Small flycatcher, rather nondescript and similar to several other species. Look at the wing first: there are no contrasting wingbars, but instead the wing feathers (especially greater coverts) are boldly edged with yellow along their entire length. This helps separate Yellow-margined from most tyrannulets in range and Greenish Elaenia. Also note the dark eye, which is one of the key features to separate from Yellow-olive Flycatcher. Listen for high-pitched wheezing notes, usually three or four in a row. Found singly or in pairs, usually in the canopy of forest and edges.