410 BRITISH BIRDS. 



were substantial structures, about a foot in diameter and two or three 

 inches high. The foundation was composed of dock-stalks and roots, upon 

 which was a lining of fresh green grass and herbs, the whole forming a 

 bond fide nest as different as possible from the slovenly debris on which its 

 Red-throated cousin lays its eggs. The gamekeeper assured me that the 

 Black-throated Diver always makes a substantial nest ; but this statement 

 does not agree with the observations of many ornithologists." 



Two is the usual number of eggs, but sometimes one only is laid. The 

 ground-colour is dark or light russet-brown, sometimes with a slight shade 

 of olive. The spots are nearly black, sparingly distributed over the surface, 

 rather more profusely at the larger end, and seldom as big as a pea. The 

 underlying spots are few and indistinct. The eggs vary in length from 

 3*5 to 2'9 inch, and in breadth from 2'2 to T9 inch. It is very important 

 that eggs of this bird should be carefully identified, as large examples 

 cannot be distinguished from small eggs of the Great Northern Diver, nor 

 small examples from large eggs of the Red-throated Diver. 



The Black-throated Diver cannot be regarded as a gregarious bird, 

 though it migrates in flocks. In the breeding-season two or three pairs 

 sometimes breed on the same lake, but they associate very little, and in 

 winter the adults are for the most part solitary, though the immature 

 birds frequently flock together. They are difficult birds to shoot, diving 

 at the flash, and when alarmed having the power of sinking in the water, 

 so that often only the head and neck are visible ; they are able to do 

 this, in consequence of the backward position of their feet, as long as they 

 continue in motion. 



There is no difference in colour between the sexes of this species. In 

 nuptial plumage the forehead, nape, and hind neck are pale slate-grey ; the 

 general colour of the rest of the upper parts is black, faintly glossed with 

 purple and green, with rows of large, nearly square, white spots on the 

 scapulars ; there is a similar pattern, on a smaller scale, on each side of the 

 upper back, and smaller oval white spots on the median and greater wing- 

 coverts ; the chin and upper throat are purplish grey, which shades into the 

 slate-grey of the crown on the sides of the head ; the lower throat is black, 

 glossed with purple, separated from the upper throat by a row of short, white 

 streaks, and from the hind neck by rows of long, white stripes, which are 

 continued on the sides of the lower neck, not quite meeting in the centre 

 of the neck ; the flanks are black, but the rest of the underparts, including 

 the axillaries and under wing-coverts, are silky white. Bill black ; legs and 

 feet dark brown; irides crimson. After the autumn moult the general 

 colour of the upper parts is an almost uniform blackish brown, and that of 

 the underparts, except the flanks, but including the sides of the face below 

 the eye, pure white. In young in first plumage all the small feathers of 

 the upper parts and the flanks have broad pale slate-grey margins, and 



