From page 254-255 in The Warbler Guide:
The Common Yellowthroat is one of our most widespread warblers. It is wren-like, and often skulks in marsh or low brush near water. It hops when on the ground, and it is frequently seen at or below eye level. The Common Yellowthroat has a small bill, a short neck and overall a plump appearance. It has short, rounded wings and a cocked tail in flight, and it is generally a weak flier. The adult male has a broad black mask across forehead and face, with paler border above, which is unique among warblers. When disturbed, it often pops up quickly, and then dives back down into cover. The Common Yellowthroats are the only U.S. and Canada warblers to nest in open marshes.
Warblers are among the most challenging birds to identify. They exhibit an array of seasonal plumages and have distinctive yet oft-confused calls and songs. The Warbler Guide enables you to quickly identify any of the 56 species of warblers in the United States and Canada. This groundbreaking guide features more than 1,000 stunning color photos, extensive species accounts with multiple viewing angles, and an entirely new system of vocalization analysis that helps you distinguish songs and calls.
The Warbler Guide revolutionizes birdwatching, making warbler identification easier than ever before. For more information, please see the author videos on the Princeton University Press website.