Abstract
We observed the food items consumed by the Siberian flying squirrel, Pteromys volans orii, in Obihiro, Hokkaido. We recorded thirteen tree species that nineteen radio-tagged flying squirrels foraged from September 1991 to August 1993 and from May 2005 to August 2006. The number of tree species foraged by flying squirrels differed according to the vegetation of the sites. Flying squirrels foraged leaves, buds, catkins, seeds, infructescences, acorns and fruits from both broadleaf trees and conifers. Leaves, buds and seeds appear to be the main food items for the Siberian flying squirrel, since they consumed these items over a long period. The flying squirrels frequently fed on leaves from May to July, when they had low fiber and a high nutritive value, but ate more fibrous mature leaves in late autumn due to the low availability of their preferred items. Flying squirrels also foraged more pine tree seeds in early autumn, suggesting a strategy for increasing their weight for survival over the winter. The pollen and acorns used by flying squirrels may be related to their reproductive cycle, due to the high nutritive value of these items. One of prerequisites for conservation of the Siberian flying squirrel is that their food trees and items are investigated at different sites.
