Daily nest site use by the Siberian flying squirrel Pteromys volans orii in fragmented small woods

We studied the nest types used by Pteromys volans orii in two small, fragmented woods (2.1 ha and 3.1 ha) in Obihiro, Hokkaido from April 2005 to March 2006. Three nest types (cavity, nest box, drey) were used by eight flying squirrels. Each flying squirrel made use of two to eight nest-sites. The flying squirrels in our study area appear to have been restricted as to nest resources, since these woods are fragmented and small, they are surrounded by roads and fields. The preferred nests during snow-free and the snowy season were, respectively, cavity and nest box, and cavity and drey. We suggest that longer and more frequent use of nest boxes during the snow-free season might be related to rises in temperature and numbers of ectoparasites. The use of specific cavities during the snowy season appears to relate to their internal thermal characteristics. We also suggest that, to conserve flying squirrel populations which inhabit small, fragmented patches, more available nests of better quality are needed