Plate 20 – Blue Winged Yellow Warbler

John James Audubon was no different from any other birdwatcher trying to sort out the many different species of warblers and the variation of colors of feathers within species. One example is the Blue Winged Yellow Warbler, Golden-winged Warbler (Plate 414), and Carbonated warbler (Plate 60). Audubon was most familiar with the Blue Winged Yellow Warbler since the bird seemed to migrate mostly to the east of the Appalachian Mountains. The bird “first makes its appearance in Louisiana or Kentucky, it usually resorts to the higher branches of trees, where, amid the opening leaflets and blossoms, it actively searches for its insect food, occasionally following its prey on wing to some distance, and moving by short leaps among the twigs.” The current name for the little bird leaping among the twigs is the Blue-winged warbler (Vermivora cyanoptera). As far as Audubon was able to determine, the Golden-winged warbler (Vermivora chrysoptera) tended to stay mostly west of the Appalachian Mountains when migrating. What would have been that much more difficult for Audubon to observe is that even though the birds might use different routes for migration, they end up in many of the same areas for nesting. The overlap that has since been documented has resulted in instances of interbreeding to create at least two known hybrids: the Brewster’s warbler and the Lawrence’s warbler. There is a chance that the Carbonated warbler was also a hybrid species that has since disappeared. The only record of the Carbonated warbler is in Birds of America.