BLACK-THROATED DIVER. 297 



Black-throated Diver. Colymhus ardicus Linn. 



The Black-throated Diver (Plate 129), ranges over northern 

 Europe and Asia, and in winter visits the Mediterranean, 

 and other southern waters. It nests in the north of Scotland 

 and the Outer Hebrides, and exceptionally in Skye and tlfe 

 Orkneys. wSome birds remain all winter in Scottish waters, 

 but there is a general southerly movement in autumn, when, 

 and on the return in spring, the bird is not infrequent off our 

 coasts and on inland waters ; it is rare in English seas in 

 winter. On passage it is more regular on the west coast than 

 is supposed. 



There is little difficulty in distinguishing the three divers 

 when in summer plumage ; the fourth is very rare. In size 

 this species is intermediate and may be known by its sharply 

 denned, shield-shaped, purple-black throat, bordered on either 

 side by wavy white streaks. There is a half-collar of black and 

 white dashes above the shield, whereas the Great Northern 

 Diver has in addition a second and larger streaked collar. 

 The throat of the smaller species is red. The winter and 

 immature plumages are more difficult, but the ashy brown 

 upper parts are in this bird usually more uniform than in the 

 Great Northern, and are sprinkled with a few white spots, but 

 not so profusely as in the Red-throated. The best distinction is 

 in the bill, which is less massive than that of the larger bird, 

 and lacks the slight but perceptible uptilt of the Red-throated. 



Compared with the bulk, the short wings of the Black- 

 throated Diver look feeble, yet it can fly with speed and power ; 

 it flies straight, close to the surface or at a considerable ahitude. 

 The neck is outstretched in flight, but looks short and thick, 

 for there is little difference between the width of the head and 

 neck ; on the wing the bird is cigar-shaped. It swims low, 

 often with the lower neck awash, and forges forward with 

 great speed, turning its supple neck from side to side. At the 



