LARIDjE — STERNIN^: TERNS, SEA SWALLOWS. 



1001 



Wings extremely lengthened, narrow, and acute; 1st primary much the longest, the rest rap- 

 idly graduated. Secondaries short and inconspicuous. Tail usually much elongated and 

 deeply forked, the lateral feathers being more or less attenuated and filiform, forming stream- 

 ers ; only occasionally short and bniad (Gelochelidon, Hydrochelidon, subgenus Thalasseus oi 

 Sterna, etc.), or graduated (Anoiis, etc.). Legs placed rather farther back, and less decid- 

 edly ambulatorial than in Larime. Tibia denuded for a varying distance. Tarsi short 

 and usually slender; scutellate and reticulate, as m LarincB. Toes of moderate length, and 

 of the usual relative proportions. Webs rather narrow, and (except in Anous, etc.) more 

 or less incised. Claws small, compressed, but much curved and acute. Size moderate, or 

 very small. General form slender and delicate. Plumage as in other subfamilies, but pte- 

 rylae narrow; sexes hardly differing in coloration, but variations with age and season very 

 great. 



Terns are not distinguished from Gulls by any strong structural peculiarities, but they 

 invariably show a special contour, in the production of which the longer, slenderer, and acutely 

 paragnathous bill is conspicuous. Only one species has the bill 

 in any noticeable degree like a Gull's. A few of the Terns are 

 as large as middle-sized Gulls, but the usual stature is much 

 less; and they are invariably of a slenderer build, more trim in 

 shape, with smoother, closer-titting plumage. Great length and 

 sharpness of wiug relative to bulk of body confer a dash and 

 buoyancy of flight wanting in Gulls; in flying over the water 

 in search of food, they hold the bill pointing downward, which 

 makes them look curiously like colossal mosquitoes; and secure 

 tlieir prey by darting impetuously U})on it, wlien they are usu- 

 ally submerged for a moment. The larger kinds feed princi- 

 pally upon little fish, procured in this way ; but most of the 

 smaller ones are insectivorous, and flutter about over marshy 

 spots like Swallows or Nighthawks. The general appearance 

 and mode of flight have suggested the name of "sea-swallow," 

 the equivalent of which is applied in nearly all civilized lan- 

 guages. Forking of the tail is an ahuost universal character 

 Terns, the Black Tern and its allies, and a few others, the forking is moderate, and not accom- 

 panied by attenuation of lateral feathers; but ordinarily, these are remarkably lengthened and 

 almost filamentous, as in the Barn Swallow. It should be observed that in all such cases the 

 narrowing elongation is gradual, and consequently less evident in the young; and that it is 

 very variable in its development. Noddies ofi'er the peculiarity of a tail lightly forked centrally, 

 but rounded laterally. The feet are small and relatively weak throughout the group; Terns 

 walk but little, and scarcely swim at all. Ordinarily, the webbing is rather narrow, and much 

 incised, jjarticularly that between the middle and inner toe; in Ili/druchelidon, this occurs to 

 such extent that the toes seem simply semipalmate. The webs are fullest in Anous, where 

 also tlie hallux is unusually long ; in some species, this toe is slightly connected with the tarsus 

 by a web. The inner toe is shorter tlian the outer, and much less than the iniddle, which, 

 especially in HijdrocheUdon, is much lengthened, and has the inner edge (»f its claw dilated, or 

 even slightly serrate. The pattern of crdoration is very constant, almost throughout the sub- 

 family. Most of the species are white (often rosy-tinted below), with a pearly-blue mantle, a 

 black cap on the heail, and dark-C(dored primaries, along the inner web of which usunlly runs 

 a white stripe. These dark-colored quills, when new. are beautifully frosted or silvered over; 

 but this hoariness being very superficial, snnii wears nil", leaving the feathers simply blackish. 

 The black cap is often interrupted by a white frontal crescent ; it is sometimes pndonged into 

 a slight occipital crest ; in ix few species, it is replaced by a black bar on each side of the head. 



Fio. 689. —Roseate Tern. (From 

 Tenney, after Audubon.) 



In the Caspian and Marsh 



