Natal dispersal of introduced Siberian chipmunks, Tamias sibiricus, in a suburban forest

The Siberian chipmunk, Tamias sibiricus, was introduced into the suburban forest of S,nart in the late 1970s where it naturalised. Juvenile dispersal of this solitary ground-dwelling squirrel is not known, while it is an important component of the invasion process. From 2003 to 2007, mark-recapture techniques were used to determine how dispersal movements differed between year, cohort, sex and body mass. Distances moved were calculated between the location of first capture during the year of birth and the arithmetic centre of the trapping locations obtained the next year. Excluding heaviest individuals, e.g. 80 g, that must have already dispersed and thus lowered the estimation of averaged distance moved, our results shows that the dispersal distance in juvenile males (168 +/- A 24 m, n = 39) was greater than in females (83 +/- A 11 m, n = 66), with no effect detected for either year or cohort. Juveniles are thus involved in the spread of this ground squirrel, bearing in mind that movements estimated may have been underestimated due to the use of capture-mark-recapture methods on a limited trapping area.