Sorry. This occurred because I made subspecies checklists for Oregon and Washington. The subspecies Yellow Warbler aestiva does not breed in those states, so I did not include it. Since that subspecies is attached to the thing American Yellow Warbler in the ABA subspecies taxonomy (the full species is attached to Golden Warbler, as in the Clements tax list), it was taken off the checklists. Adding it back on is obviously the best thing to do, as this thing is attached to the full species in the ABA w/o subspecies taxonomy. Besides, it probably occurs as a rare migrant in the states, so it should be on them anyway. 
Nick |