690 STERNA DOUGALLI, ROSEATE TERN. 



is nearly pure black, lislit'-iiing a little at the tip. Tlie dark portion of the feathers 

 grows liji'liter on each hiiccesbivel^-, nutil the inner ones are very lij^ht pearl — so light 

 as to appear to fade insensibly into the white which broadly margins them. The sec- 

 ondaries are white, witli the greater part of their outer and a small part of their inner 

 webs pearl-blue. The tail is exceedingly short, measuring less than four inches, the 

 amount of emarginatiou being only one iuch, or even less. The outer pair of rectrices 

 are narrower than the others, but hardly longer than the next pair, and not more 

 acutely pointed. The rcctrices are pearl-blue, darkest on their outer vanes, so light as 

 to be almost white on their inner. The outer web of the outer feather, however, is uot 

 so dark as the next. Toward the extremities of the rectrices there is a subtermiual 

 border of brownish-black extending around the tip, and for half an inch or more down 

 on eich side. External to this rim of black there is another, which ends tiie feather, 

 of pure or yellowish white. The markings of the tail are abrupt and well detiued. 

 The legs and feet are dull greenish-black, like the bill, with a shade of reddish 

 slightly apparent over some of the joints ; the soles inclii ing to yellowish, the claws 

 black, with whitish tips. Length of tarsus, 0.75 ; middle toe and elav.-, O.'JO. The 

 ground color of the upper parts is a very light pearl-blue, much as in the adults, and 

 ]s pretty pure and uninterrupted on the rump and greater wing-coverts. But on 

 the back, the hind neck between the shoulders, the scapulars, tertials, median coverts 

 and inner secondaries, this color Is almost completely obscured and hidden by a very 

 beautiful, tine, delicate, continuous mottling of black and light yellowish or faAvn- 

 color. This black is disposed chiefly in narrow, irregular, zigzag transverse lines, but 

 their continuity everywhere interrupted by the mottling of fawn-color. Tiis appear- 

 ance is very difficult to describe ; it is quite unlike anything else I have seen among 

 Terns, and rather reminds one of the delicately but inextricably blended colors of a 

 Scojis, a CaprimnJgus, or perhaps of some Scoloj}acincv. On the tertials, inner secondaries, 

 inner longest coverts, the pattern of mottling becomes larger and more distinct, for 

 the feathers are, toward their termination, almost wholly black, with ytllowish borders. 

 The head is as peculiar as the back. The forehead and cheeks are of a uniform, deli- 

 cately blended, and soft, light grayish-brown, which on the vertex and occiput becomes 

 resolved into small, broad, indistinct longitudinal stripes of quite deep black and dull 

 fawn-color, the streaks again being lost on the nape in perfectly uniform dull blackish. 

 Just before and above the eye there is a spot almost pure silvery white ; the eye is en- 

 circled by nearly pure black, aggregated into a pretty well-detined semilnue before it, 

 stretching out behind it as an extensive spot, covering the auricular and temporal 

 regions ; pretty sharply defined with the white below ; being iuseiisibly blended with 

 the color of the occiput above. The under parts are pure white ; but on the sides of 

 the breast, or quite across it, the extreme tips of the feathers are a little obscured by 

 dusky, causing them to appear exactly as if soiled. There is the ordinary band along 

 the edge of the fore-arm of dull black, but it is obscured by some light fawn-colored 

 tips of the feathers. 



Dimensions of the advli. — Length, 14 to a little over 15 inches ; extent, about 30 ; 

 wing, from carpus, 'JJ to 9|-; tail, 1^ to 7|; depth of fork, :5i to 4| ; bill, along culuien, 

 1.50 ; from nostrils to tip, 1.'25; from feathers on side of lower mandible to tip, 1.75 ; 

 height at base, 0.35; gonys, 1; rami, 0.75 ; tibiaj bare, 0.4U ; tarsus, 0.85; middle toe 

 toe alcne, 0.75 ; its claw, 0.25. 



Dimensions of )jom>f/-of-ijear. — Length, average, about 11 inches ; extent, 28; wing, 

 from carpus, 9.25; tail averaging 4 inches, with a depth of forking only 1 to li ; 

 length of bill, 1.35 ; its other dinieusious, and those of the feet, corres[iondingly less 

 than in the adult. (Compare also measurements given in the descrii)tiou of the young- 

 of-the-year before the first moult.) 



Though of about the same size as the typical species of Sterna, its form is more slen- 

 der. The bill is relatively longer, slenderer, more acute, with a but slightly convex 

 culmen, r.ud the gonys longer than, instead of about equal to, the exposed portion of 

 the rami. The wings are shorter, with less tapering and acute tip. The relative 

 length and attenuation of the exterior rtctrices surpasses that of any other species of 

 Sterna. The libia' are bare for a considerably shorter space. The claws arc remark- 

 ably arched, especially that of the outer toe. In the pattern of coloration it adheres 

 more closely to the type, though the bill is black and the pilcutn of a different shape 

 and degree of persistency in winter. No other species of btenta proper has so marked 

 a roseate tint on its under parts, it being in this respect, for its genus, what (jaleneulata 

 is for " Thalassens." 



The bill of perfectly adult birds is iiure black, except the extreme base, which, with 

 the mouth, is bright red. In immature specimens of various ages it is, for a greater 

 or less extent toward the base, light-coloryd.) "\vith considerable of a vermilion or 

 rather light carmine tint during life. In others the whole bill is pure bUn-k. I liave 

 never seen it, however, so largely red as it is represcmted to be in Audubon's plate. 

 The other variations, beyond those normal and constant ones of age and sea: on above 

 detailed, consist chiefly in a greater or less elongation of the tail. 



It is impossible to confound this species, in nniture summer xdumage, with any other 



