idänkäki Cuculus optatus

Typical gray cuckoo, indistinguishable from Himalayan Cuckoo in the field by plumage. Dark bands on the breast average broader in Oriental. Both also extremely similar to Common and Lesser cuckoos, but with buffy rather than white vent. Brownish-yellow iris readily distinguishes Oriental from the smaller, darker-eyed Lesser Cuckoo. Best identified by song, a mellow series of “boop-boop” notes, given in flight or from a high (often concealed) perch. When not singing, quiet and unobtrusive, foraging solitarily in upper and middle levels of boreal forest and mixed woodlands.