470 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



bill 67-75. Seven unsexed examples : wing 365-395, bill 65-80. 

 Bill thus usually longer than in C. immer and shape different, upper 

 line of top of upper mandible being remarkably straight and not 

 descending towards tip, sides of bill natter not so rounded as in 

 C. immer, upward slope of gonys more abrupt than in C. immer 

 and forming a more sharply denned angle with line of basal half, 

 giving tip of lower mandible slightly upturned appearance. 



Soft parts. — As in C. immer but bill of adult whitish -yellow 

 tinged brownish at base, of young whitish, dusky at base. 



Breeding-habits. — Very little definitely recorded but probably 

 resembles Great Northern Diver closely. Nest. — On hummock 

 surrounded by water or a few feet back from water's edge on island 

 or close to edge of pool on tundra. Eggs. — 2, very similar in colora- 

 tion to those of C. immer. Average of 17 eggs, 89x56.9. Max. : 

 95x60 and 92x66. Min. : 80x56 and 85x53.5 mm. (Bent). 

 Breeding -season. — From early June in Alaska onward. Incubation. 

 - — No exact data ; probably similar habits to C. immer. 



Food. — Hardly any reliable information. Fish, including Cottus, 

 nearly 11 in. long (Collett). 



Distribution. — Great Britain. — One near Embleton (Northumber- 

 land) Dec, 1829, one Pakefield, near Lowestoft (Suffolk) spring 

 1852. [One Hickling (Norfolk) Dec, 1872, one Northumberland 

 Jan., 1879, one Loch Fyne (Argyll.) autumn 1893, and another 

 Suffolk are C. immer. Others recorded Emsworth Harbour (Hants) 

 winter 1895-6 and Filey (Yorks.) Jan., 1897, are uncertain, cf. Brit. 

 Birds, xvi, pp. 9-12 and 59.] 



Distribution. — Abroad. — Arctic portions of Northern Hemisphere 

 from Taimyr eastward in Old World. In winter more to the south ; 

 in America to Nushagak, Alaska, Greenland, in Europe rare Scan- 

 dinavia, Finland, Caspian Sea, Austria-Hungary and apparently 

 twice in Italy. Casual Japan and Commander Islands. 



COLYMBUS ARCTICUS 



358. Colymbus arcticus arcticus L.— THE BLACK-THROATED 

 DIVER. 



Colymbus arcticus Linnaeus, Syst. Nat., ed. x, i, p. 135 (1758 — Europe 



and America. Restricted typical locality ; Sweden). 



Colymbus arcticus Linnaeus, Yarrell, iv, p. 105 ; Saunders, p. 713. 



Description. — Adult male and female. Winter. — Fore-head, crown 

 and back of neck brown washed greyish ; base of back of neck and 

 rest of upper -parts black-brown and somewhat glossy, some 

 scapulars with a pair of small subterminal whitish spots ; under- 

 pays white ; white on sides of head extending from base of lower 

 mandible under eye and slightly backwards on sides of nape with 

 slight mottling at juncture of white and brown ; usually a narrow 

 line of brown-tipped feathers across upper -throat ; at base of 

 sides of neck and sides of upper -breast white, feathers next to brown 



