Wilson's Warbler

From the U.S. Fish and Wildlife Service:

Wilson's warblers can be found throughout the U.S. during their migration. However, because warblers are small and secretive, their migration often goes unnoticed. These birds spend their days in the heavy riparian vegetation, making them difficult to observe. Sitting quietly with a pair of binoculars can reveal the secret world of warblers. As fall migration begins, keep on the lookout for beautiful birds like this one!

Photo: Female Wilson's Warbler by Tom Koerner,#USFWS