Chestnut-sided Warbler

In leafy second-growth woods, clearings, and thickets, this warbler is often common, hopping about in the saplings with its tail cocked up at a jaunty angle. It is apparently much more numerous today than it was historically: John James Audubon, roaming eastern North America in the early 1800s, saw this bird only once. The cutting of forests evidently has created more brushy habitat for Chestnut-sided Warblers, even as it has made other birds less common.