Nutrition 

    The Norway lemming feeds primarily on grasses, shrubs, and mosses.  Occasionally in the summer they feed on insects. To battle the harsh temperatures, Norway lemmings migrate to where more food is available.  Like other mammals, lemmings have a closed circulatory system to transport nutrients.  They also store their nutrients as fats.

Image from http://commons.wikimedia.org/wiki/Image:Lemming.jpg
Image taken by Frode Inge Helland.