Microtus pennsylvanicus

ID

  • Dense, soft fur of a chestnut brown in the summer and a darker gray in the winter
  • Tail is usually at least twice as long as the hind foot
  • Six tubercles on the soles of the hind feet (Whitaker)

Distribution

 Credit: Smithsonian Institution

Reproduction

  • Can produce as many as 17 litters in a year
  • Gestation is 20-21 days with litters ranging from 1 to 11 young
  • Females can breed by 3 weeks old
  • Both males and females are promiscuous (Whitaker)

Behavior

  • Males will often kill babies in nests that they find unless the mother is a female with whom he has mated
  • Most prolific mammal in the world
  • Spend a lot of time above ground on runway trails that are maintained by the voles chewing anything that sprouts in the path
  • Active both day and night, but peak activity hours are early morning and late afternoon
  • Can swim, but cannot climb
  • Individuals can apparently orient themselves by the sun

Food Habits

  • Grasses, seeds, rootstocks, tender barks. Stores roots, tubers, leaves, and other plant parts for winter
  • Eat more than their weight in food daily and need to engage in coprophagy in order to absorb adequate nutrition

Size/Life Cycle

  • Average measurements: 167 mm (total length), 33-65 g (total weight) (Smithsonian)

Predators

  • Almost anything, but especially weasels and house cats

Habitat

  • Moist fields of dense vegetation containing grasses and sedges, low meadows, swampy pastures, fields with protecting covers of dead grasses and herbs, coastal salt meadows, and bluegrass fields