The Relationships of the Sharpbill (Oxyruncus cristatus)

Abstract

-The Sharpbill (Oxvruncus cristatus) is a Neotropical suboscine passerine whose affinities have been unclear. The tyrant flycatchers, cotingas, and manakins of the superfamily Tyrannoidea have been suggested as the closest relatives of the Sharpbill. DNA-DNA hybridization comparisons between the radioiodine-labeled single-copy DNA of the Sharpbill and the DNAs of cotingas, manakins, tyrant flycatchers, and representatives of the other Neotropical superfamily, the Furnarioidea, indicate that Oxyruncus is a cotinga. We place it in the subfamily Cotinginae, family Tyrannidae. The Sharpbill (Oxyruncus cristatus) is a medium-sized (ca. 16 cm) suboscine passerine with a straight, pointed bill and short rictal bristles. In the adult male the crested crown has a crimson center bordered by olive feathers tipped with black. The back is bright olivegreen, wings and tail blackish, underparts white with black spots, and the flanks pale greenishyellow. The plumage colors of the adult female are less intense than those of the male and the coronal stripe is inconspicuous. The Sharpbill apparently has a discontinuous range in the humid montane forests of Costa Rica, Panama, southeastern Venezuela, southern Guyana and Surinam, northeastern and southeastern Brazil, southern Paraguay, and central Peru (Mees 1974, Traylor, 1979). Extensive field observations of the Sharpbill have not been recorded but Sick (197 1) reviewed the sparse literature and reported on his encounters with the species during his many years of field studies in Brazil. He found that Sharpbills tend to occur most often in dense tall forest, although they sometimes feed on fruits at the forest edge or in solitary trees. Fruits are the principal food but insects have been found in the stomachs of specimens and Sick observed Sharpbills hanging upside down from twigs to capture insect larvae. The vocalizations are relatively simple and similar to those of certain cotingas. Sick found the birds most often in pairs and in mixed flocks of tanagers, furnariids, troupials, cotingas, woodpeckers, etc. feeding on fruiting trees. A captive Sharpbill ate fruits and cast hard pellets composed of the skins. Bangs and Barbour (1922) also observed Sharpbills feeding in fruiting trees with cotingas; Mees (1974) found them solitary, in pairs, and in mixed bird swarms in Surinam. Wetmore (1972:605) saw “four or five” together in Panama and recorded spiders, ants, and seeds from stomach contents. Brooke et al. (1983) found the first recorded nest of the Sharpbill near the top of a 30-m tree in the montane forest of the Serra do Tingua, 50 km north of Rio de Janeiro, Brazil. The nest, which was built by the female, was “saddled onto a slender (ca. 3 cm) horizontal branch” and was a “simple . . . shallow cup . . . composed of roughly interlaced leguminous petioles . . . and a very few dry leaves.” The outer surface “was a thin coat of mosses, liverworts, and spider’s web. . . with a texture akin to thin cardboard, possibly resulting from the application and subsequent drying of saliva.” The female fed the young by regurgitation, as do cotingas, rather than as in insectivorous tyrannids. Brooke et al. (1983) observed adult Sharpbills feeding in the ways described by Sick (1971).