The Common Loon 



PETRELS are professional vagrants, but we have no guarantee that 

 this Oceanic cuss, who hailed from Antarctica, will ever turn up again off 

 our coasts, as he did (to his undoing — see specimen No. 18742, in Mus. 

 Vert. Zool., Berkeley) on August 24, 1910. 



Wilson's Petrel breeds in certain favored localities on the Antarctic 

 Continent, as well as on adjacent islands, and has been seen some sixty 

 miles from open water in Latitude 78 degrees 30 minutes South. It ap- 

 pears to be tireless on the wing, and has been compared both for the height 

 and the grace of its aerial evolutions with the Martins or the Swifts. In 

 this respect it is utterly unlike our native petrels, as well as by reason of 

 its long legs, which enable the bird to tread the water as though to steady 

 itself while picking up a dainty morsel. 



No. 417 



Common Loon 



A. O. U. No. 7. Gavia immer (Briinnich). 



Synonyms. — Loon. Great Northern Diver. 



Description. — Adult in summer: Head and neck black with metallic reflections, 

 most intense on lower neck; middle of the throat crossed by a narrow bar of white 

 streaks; a similar but wider bar on each side of neck lower down; underparts in general 

 pure white, the sides like back; a narrow open-V-shaped anal band of dusky; under 

 tail-coverts black or variously tipped with white; upperparts greenish black, sharply 

 spotted with white in regular transverse rows, — the spots mostly squarish, smallest 

 on the upper back and rump, largest on lower scapulars; the sides similarly ornamented 

 with rounded spots; sides of cervix black-and-white, streaked or striped; wing-quills 

 blackish, with warm purplish reflections. Bill black; feet and legs black externally, 

 yellow internally; iris carmine. Adult in winter and immature: Above dark brown, 

 clear and greenish glossed on crown and back of neck, feathers of the back, etc., more 

 or less heavily tipped with ashy gray or dull buffy; underparts white; throat white, 

 or faintly dusky-flecked-and-shaded, on sides of head and neck, shading or alternating 

 with brown of upperparts in large dentations; dusky of sides much restricted. Bill 

 light blue with dusky ridge; feet brownish dusky externally, yellowish internally. 

 Length 711. 2-914.4 (28.00-36.00); wing 355.6 (14.00); tail 66 (2.60); bill 73.66 (2.90), 

 along gape 101.6 (4.00); tarsus 86.4 (3.40). 



Recognition Marks. — Brant to eagle size; back black speckled with white; 

 head and neck black interrupted by white-streaked spaces; below white; large, pointed 

 bill. Large size distinctive as compared with other divers. 



Nesting. — Nest: A bulky platform of rushes or sticks and trash, on ground near 

 water, or else eggs laid in depression of sand or gravel. Eggs: 2, 3 of record; elliptical 

 oval, elongate ovate, or, rarely, fusiform; buffy olive or light brownish olive to brownish 

 olive, olive-brown, or rarely deep olive, spotted sparingly with darker or blackish. 



20J0 



