Kaempfer's Tody-Tyrant

Kaempfer's tody-tyrant is about 10 cm (3.9 in) long. The sexes have the same plumage. Adults have a buffy olive crown and buffy face, sometimes with some rufous. Their back and rump are dark olive. Their wings are dark olive with wide pale yellow or greenish yellow outer webs on the innermost secondaries. Their wing coverts have buffish yellow-olive tips that show as two wing bars. Their tail is dusky olive with pale tips on the outer feathers. Their throat is yellow to buff and their breast is dull ochraceous buff with a greenish olive wash. Their belly is pale yellow with a sharp edge between it and the breast. They have a brown to warm fawn-brown iris, a gray maxilla, a paler mandible, and dark gray legs and feet.

Kaempfer's tody-tyrant was known from a few localities in southeastern Brazil's Santa Catarina state. By 2025 it was known from 10 sites in northeastern Santa Catarina and one in adjacent southeastern Paraná. It is native to the Serra do Mar coastal forests, where it inhabits tropical evergreen forest, early-stage secondary forest, and open low-stature woodland. It favors thick undergrowth, often with Cecropia and Heliconia, and often near rivers. In elevation it is known only from near sea level to about 250 m (800 ft).

Kaempfer's tody-tyrant feeds on insects. It typically forages singly or in pairs and is not known to join mixed-species feeding flocks. It mostly forages in dense vegetation between about 0.5 and 3 m (2 and 10 ft) above the ground. It takes prey using short upward sallies from a perch to grab it from the underside of leaves and also while briefly hovering after a short flight.

Kaempfer's tody-tyrant was long known only from two specimens, the type specimen collected in 1929 and another in 1950; the second was only later correctly identified. It was not seen again until 1991 and then intermittently after that.