580 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



gregations of the prairie birds that were successively disturbed by our ad- 

 vancing wagon-trains consisted of all three of these, with a considerable 

 sprinkling of Savanna Sparrows, Shore Larks, and Bay-winged Bunt- 

 ings. The first eggs I secured were taken July 18, nearly a week after 

 I had found young on wing ; these were fresh ; other nests examined 

 at the same time contained newly hatched young. Again, I have found 

 fresh eggs so late as the first week in August. During the second 

 season, the first eggs were taken July G, and at that time there were 

 already plenty of young birds flying. The laying-season must conse- 

 quently reach over a period of at least two months. I was not on the 

 ground early enough to determine the commencement exactly ; but sup- 

 posing a two weeks' incubation, and about the same length of time 

 occupied in rearing the young in the nest, the first batches of eggs must 

 be laid early in June to give the sets of young which fly by the first of 

 July. There is obviously time for the same pair to get a second, if not 

 a third, brood off their hands by the end of August; I should say that 

 certainly two, and probably three, broods are reared, as a rule. The 

 result of all this is, that from the end of June until the end of August 

 young birds in every state of plumage, and the parents in various 

 degrees of wear and tear, are all found together. The young males very 

 soon show some black on the under parts, but do not gain the distinct- 

 ive head-markings until the next season. The completion of general 

 moult is delayed until September, to nearly the time the Prairie Chickens 

 have theirs ; with its completion, both old and young acquire a much 

 clearer and richer plumage than that worn during the summer. While 

 the summer adults rarely show the bend of the wing black, this feature 

 comes out strongly in September. Comparatively few of the birds of this 

 region show the mahogany-color on the under parts, described as being 

 very conspicuous in those of some other portions of the country. Many 

 of the females, in high plumage, are scarcely distinguishable from the 

 males. The extent of white on the tail is a conspicuous feature when 

 the birds are flying, serving for their instant recognition among their 

 allies. There is a good deal of variation in dimensions, as indicated by 

 the measurements given in the table beyond. 



The nest, of course, is placed on the ground, usually beneath some 

 little tuft of grass or weeds, which effectually conceals it. Like that of 

 other ground-building sparrows, it is sunk flush with the surface of the 

 ground, thin at the bottom, but with thicker and tolerably firm brim ; 

 it consists simply of a few grasses and weed-stems, for the most part 

 circularly disposed. In size, the cup is about 3^ inches across the 

 brim and nearly 2 in depth. During the first season, I only found 

 four eggs or young in a nest ; but I afterward took one containing 

 six eggs. These measure about f long by f broad, of an ordinary 

 shape. They are difficult to describe as to color, for the marking is in- 

 tricate as well as very variable heire as elsewhere in the genus. I have 

 called them " grayish- white, more or less clouded and mottled with pale 



