I. Streak behind eye, and tinge on side of breast, rufous. Egg pale blue, or bluish-white, blotched with pale brown, or sprinkled with reddish.
1. S. monticola. Crown bright rufous, undivided medially; a dusky spot on lore; wing-bands sharply defined, pure white. A black spot on breast; jugulum tinged with ashy. Bill black above, yellow below. Length, 6.25; wing, 3.00. Hab. Whole of North America; north of the United States only, in summer.
2. S. pusilla. Crown dull rufous, indistinctly divided medially; lores entirely whitish; wing-bands not sharply defined, pale brown. No black spot on breast; jugulum tinged with buff. Bill entirely light brownish-red.
Wing, 2.70; tail, 2.80; bill, from forehead, .37. Hab. Eastern Province United States … var. pusilla.
“Similar, but colors clearer, and bill more robust.” Hab. Peten, Guatemala … var. pinetorum.[1]
II. Streak behind the eye blackish. No rufous tinge on side of breast. Egg deep blue, with black dots and streaks round larger end.
3. S. socialis. Crown bright rufous, not distinctly divided, generally plain. Forehead black, divided medially with white. Streak of black on lore and behind eye. Rump pure bluish-ash. Bill blackish, lower mandible paler.
Auriculars deep ash, in strong contrast with pure white of the superciliary stripe and throat; breast without ashy tinge. Dorsal streaks broad. Wing, 2.80; tail, 2.30. Hab. Eastern Province of United States … var. socialis.
Auriculars lighter ash, less strongly contrasted with the white above and below; breast strongly tinged with ash. Dorsal streaks narrow. Wing, 3.00; tail, 2.90. Hab. Western Province of United States, and table-lands of Mexico … var. arizonæ.
b. Crown light grayish-brown, with distinct black streaks; young differing in streaked. Egg deep blue, with black streaks and dots (precisely as in socialis).