurasian beavers were left in their native area. Eight relict populations survived, according to IUCN, in Belarus, China, France, Germany, Kazakhstan, Luxembourg, Mongolia, Norway and Russia.
Beaver effects on ecosystem and habitat
Beavers are considered ecosystem engineers for their ability to create complex wetland ecosystems by tree-felling, dam-building, and burrowing. Wetlands provide habitats for many other species of fish, birds, mammals, and vegetation, leading to increased biodiversity. Beaver dams push water laterally onto flood plains, increasing groundwater and surface water storage. Presence of beavers can improve water quality through sediment trapping in dams, and provide natural flood control. Ponds and canals store water in areas susceptible to drought. Beaver reintroduction causes flooding in areas that were not previously flooded. Over saturation causes some plants and trees die, increasing coarse woody debris (CWD) in the area. CWD attracts wood insects, and provides nesting holes for waterfowl and areas of refuge for fish. Trees and vegetation migrate to drier areas, leading to diversified plant species. Presence of beavers increases numbers in aquatic invertebrates, insects, amphibians, birds and bats. Ponds create nursing ground for fish, increased fish habitat and habitat complexity. Beaver dams can have a negative impact on migratory fish such as salmonids, preventing fish from moving upstream to headwaters. Deep beaver ponds provide overwintering habitat for fish, reduce ice cover, and stabilize temperature regimes.
Reintroduction methods Beavers are reintroduced through planned and unplanned releases, such as escapes from captive populations. Unplanned releases can happen through escapes from zoos or wildlife centers, or through natural spread. Planned releases are managed by governmental organizations and environmental non-profits. These are most successful when managed locally. Successful trials to reintroduce beavers start by raising community awareness and support, through community outreach and education.
The reintroduction of a species can cause rapid change to high-use domesticated landscapes. These changes cause a range of emotional reactions to the community present. Attempting to understand these reactions is important for managing organizations to aid in coexistence between humans and beavers, and population success. The health of a reintroduced species impacts humans and domesticated animals, and other wildlife. Health assessments should take place before and regularly after its reintroduction. In unplanned releases or escapes, it is difficult to produce a health baseline of a species.
As a flagship species, beavers raise awareness and resources for wide-scale riparian and woodland restoration programs by stimulating conservation awareness. Beavers increase ecotourism, as interest in beavers and other biodiversity in ecosystems with beavers increases. Beaver ecotourism has positive socio-economic impacts for local businesses and community members.
Reintroductions By 2020, due to government-approved and unofficial reintroductions, as well as protection programs and consequent natural migration, there were at least 1.5 million beavers in Europe.
Initial reintroduction populations show a time lag between the rate of population growth and the resource growth rates. This is seen in an initial population growth followed by decrease in populations to settle into the amount of resources available to the beaver populations.
Government-approved reintroductions Successful government-approved introductions began in Sweden in 1922, followed later in the 1920s by Norway and the USSR in Russia (both of which had remnant populations) as well as in Latvia. Finland followed in the 1930s, as did Germany (which also had a remnant population). In the 1940s and 1950s, Russia, Poland, Belarus (remnant population), Estonia, Lithuania, Norway (remnant population), Mongolia (remnant population), France (remnant population) and Switzerland had reintroduction programs. In the 1960s and 1970s, Germany, Poland and Latvia resumed reintroductions, while Austria and Kazakhstan began them. Hungary began in 1980. Ukraine's beaver restoration was underway by the 1970s.
In 1988, Netherlands began reintroduction, followed by Czech Republic (1991), China (1992 - translocation from a Chinese native population) Slovakia (1995), and Croatia (1996), Belgium (1998), Romania (1998) and Denmark (1999).
Reintroduction programs followed in Serbia (2003), Spain (2003), Bosnia and Herzegovina (2006), and United Kingdom (2009).
Unofficial reintroductions
In 2004, 18 Eurasian beavers were detected in Spain between Milagro and Alfaro, in the Ebro river. Investigations determined they originated in Bavaria and had been released in March 2003, though those responsible were never identified. Regional government plans to remove the animals met criticism from conservation groups arguing the Eurasian beaver is native to Spain with a fossil history of 1.4 million years and historical references until around 1583. After consulting with the European Union, the removal plans were terminated. By 2020, beavers had colonised the Ebro in La Rioja, Navarre, and Zaragoza; the Zadorra river up to Vitoria-Gasteiz, the Arga up to Pamplona, the Huerva up to Mezalocha, and the Jalón into the province of Soria. In November 2021, a young beaver was photographed for the first time outside of the Ebro basin, in the upper Duero in Soria. In June 2024, a beaver was sighted at the Tagus river basin near Zorita de los Canes.
In 2020, beavers were introduced secretly to two sites in central Italy, and have since spread rapidly.
Reintroduction by migration
Due to beavers travelling across borders, populations became established by 2020 in Slovenia (from Croatia and Austria), Liechtenstein (from Switzerland), and Luxembourg (mostly from Belgium, though according to IUCN, Luxembourg's native population was never extirpated).
Beaver populations also became established by 2021, by migration from Romania, in Bulgaria and Moldova.
In 2023, researchers found signs of beaver activity in Portugal, some 5 km from the Spanish border.
Planned reintroductions In 2022, researchers published a feasibility study on the reintroduction of beavers to areas of Greece bordering Albania, North Macedonia and Bulgaria.
Specific reintroductions
Reintroduction within Russia
In Russia, by 1917, beaver populations remained in four isolated territories: in the Dnieper basin; in the Don basin; in the northern Urals and in the upper reaches of the Yenisei along the Azas river. The total number of beavers did not exceed 900. Beaver hunting was banned in 1922. In 1923, a hunting reserve was organised in the Voronezh region along the Usman river, which in 1927 was transformed into the Voronezh State Reserve. At the same time, two more such reserves were created: Berezinsky and Kondo-Sosvinsky. 1927 also the first attempts to reintroduce beavers in other areas. As a result, by the end of the 1960s, the beaver's range in the Soviet Union was almost as large as in the 17th century. The beavers' growing numbers made commercial capture possible again. In 2016, there were an estimated 661,000 beavers in Russia; in 2019, the estimate was 774,600.
Reintroduction into Scotland The first sustained and significant population of wild-living beavers in the United Kingdom since the late 16th century became established on the River Tay catchment in Scotland as early as 2001, and spread widely in the catchment, numbering from 20 to 100 individuals. Because these beavers were apparently escapees from captive beaver enclosures, such as Bamff Estate in Perthshire, Scottish Natural Heritage initially planned to remove the Tayside beavers in late 2010. Proponents of the beavers argued that no reason existed to believe that they were of "wrong" genetic stock, and that they should be permitted to remain. One beaver 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 reintroduction.
In 2005, the Scottish government had 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, termed the Scottish Beaver Trial, was accepted, and the first beavers were released on 29 May 2009 after a 400-year absence, with 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 pre-existing population of beavers along the Tay was monitored and assessed.
Following receipt of the results of the Scottish Beaver 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 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. A survey of beaver numbers during the winter of 2017–18 estimated that the Tayside population had increased to between 300 and 550 beavers, with beavers now also present in the catchment of the River Forth, and the Trossachs area.
In 2023, two pairs of beavers were released in the Cairngorms. There have also been releases into the Glen Affric area.
Reintroduction into England and Wales