Abstract
The relations between nest condition of harvest mouse (Mycromys minutus) and grassland management in a yato (small valley with paddy fields) in an urban area were investigated on the Tama Hills, near Tokyo. The survey field was divided into three areas based on grassland management and farming situation. In the area where vegetation was managed repeatedly, the vegetation was mowed in May so that suitable sites for nesting disappeared. However, the number of globular nests of harvest mouse was drastically increased in August with the growth of plants. Most of globular nests were made of Miscanthus sacchariflorus leaves. We considered that it is necessary to control mowing frequency in yatos for conserving habitat and population of Mycromys minutus, and that it is important to reserve grassland vegetation established in abandoned paddy fields in yatos as nesting habitat.
