STERNA MACRTTRA, ARCTIC TERN. 687 



have a inncli lighter wash of plumheous. The deep carmine of the bill and feet 

 b. conies lighter and duller, but does uot assume the coral-red tiut of the feet of hirundo 

 or forslcri. Otherwise generally as in summer. 



Plumage of the young-of-ilie-yiar. — The bill is much smaller than in the adults, being 

 only lo inches long; brownish-black toward its tip ; the gonys and the sides of the 

 lower mandible toward the angle of the mouth dull orange-color, as are also the 

 mouth and tongue. The feet are only orange-colored on the soles, being otherwise 

 brownish-red. The tail is much shorter than in the adults, being only 4.7,^> to 5 

 inches long, and the outer pair of rectrices are much broader and scarcely at all taper- 

 ing in form. The forehead is white, the crown streaked with narrow, longitudinal 

 spots of v^hite upon a black ground color, which extends as far as the eyes, and runs 

 back over the temples and auriculars as far as the nape ; whole under parts, from the 

 chin, including the inferior caudal tectrices and under surfaces of the wings, pure 

 white. On the back there predominates everywhere .1 uniform, light bluish-gray 

 (soniewbat darker than in S. hirundo), all the feathers tipped with yellowish-white or 

 white, most of them with a blackish-brown streak or crescent-shaped spot near the end ; 

 tin se spots darkest on the tertials and inner secondaries, and aggregated into a single, 

 broad, slate-colored streak on the least wing-coverts along the edge of the wing The 

 ji>?hen-blue primaries deepen into slate color toward their tips ; their shafts are white, 

 .their inner webs with a longitudinal space of white, the outer web of the first slaty- 

 black. The inner tail feathers are white, as are their shafts ; their ajiices white, each 

 with a subtermiual crescent-shaped spot of brownish-black. 



When the young have flown for some time, the bill and feet become considerably 

 redder, and the dark spots on the back lighter, though still not so much so as in the 

 young hiruudo. After their first moult, which begins while they are migrating and 

 only ends when they have reached their winter habitat, they acquire a plumage very 

 like that of the old birds in winter, but still distinguishable from it by the yet remain- 

 ing dark tips of the tail-feathers. These, however, are gradually lost, growing lighter 

 and ligliter until, by the following spring, they diti'er but slightly from the adults.* 



The brilliant color of the feet is sometimes washed off on the plumage, staining it 

 red or salmon color. 



D'nueumons of the adult. — Length (extremely variable from the varying length of the 

 tail), 14 to 17 inches ; extent, 29 to '.V.i ; wing, from the carpus, 10 to lO.Tf) ; tail, usually 

 7 to 8, sometimes 6.50 to 8.50 ; depth of fork, 4 to 5 ; tibiae bare, 0.45 ; tarsus, 0.55 to 

 0.65; middle toe and claw, 0.80 to 0.85 ; inner toe and claw, 0.55 ; bill, along culmen, 

 1.20 to 1.40; height at base, 0.30; from feathers of side of lower mandible to tip, 

 1.40 ; gape, 1.90; gonys, 0.75. 



Accidental variations. — These are chiefly noticeable in dimensions, and in the intensity 

 of the color of the under parts. The species is subject to very considerable variations 

 in size, even among apparently equally adult examples. The bill, particularly, is some- 

 times verj^ much smaller than is usual, and much more slender. Thus, e. g., a female 

 fioin Nova Scotia, before us, has a bill only 1.08, or less than that assigned to Sterna 

 pikei ; and it is quite as slender as in that species. The tail, as might be expected from 

 its shajte, varies greatly. Two adult summer birds before me dift'er two inches in the 

 amount of elongation of the external rectrices ; and one and a half inches is a very 



* The two preceding paragraphs are compiled from Naumaun's Naturgeschichte 

 Vogel Deutschlands. Mr. Maynard gave the following description of the same stage : 



" T//e young-of-the-year in autumn dill'ers from the preceding in having the forehead 

 quite white; a few white feathers on the back of the head; the black is not quite as 

 intense — more brownish. The featluis of the back are edged with rufous. The should- 

 ers are darker. The tips of the tail-feathers are rufous. The whole under parts are 

 pure white. The white line from the base of the bill is discontinued just in front of 

 the eye, and the portion occu])ied by it is quite dusky, almost black. The feet are dull 

 orange. The bill is black, with the base of the lower mandible orange. » » » » 

 Yonng-of-the-year are readily distinguished [from hirundo'] by the rump of hirundo 

 Ix'ing ai^hy, the feet larger, the tarsi longer, with a smoother appearance. The bill is 

 mucli the same color, but in hirundo it is longer. It never Las the dusky appearance 

 below the eye seen iii macrura." 



Messis. Sharpe and Dresser give the following: 



" Young-hird-of-the-ycar. — The upper plumage, though gray like the adult's, is much 

 motth'd with blackish, and has all the back-feathers conspicuously tipped with white, 

 the wings and tail feathers being marked in the sanu^ manner; the forehead is white, 

 and the hinder jyartof tlui liead black, mixed on \\\c forepart with a. few whitish spots; 

 the cheeks, hinder neck, and entire under surface of the body are pure white, 

 without any admixtiiro of gray ; bill black, re<ldi.sh at ba.s(> of lower mandible. 

 NextUng : Covered with golden-bulV down, inclining to ochre, the upper surface varied 

 with little blackish markings ; theibrehead and throat browni.sh-black ; under surface 

 of the body yellowish-white, with the flanks and lower abdomeu iucliuiug to 

 browni.sh.'' 



