982 SYSTEMATIC SYNOPSIS.— LONGIPENNES. 



Arctic circle, and seldom wandering in winter so far south. It is less common in the U. S. at 

 that season, and mainly observed in the Northern States; but is known to have reached the 

 Gulf of Mexico. {S. parasiticus of many writers ; S. erepidatus of some ; S. buffoni of former 

 editions of the Key; S. longicaudus A. 0. U. Lists, No. 38.) 



Family LARID^ : Gulls, Terns, Skimmers. 



Lon^-winged SvA'immers with horny covering of bill continuous (no cere) ; lateral nostrils 

 pervious (and not tubular) ; middle tail-feathers not long-exserted ; coeca of moderate length, 

 and sternum double-notched on each side of posterior border. The characters of LaridcB 

 as defined are simply those of the order Longipennes or Gavice, minus those of the family 

 StercorariidcB (see p. 975). This family is a large and important one, including 18 or 20 

 genera and some 110 species, of all parts of the world — all of the order excepting the 6 or 

 7 species of Skuas or Jaegers. It is obviously and naturally divisible into 3 subfamilies, 

 according to the analysis on p. 975 ; and these subfamilies are more fully described under the 

 following heads of Larince, SternincE, and Rhi/nchopince. 



Subfamily LARIN>E: Culls. 



Bill more or less strongly epignathous, compressed, with more or less protuberant gonys ; 

 nostrils linear-oblong, median or sub-basal, pervious. Tail even or nearly so, rarely forked 

 (in Xema and Creagrus') or cuneate (in BJwdostethia) , without projecting middle feathers. 

 Certain of the small slender-billed species resemble Terns, but may be known by the not 

 forked tail (except Xema) ; in all the larger species, the hook of the bill is distinctive, and 

 the short symphysis of the lower mandible makes a prominent gonydeal angle. Gulls average 

 much larger than Terns, with stouter build; the feet are larger and more ambulatorial, the 

 wings are relatively shorter and not so narrow ; the birds winnow the air in a steady course 

 unlike the buoyant dashing flight of their relatives. They are cosmopolitan ; species occur in 

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

 seen together, not only at their 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 trying to do so. Many kinds procure food by plunging for 

 it, like Terns ; others pick up floating substances ; some of the smaller kinds are adroit para- 

 sites of Pelicans, snatching food from their very mouths. They all swim lightly — a fact 

 explained by the small bulk 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 ; they 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 wiiine. The nest is commonly built on the 

 ground ; the eggs, 2-3 in number, are variegated in color, being heavily marked with dark 

 brown shades on a pale brownish, greenish, or olivaceous ground. Nestlings in down are 

 spotted. 



Several circumstances render the study of these birds difficult. With some few generic 

 exceptions, they are almost identical in form ; while in size they show an unbroken series. 

 Individual variability in size is high ; northerly birds are usually appreciably larger than 

 those of the same species hatched farther south ; the ^ exceeds the 9 a little (usually) ; very 

 old birds are likely to be larger, with especially stouter bill, than young or middle-aged ones. 

 There is, besides, a certain plasticity of organization, or ready susceptibility to modifying in- 

 fluences, so marked that individuals hatched at a particular spot may be appreciably diff'erent 

 in some slight points from others reared but a few mUes away. One pattern of coloration runs 



