Where does the island-endemic frog Glandirana susurra survive during the nonirrigated season?

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2025-04, Vol.381, Article 109433
• Main Authors: Kishimoto-Yamada, Keiko, Satoh, Ryo, Kokura, Masafumi, Mitsuo, Yoshito
• Format: Article
• Language: English
• Subjects: Abandoned field; Endangered species; Rice paddy field; Sado wrinkled frog
• ISSN: 0167-8809
• DOI: 10.1016/j.agee.2024.109433

The Sado wrinkled frog, Glandirana susurra, endemic to Sado Island, 40 km from the mainland of Japan, is an endangered species that requires urgent conservation efforts. This study was conducted to reveal the habitat of this frog and its tadpoles during the nonirrigated season by investigating their abundances in paddy fields, two types of ditches (shallow concrete and earthen), and abandoned fields within an unconsolidated paddy field area. A field experiment was also conducted in an abandoned paddy field, creating water pools under different plant cover conditions, to understand the effects of microhabitat environments on overwintering frogs. Immediately after rice harvesting, tadpoles were found in both types of ditches and frogs appeared in the paddies as well as in the earthen and concrete ditches. As winter approached, the frogs primarily inhabited the earthen ditches and abandoned paddy fields. Furthermore, in these abandoned fields, larger water pools positively affected the abundances of overwintering frogs. The field experiment suggested that opened quadrats and mowed areas tended to reduce habitat suitability. Although the function of plant cover in the abandoned fields is not well understood, our study emphasized that not only wet environments but also plant covering on water pools and dense grassy environments could be important for the frogs’ overwintering sites. •Drying during the nonirrigated season harms overwintering frogs in paddy fields.•Endangered Sado wrinkled frog’s habitat in nonirrigated season needs urgent study.•We found that the frogs used abandoned fields as overwintering sites.•The field experiment also showed that plant cover promoted overwintering frogs.•Abandoned paddies can benefit frogs during the nonirrigated season.