Habitat selection and seasonal occurrence of the Japanese newt, Cynops pyrrhogaster , in ill-drained paddy fields

The Japanese newt, Cynops pyrrhogaster , is an endemic species in Japan that inhabits lentic areas, from mountains to plains. In particular, this species inhabits the paddy water system, but its habitats have drastically declined in response to land consolidation in paddy fields during the 1960s. We investigated the status of Japanese newt habitat in ill-drained (traditional) paddy fields and adjacent side ditches in Shiga, Japan. Larval newts appeared and increased in number in side ditches in July, but few were captured in paddy fields, indicating that side ditches are suitable larval newt habitat due to optimal cover and water temperature. Many adult newts were found in both types of water body, but their peak abundance differed between site types. Both male and female newts were more abundant in side ditches than in paddy fields from May to June, whereas both were captured mainly in paddy fields from July to August. This is likely due to seasonal migration for reproduction, spawning, foraging, etc. We suggest that ill-drained paddy fields and side ditches are both important habitats in the life history of Japanese newts.