Meadow vole.
Red-backed mouse.
Red-backed mouse.
The several species of mice vary in abundance from year to year. In places where some of them have been studied, a well-defined 3 or 4 year cycle has been noted. The mouse populations have a tremendous influence on our wildlife economy. Foxes, martens, weasels, owls, hawks and a host of others feed extensively on this fauna and react to its abundance. When the lemming increase in the north, the snowy owls (and others) increase, and when the lemming become scarce, these owls come south in search of food and we have the snowy owl invasions, especially in north-central and eastern states. In 1955, when mice were abundant, the hawk owls in the park reached a high point, but again became scarce when the mouse population dropped.