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.

Interactions between gray-sided voles (Clethrionomys rufucanus) and bilberry (Vaccinium myrtillus), their main winter food plant

“…However, these defense substances seem to have little or no deterrent eVect on gray-sided voles, since bilberry twigs are still their most preferred winter food sources (Kalela 1957;Ericson 1977;Tolvanen et al 1992;Hambäck and Ekerholm 1997;Hambäck et al 1998Hambäck et al , 2002Strengbom et al 2003) and up to 80% of bilberry ramets were eaten year after year on the predator-free islands. Many plants have been found to produce defense substances in response to herbivory, thereby reducing their palatability and the Wtness of the herbivores (Agrawal 1998).…”

“…Bilberry leaves and ramets contain a wide rage of defense substances (Laine and Henttonen 1987;Oksanen et al 1987;Hambäck et al 2002;Strengbom et al 2003) and several authors have postulated that variations in the food quality of bilberry plants may be explanatory factors for the Xuctuations in microtine populations (Laine and Henttonen 1987;Selås 1997Selås , 2006. However, these defense substances seem to have little or no deterrent eVect on gray-sided voles, since bilberry twigs are still their most preferred winter food sources (Kalela 1957;Ericson 1977;Tolvanen et al 1992;Hambäck and Ekerholm 1997;Hambäck et al 1998Hambäck et al , 2002Strengbom et al 2003) and up to 80% of bilberry ramets were eaten year after year on the predator-free islands.…”

“…Bilberry is considered to be the most important winter food plant for gray-sided voles, although they also consume other dwarf shrub species (Kalela 1957;Ericson 1977;Tolvanen et al 1992;Hambäck and Ekerholm 1997;Hambäck et al 1998Hambäck et al , 2002Strengbom et al 2003). Vole herbivory has been found to severely reduce the abundance of bilberry twigs in these ecosystems (Hambäck and Ekerholm 1997;Hambäck et al 2004;Olofsson et al 2004;Dahlgren 2006).…”

Moose recruitment in relation to bilberry production and bank vole numbers along a summer temperature gradient in Norway

“…Hambäck et al 2002;McArt et al 2009). Although herbivores are able to detoxify plant defence compounds, the cost of detoxification is often high (Dearing et al 2005).…”

Nitrogen and Carbon Concentrations in the Stomach Content of Bank Voles (Myodes glareolus). Does Food Quality Determine Abundance?

“…Small mammalian herbivores such as the bank vole have high energy metabolism and turnover of essential nutrients. This suggests that small mammalian herbivores face a relative shortness of N and that this situation may be a potential cause for variations in population density between seasons and years (Hansson 1987, 1995, Batzli 1992, Hambäck et al 2002, Wereszczynska et al 2007. Protein requirement is a result of two components a) endogenous urinary excretion and b) fecal loss.…”