Species information
Scientific name: Rana ulma
Japanese Name: リュウキュウアカガエル
Chinese Name: 琉球赤蛙、沖繩林蛙
English Name: Ryukyu brown frog
Origin: Okinawajima, Kumejima
Ecology and description
Brown frog populations from Tokunoshima, Amamioshima, Okinawajima, and Kumejima were once all classified as same species. However, recent studies revealed that although frogs from Okinawajima and Kumejima resemble those from Tokunoshima and Amamioshima in appearance, their vocalizations are noticeably different. As a result, they have been split into two species: Rana kobai (Amami brown frog) on Tokunoshima and Amami Oshima, and Rana ulma (Ryukyu brown frog) on Okinawajima and Kumejima. The species name ulma shares its origin with the place name Uruma in Okinawajima, both derived from an Okinawan word meaning “coral island.”
Rana ulma breeds in mid-December during the winter. Large numbers of males and females gather in shallow mountain streams to breed communally. After the breeding season, the frogs remain active on the forest floor but become much harder to find. Their dorsal coloration varies greatly between individuals, ranging from yellow-brown to reddish-brown.
Field photographs taken during our tours, with observation dates
The breeding season for this species occurs in winter. During the 【Herping】 tour from autumn to the following spring, there are opportunities to observe this species active on the forest floor.
