348 PATAGONIAN EXPEDITIONS: ZOOLOGY 



Under parts : Chin and upper throat white. The rest of the throat 

 abruptly clear bright chestnut, shading to paler, until this color disappears 

 on the sides of the breast. The middle of the lower part of the neck, of 

 the breast and the entire remainder of the lower parts pure white. Under 

 wing-coverts and axillaries white. 



Bill, black. 



Feet and legs, bluish grey with black claws. 



Iris, deep hazel brown. 



Adult male in breeding plumage ; much duller m color fJiau the breed- 

 ing female. 



The upper parts are fuscous brown bordered with greyish brown. The 

 vinous portions of the upper surface indicated, but dull and obscure. 

 Rump and upper tail-coverts white, all the feathers except the lateral 

 upper tail-coverts with a subterminal U-shaped line of dusky brown. The 

 lateral upper tail-coverts pure white. Duller chestnut and rufous on 

 the head, neck and lower parts, as in the female. Rest of lower parts 

 white. 



Adults in 7vinter\\2iwt the upper surface ashy grey, the feathers margined 

 and fringed with white. Rump and upper tail-coverts white, the longer tail- 

 coverts ashy grey with white edging. The ashy grey extends over the 

 back of the neck and the crown of the head. The forehead, and a broad 

 eyebrow, as well as the sides of the face white. A dusky triangular spot 

 in front of the eye. Entire under part pure white. 



Young birds have the upper surface mottled, the blackish feathers with 

 sandy buff margins producing this effect. The rump feathers white with 

 dusky centers and the upper tail-coverts pure white. Forehead, eyebrow, 

 sides of face and under surface white, the rufous areas of the under surface 

 of the full-plumaged bird replaced by isabelline ; the sides of the breast 

 and the flanks mottled, having dusky centers to the feathers. 



Adults are in the full breeding plumage but a short period, the first of 

 June being about the height of its development. By the last of July the 

 fall moult is about half completed. 



Geographical Range. — Breeds in Temperate North America from Illi- 

 nois and Utah northward to the Saskatchewan region. Migrating south 

 chiefly in the interior, through Central America, Brazil etc., to Patagonia 

 and the Falkland Islands. 



