322 THE NESTS AND EGGS OF 



Family COLYMBTD^. Genus Colymbus. 



GREAT NORTHERN DIVER. 



Colymbus glacialis, Liniiceus. 



(British : Possibly breeds ; fairly common nomadic autumn and 

 winter migrant.) 



Single Brooded. Laying season, June. 



Breeding area : Northern Nearctic region, extreme 

 North-western Palaearctic region. The Great Northern 

 Diver is not known to breed anywhere in Europe except 

 in Iceland. It is an American species, breeding from 

 Greenland westwards across the Nearctic region, south 

 of the Arctic Circle to Alaska, and southwards to the 

 Northern United States from Dakota to Michigan, New 

 York, and Maine. 



Breeding habits : The Great Northern Diver 

 reaches its breeding grounds towards the end of May, 

 or early in June, as soon as the waters it frequents are 

 free from ice. It is a nomadic species, and wanders no 

 further south than the necessities of life demand. The 

 favourite breeding haunts of this Diver are the wild and 

 secluded northern lakes and tarns. It is not gregarious, 

 and breeds in isolated pairs which show no social 

 tendencies. There can be little doubt that this Diver 

 pairs for life, and is much attached to certain breeding 

 places. Wherever possible, an island is preferred for a 

 nesting site. The nest varies a good deal in construction, 

 according to the locality frequented. Where the ground 

 is marshy, it is large and flat, and composed of a heap 

 of half-rotten sedges, rushes, reeds, and similar aquatic 

 v^egetation, lined with drier and finer material, such as 

 bits of broken reeds and withered grass. Wliere the 

 shore of the lake is dry and bare, the nest is little more 



