Grazing by sheep Ovis aries reduces island populations of water voles Arvicola amphibius

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Karl Frafjord

Abstract

The population of water voles Arvicola amphibius was surveyed on 21 islands in the Solvær archipelago, northern Norway, in August 2012; 11 islands with semi-wild domestic sheep Ovis aries and 10 islands without sheep. Signs from water voles are very easy to detect and were used as a measure of the population (on a scale 0-10), and the numbers of sheep were counted. The ranking of signs on islands with and without sheep was compared, and a significant difference was found. Islands with sheep had, with one exception, only very small and fragmented populations of water voles, the one exception being a fairly large Carex swamp that was not grazed by the sheep and where a moderate-sized population of voles was found. Islands without sheep had much larger populations of water voles, giving a ranking about four times higher. One reason for the devastating effect of sheep on water voles is probably the fact that the sheep are living year-round on these islands with no supplemental food.

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How to Cite
Frafjord, K. (2014). Grazing by sheep Ovis aries reduces island populations of water voles Arvicola amphibius. Fauna Norvegica, 34, 79-81. https://doi.org/10.5324/fn.v34i0.1673
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Short Communications