STERCOUAiUIU.K— THE SKUAS AiNl) JAEUKUS. 217 



aS*. pomariniis. Occasionally the middle rectrices are nearly as 

 long and attenuated as in S. longlcaudm, and in the plumage 

 there is sometimes hardly any difference between examples of 

 the two species. They differ constantly, however, in the form 

 of the bill and, in adult birds, in the color of the tarsi: n binl 

 with black tarsi and having the nasal shield (measured along 

 the culmen) decidedly longer than the terminal portion of the 

 bill (from the point to the anterior edge of the nostril) being 

 with coi'tainty S. j}itr<(n!tivax, while an example iu adult plumage 

 having pale bluish tarsi and the nasal shield not longer than 

 the terminal portion of the bill, is sure to be S. longicaudiw. 

 It is scarcely probable that the two forms are conspecific, but 

 possibh' they maj' interbreed to a slight extent, and thus ]jro- 

 duce hybrids. 



The Parasitic Jaeger is known as an Illinois bird only on ac- 

 count of its occasional occurrence on Lake Michigan during 

 winter. Its habits are not obviously different from those of 

 the Pomarine Jat^ger {S. pomariniis), as briefly described on 

 page 214. 



Stercorarius longicaudus Vieill. 



LONG-TAILED JAEGES. 



Popular syDOnyms. Arctic Jaecer; Buffou's Skua; Long-tailed Bliua; Wliip-iail icod- 



flshormi-n); Marling-spilte (do.). 

 Stercorarius longicaudas Vieill. Ncuv. Diet, xxxii. 1819. 157.— Stejn. Proc. U. 8. Nat. 



Mu9. V, 1882, 42.— B. B. & K. Water B. N. Am, li, 1884, .T3!).— A. 0. U. Cheek List. 



188«, No. S8.— Broow. Man. N. Am. B. 1887. 23. 

 Stercorarius lonaicandutus De Selys, Faun. Bolg. 1842, 156. 

 Lestrts parasitica Illio. rroilr. 1811, 273 (nee Larus parasiticus LiNN.).— LB88. Man. 



ii, 1828. 288.— S\v. & Ilicn. F. B.-A. ii. 1831, 430.— NuTT. Man. il, 1834. 317. 

 Lestris parasiticus Temm. Man. Orn. ed. 1815, 512.— AuD. Orn. Biog. lii, 1835, 470, 



Synop. 1839, 333; B. Am. vii, 1844, 192, pi. 4.''>2. 

 Stercorarius parasiticus Saund. P. Z. 8. 1876, 330.— BlDOW, Nom. N. Am. B. 1881, No. 



699. 

 Laru» erepidata Bbebm & Scbill. Beit. Z. V6k. iii. 1822, 212 {nee BjiNEBl. 

 Lestris buffoni BoiE, ,Heyer'8 Tasoh. iii. 1822, 212.— DeK^t. N. Y. ZooI. il, 1844, 315. pi. 133. 



flK. 291. 

 Stercorarius l,uff„ni CoUES, Proc. Acad. Sei. Pliila. 1803, 1.36; Key, 1872, 309; Check List, 



187.1, No. M2: 2d <^d. 1882. No. 767; B. N. W. 1874,615. 

 Stercorarius cepnhus Stephens, Shaw's Oen. Zool. xili.l82C, 211, pi. 2:1.- Lawr. in Baird's 



B. N. Am. 18.58. 810.-BAinD, Cat. N. Am. B. 18.V.I, No. 655. 

 Lestris microrlit/nrlius Bbeiim, Handb. V6(f. Deut«chl. 1831. ?2S. 

 Lestri' lessoni Deol. Mem. Ac. K. Lille, 1838,108. 

 lycstris brachvrhynchus BliEUM, VoRolf, IKSS.SJ?. 



—28 



