Beyond the Paddy Fields: Riparian Reed Beds as Essential Natural Habitat for the Critically Endangered Suweon...

The Suweon treefrog (Dryophytes suweonensis (Kuramoto, 1980)), a critically endangered amphibian endemic to the Korean Peninsula, is widely regarded as being closely associated with rice paddies. However, given that rice agriculture represents a relatively recent feature in the species' evolutionary history, strict dependence on this habitat warrants re-examination. To assess habitat use during the non-breeding season, we conducted intensive field surveys in Pyeongtaek, a core distribution area, during the pre-breeding period of 2024. We detected 701 Suweon treefrogs, including 697 individuals within the 1.6 km² study area (436 frogs/km²). No individuals were found inside rice paddies during the survey; instead, all were located on emergent vegetation within riparian waterways, with 97% occurring on the Common reed, Phragmites australis. These findings indicate that riparian reed habitats play a critical role during the non-breeding season and may better reflect the species' ancestral ecological niche. Previous emphasis on rice paddies likely reflects a bias toward breeding-season observations. Although rice paddies remain important breeding sites, conservation strategies focused solely on these habitats risk overlooking essential non-breeding environments. We therefore recommend that conservation planning incorporate the protection and restoration of reed-associated wetlands and that monitoring efforts encompass the full annual cycle. More broadly, our results highlight the need to reassess habitat associations in species traditionally considered dependent on anthropogenic environments.