310 LARIDZ, GULLS. 
jecting 8 or 10 inches, very slender and almost filamentous for a great part of 
their length; smaller still; wing about 12; tail about 6; tarsus 14-13; bill 
1-14; plumage as in the last. Same habitat. Lestris parasiticus Sw. and 
Rion., F. B.-A. ii, 430; Nurr., ii, 317; Aup., vii, 192, pl. 453; S. cep- 
phus Lawr. in Bp., 840; S. buffonit Cougs, 1. c. 136. . . . BUFFONIIL. 
Subfamily LARINA. Gulls. 
Covering of bill continuous, horny 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 nearly so, rarely forked or cuneate, 
without projecting middle feathers. Certain of the smaller slenderer-billed species 
alone 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. 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 asteady 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 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 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 parasites of the pelicans, snatching food from 
their 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; 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 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 variability in size is high; northerly birds are usually 
appreciably larger than those of the same species hatched further south; the ¢ 
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 
that the individuals hatched at a particular spot may be appreciably different in some 
slight points from others reared but afew miles away. One pattern of coloration runs 
through nearly all the species : they are white, with a darker mantle (stragulwm ; § 38, 
p- 17), andin 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 continually 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 
peach-blossom hue. The sexes are always alike; the moult appears to be twice a 
year, so that a winter plumage more or less different from that of summer results ; 
while the young are never like the old. The change is slow, generally requiring 
