A large, elusive cuckoo of lowland woodlands; plumages of both adults and juveniles mimic plumages of sparrowhawks. Adult gray above and pale below, with light orange suffusion on breast and sides; strikingly similar in plumage to Japanese and Chinese sparrowhawks, but has a much thinner bill (bicolored in adults) and a more lithe and smaller-headed profile. Juvenile brown above and white below, with heavily streaked underparts. Song a feverish, rapidly accelerating "chu-witchy-chu-witchy!”