328 LONG-WINGED SWIMMERS — LONGIPENNES. 



Family STERCORARIID^. — The Skuas and Jaegers. 



Char. Covering of the maxilla not entire, as in the Laridcv, the basal half 

 being furnished with a horny cere, the lower edge of which overhangs the nostrils; 

 toes fully webbed ; claws strongly curved ; tail more or less graduated, the central 

 pair of rectrices projecting a greater or less distance beyond the rest. 



The Family Stercorarildm is separable from the Larido} chiefly on account of the 

 peculiar bill, which shows a not distant approach in character to that of some forms 

 of the Ixaptores. The species are all predatory in their nature, the smaller kinds 

 pirating upon the Gulls and other sea-fowl, the larger ones beating along the shores, 

 or even over the land, and preying upon varioi;s birds, much in tlie manner of the 

 Falconidci'. Indeed it is said that at Kerguelen Island the Mefjalestris antarcticus is 

 seldom seen near the water, but keeps strictly to the land, where it is very destructive 

 to Ducks aiid otlu'r water-fowl. 



Tlie two North American genera may be thus defined : — 



Megalestris. Size large (about equal to Larus argentatus), form robust and powerful ; depth 

 ui' the liill through the base equal to one half or more of the length of the mandil^le meas- 

 ured along the side ; tarsus shorter than the middle toe and claw ; tail short, the middle 

 rectrices scarcely projecting beyond the rest. 



Stercorarius. Size medium (about that of the medium-sized Gulls, Larus delawarensis and 

 caniis), form more graceful and slender ; depth of bill through the base less than one half 

 the length of the mandible, measured as above ; tarsus decidedly longer than the middle 

 toe and claw ; middle rectrices (in full adult birds) projecting far beyond the rest. 



Genus MEGALESTRIS, Bonaparte. 



Catharactn, Brijnn. Orn. Ror. 1764, 32 (type, C. skua, Brijnn.) ; nee Catharadcs, Briss. 1760. 

 Megalestris, Bonap. Cat. Parzudaki, 1856, 11 (type, Larus catarractes, LiNN. = Catharacta skua, 



Brunn.). 

 Buphagus, " Moeiir.," CouEs, Pr. Phil. Acad. 1863, 124 (same type). 



The characters of this genus have been sufficiently indicated above. Only three species (per- 

 haps more properly geographical races) are known, but one of which (M. skua) belongs to the 

 North American fauna; the other two belonging, one to Chili, the other to the Antarctic seas. 



Megalestris skua. 



THE SKUA GULL. 



Catharacta skua, Brunn. Orn. Bor. 1764, 33. 



Buplmgus skua, CouES, Pr. Acad. Nat. Sci. Philad. 1863, 12.5 ; B. N. W. 1874, 604. 



Stercorarius (Buphagus) skua, CoUEs, Key, 1872, 309. 



Stercorarius skua, Coues, Check List, 1873, no. 539 ; ed. 2, 1882, no. 764. 



Megalestris skua, PiIDGW, Nom. N. Am. B. 1881, no. 696. 



Larus catarractes, Linn. S. N. L 1766, 226. 



Lestris catarractes, Tlmg. Prodv. 1811, 272. — Nutt. Man. II. 1834, 312. 



Stercorarius catarractes, Bonap. Consp. II. 1856, 206. — Lawr. in Baird's B. N. Am. 1858, 838. 



Baird, Cat. N. Am. B. 1859, no. 652. — Elliot, lUustr. B. Am. II. pi. 56. — Saunders, 



P. Z. S. 1856, 319. 

 Catarracta fusca, Leach, Syst. Cat. 1816, 40. 



