Yellow-bellied Flycatchers wait on a perch low or in the middle of a tree and fly out to catch insects in flight, sometimes hovering over foliage.

It has a more prominent eye ring than any migrant species, and despite that species' name, is yellower below than Yellow-bellied Flycatcher.

The Yellow-bellied Flycatcher (Empidonax flaviventris) is a small insect-eating bird of the tyrant flycatcher family.

The three primary call notes of Yellow-bellied Flycatcher are a clear, ascending "chu-wee," a sharp, gruff "peekk", and a soft, descending "pyu."

The Yellow-bellied Flycatcher's song can be transcribed as a rough, descending "TSE-berk," which can be similar to the more common Least Flycatcher's snappier, more evenly pitched "che-bek."

Historically North Mountain was home to Olive-sided Flycatcher, and "was one of the few places one could enjoy the songs of all of Pennsylvania's native thrushes"; today it is home to the state's largest Yellow-bellied Flycatcher population.

A junior synonym of flaviventris is johnstoni, but the latter was used when Euler's Flycatcher was placed in the genus Empidonax, as flaviventris is preoccupied in that genus by the Yellow-bellied Flycatcher (E. flaviventris).

Bird watchers have observed over 200 species of birds in the park, including the Great Blue Heron, Northern Harrier, White-throated Sparrow and highly sensitive species which are rare as breeding birds in Pennsylvania such as Northern Goshawk and Yellow-bellied Flycatcher.

The Yellow-bellied Flycatcher (Empidonax flaviventris) is a small insect-eating bird of the tyrant flycatcher family.