In northern Illinois we have seven regularly occurring species of vireos. In the U.S. there are 14. Each of these vocal vixens are often heard more than seen as they sluggishly skulk in the shrubbery. Problem is, their sounds are often similar, so identifying them can be a bit tricky.
Gray Vireo song: “short whistled phrases with burry sound, similar to Plumbeous Vireo’s song”
Plumbeous Vireo song: “short whistled phrashes with burry quality, much like Cassin’s Vireo”
Cassin’s Vireo song: “like Blue-headed Vireo’s but with burry sound”
Blue-headed Vireo song: “Like Red-eyed Vireo’s but higher-pitched”
So, a Gray Vireo sings a short-whistled, high-pitched, burry, Red-eyed Vireo song. That simplifies things!
In our area we have three distinct sounding vireos, Bell’s, White-eyed, and Warbling. We’ve somewhat mastered the Yellow-throated song, so all that remains are Blue-headed, Philadelphia, and the always present Red-eyed.
But despite their similarities, vireos are wonderful birds to have around, even if they may not be as colorful (debatable) or active as the wood-warblers.