The Hokkaido wolf (Canis lupus hattai), also known as the and in Russia as the Sakhalin wolf, is an extinct subspecies of gray wolf that once inhabited coastal north-east Asia. Its nearest relatives were the wolves of North America rather than Asia. It was exterminated in Hokkaido during the Meiji Restoration period, when American-style agricultural reforms incorporated the use of strychnine-laced baits to kill livestock predators. Some taxonomists believe that it survived up until 1945 on the island of Sakhalin. It was one of two subspecies that were once found in the Japanese archipelago, the other being the Japanese wolf (C. l. hodophilax). Taxonomy and origin The Ezō wolf or Hokkaidō wolf (Canis lupus hattai Kishida, 1931) is an extinct subspecies of the gray wolf (Canis lupus). In 1890, the skulls of Japanese wolves (Canis lupus hodophilax) were compared with those of wolves from Hokkaido in the British Museum. The specimens were noticeably different and explained to be local varieties of the same subspecies. Later, explorers to the Kuril islands of Iturup and Kunashir believed that the wolves they saw there were the Japanese subspecies. In 1889, the wolf became extinct on Hokkaido island. In 1913, Hatta Suburō proposed that the wolf might be related to the Siberian wolf but had no living specimens to undertake further analysis. In 1931, Kishida Kyukishi described a skull from a wolf killed in 1881 and declared it to be a distinct subspecies. In 1935, Pocock examined one of the specimens in the British Museum that had been obtained in 1886 and named it Canis lupus rex because of its large size. Analysis of its mitochondrial DNA showed it to be identical with gray wolf specimens from Canada, Alaska and the USA, indicating that the ancestor of the Ezo wolf was genetically related to the ancestor of North American wolves. The coalescence time back to the most recent common ancestor for two Ezo wolf samples was estimated to be 3,100 (between 700–5,900) years ago, and the Ezo wolf is estimated to have diverged from North American wolves 9,300 (between 5,700–13,700) years ago. These estimates indicate that Ezo wolves colonized Japan more recently than Japanese wolves from the Asian continent during the last glacial period via a land bridge with Sakhalin Island, which existed up to 10,000 years ago. The Tsugaru Strait was 3 km wide during the last glacial period, which prevented Ezo wolves