Population biology and behaviour of the flying squirrel (Pteromys volans) in forest landscapes: a radio-tracking study

llpo K. Hanski, University of Helsinki
Vesa Selonen, University of Helsinki

Flying squirrel (Pteromys volans) is a nocturnal, arboreal rodent. It occurs in boreal coniferous forests and its population numbers have declined in recent decades apparently due to forest management practices. Since 1996 we have studied home ranges, habitat use, dispersal and movements of adult and juvenile flying squirrels by radio telemetry in three study areas in southern Finland.

Adult males showed larger scale space use than females. The mean home range size of males was 36 33 ha and females 3 1 ha, and nocturnal movements from the nest were up to 1500 m in males but less than 200 m in females. Within the home range flying squirrels concentrated most of their activities in the small core areas where the density of deciduous trees (their main food source) was higher than elsewhere in the home range.

The landscape structure in the three study areas ranges from heavily fragmented managed forest to continuous forest approaching the natural condition. The aims of further studies are to investigate the effect of landscape structure on home-range selection, movements, use of corridors, juvenile dispersal and reproductive output and survival (source-sink dynamics) in flying squirrel. Together with the space-use patterns among males and females and genetic paternity analyses of juveniles we will determine the mating system of the flying squirrel. Based on life-history parameters and spacing behaviour we will perform population viability analyses to predict the vulnerability of local flying squirrel populations in relation to changes in forest structure in the future.

Fig.1. An example of home ranges of an adult female (no 673, blue dotted polygon) and her two young after dispersal (nos 116 and 978, red dotted polygons). Red lines indicate the movements of juveniles (strait line between consecutive fixes) in the forest-field landscape. Yellow circles indicate cavity nests and blue circles dreys (nest made of twigs and lichens).