[The ecological connections of dispersal in small mammal populations]

The dispersal of 27 Holarctic species of rodents was quantitatively described on the base of long-term catch method. The relative proportion of non-territorial individuals is an important parameter that reflects the intensity of dispersal. This parameter is statistically related to population (abundance and population type) and species characters (the size of species range and the level of intraspecific differentiation). The contribution of species characters to the variance of migrant portion is lower than contribution of population ones. Isolation and population specialisation are accompanied by the decrease in the portion of disperser, while in pessimal environment the increase in population fluidity is observed. Intensity of dispersal is positively correlated with the size of species range and negatively--with the level of intraspecific differentiation. Thus the dispersal in populations of small mammals serves for colonisation and reparation, providing the stable existence of given group in variable environment.