The Southern Beardless Tyrannulet is 10.2 cm long, weighs 7.5g and often resembles a tiny Yellow-bellied Elaenia. The head is dark brown or grey with an erectile crest and pale supercilium. The upperparts are grey-green becoming paler on the rump. The wings are brown with yellow feather-edging and two whitish, yellowish or cinnamon wing bars. The tail, which regularly is held cocked, is brown, the throat grey, the breast yellowish, and the abdomen yellow. The bill is black, but at least the base of the lower mandible is pale.
Habitat and Distribution
This species is found in light forests, cultivation, gardens with trees and dry cerrado savanna. It breeds from Costa Rica through South America south to Paraguay, Bolivia, and Argentina.
They are active birds, feeding in a vireo- or warbler-like fashion on insects, spiders and berries. Animal prey is either picked out of the air or off plants with a dedicated sally flight, or gleaned from vegetation.
Southern Beardless Tyrannulets make a domed nest out of plant fibre or leaves with a side entrance. The nest is placed by a tree fork, usually near a wasp nest, which presumably provides some protection from predators. The typical clutch is two white eggs, which are marked with rufous and lilac mostly at the larger end. Incubation by the female is 14 to 15 days to hatching, with another 17 days to fledging.
Calls and Songs
The call of this bird is a loud whistled TLEEE-tee-tee-tee. In courtship they give a churring pee-chrrr-pee-chrrr call.