The Hokkaido frog, Rana pirica, also known as the Ezo brown frog, is a member of the true frog family Ranidae. It was described by the herpetologist Masafumi Matsui in 1991, and is found in Hokkaidō, Japan, and Sakhalin, Russia, making it one of the northernmost brown frogs of the Japanese archipelago.
Identification
Openly accessible sources do not give measurements or a detailed description of R. pirica, so no size or colour figures appear here; the facts box carries only what is confirmed. The Wikimedia Commons photograph used on this page, taken at the Shibetsu Salmon Science Museum in Japan, shows the compact, brown-toned build typical of the genus Rana, the same general body plan as the other brown frogs covered on this site.
Habitat and range
The species keeps to boreal and temperate forests, temperate shrubland and grassland, rivers, swamps, intermittent freshwater lakes and marshes, ponds, arable land and irrigated land, a spread covering both natural wetland and forest and farmed, human-shaped ground. Within that range it is confined to Hokkaidō, Japan, and Sakhalin, Russia, the two landmasses that face each other across the La Pérouse Strait at the northern edge of the Japanese archipelago.
Behaviour and breeding
Little about this species’ calls, breeding season or tadpole development is documented in openly accessible, English-language sources; the English Wikipedia article is a stub, and AmphibiaWeb’s and the IUCN Red List’s own accounts cannot currently be opened to check. What is established is only its range of habitats, from forest and marsh to rice paddy and irrigation ditch, which suggests the same tolerance for both natural and farmed wetland seen in other Japanese brown frogs. No documented behavioural or breeding detail is specific to R. pirica itself.
Conservation
The facts box carries the species’ current IUCN Red List category, Least Concern, reflecting a range that still includes substantial natural forest and wetland habitat on both Hokkaidō and Sakhalin alongside the farmland it also tolerates.
Similar species
No look-alike sharing Hokkaidō itself is documented in the sources checked for this profile. Across the strait on Sakhalin, the Hokkaido frog’s range overlaps with that of Rana amurensis, another brown frog whose own range runs through western Siberia, northeastern China, northeastern Mongolia, the northern Korean Peninsula and Sakhalin. No documented measurement or field mark distinguishes the two where their ranges meet; this page lists no description for R. pirica itself, so no comparison is made here.