Inter-habitat movement of Japanese squirrels in urban landscapes across seasonal changes and between sexes

Abstract

Wildlife habitats in urban areas are generally highly fragmented and this has negative impacts on mammalian species. However, some mammals have adapted to urban environments sufficiently well to maintain and expand their population. The Japanese squirrel (Sciurus lis), an arboreal animal, is thought to be sensitive to habitat fragmentation. In some urban areas, they do move between habitats. To clarify the inter-habitat movement of squirrels within the urban landscape based on seasonal changes and sex differences, we radio-tracked 18 squirrels in Morioka City, Iwate Prefecture, Japan. We observed 204 movements between habitats in eight males and three females. The number and frequency of inter-habitat movement of individuals were significantly higher in males than in females. Males showed a high frequency of inter-habitat movement during the leaf expansion period and significantly less movement during the deciduous period. The different movement patterns between the sexes were attributed to differences in habitat use and mode of establishing home ranges. Seasonal changes in inter-habitat movement are thought to be driven by changes in food resources and endeavor to avoid predation risks. Little movement was observed during the mating season, suggesting that genetic exchange was not promoted by the inter-habitat movement of adults within the study site.