Woodland Vole - Social Behavior and Reproduction

Social Behavior and Reproduction

Woodland voles live in family groups in burrow systems in home ranges around 40-45 sm. The burrows are exclusive to the family groups, however a groups usually does not need to defend its burrows as other voles usually will not invade them. The size and location of the home range and dispersal of groups are limited by neighboring family groups. Family groups of the vole are made of a breeding female, a breeding male their 1-4 offspring and sometimes a few other member that serves as helpers. Helpers are immigrants from other groups. Group emigration is uncommon and dependant on whether there available positions in other groups. Staying in a group as a non-breeding individual is beneficial as burrow systems are major investments and a limited resource.

In the north, the breeding season last from March to sometime between November and January. In the south, the breeding season continues throughout the year. In order to enter estrus, a female must sense chemosignals in a male and have physical contact. Because females are dispersed with little overlap of different colonies, polygamy is rare among voles. In addition, breeding female in a family group will stress the reproduction of female helpers. Females are fiercely loyal to their partners and are highly aggressive towards unfamiliar males. A young female vole usually first conceives around 105 days but can conceive as early as 77 days. A female will develop a vaginal plug after copulation which last for three days. Gestation lasts 20–24 days with 1-4 litters produced per year, each with 1-5 young. When a vole’s partner dies, it is replaced by an unrelated individual. This results in a conflict between the surviving parent and its offspring of the same sexes for mating opportunities. A new male in a group gives a non-breeding female a chance to breed although the resident breeding female is still an obstacle.