THE GREAT AUK. 795 



to western Mediterranean to Malta and casual Adriatic, Maroccan 

 coast to Mazagan, and casual Canary Islands (once Azores), in 

 America to Long Island and casually to North Carolina. Recorded 

 from Bear Island and Spitsbergen. 



ALCA IMPENNIS 



466. Alca impennis L.— THE GREAT AUK. 



Alca impennis Linnaeus, Syst. Nat., ed. x, i, p. 130 (1758 — Arctic 



Europe). 



Alca impennis Linnseus, Yarrell, iv, p. 61 ; Saunders, p. 697. 



Description. — Adult male and female. Summer. — Apparently 

 moulted body-feathers as Razorbill. Large white patches roughly 

 oval in shape in front of eyes each extending from near base of 

 exposed culmen to about middle of orbit and to within 5 mm. of 

 horny ridge along gape, divided on top of fore-head by black line 

 about 12 mm. wide ; rest of plumage like adult summer Razorbill 

 but white tips to secondaries rather narrower and under wing- 

 coverts hoary-brown and not white ; white extending rather 

 further up centre of throat and in a sharper V-shape rather than 

 U-shape. Winter. — No specimen examined but chin and throat 

 described as white as in winter Razorbill. 



Measurements and structure. — Wing 160-1 78 mm., tail 83-95, tarsus 

 55-62, bill from feathers 85-90, greatest depth 44-46 (3 measured). 

 Primaries : 1st longest, 2nd 2-5 mm. shorter, 3rd 8-15 shorter, 

 4th 18-22 shorter, 5th 27-32 shorter. Bill shaped much as in 

 Razorbill but upper mandible not so arched, deep groove at base of 

 exposed portion of upper mandible as in Razorbill but rest of 

 proximal half smooth and flat, distal half with six or seven deep, 

 narrow, grooves closely set and curved backwards on ridge of 

 culmen, under mandible with no groove at base and distal part 

 with nine or ten more or less straight grooves. Rest of structure as 

 Razorbill but wing much reduced in size actually smaller than 

 Razorbill's although bird itself twice as large, primaries extending 

 only about 45 mm. beyond primary-coverts against 75 in Razorbill. 

 Tail small but otherwise like that of Razorbill, wedge-shaped, 12 

 feathers, pointed and narrow, central pair longest. 



Soft parts. — Bill, legs and feet black. 

 Breeding-habits. — Formerly bred in colonies on shelving rocks 

 and low-lying skerries and islands, making no nest. Egg. — One 

 only, pyriform, probably ranging in colour from greenish or bluish 

 to creamy-yellow or white, blotched and spotted or sometimes 

 streaked with varying shades of dark brown to black. Average 

 size of 36 eggs, 123.4 x 76.4 mm. Max. : 140 X 70 and 126.5 x 83.5. 

 Mn.: 111x72.2 and 113.8x70.6 mm. Breeding -season and 

 Incubation. — No reliable data. 



Food. — Little definite recorded but Fabricius specifies Cottus 

 scorpio and the lump-fish [Cyclopterus lumpus). Naumann adds 

 Clupea sp. and W. Blasius includes Crustacea (crabs, etc.). 



