This Vireo
was at Paradise Pond, Port Aransas, Nueces county, TX in early May 2009; clearly it is suffering from some kind of health issue! In the field I felt it was likely a Black-whiskered Vireo, but the distortion caused by the damage/feather loss on the head caused me to speculate whether this bird has genetic abnormalities that might also have affected other aspects of its morphology... So, is it identifiable?:
