Lutra 46(2)_Jones et al_2003

Felling and foraging: results of the first year of beaver (Castor fiber) activity in an enclosed Scottish site

A trial reintroduction of the European beaver (Castor fiber) to Scotland has been proposed and is awaiting Scottish Executive approval. Currently, no data have been published on the actual effects of beavers on the Scottish landscape, although many authors have predicted potential impacts. Such predictions have been based on the impacts of the beaver in other European countries. The aim of this study is to provide a better predictive capability as to the potential effects on tree felling immediately following beaver reintroduction by using data of beavers in captivity. In 2002, four European beavers were released into two large, semi-natural enclosures – the Willow Carr Site and the Lake Site - in eastern Scotland. This paper represents data from the first year of a threeyear monitoring programme to investigate the felling and feeding activities of these beavers. In absolute terms, willow (Salix spp.) were the favoured species at both sites, being felled in the greatest numbers, followed by alder (Alnus spp.) and birch (Betula spp.). In terms of relative abundance, only the selections against birch at both sites, and for willow at the Lake site, were found to be significant. No size-selectivity at the Willow Carr Site was evident, but significantly smaller than average trees of all three genera were felled at the Lake Site. Decreased felling activity was observed with increasing distance from the lodge at the Willow Carr Site, whilst most trees felled at the Lake Site were situated within the shallow margins of the lakes. Approximate felling rates were 0.5 and 0.8 trees per beaver per day, at the Willow Carr Site and Lake Site respectively.