STERCORARIUS. 21 



a 1 . Axillars and under wing-coverts sooty, with little or no rufous. 



b 1 . Below grayish brown, with more or less distinct lighter, more cinnamon- 

 colored, spots or dashes on fore-neck and chest. Adult : Dull brown, the 

 scapulars, interscapulars, and wing-coverts striped medially with pale 

 cinnamon, the neck streaked with the same; lower parts indistinctly 

 striped with grayish brown and pale cinnamon, the former prevailing 

 (sometimes uniform). Sometimes (in melanistic specimens?) uniform 

 dusky or sooty brown, except white wing-spot. Young : Similar to adult, 

 but more distinctly streaked with yellowish, especially on head and neck. 

 Downy young (of M. skua) : Uniform " brownish or cinnamon-gray . . . 

 rather darker in color on the upper parts than on the under surface of the 

 body." (Dresser.) Length about 22.00, wing 15.75-16.15 (15.91), cul- 

 men 2.05-2.10 (2.06), depth of bill at base .80-.88 (.82), tarsus 2.40-2.75 

 (2.63), middle toe 2.15-2.55 (2.40). Eggs 2-3, 2.74 X 1-96, ovate or 

 short-ovate, light brown or olive, rather sparsely blotched and spotted 

 with deep brown. Hab. Coasts and islands of North Atlantic, south to 

 Spain and (casually) Massachusetts ; California ? 



35. M. skua (BrDnn.). Skua. 

 b'. Darker colored, larger, and with stouter bill ; under parts uniform dark 

 sooty, the neck however sometimes streaked with yellowish ; wing 

 16.05-16.90 (16.29), culmen 2.20-2.85 (2.38), depth of bill at base .95-1.00 

 (.98), tarsus 2.70-3.20 (2.95), middle toe 2.55-2.80 (2.67). Sab. Antarctic 

 seas, north to Cape of Good Hope and Cape Horn. 



M. antarcticus (Less.). Antarctic Skua. 1 

 a 2 . Axillars and under wing-coverts chiefly deep cinnamon. 

 Lower parts uniform dull rusty or cinnamon. 



M. chilensis (Bonap.). Chilian Skua. 2 



Genus STERCORARIUS Brisson. (Page 20, pi. VII., fig. 2.) 



Eggs 2-3, ovate or short-ovate, ground-color varying from pale greenish olive 

 and pale brown to very deep olive, relieved by a greater or less amount of spotting 

 of deep brown, usually mixed with stone-grayish. 



Species. 



a 1 . Culmen 1.45 or more, tarsus 2.00 or more, wing usually more than 13.50 ; length- 

 ened middle tail-feathers broad and rounded at ends. Light phase, adult : Top 

 and sides of head, with upper parts, sooty slate or dusky ; rest of head and 

 neck, including nape, together with lower parts, white, the ear-covert region 

 tinged with straw-yellow, and the lower tail-coverts slaty. Young : Head, 

 neck, and lower parts dull buff, everywhere barred with dusky ; upper parts 

 brownish dusky, the feathers of back, etc., tipped with buff, the rump and 

 upper tail-coverts spotted with same. Dark phase, adult : Entirely dark sooty 



1 Lestris antarcticus Less., TraitS Orn. 1831, 616. Megalestris antarcticus Gould, P. Z. S. 1859, 98. 



2 Lestris antarcticus, Tar. b. chilensis Bonap., Consp. ii, 1857, 207. 



