94 BRITISH BIRDS 



186. Redthroated - diver \Qawa, stellata (Pontoppidan) ; 

 Colymbus septentrionalis Linnaeus]. Breeds in Scotland and 

 Ulster. Winter visitor and bird of passage to all our coasts, 

 also to inland waters. 



Bird. Length 24 in., therefore much smaller than the 

 preceding, and easily distinguished in breeding plumage by 

 the chestnut-red throat and the dark brown, instead of black, 

 mantle which is without the conspicuous bands of white spots, 

 being merely flecked with white or buff. Like the rarer Uack- 

 throated-diver (No. 187), it has the head and nape ash-grey, but 

 streaked white and black-brown down the hinder top of the head 

 and the nape, these darker streaks continuing down the white 

 neck, sides, and flanks. Under-parts white. After the autumn 

 moult it is distinguished by its smaller size (see No. 187). 



Nest. Usually on the margin of a small lake or hill tarn, 

 less often on an islet in the same ; a depression in the 

 ground made by the bird, and more or less lined with a few 

 bents, rushes, &c. 



Eggs. Usually 2. From chocolate to olive-brown, sparingly 

 spotted with brownish-black. Av. size, 2*89 x 1-82 in. Laying 

 begins in May. One brood. 



187. Blackthroated-diver [Gavia arctica (Linnaeus) ; Colym- 

 bus arcticus Linnaeus]. Breeds Perth and Argyll, north to the 

 Shetlands. Uncommon winter visitor and bird of passage on 

 our coasts. 



Bird. Length 27*5 in. Sexes alike. Distinguished in 

 breeding plumage from both the preceding by the uniform 

 ash-grey of the head and neck, with slate-grey on the crown. 

 Back and wings greenish-black with white spots forming bars. 

 Throat purplish-black. Longitudinal black and white stripes 

 on sides of neck and breast. Flanks black. Rest of under- 

 parts white. See Nos. 185-6. After the autumn moult the 

 ash-grey becomes pale brown. Ash-brown without spots on 

 the rest of the upper-parts. Under-parts white, except the 

 brownish-black flanks. The redthroated form also has the 

 under-parts white, but the flanks and upper-parts are slate- 

 grey, the latter being mostly spotted or speckled with white. 

 The young blackthroated-diver resembles the adult in winter, 

 but has grey margins on the upper-parts, these being white in 

 the young redthroated-diver. 



Nest. Usually on islets in lochs. A depression in the vege- 

 tation, sometimes lined with heather, grass, &c. 



Eggs. Usually 2. Olive-brown to olive-green or deep brown 

 sparingly spotted with blackish-brown. Av. size, 3'33x2'04 

 in. Laying begins May. One brood. 



