Bay-ringed Tyrannulet

The bay-ringed tyrannulet is about 12 cm (4.7 in) long and weighs about 8 g (0.28 oz). The sexes have the same plumage. Adults are rufous-chestnut at the lores whose color extends to a wide eye-ring. The upper part of their face is olive and the lower part pale yellow. Their crown and upperparts are bright olive. Their wings are dusky with olive edges on the flight feathers. Their wing coverts are dusky with pale yellow tips that form a wing bar. Their tail is dusky with olive edges to the feathers. Their chin is yellow, their throat a paler yellow, and the rest of their underparts are mostly whitish with a greenish dusky tinge on the sides of the breast and flanks and yellow undertail coverts. Both sexes have a bright white iris, a pointed black bill, and bluish gray to slate legs and feet.

The bay-ringed tyrannulet is found in southeastern Brazil from southern Minas Gerais and Espírito Santo south to Santa Catarina and west into eastern Paraguay and northeastern Argentina's Misiones Province. It inhabits the interior and edges of humid evergreen forest in the lowlands and foothills. In elevation it ranges from sea level to 600 m (2,000 ft).

The bay-ringed tyrannulet feeds primarily on insects and also includes small fruits in its diet. It forages actively, mostly in the forest's canopy. It typically perches horizontally on a branch, usually with its tail cocked up, and makes short sallies to snatch or hover-glean prey from leaves and twigs. It typically forages singly or in pairs and occasionally in small family groups, and often as part of a mixed-species feeding flock.