Olive-backed Euphonia

The olive-backed euphonia is 9 to 10 cm (3.5 to 3.9 in) long and weighs about 11 to 16 g (0.39 to 0.56 oz). It is a small euphonia with a thick stubby bill. The species is sexually dimorphic. Adult males of the nominate subspecies have a yellow forehead; the patch extends to the rear of the eye and sometimes has light black flecks. The rest of their crown, and their nape, upperparts, and tail are olive-green. All of them except the uppertail coverts have a bluish gray gloss. Voice: The olive-backed euphonia's song is "a rapid jumble of chatters, buzzes, and harsh whistles". Its calls "include a chi'chi'chi'cheet and a liquid tsip'please-seeee'up!. Another description of its song is "a rambling medley of whistles, chatters and staccato notes, some dry and chaffy, some musical" that may continue for a long time.