108 PHEASANT-TAILED GROUSE. 



then shooting or floating, swinging from side to side, gradually falling, and 

 thus producing a clapping, whirring sound. When started, the voice is cuck, 

 cuck, cuck, like the Common Pheasant. They pair in March and April. 

 Small eminences on the banks of streams are the places usually selected for 

 celebrating the weddings, the time generally about sunrise. The wings of 

 the male are lowered, buzzing on the ground; the tail, spread like a fan, 

 somewhat erect; the bare yellow oesophagus inflated to a prodigious size, — 

 fully half as large as his body, and, from its soft, membranous substance, 

 being well contrasted with the scale-like feathers below it on the breast, and 

 the flexile, silky feathers on the neck, which on these occasions stand erect. 

 In this grotesque form he displays, in the presence of his intended mate, a 

 variety of attitudes. His love-song is a confused, grating, but not offensively 

 disagreeable tone, — something that we can imitate, but have a difficulty in 

 expressing — Hurr-hurr-hurr-r-r-r-hoo, ending in a deep, hollow tone, not 

 unlike the sound produced by blowing into a large reed. Nest on the 

 ground, under the shade of Purshia and Artemisia, or near streams, among 

 Phalaris arundinacea, carefully constructed of dry grass and slender twigs. 

 Eggs, from thirteen to seventeen, about the size of those of a common fowl, 

 of a wood-brown colour, with irregular chocolate blotches on the thick end. 

 Period of incubation twenty-one to twenty-two days. The young leave the 

 nest a few hours after they are hatched. In the summer and autumn months 

 these birds are seen in small troops, and in winter and spring in flocks of 

 several hundreds. Plentiful throughout the barren, arid plains of the river 

 Columbia; also in the interior of North California. They do not exist on 

 the banks of the river Missouri; nor have they been seen in any place east 

 of the Rocky Mountains." 



Tetrao urophasianus, Bonap. Amer. Orn., vol. iii. pi. 21. 



Tetrao (Centrocercus) urophasiands, Cock of the Plains, Swains. & Rich. F. Bor. 



Amer., vol. ii. p. 358. 

 Cock of the Plains, Nutt. Man., vol. i. p. 666. 

 Cock of the Plains, Tetrao urophasianeUus, Aud. Orn. Biog., vol. iv. p. 503. 



Male, 30, 36. Female, 22. 



Rocky Mountains and Columbia river, northward. Once seen on the 

 Missouri. Abundant. Partially migratory from high to low grounds in 

 autumn and winter. 



Adult Male. 



Bill shortish, strong, somewhat compressed; upper mandible with the 

 dorsal line arcuato-declinate, the ridge flattened at the base and narrowed on 

 account of the great extent of the nasal sinus, which is feathered, the sides 

 convex toward the end, the edges inflected, the tip narrow and rounded; 



