The Yellow Tyrannulet is a unique yellowish flycatcher with a patchy distribution in southern Central and northern South America. With olive upperparts, yellow underparts, a long tail, and horizontal posture it resembles the doraditos (Pseudocolopteryx), except for its yellower face and neck. Its calls are bubbly and cheerful and include series of whistled notes and sputtery trills. It forages actively for arthropods in dense vegetation, generally in pairs or small groups. It avoids tall forest, preferring openings and edges with copious amounts of dense vegetation at low levels. It shows a particular fondness for bamboo.