Home Ranges and Natal Dispersal in the Siberian Flying Squirrel

The Siberian flying squirrel (Pteromys volans) is a herbivorous, nocturnal and arboreal rodent living in Eurasian boreal coniferous forests. It nests and roosts in daytime in tree cavities and dreys. The main food of the flying squirrel is the leaves of deciduous trees in summer, and the catkins of birch and alder supplemented with the buds in winter.

Home-range sizes and natal dispersal of P. volans were studied by radio telemetry in southern Finland in 1996 - 1998. To each animal I fitted a TW-4 radio-collar (230-231 MHz) weighing 5.5 g (from Biotrack, UK). The tag represents on average 4% of the body weight of adults. The collar had a brass loop antenna with a Velcro lining on the inside of the collar. The lifetime of radio-collars was from 6 to 7 months and the range of the signal was up to 1.5 km. The animals were located once a night up to five times a week with RX-81 and RX-8910 receivers and two- or three-element Yagi antennas (from Televilt, Sweden). The signal was followed on foot until the animal was located. The map coordinates and fixes were later obtained with a portable GPS system. The total number of radio-tagged adults was 33 and juveniles 15. The average size of home range measured by 100% minimum convex polygons (MCP) was 59.9 ha in adult males (n = 16) and 8.3 ha in adult females (n = 17). Sexes concentrated their activities in small core areas. These were clusters including 85% of the fixes and they represented 9 and 11% of the home-range area in males and females, respectively. In the core areas the densities of aspen and alder were greater than elsewhere in the home range. Nest sites were also more often located within the core areas than in other parts of the home range.

Juvenile flying squirrels of the first litter of the year were born in late April and they dispersed from their natal home range in August. The average dispersal distance in juvenile females (n = 7) was 1.4 km and in juvenile males (n = 8) 2.4 km. Before the final leaving from the birth site, juveniles made long nocturnal trips to various directions, but returned to the nest before sunrise. Based on these results, radio tracking seems to be a suitable method for studying the behavior of flying squirrels.