7 34 SYSTE3IA TIC SYNOPSIS. — L ONGIPENNES — GA VI^. 



heavy dark blotches. Nidification nonnally teirostrial ; reproduction altricial; yoimg ptilo 



pfedic. 



Analysis of Subfamilies. 



Bill epignathous, cered. (Jagers) Lesteidin^ 



Bill epiguathous, not cered. (Gulls) I^arik^s: 



Bill paragnatlious. (Terns) Stkknikjs 



Bill bypognathous. (Skimmers) ^ . . . RHyNCHOPiK^ai 



70. Subfamily LESTRIDIN>E: Jagers, or Skua Culls. 



Covering of bill discontinuous, the upper mandible being saddled with a large horny 

 " cere," beneath the edges of which the nostrils open (unique, among water-birds) ; bill epigna- 

 thous. Tail nearly square, but the middle pair of feathers abruptly long-exserted. Feet 

 strong ; tibiae naked below, the podotheca granular or otherwise roughened behind, scutellate 

 in front ; webs full ; claws large, curved, acute. Certain pterylographic characters have been 

 already noted. A leading anatomical peculiarity in the large size of the cceca, as compared 

 with the cases of the other subfamOies. Another is that the sternum is single-notched behind, 

 there being two notches on each side in the other subfamilies. There is but one genus, and 

 only four species are well determined. They belong more particularly to the northern hemi- 

 sphere, 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 the gulls ; eggs 2-3, dark-colored, variegated. The sexes 

 are alike ; the young different, excepting one species ; there is also a particular melanotic plum- 

 age, appai'ently a nonnal special condition. At first the central tail-feathers do not project, 

 and they grow tardily. The skua gulls are eminently rapacious, whence their name of " jager " 

 (hunter) ; they habitually attack and harass terns and the smaller gulls, until these weaker and 

 less spmted birds are forced to drop or disgorge their prey. Their flight is \dgorous ; lashing 

 the air with the long tail, they are able to accompUsh 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 furnishes a curious analogy to the true birds of prey. 

 307. STERCORA'KIUS. (Lat. sfercoranws, a scavenger.) Jagers. Character of the subfamily, 

 as above. The species of Megalestris differs decidedly fi'om the rest, and might form a genus 



apart. 



Analysis of Species. 

 Bill shorter than middle toe witbout claw ; tarsus shorter than middle toe and claw ; central rectrices little 

 projecting, broad to the tip. (Megalestris.) 



Of great size, and robust form. Bill about 2 inches long skua 764 



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. 



Central rectrices projecting about 4 inches, broad to the end pontatorkinus 765 



Central rectrices projecting about 4 inches, acuminate parasiticus 766 



Central rectrices projecting 8-10 inches, acuminate buffoni 767 



764. S» sku'a. (Faeroese name.) Skua. Bill shorter than the middle toe without the claw ; 

 exceedingly robust ; width at base about equal to the height, which is a third oi the length of 

 culuien. Strife and sulci numerous and well marked. Encroachment of feathers on bUl 

 moderate, and nearly the same on both mandibles. Occiput scarcely crested. Wings only 

 moderately long for this subfamily ; the primaries very broad, and rounded at their tips. Tail 

 very short, broad, nearly even, the feathers truncated ; central pair projecting but little, and 

 broad to their very tips, which are also truncated. Feet large and stout ; tarsi shorter than 

 the middle toe and claw. Size large; form robust and heavy; general organization very 

 powerful. Colors much the same over the whole body ; not subject to any very, remarkable 

 changes with age, sex, or season. Adult $ 9 ; Latero-nuchal feathers elongated, rigid, with 

 long disconnected fibrillte. Above, blackish-brown, more or less variegated with chestnut and 



