The pearly-breasted cuckoo (Coccyzus euleri) is a species of bird in the tribe Phaenicophaeini, subfamily Cuculinae of the cuckoo family Cuculidae. It is found in Argentina, Bolivia, Brazil, Ecuador, French Guiana, Guyana, Paraguay, Suriname, Venezuela, and possibly Colombia and Panama. Taxonomy and systematics The taxonomic history of the pearly-breasted cuckoo is complicated. For many years it was considered a subspecies of the yellow-billed cuckoo (Coccyzus americanus) due to confusion about the identity of a specimen collected on Sombrero Island in the Lesser Antilles. The specimen was originally described as a species with the binomial C. julieni. The identity of the South American birds bounced between that treatment and treatment as the yellow-billed subspecies before its current designation as C. euleri was settled in 1992. The pearly-breasted cuckoo is monotypic. Description The pearly-breasted cuckoo is long, about half of which is the tail. Males weigh about and females about . Their bill is stout and somewhat decurved. Its maxilla is brown to black with a yellow base and its mandible yellow to orange with a black tip. Males and females have the same plumage. Adults' upperparts are grayish brown with a light bronze gloss. Their wings are grayish brown with white on the primaries' inner webs. The upper surface of their tail is grayish brown; the underside of the central pair of feathers is brownish gray, the next pair blackish with narrow white spots on the tips, and the rest blackish with wide white spots on the tips. Their face has a wide dark gray "mask" past the eye, which is surrounded by a narrow ring of bare skin that is usually black but can be yellow or red. Their underparts are pearly grayish white from throat to breast, the belly white, and the undertail coverts light pearly gray. Juveniles are similar to adults but have fine pale edges on their wings, no facial mask, and only traces of white on the tail. Distribution and habitat The pearly-breasted cuckoo nests in Argentina, Brazil, French Guiana, Paraguay, and Venezuela, and is found in Bolivia, Ecuador, Guyana, and Suriname as a non-breeder. A sight record in Colombia leads the South American Classification Committee of the American Ornithological Society (AOS) to class it as hypothetical in that country. A record in Panama has apparently not been accepted by the North American Classification Committee of the AOS. The pearly-breasted cuckoo inhabits a very wide variety