American Dusky Flycatcher
Empidonax oberholseri
Adults have olive-gray upperparts, darker on the wings and tail, with whitish underparts; they have a noticeable medium-width white eye ring, white wing bars and a medium length tail. The breast is washed with olive-gray. The bill is mainly dark. It is a bit smaller than the American grey flycatcher and a bit larger than the Hammond's flycatcher. Voice: The male sings a three-part song. A common call is a dry whit, similar to that of other Empidonax flycatchers. A less common call, that is possibly only given by the male, is a sad dew-hic.
ID text from Wikipedia, CC BY-SA 4.0
Yellow-bellied Flycatcher
Empidonax flaviventris
Adults have greenish upperparts and yellowish underparts (especially on the throat), with a dusky wash on the chest. They have a white or yellow eye ring that lacks the teardrop projection of the western flycatcher, white or yellowish wing bars that contrast strongly against the black wings, a broad, flat bill, and a relatively short tail when compared to other members of the genus. The upper mandible of the bill is dark, while the lower mandible is orange-pink.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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