74 LIFE HISTOEIES UP NORTH AMERICAN BIRDS. 



The food of the Willow Ptarmigan, during- the early spring and summer, 

 consists principally of the buds and tender leaves of the various species of birch 

 and willows found in that region, and several kinds of berries, such as arbutus, 

 cranberry, and whortleberry, as well as insects of different species, of which 

 they find an abundant supply during the short summer season. 



All observations made on the habits of the Ptarmigan during the breeding 

 season tend to show that the male is equally devoted, and shows a strong 

 attachment for the young, assisting in taking care of them, and displaying 

 as great a solicitude for their safety as the female, differing in this respect from 

 most of the Grouse family, by whom the care and protection of the young is 

 apparently almost entirelj^ left to their mates. 



The nests of the Willow Ptarmigan are, as a rule, not particularly well 

 hidden, and judging from the large number of eggs of this species in the U. S. 

 National Museum collection, procured principally by Mr. R. MacFarlane, of 

 the Hudson Bay Company, near Anderson River Fort, in about latitude 68°, 

 they must be exceedingly abundant at this point. 



The average numb(3r of eggs to a set is from seven to eleven, and but 

 one brood is raised in a season. The eggs vary in shape from ovate to 

 elongate ovate. The ground color ranges from cream color to a pronounced 

 reddish buff, with several intermediate shades. In some specimens it is very 

 clearly seen, in others it is almost completely obscure,d by the heavy con- 

 fluent blotches and markings. The latter vary from well-defined and nearly 

 even-sized spots of different sizes to confluent and clouded blotches, and 

 smears of various shades of dark reddish and clove brown, completely ob- 

 scuring the ground color in some instances. All this coloring matter can be 

 readily removed in a freshly-laid egg, leaving the shell a pale creamy white, 

 and they show an almost endless variation in shape, color, and size. All the 

 specimens in the U. S. National Museum collection were taken in the month 

 of June, the majority about the middle of this month. 



The average measurement of two hundred and fifty specimens in the 

 U. S. National Museum collection is 43 by 31 millimetres. The largest egg 

 of this series measures 47 by 33.5, the smallest 39.5 by 28 millimetres, and 

 a runt specimen 20 by 17.5 millimetres. 



The types selected to show the variations in the styles of markings and 

 coloration were obtained as follows: No. 6023 (PI. 2, Fig. 5), from an in- 

 complete set of three, taken by G. Bannister near Whale River, Ungava 

 Bay, Labrador, June, 1862; No. 9251 (PL 2, Fig. 6), from a set of seven, 

 June 29, 1863; No. 10689 (PI. 2, Fig. 7), from a set of seven, June 20, 

 1865; all the latter being from the region east of Anderson River Fort, British 

 North America, and collected by R. MacFarlane. No. 16461 (PI. 2, Fig. 8), 

 from a set of eight, taken June 20, 1872, by W. H. Dall, U. S. Coast Survey, 

 on Popof Island (one of the Shumagin Group), Alaska Peninsula; No. 17042 

 (PI. 2, Fig. 9), from a set of six, taken June 3, 1874, near St. Michael, Alaska, 



