Similarities in Dispersal Tendency among Siblings in Four Species of Voles (Microtus)

During periods of population increase in four species of Microtus (Rodentia: Cricetidae), there are significant differences in lifetime and probability of dispersal between sibships. Identifiable familes tend to survive or disappear as a unit. No between—family differences were detected in peak and declining populations, or in popultions in which dispersal was experimentally prevented by fencing. In declining populations there were very large differences in survival among members of the same sibship.