Yellow-shouldered Grassquit

The yellow-shouldered grassquit is 10 to 11.5 cm (3.9 to 4.5 in) long and weighs 10.5 to 12.5 g (0.37 to 0.44 oz). It is a small bird with a disproportionately large head and a thick bill with a strongly curved culmen. The species is sexually dimorphic. Adult males have a black head, neck, throat, and breast. Their mantle, back, rump, and tail are grass-green. Their wings are greenish with the eponymous yellow shoulder. Their belly and flanks are greenish and their crissum rusty. Adult females have a gray head and breast with a faint green wash. Their upperparts are greenish with a yellow wash and their wings greenish with a yellow shoulder. Their belly is grayish green and their crissum a paler rusty than the male's. Both sexes have a dark iris, a horn-colored bill, and blackish legs and feet.

The yellow-shouldered grassquit is found throughout Jamaica. It primarily inhabits the edges of dry to wet forest types and also woodlands and gardens near forest. Sources differ on its upper elevational limit. One says it is found at all elevations but another says it reaches only 1,800 m (5,900 ft).

The yellow-shouldered grassquit's diet has not been studied but is known to include seeds and fruits and assumed to also include insects. It forages in pairs and family groups near the ground in bushes and trees.