The Forest Elaenia is an inconspicuous little flycatcher that would generally go unnoticed in the forest canopy except for its whistled "peeet-sweet?" call with the first note level and the second rising. This call is also the best clue to identification. It closely resembles the other Myiopagis elaenias, with a gray crown, yellow coronal patch, olive upperparts, yellow underparts, and pale wing bars and edgings. All Myiopagis elaenias perch more horizontally than the larger Elaenia elaenias. It forages somewhat lethargically for arthropods in the canopy, often in association with mixed flocks. Five subspecies vary in the coloration of their upperparts and coronal patches.