Golden-sided Euphonia

The golden-sided euphonia is about 11 cm (4.3 in) long and weighs about 12 to 16 g (0.42 to 0.56 oz). It is a smallish euphonia with a stout bill. The species is sexually dimorphic. Adult males are almost entirely dark glossy steel-blue. Their flight feathers and tail are dusky with a steel-blue tinge and steel-blue feather edges. A patch of elongated golden-yellow pectoral feathers that protrude in front of the wing give the species its English name. Adult females have a yellowish forehead and face, an olive crown and nape, and olive upperparts, wings, and tail. Their sides and flanks are olive-yellow and the rest of their underparts are gray. Both sexes have a dark brown iris, a blackish maxilla with a blue-gray base, a blue-gray mandible with a blackish tip, and dark gray legs and feet.

The golden-sided euphonia is found from northeastern Bolívar state in eastern Venezuela east across the Guianas to the Atlantic and across northern Brazil from the Negro River east along both sides of the Amazon to the Atlantic in Pará and northern Maranhão. It inhabits the canopy and edges of humid evergreen forest, secondary forest, and also drier patches of scrub and woodlands in savanna. In elevation it reaches 1,100 m (3,600 ft) in Venezuela and 600 m (2,000 ft) in Brazil.

The golden-sided euphonia feeds primarily on small fruits, and also includes smaller amounts of insects in its diet. It mostly forages singly and in pairs, less frequently in small groups, and sometimes joins mixed-species feeding flocks. It twitches or wags its tail while foraging. In the forest it forages primarily in the canopy but often down to the shrub layer in clearings and on edges.