Gliding locomotion of Siberian flying squirrels in low-canopy forests: the role of energy-inefficient short-distance glides

Abstract

Short glides of less than 20 m seem energy inefficient for the Siberian flying squirrel Pteromys volans as with the northern flying squirrel Glaucomys sabrinus. However, Siberian flying squirrels in low-canopy forests frequently use short glides. Therefore, we sought to clarify the gliding patterns of Siberian flying squirrels for energy-efficient gliding transport in low-canopy forests (mean tree height, 15.3 m) in Hokkaido, Japan, based on records of 66 glides and 35 launch and landing trees. Mean launch height, landing height, and horizontal glide distance were 14.4, 2.7, and 21.4 m, respectively. For short distances, horizontal glide distance was strongly correlated with launch heights but not with launch tree height. For glides of more than 20 m, horizontal glide distance was significantly correlated with both launch height and launch tree height. The mean heights of launch and landing trees for short glides were 15.6 and 19.5 m, respectively. For long glides, these heights were 22.7 and 19.2 m. For short glides, mean launch tree height did not differ from overall mean tree height. However, for long glides, the mean launch tree height was greater than the overall mean tree height. Also, for short glides, the height of the landing tree was greater than that of the launch tree. Launch trees used for long glides were as high as the landing trees used in short glides. From these results, we conclude that Siberian flying squirrels in low-canopy forests save energy by gliding initially from a tree with sufficient height to permit a glide to a taller tree. This taller tree then permits long-distance glides that are energetically more efficient.