Lily's "Bell's Vireo"
When it is glimpsed in low brushy thickets of the Midwest or Southwest, this bird looks totally nondescript. When it is heard, however, it is easy to recognize, singing a jumbled clinking song, as if it had a mouthful of marbles. The species has become less common in recent years in many parts of its range, partly because it is a frequent victim of cowbird parasitism; many pairs of Bell's Vireos succeed in raising only cowbirds, not their own young.
-National Audubon Society