Migratory Birds (website)
The Naruto Strait is one of the best places in Japan to see migratory birds. Majestic birds of prey traverse the skies between Shikoku and Awaji Island, a crossing especially favored by buzzards (birds in the genus Buteo, which are generally called hawks in North America). When migration season arrives each spring and fall, on the busiest days more than 1,000 of these birds may make the crossing, with flocks forming an almost unbroken line in the sky at peak hours.
The following are the four main species that travel over the strait, listed from most to least numerous. With the exception of the common buzzard, all are included on the IUCN Red List of Threatened Species.
Gray-faced buzzard (3,000–5,000 seen annually)
About the same size as the carrion crow, this bird grows to around 50 centimeters in length and migrates in very large flocks. The lower edges of its wings form a sleek, straight line in flight. When it is at rest, the tips of its wings reach almost to the end of its tail.
Common buzzard (also called the Japanese buzzard or eastern buzzard) (2,000–3,000 seen annually)
A light gray-brown bird roughly 50 to 60 centimeters in length, the long-winged, short-tailed common buzzard appears to stop and hover in midair while scanning the earth below for food. The male and female look very similar, making it difficult to tell them apart.
Eurasian sparrowhawk (around 300 seen annually)
A fully grown Eurasian sparrowhawk is about 30 to 40 centimeters in length. Its short wings are wide and rounded, giving it great dexterity as it suddenly decelerates and turns in order to capture its prey.
Crested honey buzzard (aka oriental honey buzzard) (around 300 seen annually)
This bird is distinguished by a small, pigeon-like head, a long, rounded tail, and a wide wingspan of up to 155 centimeters. Its thick, stiff plumage helps protect it from bee stings.
Routes and seasons
Both the gray-faced buzzard and the crested honey buzzard breed in Japan from spring through fall, then migrate to Indonesia and the southern Philippines, passing over Naruto from east to west. Come spring, these two birds return to Japan, crossing the Naruto Strait in the other direction. Eurasian sparrowhawks, conversely, pass over Naruto from west to east in fall as they journey from China to spend the winter in Japan. The common buzzard migrates to northern Japan in summer and winters in southwestern Japan.
Fall migration takes place from September to November. Birds take off from around sunrise, with numbers in the sky peaking between 10 a.m. and 2 p.m., especially on sunny days. Spring migration is from mid-March through early June.
