Predation on the Siberian flying squirrel, Pteromys volans, by the Ural owl, Strix uralensis, in an urban forest

Abstract

Predation on the Siberian flying squirrel (Pteromys volans) by the Ural owl (Strix uralensis) was investigated in a forest in Abashiri City, Hokkaido. We collected 163 owl pellets during the winters of 2008–2017 and analyzed 150 pellets out of them. During two of the winters (2009–2010 and 2015–2016), we detected the remains of 21 and 23 individual Siberian flying squirrels, respectively. There were annual fluctuations in the observation rate of owls (observed day/ survey day), ranging from 0% to 26.9%, and in the number of nests of the flying squirrel, ranging from 6 to 25 nests. During a winter, the owl observation rate was particularly high, and in the following year squirrel tree nest numbers decreased. Another year, the number of squirrels remains in owl pellets declined, and the number of squirrel tree nests increased in subsequent years. These results may indicate that owl predation affected the flying squirrel population.