The Warbler Guide by Tom Stephenson & Scott Whittle. On my (Christmas) wish list. The "Quick Finders" are incredible and also downloadable without buying the book: http://blog.press.princeton.edu/2013/07/25/downloadable-warbler-guide-quick-finders/
Prairie Warbler, (Setophaga discolor), is a small songbird of the New World warbler family. Their breeding habitats are brushy areas and forest edges in eastern North America. The Prairie Warbler's nests are open cups, which are usually placed in a low area of a tree or shrub.