Cassin’s Vireo is intermediate in coloration, and the westernmost in range, of the similar trio of species formerly collectively called Solitary Vireo; Blue-headed Vireo and Plumbeous Vireo are the other two.
Cassin’s Vireo is intermediate in coloration, and the westernmost in range, of the similar trio of species formerly collectively called Solitary Vireo; Blue-headed Vireo and Plumbeous Vireo are the other two.