Size: L: 15 cm. Wt: 13-14 g. Males and females are similar. Note: Indistinguishable by field marks from Willow Flycatcher (Empidonax trailli), which occupies drier habitats and differs in call.
Adult/Juvenile: upperparts olive; yellowish eye-ring; two buffy to whitish wing-bars; throat whitish; breast pale olive; belly pale yellow; bill with black upper mandible, yellow lower mandible; legs black.
Nestling: altricial and downy; skin pinkish; down pale olive-brown