12 LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS 



among the reeds and made of the usual materials. Two of the nests 

 were among the buck brush, where the water was over 2 feet deep; in 

 one "the material was piled upon coarse twigs of buck brush, appar- 

 ently brought up from the bottom"; the other "was made on de- 

 pressed branches of the bushes, a large, strong mass of decayed reeds 

 with some new material intermingled in the top." 



Mr. Edmonde S. Currier (1904) refers to a colony of from 6 to 

 10 pairs which he found breeding in Leech Lake, Minnesota, in 1902 

 and 1903. 



One nest was high and dry on a muskrat house a hollow in the side of the 

 house, and about 10 inches above the water. The muskrat house was in a 

 patch of tall canes, growing in deep, open water, forming a small island. The 

 other nests were similar in situation, style of architecture, and material used. 

 They varied only in size, and this depended upon the time the birds had been 

 laying. Nests containing only one egg were simply irregular piles or rafts of 

 floating flags soft and rotting, with the egg often awash and covered with 

 foam. In more advanced sets the nests formed quite a mass of material, with 

 a deep cup above water line. No birds were seen on the nests, or leaving them, 

 but in 1902 I saw one swimming away from a patch of canes in open water 

 that contained a nest. 



Eggs. The HolbcelPs grebe raises only one brood during the sea- 

 son, but if the nest is robbed a second set of eggs is promptly laid. 

 The set generally consists of four or five eggs; sometimes three are 

 considered enough; six eggs are occasionally laid and rarely seven 

 or even eight. The eggs resemble closely those of other grebes in 

 general appearance and vary greatly in size, so that it is not always 

 easy to identify them. In shape they vary from early "ovate" to 

 "elliptical oval," "elongate ovate" or to nearly "fusiform." 



The color of the clean, freshly-laid egg varies from pale bluish 

 white to "cartridge buff," but the color, which is never quite pure, 

 soon becomes partly or wholly obscured by muddy, dirty, nest- 

 stains and the egg is often plastered over with mud and bits of nest 

 material, giving it a dark mottled appearance. Much of this can be 

 washed off, but the stains seem to be indelible. 



The measurements of 60 eggs, in the United States National 

 Museum, average 53.7 by 34.5 millimeters; the eggs showing the four 

 extremes measure 64.5 by 37.5, 49 by 33, and 50.5 by 30 millimeters. 



Young. The period of incubation proved to be 22 or 23 days for 

 eggs of this species which we hatched out in our incubators. 



The young are very precocious and can dive and swim instinctively 

 soon after they have hatched. As soon as they are able to feed and to 

 swim about they may be seen riding in safety on their mother's back 

 as she swims about the lake, clinging to her plumage when she dives 

 and coming to the surface with her, as if nothing had happened. 

 It is said that the mother bird turns her head and feeds the young 



