stercorariidjE: jaegers, or skuas. 975 



CcEca moderate ; sternum double-notched. Bill not cered ... Family Larid^ 



Bill epignathous. Tail usually square (Gulls) Subfamily Larinic 



Bill paragnathous. Tail usually forked. (Terns) Subfamily Sternina 



Bill liypoguatbous. Tail forlced. (Skimmers) Subfamily llhynchopiiUB 



Family STERCORARIID^ : Jaegers, or Skuas. 



Long-wiuged Swimmers with the horny covering of the epignathous bill discontinuous, 

 the upper mandible being saddled with a large "cere," perhaps deciduous, beneath the edges 

 of which the nostrils open (unique, among water-birds), and the dertrum or hook at the end 

 being also marked off from the rest. Tail nearly square, but middle pair of feathers abruptly 

 long-exserted in Stercorarius. Feet strong ; tibite naked below ; podotheca granular or other- 

 wise roughened behind, scutellate in front ; webs very full ; claws large, curved, acute. Certain 

 pterylographic characters have been already noted. A leading anatomical peculiarity is the 

 large size of the cceca, as compared with Laridce. Another is that the sternum is single-notched 

 behind, there being two notches on each side in the three subfamilies of Laridce. There are two 

 genera and six or seven species of the family. Only four species are well determined. They 

 belong more particularly to the Northern Hemisphere, although some also inhabit southern seas; 

 they mostly breed in boreal regions, but wander extensively at other seasons. They inhabit sea- 

 coasts, and also large inland waters ; the nidification resembles that of Gulls ; eggs 2-3, dark- 

 colored, variegated. The sexes are alike; the young more or less different; there is also a 

 2)articular melanotic plumage, apparently a normal special condition. At first the central tail- 

 feathers do not project, and they grow tardily. Skuas are eminently rapacious, whence their 

 name of "jaeger" (hunter); they habitually attack and harass Terns and small Gulls, until 

 these weaker and less spirited birds are forced to drop or disgorge their prey. Their flight is 

 vigorous ; lashing the air with the long tail, they are able to accomplisli the rapid and varied 

 evolutions required for the successful practice of piracy. Thus in their leading traits they are 

 marine Raptores ; whilst the cered bill and strong hooked claws furnish a curious analogy to 

 true birds of prey. {Lestridina of former editions of the Key, as a subfamily of Laridcs.) 



Analysis of Genera and Species. 



Bill shorter than middle toe without claw ; tarsus shorter than middle toe and claw ; central rectrices little project- 

 ing, broad to the tip. Megalestris. 



Of great size, and robu.st form. Bill 2 inches long vi. skua 



Smaller : bill and tarsi relatively longer than in the foregoing ; latter not shorter than middle toe and claw ; central 

 rectrices finally projecting far beyond the rest. Stercorarius. 



Central rectrices projecting about 4 inches, broad to the end, and twisted s. pomatorhiniis 



Central rectrices projecting about 4 inches, acuminate, not twisted s. parasilicus 



Central rectrices projecting 8-10 inches, acuminate, not twisted s. lotigicatida 



MEGALES'TRIS. (Gr. fiiyas, megas, great, large, and XrjcrTpis, lestris, piratical, from \i}sttjs. 

 testes, a robber, thief.) Skuas. Bill shorter than middle toe without claw; exceedingly ro- 

 bust; width at base about equal to height, which is a third of the length of culnien. Striae 

 and sulci numerous and well marked. Encroachment of feathers on bill moderate, and nearly 

 the same on both mandibles. Occiput scarcely crested. Wings only moderately long for this 

 subfamily ; primaries very broad, and rounded at their tips. Tail very short, broad, nearly 

 even, the feathers truncated ; central pair projecting about ^ an inch in adults, broad to their 

 very tips, which are also truncated. Feet large and stout; tarsi shorter than middle toe and 

 claw. Size large ; form robust and heavy ; general organization very powerful. Colors much 

 tiie same over the whole body ; not subject to any very remarkable changes with age, sex, or 

 season. One northern species, M. skua, occurring in North America, and two or three others 

 of southern seas, the best known of which is M. nntarctica. (As sul>genus of Stercorarius in 

 2d-4th eds. of Key. Buphagus Coues, 18(33, after Moehring, 1752, of 1st ed. of Key.) 



