Today's Confusing Fall Warbler is this young Chestnut-sided Warbler. In the spring, both sexes, like the male in the photo below, are more striking. In the fall, both sexes have varying amounts of chestnut on their sides. The female above had no chestnut. But fall birds have a remarkable back color, which I have barely captured in my photograph. This color is a bright, grass-green color that I have seen in some tropical tanagers, but not in other North American birds. According to Richardson and Brauning (1995), Chestnut-sided Warblers have benefited from deforestation in North America--the species prefers disturbed secondary growth. This species was almost never recorded in Audubon's time, but now it is common.