Habitat selection of invasive alien Pallas’s squirrels (Callosciurus erythraeus) in an urban habitat with small fragmented green spaces

Abstract

Abstract The distribution of invasive alien Pallas’s squirrels (Callosciurus erythraeus) has expanded mainly toward the southeast with continuous forest in Kanagawa Prefecture, Japan. Recently, however, squirrels have been sighted in residential areas with only a few green spaces. We examined the habitat selection of squirrels in a city with small fragmented green spaces by censusing the animals along a 6.7 km route. Twenty-three presence data were obtained in 10 grids, which were much larger than the mean home ranges of the species, suggesting that a squirrel population had already been established in this area. Although woods of <5 ha were reported to be unsuitable squirrel habitats, the study area only had two green spaces with >5 ha, and 90% of presence data were obtained in green spaces with <5 ha. This indicates that squirrels can establish a population even in areas with small fragmented green spaces. The squirrels selected areas close to evergreen and deciduous woods, but they avoided those closer to residential areas. Since small fragmented woods, such as evergreen trees, are widely distributed in the central parts of Kanagawa Prefecture, the squirrels may use them as stepping stones to expand their range.