Although Tokyo daruma pond frogs (Pelophylax porosus porosus) were once commonly observed throughout paddy fields in Japan, their populations have recently declined. The mode by which frogs survive during the overwintering period is largely unknown. In this study, we observed the underground behavior of 12 free-living Tokyo daruma pond frogs that overwintered in paddy soil and a dry field by periodically excavating their overwintering positions from late March to early May. The mean overwintering depth of these frogs was ~ 19.8 cm, with 10 having migrated toward the soil surface (mean depth: ~ 8.6 cm) by late March, and finally, all 11 live frogs migrated further upward close to the soil surface. In addition, males tended to emerge earlier in spring than females. One monitored frog in the paddy soil that migrated close to the soil surface died, presumably from plowing. Aside from the 12 study frogs, several other mutilated frog corpses were found in the paddies. This species starts migrating to the soil surface during the same period when human disturbances begin, making the frogs vulnerable to these disturbances during this period. Consequently, it is necessary to facilitate the emergence of frogs to protect them from human disturbances—e.g., by temporarily filling fields with water.

虽然东京达摩沼池青蛙（Pelophylax porosus porosus）曾经是日本整个稻田中常见的物种，但最近种群数量下降了。青蛙在越冬期间生存的方式在很大程度上是未知的。在这项研究中，我们通过定期挖掘3月下旬至5月初的越冬位置，观察了12头在稻田和旱田中越冬的自由活动东京达摩沼蛙的地下行为。这些青蛙的平均越冬深度为〜19.8 cm，到3月底，有10只青蛙向土壤表面迁移（平均深度：〜8.6 cm），最后，所有11只活青蛙向土壤表面进一步向上迁移。另外，春季男性比女性早出现。在水稻土壤中迁移到土壤表面附近的一只受监测的青蛙死于耕作，可能是因为它死了。除了12只研究蛙以外，稻田中还发现了其他一些残缺的青蛙尸体。该物种在人为干扰开始的同一时期开始向土壤表面迁移，使青蛙在此期间易受这些干扰。因此，有必要促进青蛙的出现，以保护青蛙免受人类的干扰，例如，通过临时向田间注水。