The reintroduction of the Eurasian beaver Castor fiber to Wales: an ecological feasibility study

This report discusses the biological feasibility of the reintroduction of the Eurasian beaver Castor fiber to Wales. Beavers are one of the most extensively reintroduced species of the Euro- pean fauna, and a great deal of information is available on the methods, progress, and effects of reintroductions. In most of Europe beavers live mainly in human-dominated ‘cultural’ landscapes, and are man- aged as an element of that landscape. This assessment considers feasibility primarily in this light, that is, of the reintroduction of a formerly present element to the Welsh cultural land- scape. However, while touching on matters of desirability and management where appropriate in such a context, it is not primarily concerned with those topics but, rather, is intended to pro- vide part of the basis on which further consideration of those issues can proceed. A survey of the extensive beaver reintroduction ecology literature shows that beaver popula- tions spread rapidly through watersheds but only slowly (and with appropriate management containably), between them. This implies that reintroductions, and management, should be considered at a whole watershed scale. Accordingly, following training and experience in bea- ver ecology on the ground, fieldworkers closely familiar with Welsh rivers conducted an ap- praisal of the country and identified six river systems for more detailed analysis: the Glaslyn, Dee, Rheidol, Teifi, Eastern Cleddau, and Western Cleddau. Investigation of these river systems indicates that all, with the possible exception of the Glas- lyn, could support viable populations of beaver of varying size. Potential populations on each river, their distribution, and ecological factors such as the likely degree of dam-building activity, which is closely related to stream flow characteristics, are discussed. Beaver reintroduction to Wales is biologically feasible and would be technically unproblematic to achieve. In landscapes dominated by human activities, European experience indicates that the human element is by far the most influential in determining the practical feasibility of a pro- gramme. The biology of beaver reintroduction is very well known; the course of population de- velopment on a river system and its ecological effects can be predicted with reasonable confi- dence. It is the (human) social aspects of reintroductions that typically require the most atten- tion, care, and forethought. Beaver Castor fiber, Wales, reintroduction, feasibility, Bever Castor fiber gjeninnføring, Wales, gjennomførlighe