634 THE LOON. 



"During the day we invariably found the eggs concealed by a covering of 

 muck, as above described, but, as we ascertained by repeated visits at night 

 and in the early morning, they are uncovered at dusk by the bird, who incu- 

 bates them until the morning sun relieves her of her task." 



The eggs are probably covered thus only when there is danger of their be- 

 ing discovered by predatory Gulls and the like, as I have found them in 

 certain Illinois swamps, where no such danger existed, quite exposed. 



The hardiness of the unhatched chick may be inferred from the preced- 

 ing account. I once took a set of four eggs so incrusted with filth that not even 

 soap and water and a bristle-brush would restore the original color. Finding 

 time two days later to remove their contents, I was somewhat disconcerted 

 when the disimprisoned young ones cheeped lustily, forty hours from the nest. 



No. 317. 



LOON. 



A. O. U. No. 7. Gavia imber (Gunn.). 



Synonym. GREAT NORTHERN DIVER. 



Description. Adult in summer: Head and neck black with metallic re- 

 flections, most intense on lower neck; middle of the throat crossed by a narrow bar 

 of white streaks; a similar but wider bar on each side of neck lower down; 

 under-parts pure white ; upper parts greenish black, sharply spotted with white 

 in regular transverse rows, the spots mostly squarish, smallest on the upper 

 back and rump, largest on lower scapulars ; the sides black, similarly ornamented 

 with rounded spots ; sides of cervix black and white, streaked or striped ; wing- 

 quills blackish, with warm purplish reflections ; bill black ; feet and legs black 

 externally, yellow internally ; iris carmine. Adult in winter and immature : 

 Above dark brown, clear and greenish glossed on crown and back of neck, feath- 

 ers of the back, etc., more or less heavily tipped with ashy gray or dull buffy ; 

 entire under-parts, including sides, white, shading on sides of head or alternating 

 with brown of upper parts in large dentations; bill light blue with dusky ridge; 

 feet brownish dusky externally, yellowish internally. Length 28.00-36.00 (711.2- 

 914.4) ; wing 14.00 (355.6) ; tail 2.60 (66.) ; bill 3.00 (76.2) ; along gape 4.00 

 (101.6); tarsus 3.40 (86.4). 



Recognition Marks. Brant to Eagle size ; back black speckled with white ; 

 head and neck black interrupted by white-streaked spaces; below white; large, 

 pointed bill. Large size distinctive as compared with other divers. 



Nest, a mere depression in sand or gravel, etc., near the edge of lake or pond. 

 Eggs, 2, dark brown or olive-brown, faintly and sparingly spotted with darker 

 or blackish. Av. size, 3.50 x 2.25 (88.9 x 57.2). 



