The Blakiston Line or Blakiston's Line is a faunal boundary line drawn between two of the four largest islands of Japan: Hokkaidō in the north and Honshū, south of it. It can be compared with faunal boundary lines like the Wallace Line. Certain animal species can only be found north of Blakiston's Line, while certain other species can only be found south of it. Thomas Blakiston, who lived in Japan from 1861 to 1884 and who spent much of that time in Hakodate, Hokkaido, was the first person to notice that animals in Hokkaidō, Japan's northern island, were related to northern Asian species, whereas those on Honshū to the south were related to those from southern Asia. The Tsugaru Strait between the two islands was therefore established as a zoogeographical boundary, and became known as Blakiston's Line. This finding was first published to the Asiatic Society of Japan in a paper of 14 February 1883, named Zoological Indications of Ancient Connection of the Japan islands with the Continent. Explanations and hypotheses on the existence of Blakiston's Line The difference in the fauna can probably be attributed to land bridges that may have existed in the past. Whilst Hokkaido may have had land bridges to the north of Asia, via Sakhalin and the Kuril Islands, the other islands of Japan like Honshu, Shikoku and Kyushu, may have been connected to the Asian continent via the Korean Peninsula. As to when these land bridges existed, scientists do not agree. It may have been between 26,000 and 18,000 years ago, it may have been later than that. Sakhalin, the island just north of Japan, and Hokkaido may even have been connected to the mainland as recently as 10,000 years ago or less. Apart from these former land bridges, there are more factors that play a role in why there is a difference in the fauna north and south of the line: The Tsugaru Strait is relatively deep, the maximum depth is 449 m. The narrowest part of the Tsugaru Strait is 12.1 miles (19.5 km). Currents in the Tsugaru Strait are strong, tidal currents coincide with ocean currents The climate in the north is generally far colder than that in the south. Species north and south of Blakiston's Line Besides birds, animals that are of different origins north and south of the Blakiston Line include wolves, bears and chipmunks. Monkeys do not even