Lawrence's Warbler - Central Park - 4/29/2004
Images and text copyright © Phil Jeffrey 2004 but as always freely available for personal use
In the morning of a good migrant day a "Lawrence's Warbler" was found by several people, including David Speiser, in the Maintenance Field of the Ramble in Central Park. This bird sang, with a song reminiscent of a Blue-winged Warbler but with an extended second note in which the trill was more modulated. It was a rather spectacular male specimen of a hybrid I'd not seen before. "Lawrence's Warbler" is a hybrid between Blue-winged Warbler (Vermivora chrysoptera) and Golden-winged Warbler (Vermivora cyanoptera) and you can clearly see influences from both species in the striking facial pattern and the overwhelmingly yellow body. The plumage of these hybrids is somewhat variable, but this is a fairly "classical" Lawrence's with extensive yellow on the body and double white wing bars.
Lawrence's is the rarer of the two Golden-winged X Blue-winged Warbler hybrids. "Brewster's Warbler" is somewhat the commoner, although both of them are rare through the park, as is Golden-winged Warbler. Blue-winged Warbler breeds locally in NY and NJ in far greater numbers than Golden-winged Warbler - sites for the latter include Sterling Forest and extreme north-western NJ near the Delaware Water Gap. See this link from Cornell for a more thorough discussion of the two hybrids. Hybridization with Blue-winged Warbler is a potentially major issue in the decline of Golden-winged Warbler populations, especially in the north-east.
Both Blue-winged and Golden-winged Warblers were reported in the park on April 29th, with Blue-winged being the more numerous (inevitably).