REPRODUCTIVE ASYNCHRONY AND ITS POTENTIAL ROLE IN THE MATING SYSTEM OF MEADOW VOLES

Ims (1987a) hypothesized that the spatial distribution pattern of male voles may be influenced by the temporal distribution of females. When females enter estrus synchronously (i.e. are clumped in time) they re present a defendable resource and males should defend a territory cont aining a cluster of females. When females breed asynchronously, males should not be territorial, In this study we examined the role of femal e breeding synchrony on the spacing strategies of male meadow voles Mi crotus pennsylvanicus (Ord, 1815). Maternity was determined by the tra nsfer of a unique combination of radionuclides from mother to offsprin g. The date of conception (to the nearest week) was determined by the weight at first capture of newly recruited voles. The number of litter s conceived per week ranged from zero to four. The null hypothesis tha t the number of litters conceived per week was distributed randomly co uld not be rejected in 8 of 9 grid-years (4 years on 3 grids). This fi nding of breeding asynchrony in a vole species with nonterritorial mal es is consistent with Ims' hypothesis.