The case of the Eurasian beaver in Sweden: re-introduction project carried out before the existence of re-introduction guidelines!

Summary

The Eurasian beaver (Castor fiber), hunted to extinction in Sweden by the 1870s for its pelts and medicinal castoreum, was reintroduced entirely through private initiative, beginning when museum curator Eric Festin raised funds to import a pair from southern Norway and release them into the river Bjuralven in Jamtland province in July 1922, explicitly aiming to restore Sweden's devastated fauna. Festin's publicized effort inspired further private releases, and by 1939 roughly 80 beavers imported from Norway had been released at 19 sites across Sweden, in small founder groups of two to nine animals per site, with no consideration given at the time to inbreeding risk. Reproduction was confirmed at 11 of the release sites by 1940, and the population then expanded rapidly through natural spread and further translocations, reaching an estimated 2,200 by 1961, 7,500 by 1969, 40,000 by 1977, and over 100,000 by the early 1990s, with a 2011 estimate of 130,000-140,000 animals. Population growth locally followed an irruptive pattern of rapid increase followed by decline, attributed to overuse of local food resources. Beaver hunting was legalized in 1977 and opened nationwide by 2001, with an estimated annual harvest of 8,000-9,000 animals by 2010, yet the population continues to expand. No inbreeding depression has been detected despite the small, genetically narrow founder stock. The project rates itself Highly Successful, crediting the species' habitat flexibility, public support, and low predator pressure.