During summers in the eastern US one of the most commonly heard birds in thickets, woods margins and hedgerows is the White-eyed Vireo, not only because its disturbed, semi-weedy habitat is abundant but also because it just calls and calls TCHK iweedleiwee CHIK! over and over again. A month ago as lots of White-eyeds were arriving for the winter I frequently heard their TCHK iweedleiwee CHIK! call here but now they're quieting down. More often I hear their scolding sheh-sheh-sheh call.
Tuesday morning I heard the scolding call as I walked the road to Mexil, saw a vireo silhouette, and thought I had a Mangrove Vireo, because that species is common here year round and makes that same scolding call. However, when I snapped some pictures and got them on my computer screen, what showed up was definitely a White-eyed Vireo, as you can see yourself at the top of the page.
Because of the two species' similarities, on the phylogenetic Tree of Life they must be "sister species" arisen from a common ancestor. Especially when the birds' plumages are faded there's just not much visual difference between them -- except for the White-eyed's white irises. Of all vireo species -- and 21 are listed for Mexico -- only the White-eyed has white eyes, and that's only among adults.
White-eyed Vireos, VIREO GRISEUS, breed in the eastern US and northeastern Mexico, and winter from the US Southeast to northern Nicaragua.