STERXA FOESTERI, FORSTEE's TERX. 677 



the eye and commissural edge of superior maxilla than in hirundo. The color of the 

 back hardly differs appreciably from that species ; it is perhaps a shade lighter. The 

 wings are comparatively considerably shorter than those of hirundo, being abhulutely 

 1 little shorter, thongh forsteri is a larger bird. They are very light colored, beiujj 

 strongly silvered witn the peculiar hoariness common to most of the species of the 

 genus, this light color being very observable even on the coverts. The outer web of 

 the first primary is not black, but silvery like the others ; all the primaries want the 

 very decided white space on the inner webs which exists in hirundo and macnira ; there 

 are indications of it, indeed, on the three or four outer primaries, hut the others are a 

 nearly uniform dusky gray, moderately hoary. The entire under parts are white, with 

 scarcely a trace of the plumbeous which is so evident in hirundo, and amounts to so 

 decided a color in macrura. The tail is a slightly lighter shade of the color of the m^^n- 

 tle, separated from the latter for a short space by the decidedly white rump. The 

 lateral feathers are much more lengthened than in hirundo, the elongation generally 

 quite equaling that of macrura, and sometimes even exceeding it. These two lateral 

 feathers are white on the outer web, dusky gray on the inner. This being exactly the 

 revefte of hirundo, and a very noticeable feature, was the first to draw attention to the 

 bird ; and this character being so tangible and convenient, writers have perhaps laid 

 too much stress upon it, to the exclusion of others quite as evident and more important. 

 The feet are bright orange, tinged with vermilion ; the tarsus shorter than the middle 

 toe and claw ; the feet longer and stouter by over 0.10 of an inch than the same parts 

 in hirundo. 



Adult, winter plumage. — The black of the terminal portion of the bill increases so 

 much in extent that nearly the whole bill becomes dusty, except a small space at the 

 base of the under mandible, and a terminal space of varying extent. The feet lose 

 their vermilion tinge and become dusky yellowish. The black pilenm is more or less 

 variegated with white on the forehead to the almost complete exclusion of the black ; 

 but there is always considerable black left on the nape, and a more of less broad and 

 distinct bar always extends along the sides of the head, embracing the eyes. The lat- 

 eral tail feathers have not the elongation and attenuation of those of summer, being 

 but little, if any, longer than those of hirundo during the breeding season. The color 

 of the inner web is usually somewhat darker, and sometimes extends on the outer as 

 well as the inner, especially toward the tip of the feather. 



At the time of the moult the old primaries lose their silvering and become plain brown 

 and white, their shafts being of a decided yellow. The inner webs at this season have 

 white spaces, with nearly as distinctly-defined margins as are found in hirundo and 

 macrura. 



Young. — Bill in all its proportions considerably smaller and weaker than that of the 

 adults, and wanting its very acute tip and sharply-defined ridges and angles ; brown- 

 ish-black, fading into dull flesh-color at the base of the under mandible. Front white, 

 but the crown and nape show considerable traces of the black that is to appear, which 

 is now mixed with a good deal of light brown. The pearl-blue of the back and wing- 

 coverts is everywhere interrupted by irregular patches of light grayish-brown, showing 

 a tendency to become transverse bars ; this grayish-brown on the tertials deepens into 

 brownish-black, and occupies nearly the whole extent of each feather. The primaries 

 differ from those of the adult in having less of the silvery gloss, and the inner white 

 spaces are more marked, being in fact like those of the adult hirundo. The rump and 

 under parts are pure white. The tail intensifies, so to speak, its adult characters as 

 regards color ; and, independently of any other feature, will always serve to identify 

 the species. It is deeply emarginate, but the lateral feather is not greatly produced, 

 surpassing the second by scarcely more than the latter surpasses the third. Its inner 

 web, for an inch or so from the tip, and both webs of the other feathers, are quite de- 

 cidedly grayish-black; the intensity of this color, and also its extent, decreasing suc- 

 cessively on each feather from without inward, so that the central pair scarcely deepen 

 their color at the tips. The outer web of the lateral feather generally stays pretty 

 uninterruptedly white, but sometimes is just at the tip invaded by the darker color of 

 its inner web. 



The foregoing descriptions embrace all the stages of plumage of this species which 

 are well characterized. Between them, of course, there will be found every gradation. 

 The number of immature specimens of this species which are found in collections, as 

 compared vrith the adults, is surprising. Fully one-half of all the examples before me 

 are in the "hareUi" state of plumage, having white fronts and the ordinary ocular 

 fascia. This is doubtless owing to the northern localities in which the bird breeds 

 Few, if any, United States specimens are to be taken, except in winter. 



Sterna forsteri alfords a good illustration of a species bearing so intimate a general 

 resemblance to another as to be confounded with it at first glance, and yet when care- 

 fully examined proving to be totally distinct. It is perfectly easy to separate it from 

 the hirundo by its characters of bill, wings, tail or feet, either of which, taken, alone, 

 would identity it. The following table will exhibit at a glance the distinctive features 

 of our three most intimately allied species. 



