2016 Volume 56 Issue 2 Pages 199-205
In this study, we surveyed the range expansion of invasive tree squirrels (Callosciurus erythraeus and C. finlaysonii) in Hamamatsu, Shizuoka Prefecture, Japan. Although previously conceived that the northern limit of the range was south of a highway thought to act as a barrier that slowed range expansion, we here suggest that invasive squirrels have already expanded their range across the highway and into a green park located approximately 2 km north and away from the highway. The distance from the range–forefront that we suggested to the mountainous area is only 7 km, and some small woodlots appear between the areas. We fear that invasive tree squirrels could easily expand their range to those woodlots and, in the near future, further into the mountainous area. Developing a contingency plan to discourage squirrel range expansion is essential before the range expands further, because eradicating the squirrels would likely be difficult in such a mountainous area.
