304 BULLETIN 16 2, UNITED STATES NATIONAL MUSEUM 



ish white." They are generally quite evenly marked with small 

 spots and fine dots of dark brown, " bister," or " brownish olive " ; 

 in very light-colored eggs the spots are in very pale shades of brown 

 or olive. The markings are very easily washed off when the eggs 

 are fresh. The eggs in a set are seldom, if ever, uniform in type; 

 there are usually two or more conspicuously different types in each 

 set. The measurements of 110 eggs average 55 by 38 millimeters; 

 the eggs showing the four extremes measure 59.5 by 39.5, 58.5 by 40.5, 

 51 by 37, and 56.5 by 35.5 millimeters. 



Young. — Bendire (1892) gives the period of incubation as 22 days. 

 This duty is performed by the female alone, as the polygamous 

 males desert the females as soon as the eggs are laid and associate in 

 flocks by themselves. Consequently the full care of the young rests 

 on the devoted mother. Mrs. Irene G. Wheelock (1904) writes: 



Like all grouse nestlings, they run about as soon as the down is dry, which 

 is about fifteen minutes after the shell breaks. They pick up food at her 

 scratching all day, and at night they nestle on the ground under her wings, only 

 a row of little heads being visible. As soon as their own feathers are developed, 

 they sleep every night in a circle about her, each one with head pointed to 

 the outside as before, and always on the ground ; for the Sage-Grouse never 

 trees. It is not difficult to come upon a brood sleeping this way on a moon- 

 light night ; but the only satisfaction will be to hear the sharp alarm of the 

 mother, a whirr as she runs by you, and a knowledge that though the young are 

 hiding on the dust at your feet, you could not find them were your eyes ten- 

 fold sharper. I have groped carefully on hands and knees among them, and 

 actually touched one before I saw it at all. For the desert hides its secrets 

 well, and the little grouse have learned to trust to it for safety. 



Grinnell, Bryant, and Storer (1918) say: 



After the young birds have learned to fly, they descend from the uplands 

 down along the larger canons, often invading the meadow lands, where small 

 tender weeds are added to their diet. At such places the young birds may 

 gather into large flocks. When approached they crane their necks and make 

 a weak attempt at cackling. When closely pressed they run rather than fly. 

 By the last of August or early September the young birds are joined by the old 

 male birds, which come off the higher slopes and ridges where they have stayed 

 during the summer and large flocks become the rule. 



Plumages. — The sage-grouse chick is well colored to escape de- 

 tection when crouching on the ground in the gray shadows of the 

 desert. The crown, back, and rump are mottled and marbled with 

 black, dull browns, pale buff, and dull white; the sides of the head 

 and neck are boldly spotted and striped with black; there are two 

 large spots of " sayal brown " bordered with black, on the fore neck 

 or chest; underparts grayish white, suffused with buff on the chest. 



The juvenal plumage comes in first on the wings, while the chick is 

 very small, then on the scapulars, back, tail, sides of the breast, and 

 flanks, lastly on the rump, head, neck, and belly. The juvenal plum- 

 age is much like that of the adult female ; but the breast is more 



