Habitat selection of European beaver Castor fiber (Rodentia: Castoridae) in the Goričko region (Northeastern Slovenia)

Abstract

The European beaver was considered an extinct species in Slovenia and much of Europe in the early 20th century. At the end of the 20th century, it expanded again following numerous reintroductions and the implementation of conservation measures. In Slovenia, it has been present again since 1998 and in Goričko since 2016. During the winter of 2021/22, we surveyed six water bodies in the Goričko region, where beaver presence was confirmed between 2016 and 2020. The purpose of the survey was to determine the characteristics of beaver habitat at Goričko based on key environmental factors that enable its survival. Due to the early stage of colonization, we assumed that beavers had chosen optimal habitats for their territory. We surveyed 82 plots in selected sections of the water bodies. Beaver activity was confirmed on 71% of plots with standing water and 26% of plots with flowing water. The commonest types of terrestrial habitats were fields, while forests were present on 18% of the plots. Beavers were most frequently found on plots with forested areas (73%). The banks of the water bodies were generally very steep (> 60°). Signs of beaver activity were most commonly found on banks with a height of up to 1 meter, a slope of 30°–60°, and an average distance of 500 metres from settlements. The watercourses inhabited by beavers at Goričko are relatively narrow and shallow, yet beavers can still be found there. The most important environmental factor for beavers is the availability of suitable woody vegetation, which they primarily feed on in the autumn and winter. Understanding habitat characteristics and selection is essential for conservation management and monitoring of beavers at Goričko and Slovenia.