Small flycatcher, extremely similar to several other species. Generally shy and inconspicuous; breeds in spruce forests often near boggy areas. Migrants tend to be found in denser wet areas within woods. Olive-greenish above with distinctive yellow wash on throat and belly. Black wings with bold white wingbars. Nearly identical to Pacific-slope and Cordilleran Flycatchers, but no range overlap. Within range, main confusion species is Least Flycatcher. Bright yellow throat and belly is usually enough to identify Yellow-bellied Flycatcher, but some worn birds can be very similar. Song is similar to Least Flycatcher ("chebek") but more slurred, with a soft buzzy tone. Not frequently repeated like Least Flycatcher. Soft whistled call note, "pwee," unlike Least's sharp "whit" call.