Sourcing Eurasian beaver Castor fiber stock for reintroductions in Great Britain and Western Europe

Abstract

Eurasian beaversCastor fiber, formerly threatened with extinction, have been widely reintroduced since the 1920s. Reintroductions and studies of possible reintroductions are continuing. 2. The International Union for Conservation of Nature (IUCN) guidelines for reintroductions state that 'the source population should ideally be closely related genetically to the original native stock'. 3. Palaeoecological studies suggest that the species survived the last Ice Age in two refugia: in the west in Iberia and Southern France and in the east in the Black Sea region. The post-Ice Age population of Western Europe, including Great Britain, recolonized from the western refugium. Recent mitochondrial deoxyribonucleic acid studies strongly support this view, and extant beaver populations are clearly divided into eastern and western evolutionarily significant units (ESUs). 4. The western ESU is composed of three stocks which survived the 19th and early 20th century as very small, isolated populations. They are very closely related to each other. Each is genetically depauperate, apparently as a result of genetic drift at low population levels. 5. There is evidence of inbreeding depression and of phenotypic abnormalities in beaver populations descended from unmixed stocks. 6. The evidence suggests three coherent management options for sourcing reintroduction stock for Great Britain and for unoccupied areas of western continental Europe. These are (i) use animals from a single western ESU stock; (ii) intentionally mix animals from two or all three of the surviving western ESU stocks; (iii) make an informed exception to the IUCN guidelines and reintroduce animals of mixed eastern and western ESU provenance. 7. These options are discussed with regard to IUCN guidelines, conservation biology and animal welfare considerations. It would be advantageous if a common policy on the origin of reintroduction stock were agreed by the national agencies responsible.

Aerial photography collected with a multirotor drone reveals impact of Eurasian beaver reintroduction on ecosystem structure

“…Ground-based surveying can generate useful geomorphological information (Nyssen et al 2011;Burchsted and Daniels 2014;de Visscher et al 2014); however, detailed ground-based surveying can be time consuming, challenging in complex wetland environments, and risks disturbing the study habitat (Shuman and Ambrose 2003;Chabot and Bird 2013). Beaver activity is a dynamic, year-round process (Collen and Gibson 2000); in particular, the construction and alteration of dams and canals can rapidly alter channel geomorphology and water storage (Halley 2011;Loeb et al 2014). Consequently, infrequent sampling, for example, yearly or greater (Johnston and Naiman 1990;Wright et al 2002;Polvi and Wohl 2012;Malison et al 2014), may fail to capture the rate and extent of ecosystem change.…”

Genetic monitoring of Eurasian beaver (Castor fiber) in Switzerland and implications for the management of the species

“…Individuals from three refugium populations in France (Castor fiber galliae), Norway (C. f. fiber) and Russia (C. f. orientoeuropaeus; Ducroz et al, 2005;Durka et al, 2005;Senn et al, 2014) have been released in Switzerland. The refugium populations C. f. galliae and C. f. fiber belong to the Western Evolutionary Significant Unit (ESU, Moritz, 1994), C. f. orientoeuropaeus belongs to the Eastern ESU (Durka et al, 2005;Halley, 2011, but see also Frosch et al, 2014;Biedrzycka et al, 2014).…”

ESTABLISHMENT OF A HEALTH SURVEILLANCE PROGRAM FOR REINTRODUCTION OF THE EURASIAN BEAVER (CASTOR FIBER) INTO SCOTLAND

“…The first known beaver reintroduction program, in 1922, was in Sweden, with animals from Telemark, Norway. Since then, at least 203 translocations to distinct sites have been recorded outside the former Soviet Union (Halley, 2011).…”