This video from the USA says about itself:
11 June 2011
Note that the Blue-winged has yellowish wingbars and the Golden-winged sings a Blue-winged song. Lots of interbreeding in this area and Golden-winged Warblers are rarer every year.
From the Cornell Lab of Ornithology in the USA:
Mixed-wing Warblers: Differences Are Only Feather Deep
In 1835 John James Audubon suspected that Golden-winged Warblers and Blue-winged Warblers might be the same species. More than 180 years later, the most advanced methods of genetic analysis show Audubon was on to something.
A team led by scientists from the Cornell Lab found that, genetically speaking, Golden-winged and Blue-winged warblers are 99.97 percent alike.
Will this affect the conservation strategy for Golden-winged Warblers, one of the fastest-declining songbirds in North America? Read our Living Bird article and find out.
A gene newly associated with the migratory patterns of golden-winged and blue-winged warblers could lend insight into the longstanding question of how birds migrate across such long distances: here.