"Meadow Voles have a remarkable reproductive output: they are the world's most prolific mammals. Females can breed when they are a month old and produce litters of 3-10 pups every three weeks for the rest of their lives. A captive female produced 17 litters in one year. They are known for their boom-bust population cycles. Population density can vary from several Voles to several hundred per hectare over a 2-5 year period. Biologists have been studying - and trying to explain - these boom-bust cycles for more than half a century. At peak density, Meadow Voles are capable of real damage to farms and orchards. They are also a very important food source for many predators."

Links:
Mammal Species of the World
Click here for The American Society of Mammalogists species account