310 LAPJD^, GULLS. 



jecting 8 or 10 inches, very slender and almost filanieiitous for a great part of 

 their length ; smaller still ; wing about 12 ; tail about 6 ; tarsus 1J-1§ ; bill 

 1-1^ ; plumage as in the last. Same habitat. Lestris parasiticus Sw. and 

 EicH., F. B.-A. ii, 430; Nutt., ii, 317; Aud., vii, 192, pi. 453; 8. cep- 

 phus Lawr. in Bd., 840; S. buffonii Coues, I. c. 136. . . . buffonii. 



Subfamily LARINJE . Gulls. 



Coverhig of bill continuous, hornjr throughout : bill more or less strongly epi- 

 gnathous, compressed, with more or less protuberant gonys ; nostrils linear-oblong, 

 median or sub-basal, pervious. Tail even or nearlj^ so, rarely forked or cuneate, 

 without projecting middle feathers. Certain of the smaller slenderer-billed species 

 alone resemble terns, but maj^ be known by the not forked tail (except Xe7na) ; in 

 all the larger species, the hook of the bill is distinctive. Gulls average much larger 

 than terns, with stouter build ; the feet are larger and more ambulatorial, the wings 

 are shorter and not so thin ; the birds winnow the air in a steady course unlike the 

 buoyant dashing flight of their relatives. Thej^ are cosmopolitan ; species occur in 

 abundance on all sea coasts, and over large inland waters ; in general, large numbers 

 are seen togetlier, not only at the breeding places, but during the migrations, and 

 in winter, when their association depends upon community of interest in the matter 

 of food. This is almost entirely of an animal nature, and consists principally of 

 fish ; the birds seem to be always hungry, always feeding or trving to do so. Many 

 kinds procure food bj^ plunging for it, like terns ; others pick up floating substances ; 

 some of the smaller kinds are adroit parasites of the pelicans, snatching food from 

 tlieir very mouths. They all swim lightly — a circumstance explained by the small- 

 ness of the body compared with its apparent dimensions with the feathers on. The 

 voice of the larger species is hoarse, that of the smaller shrill ; thej'" have an 

 ordinary note of several abrupt syllables during the breeding season, and a harsh cry 

 of anger or impatience ; the young emit a querulous whine. The nest is commonly 

 built on the ground ; the eggs, 2-3 in number, are variegated in color. 



Several circumstances conspire to render the study of these birds difficult. 

 With few exceptions, they are almost identical in form ; while in size they show an 

 unbroken series. Individual variabilitj' in size is high ; northerly birds are usually 

 appreciably larger than those of the same species hatched further south ; the <y 

 exceeds the 9 a little (usually) ; very old birds are likely to be larger, with espec- 

 ially stouter bill, than young or middle aged ones. There is, besides, a certain plas- 

 ticity of organization, or ready susceptibility to modifying influences, so marked 

 tliat the individuals hatched at a particular spot may be appreciabl}' ditferent in some 

 slight points from others reared but a few miles away. One pattern of coloration runs 

 through ueaidy all the species : they are ivhite, with adarker mantle {stragulum ; § 38, 

 p. 1 7) , and in most cases with black crossing the primaries near the end, the tips of the 

 quills white. The shade of the mantle is very variable in the same species, accord- 

 ing to climate, action of the sun, friction and other causes ; the pattern of the 

 black on the quills is still more so, since it is conUnuaUy changing with age, at least 

 until a final stage is reached. Incredible as it may appear, species and even genera 

 have been based upon such shadowy characters. One group of species has the 

 head enveloped in a dark hood in the breeding season, the under parts tinted with 

 petich-blossom hue. The sexes are always alike ; the moult appears to be twice a 

 year, so that a winter plumage more or less ditferent from that of summer results ; 

 while the young are never like the old. The change is slow, generally requiring 



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