Eurasian Beaver (Castor fiber) Winter Foraging Preferences in Northern Poland—The Role of Woody Vegetation Composition and Anthropopression Level
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Department of Forest Zoology and Wildlife Management, Institute of Forest Sciences, Warsaw University of Life Sciences, Nowoursynowska 159 St, 02-787 Warsaw, Poland
2
Institute of Environmental Protection—National Research Institute, Krucza 5/11D St, 04-565 Warsaw, Poland
3
College of General Studies, University of Boston, 871 Commonwealth Avenue, Boston, MA 02215, USA
*
Author to whom correspondence should be addressed.
Animals 2020, 10(8), 1376; https://doi.org/10.3390/ani10081376
Submission received: 28 June 2020
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Revised: 31 July 2020
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Accepted: 4 August 2020
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Published: 8 August 2020
(This article belongs to the Special Issue Anthropogenic Impacts on Urban Mammals)
Simple Summary
The food preferences of beavers depend on many factors, such as forage taxonomy, stem diameter, and the distance from a riverbank. In this study, we investigated beavers’ diets and food preferences in an urban area of northern Poland subject to varying levels of human disturbance. In the course of the study, we confirmed a similar preference for the browsing of woody plants, as described in other studies. The most popular and preferred woody plants in beaver’s diet were willows and maples, and most woody plants were characterized by a stem diameter less than 10 cm. We also found that human disturbance played an important role in shaping the beavers’ diets. We discussed this phenomenon from the basis of optimal foraging theory.
Abstract
We studied beavers’ dietary preferences and the role of several factors (such as plant species, size and anthropopression level) that affect the beavers’ foraging in northern Poland. Woody plants along the river were measured and classified according to species in six 100 m-long transects that were characterized by a diversified human disturbance level. Ivlev’s electivity index was used to present the beavers’ preferences for various plant species and sizes, and the generalized linear model was used to assess the significance of studied factors in beavers’ browsing choices. Most popular in the beavers’ diets were willows (Salix), maples (Acer) and alder (Alnus), but only willows and maples were preferred. We noted a decrease in the beavers’ foraging preference in parallel to an increase in the shoot diameter; plants with a diameter below 10 cm were preferred. All factors included in the generalized linear model (GLM) were significant in shaping the beavers’ foraging choices. A negative correlation between the shoot diameter and the human disturbance level was found, but the species composition of the browsed woody plants was the same in each transect. Beavers’ foraging preferences, as observed in our study, were similar to those described in the literature and confirmed the role of woody species and their diameters in shaping the beavers’ diet. We also suggested the potential role of anthropopression in the shaping of the beavers’ foraging behaviors.
Keywords:
foraging ecology; feeding behavior; beavers’ diets; human disturbance
