Nutritional Ecology of Microtine Rodents: Effects of Plant Extracts on the Growth of Arctic Microtines

Abstract

This report contains the first experimental evidence showing that plants avoided by herbivorous mammals in the field contain chemicals deleterious to the animals. In northern Alaska, brown lemmings eat primarily sedges, collared lemmings eat primarily willows, and tundra voles eat both sedges and willows. All of these rodents avoid ericaceous evergreen shrubs. When fed ethanol extracts of the most common sedge ( Carex aquatilis ), the most common willow ( Salix puchra ), and the most common evergreen shrub ( Ledum palustre ) the growth rates of weanling animals were consistent with predictions based upon their natural diets. Brown lemmings grew poorly on the Salix extract, collared lemmings grew poorly on the Carex extract, and all three microtines grew poorly and survived poorly on the Ledum extract. We conclude that the forage preferences of these rodents in the field are enforced by the presence of secondary plant compounds and that the microtine species respond differently to the same chemicals.