Water Vole Facts

Microtus richardsoni, better known as the water vole, is a small rodent in the meadow vole genus. As its name suggests, it is a semi-aquatic species which is sometimes referred to as a water rat. Compared to most voles it is one of the larger species and is also sometimes called the giant water vole.

  1. Description

    • The water vole grows to be almost 10 inches in length and weighs up to 5 ounces. It is usually gray-brown to dark brown in color, but is sometimes reddish-brown. The underside of its body is a paler gray to white coloration. It resembles a large mouse in appearance with small rounded ears, a pointed snout and a long, thin bicolored tail. Its upper incisor teeth are prominent and continuously growing as chewing activity wears them down.

    Habitat and Range

    • The water vole is native to the western U.S. and ranges from southern British Columbia and Alberta down as far as Utah. It is always found near water in alpine and subalpine habitats between 3,000 and 10,000 feet above sea level. This altitude preference creates two distinct populations located in the Cascade and Rocky mountain ranges. The vole lives in complex burrow systems that it digs in river banks. The systems have multiple entrances, some of which are actually below the water.

    Diet

    • The vole is exclusively vegetarian and in the summer months will eat its weight in food each day. It feeds on plants such as avalanche lily, violet lovage, sweet colt's foot and dogtooth. In rural areas, the vole is viewed as a pest because it feeds heavily on crops including grains, potatoes and turnips. During the winter the vole eats less and is less active, but does not hibernate. It survives on the dry dead portions of plants and roots during the winter.

    Breeding

    • Water voles live a solitary lifestyle outside of the breeding season. The mating season runs from mid-June to late August during which time two litters are generally produced and born in the female's burrow system. Gestation lasts around 22 days with litter sizes ranging from two to eight offspring. The mother is the sole caregiver, and once the babies are weaned she does not offer much further care. The babies mature quickly and offspring from the first litter are usually able to reproduce even before the breeding season ends.