The Cocos cuckoo (Coccyzus ferrugineus) is a Vulnerable species of bird in the tribe Phaenicophaeini, subfamily Cuculinae of the cuckoo family Cuculidae. It is endemic to Cocos Island, an island in the Pacific Ocean which is part of Costa Rica. Taxonomy and systematics The Cocos cuckoo was at one time treated as a subspecies of the mangrove cuckoo (C. minor), and the two are now considered sister species. The pearly-breasted cuckoo (C. euleri) and yellow-billed cuckoo (C. americanus) are also closely related to those two. The Cocos cuckoo is monotypic. The Cocos cuckoo's generic name coccyzus is from the Ancient Greek kokkuzo, meaning a common cuckoo's cry. The specific epithet ferrugineus is derived from Latin and means "rusty", referring to the color of its upperparts. Description The Cocos cuckoo is long, about half of which is the tail, and weighs about . Their bill is stout and somewhat decurved. Its maxilla is black and its mandible yellow to yellow-orange with a black tip. Males and females have the same plumage. Adults' forehead and crown are slate gray and their upperparts grayish brown. Their wings are rufous. The upper surface of their tail is grayish brown and the undersides black with wide white tips. Their face has a narrow blackish "mask" past the eye, which is surrounded by a narrow ring of yellow to orange yellow bare skin. Their throat and breast are buffy white and the belly and undertail coverts rich buff. Juveniles are similar to adults but have less contrast between the head and back colors, a less contrasting facial mask, a whitish throat, chest and belly, and less white on the tail. Distribution and habitat The Cocos cuckoo is found only on Cocos Island, which is about miles off Costa Rica's Pacific coast. It inhabits essentially the entire island, using most of the plant communities on it: flooded bay forest, riparian forest, tropical rainforest, and tropical cloudforest. It is found from sea level the highest points on the island at about . Behavior Movement The Cocos cuckoo is a year-round resident throughout the island, but it tends to occur at forest edges during the breeding season and in the forest interior when not breeding. Locomotion The Cocos cuckoo usually makes only short flights. It often moves among and within trees by hops along branches and short flutters and glides. Feeding The adult Cocos cuckoo feeds primarily on caterpillars,