The effect of kinship on spacing among female red-backed voles, Clethrionomys rufocanus bedfordiae.

I examined the effect of relatedness on spatial organization and reproduction in enclosed populations of red-backed voles (Clethrionomys rufocanus bedfordiae) in 1984 and 1985. Enclosures with low and high coefficients of relatedness among females were established, and the proximity and overlap of the home ranges of these females were recorded before and after the introduction of males. The following conclusion were reached: 1. The number of females that established home ranges and gave birth to young did not differ significantly among the enclosures. 2. Before males were introduced, sisters had home ranges in closer proximity than non-sibling females. After males were introduced, some sibling females still remained close to each other but occupied exclusive home ranges near those of their sisters. Other sibling groups, particularly in 1985, dispersed after the males' introduction. 3. The overlap or proximity between neighboring females decreased after the males' introduction, but the trend was more pronounced for kin than for non-kin. 4. A female was better able to acquire an exclusive home range when the neighboring female was a sister than when the neighbor was not a sister. 5. The tendency for female littermates to disperse was non-random. The difference in body weight between dispersers and residents was significant within the sibling groups but not within the non-siblings groups introduced at the same locations.