Red-eyed Vireos are small birds with olive colored back and tail. The bottom of the tail is gray, same as the cap, supercilium, eye-stripe, bill, and legs. The bill and legs can be a bit bluer than the other gray parts. The belly is white with occasional buff on the breast. The undertail coverts are a washed light yellow, but can only be seen in good lighting. Hence their name, they have red eyes. They also have a slightly hooked bill.

This is a high whistle call followed by a snippet of the song.

These calls a Red-eyed Vireo makes when agitated or fighting. The calls in this video were produced by three fighting Vireos, although you cannot see all of them.

This is just one phrase of the Red-eyed Vireo's unique song that usually has 4-6 phrases but can have double or triple that.

This is what is believed to be a Red-eyed Vireo mating display, although it has not been proven to be so. A Vireo circles the other by hoping on branches while te other watches. This footage was taken at Long Branch's Poplar Pond.

Philadelphia Vireos are very similar to Red-eyed Vireos. They both have gray eye-stripes and caps, an olive back, and questioning calls. Note that the Philadelphia Vireo has slower calls than the Red-eyed Vireo. Another difference is the fact that Philadelphia’s have a buffier Breast than Red-eyeds, and are just richer in color. Philadelphia’s are also less common and are not here in summer.

White-eyed Vireos are similar to Red-eyed Vireos in a small number of ways, note that White-eyeds have yellow in their flanks and in a spectacle design on their face. They also have a gray nape and a more disorganized song. They also inhabit lower and brushier areas.

Blue-headed Vireos are mildly similar to Red-eyed Vireos, but note that they have a slaty gray head with white spectacles and no eye-stripe. They are also found in more suburban areas and are not here in the summer.