Yellow-throated Euphonia

The yellow-throated euphonia is a small, short-billed, short-tailed arboreal passerine with pointed wings. An adult is 10–12 cm long with the tail contributing 3.3 to 3.6 cm. The wingspan is 5.8 to 6.1 cm and weight about 11.6 – 17.8 g. The adult male of the nominate species has a small bright yellow patch on its forehead that extends back to about the middle of the eyes. The rest of the head, upperparts including upper-wing coverts, and the upper-tail coverts are a glossy blue-black. The flight feathers are black with steel blue edgings and the entire underparts are yellow. The underwing coverts are white and the under-tail coverts are a dark dull grey. The inner webs of the outer 2-3 feather pairs are mostly white forming a large, white, oval-shaped area on the wing undersurfaces. The beak tip is black, becoming blue-gray beneath nostrils and on mandible. The irises are brown and the legs and feet are dusky dark gray. The adult female has an olive-green faintly glossy metallic coloration on top of her head, side of head, and upperparts. The throat, center of breast and lower underparts are whitish to greyish-white and sides of breast, sides, and flanks are bright yellowish olive-green. Under tail-coverts are pale olive-yellowish and the beak is similar to the adult male. Juvenile males look similar to females, but plumage is of a looser texture and the olive-green of upperparts lacks gloss. Immature males also resemble females and first assume yellow feathers on the throat and median underparts as their whole ventral surface turns yellow before black begins to appear. The males then develop a black mask, black on their crown and head or a crown with mixed black and olive. The back, sides, and wings start out olive-green and are the last part of the bird to turn dark blue. The male's song includes high pitched shrill and squeaky notes that often rapidly alternate in a choppy pattern of 2-4 notes with moderately pitched notes. Some male songs are reported to include mimicked notes from other birds, but with a smaller repertoire than the closely related E. violacea and E. laniirostris. Callnotes include a rapid “pidgel-eece,” a conversational “chi-bib-bib-bib-bib,” a rough hurried “tuck-a-tuck” or “chuck-a-chuck,” a clear “weet,” and a full-throated “queer” or “gleer”. Its calls have been described as short and explosive. Females produce calls that are thin and “chaffy” in quality and are high pitched and almost trilled. Yellow-throated euphonia males are distinctive across most of their geographic range due to their yellow throat, however they overlap with the similar thick-billed euphonia in southwestern Costa Rica and western Panama. Thick-billed euphonia also have a yellow throat, but have a more extensive yellow crown than yellow-throated euphonia and are much more common in geographic areas where their ranges overlap. Female yellow-throated euphonia are distinguishable from other sympatric Euphonia females due to their whitish or pale grey throat, center of breast, and belly, and their yellow flanks. Female scrub euphonia, thick-billed euphonia, and yellow-crowned euphonia have entirely greenish yellow to yellow ventral parts, and female white-vented euphonia have whitish throats, but a yellow breast.