Abstract
A proximate factor causing the vertical habitat segregation of two sympatric wood mice, Apodemus argenteus and Apodemus speciosus, was analyzed by removal, and food supplementation, experiments. A. argenteus became actively arboreal during summer and autumn, while A. speciosus' arboreal activity was negligible throughout the year, causing seasonal habitat segregation between the two species. Removal experiments showed that the arboreal habits of A. argenteus increased from summer to autumn on both removal and control grids, regardless of the removal of A. speciosus. Food supplementation, however, showed that the provision of additional food led to a rapid decrease in the arboreal habits of A. argenteus. These findings suggest that the arboreal habits of A. argenteus are not the result of interference competition between species, but are a behavioral response to temporal and spatial fluctuations in food availability.
