Pine vole colonies consist of one breeding female, one breeding male, one to five offspring, and occasionally some helpers (Geyer, Beauchamp, Seygal, & Rogers; 1981) (Lapasha & Powell; 1994) (Whitaker & Hamilton). Together, these colonies or family groups share the same home range (Lapasha & Powell). Occasionally individuals leave one family group to join another, but this is rare and usually dependent on available spots in other colonies (Lapasha & Powell). Helpers will only move to other colonies if their reproductive success will increase, but sometimes it is most beneficial to be a non-breeding helper because burrow systems are major investments and a limited resource (Lapasha & Powell). Therefore, the limited availability of burrow systems definitely contributes to the complex social systems in pine vole colonies as well as sex, familiarity, and isolation do (Geyer, Beauchamp, Seygal, & Rogers) (Lapasha & Powell). Females are aggressive to unfamiliar male pine voles; this is probably due to the fact that pine voles are predominantly monogamous and would therefore want to avoid unfamiliar members of the opposite sex (Geyer, Beauchamp, Seygal, & Rogers).

Pictures of pine voles- Permission to display pictures granted by Chuck Friedrich of Permatill (Carolina Stalite Co. or August Martin, Intl).