LIFE HISTORIES CF NOETH AMERICAN DIVING BIRDS. < O 



Dr. Joseph Grinnell (1909) describes a nest found at Glacier Bay, 

 Alaska, on July 16, 1907, as follows : 



This was in the ranli grass at the edge of a pond a few yards baclj from the 

 shore of one of the small islands on the east side of the bay. The parent was 

 seen to swim away from the nesting place, and by her peculiar actions indicated 

 its proximity. There were two eggs on the point of hatching. Instead of the 

 usual floating structure, the eggs in this case rested on the bare, wet mud, 

 2 feet back from the water's edge, there being no nesting material whatever. 



Eggs. — The red-throated loon, like others of this genus, regularly 

 lays two eggs. Most writers agree that this is the invariable num- 

 ber, but Audubon and some others have stated that three eggs are 

 often laid. Sets of three must be exceptional, and occasionally one 

 egg ma}^ be all that a nest contains. Frequently only one young 

 bird is hatched, but in such cases the other ^gg is infertile. 



The Q^,g is " elliptical ovate " or " cylindrical ovate " in shape, 

 with occasionally a tendency toward " ovate " or toward " fusiform," 

 The shell is smooth and somewhat glossy. The ground color is 

 " bister " or " sepia " in the darkest eggs, " auburn," " Brussels 

 brown," " brownish olive," " light brownish olive," or " Saccardo's 

 umber " in others, and " Isabella color " or " deep olive buff " in the 

 palest eggs. Some eggs are nearly spotless, but usually they are 

 sparingly and irregularly spotted with small spots or with scattering 

 larger spots, rarely with irregular blotches, of the darkest shades 

 of brown, such as " clove brown " and " blackish brown " ; some eggs 

 also have underlying spots of various shades of drab and very rarely 

 these are the only markings. The measurements of 58 eggs, in the 

 United States National Museum, average 72.5 by 45 ; the eggs show- 

 ing the four extremes measure 80 by 47, 79.5 by 48, 62.5 by 41.5, 

 and 68 by 40.5 millimeters. 



The period of incubation seems to be unlmown; it is probably 

 somewhat less than that of the common loon, as it is a smaller species. 

 Both Yarrell (1871) and Macgillivray (1852) state that both sexes 

 assist in the incubation. Certainly the pairs remain together all 

 through the breeding season, to guard the nesting site and to care 

 for the young jointly. Macgillivray (1852) says: 



The female continues to sit, crouching over her eggs, until a person comes 

 very near, when she starts forward, plunges into the water, and on emerging 

 usually takes to wing, but sometimes swims about with great anxiety, as does 

 the male, should he happen to be present. On being deprived of their eggs, 

 they may be heard for several evenings lamenting their loss with loud melan- 

 choly cries. 



Young. — Both parents are very solicitous in the care of the young. 

 When danger threatens the old bird sinks her body below the sur- 

 face, with only the head and neck stretched up above it, the young 

 bird climbs upon her back and she swims away with him to safety. 



