Scarlet-thighed Dacnis

The scarlet-thighed dacnis is 11 to 12 cm (4.3 to 4.7 in) long and weighs 15 to 17 g (0.53 to 0.60 oz). It has a short pointed bill. The species is sexually dimorphic. Adult males of the nominate subspecies have a mostly turquoise-blue head with a triangular black mask from the forehead and lores to just past the eye and extending down the throat. Their back, scapulars, and rump are turquoise-blue. Their longest uppertail coverts are black and the rest turquoise-blue. Their wings and tail are black. Their breast, belly, and undertail coverts are deep greenish black. Their eponymous scarlet thighs are usually not visible. Adult females have a greenish olive head tinged with bright blue on the face. Their upperparts are greenish olive with a bright blue tinge on the scapulars and rump. Their wings and tail are dusky. Their throat is grayish, their upper breast gray-brown, their lower breast, sides, and flanks grayish olive, and their belly and undertail coverts yellowish buff. Their breast has a faint blue tinge. Their thighs have only a tinge of red at their base. Subspecies D. v. fuliginata is smaller than the nominate, and males have deeper sooty black underparts with little or no green. Males of both subspecies have a bright red to deep red iris, a black bill, and dark gray or dusky legs and feet. …

The nominate subspecies of the scarlet-thighed dacnis is the more northerly of the two. It is found from the Cordillera de Tilarán in north-central Costa Rica along the Caribbean slope into Panama to the Canal Zone. It also is found on the Pacific slope from Costa Rica's Cordillera de Talamanca into Panama. Subspecies D. v. fuliginata is found from Darién Province in eastern Panama south into Colombia. There it is found on the northern base of the Central Andes and south in the Cauca and Magdalena river valleys. It also continues from Panama south along the Pacific slope of Colombia's Western Andes and into northwestern Ecuador to far northern Guayas Province. The species primarily inhabits the canopy and edges of evergreen forest in the tropical and subtropical zones. It also occurs in gaps caused by fallen trees, around the edges of lakes, in cleared areas that retain a good number of trees, and shady plantations. In elevation in Costa Rica it ranges between 400 and 1,500 m (1,300 and 4,900 ft) on the Pacific slope and between 1,300 and 1,500 m (4,300 and 4,900 ft) on the Caribbean slope. It reaches 1,000 m (3,300 ft) in Colombia and 800 m (2,600 ft) in Ecuador.

The scarlet-thighed dacnis feeds on small fruits, arthropods, and nectar. It forages very actively, mostly in the forest subcanopy and canopy but lower on the edges, gleaning prey and fruit from live foliage. It forages singly, in pairs, and in family groups and regularly joins mixed-species feeding flocks.