There are sightings of flying squirrels (Pteromys volans) around the Kaupunginselkä trail in Suvilahti and Hietalahti. The back of the flying squirrel is silvery grey, and on its belly, the fur is almost entirely white. The squirrel has skinfolds on the sides, between front and hind legs, which it uses to glide.
The flying squirrel is the most active during dusk and nighttime. It thrives especially in old mixed forests where it uses the old nest holes of great spotted woodpeckers. The nest hole is often in an aspen tree. The flying squirrel also lives as a neighbor to humans in built areas where it might have its nest in buildings or bird houses.