Lesser Cuckoo

The lesser cuckoo is a small, slender Cuculus cuckoo about 25 cm long. Grey-morph adults have slate-grey upperparts, a pale grey throat and breast, a darker tail with white tips and side spots, and a white belly crossed by relatively sparse black bars. A yellow eye-ring and fine bill are useful marks. Rufous or hepatic birds are barred brown and black above, while juveniles show pale-edged upperparts and strongly barred underparts (Hong Kong Bird Watching Society; BirdForum species account).

It breeds across East Asia and the Himalayas and migrates long distances to wintering grounds extending to East Africa and Sri Lanka. Tracking work on Jeju Island found birds using a varied mosaic of fields, grasslands and forest, with females favouring forest within core areas. Like other Cuculus cuckoos it is a brood parasite; research in central Honshu found it specialising on Japanese bush warbler nests, with eggs adapted to resemble those of its host (Journal of Ecology and Environment 2020; Uchida 2011).