We were pleased to encounter two of these vireos. They are a rather rare migrant in this area as they continue to decline in California possibly due to nest parasitism by Brown-headed Cowbirds. These vireos breed locally at higher elevations in the Santa Cruz mountains, but in the lowlands such as here, they appear sparingly as migrants usually in April and September. Their presence is usually announced by their distinctive "question-and-answer" song, but our birds were completely silent. This species was traditionally lumped with the Blue-headed and Plumbeous Vireos under the name "Solitary Vireo" but were split into three species in 1998. Together, all three form a "superspecies."