eWestern BirdsThe Quarterly Journal of Western Field Ornithologists
Vol. 41, No. 4
Western Field Ornithologists
An Apparent Hybrid Philadelphia x Red-eyed Vireo on Southeast Farallon Island, California
Ryan S. Terrill, James R. Tietz, and Matthew L. Brady
ABSTRACT: Interspecific hybrids in the Vireonidae have seldom been reported, and the hybrid combination of the Philadelphia (Vireo philadelphicus) and Red-eyed (V. olivaceus) Vireos has been reported only twice before. We here report an apparent hybrid that remained on Southeast Farallon Island 7–13 September 2008. Its breast color, head pattern, head shape, and measurements were intermediate between those of the Philadelphia and North American subspecies of the Red-eyed. Details of the wing structure eliminated the Warbling (V. gilvus) and South American subspecies of the Red-eyed as possible parental species.