High Quality Content by WIKIPEDIA articles! The Yellowbill (Ceuthmochares aereus) is a species of cuckoo in the Cuculidae family. The species is sometimes known as the Green Malkoha. It is monotypic within the genus Ceuthmochares. There are three subspecies that display some differences in plumage colouration; all subspecies have a greyish belly, head and throat but C. aereus aereus has a greenish and blue tail, wings and back, C. aereus australis has a green tail, wings and back and C. aereus flavirostris has a blue tail, wings and back. All subspecies have a heavy yellow bill which gives the species its name. The species has sometimes been split into two species, a western species the Chattering Yellowbill or Blue Malkoha C. aereus and the eastern species Whistling Yellowbill or Green Malkoha, C. australis.