Dark-eyed juncos are unique sparrows that nest on or near the ground in forests. In winter, they typically form flocks and often associate with other species, including chipping sparrows, pine and palm warblers (in the southeastern United States.), and bluebirds. When disturbed the entire flock suddenly flies up to a tree, usually perching in the open and calling in aggravation at the intrusion. Polytypic. Length 6.3".

A fairly lean sparrow with a long notched tail and a small pinkish or horn-colored bill (bicolored in dorsalis). Two prominent white outer tail feathers in most subspecies; 3 outer­most in the “white-winged.” Most subspecies have a gray or brown head and breast sharply set off from a white belly. Otherwise highly variable.