Winter herbivory by voles during a population peak: the importance of plant quality

Abstract

Bilberry shoots are one of the main food sources for grey‐sided voles Clethrionomysrufocanus during winter. This study examined the relation between plant quality variables of bilberry Vacciniummyrtillus shoots, overall vegetation height, and the winter consumption of bilberry by grey‐sided voles. Results show that only the phenolic concentration correlated significantly with the amount of bilberry biomass consumed, and bilberry consumption decreased with an increasing phenolic concentration. The best predictor of herbivory on bilberry was not plant quality but rather the overall vegetation height. This may be because the quality of bilberry shoots is high in all habitats and that predation is a greater mortality risk than nutritional deficiencies during winter.