Abstract
In April, 1955, the author found the breeding colonies of the Japanese Kestrel, Falco tinnunculus, near Nirazaki City, Yamanashi. The colonies were found along the extensive valley cliffs of the River Kamanashi and its tributary, Shiokawa, which flow through the volcanic lava of Mts. Kayagatake and Yatsugatake to penetrate the Nirazaki City into Kofu Plain.
Five separate colonies were found at: 1) Takanosu cliff 38m high and 350mlong: 17 nests, 2)Kannonbuchi cliff (about 500m from 1) 33m high and 150mlong; two groups of nests, 3) Unnamed cliff (1000m from 2) 29m high and 150m long; 2 nests, 5) Shichiriiwa] cliff (near Nirazaki) 29m high, 4 colonies along a 3km cliff. Notes are given of its nests (natural hollows of lava, etc. at least 6 meters apart from each other), flight, voice, food (with some evidence of group feeding), relation to other birds and breeding behavior.
