208 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



the under parts are white. There are sometimes no dark markings, 

 but usually the upper parts are more or less heavily spotted or mot- 

 tled with dusky. As the young bird grows the color on the upper 

 parts fades to almost white. The first plumage appears on the 

 scapulars and back. In the juvenal plumage the young Caspian tern 

 is distinctively marked, differing from all other young terns in 

 corresponding plumages. The most striking character is the black 

 crown, which in all other terns is largely white ; in the young Caspian 

 the entire upper half, or more, of the head is black, including the 

 lores and cheeks, down to a line running from the commissure 

 straight back to the occiput ; the black is more or less relieved on the 

 forehead and crown by whitish or grayish streaks. The feathers of 

 the upper parts, back, scapulars, and wing-coverts are basally " light 

 gull gray," but they are so broadly edged or tipped witli pale buffy 

 shades, " cartridge buff," or " tilleul buff," that they impart this 

 color to the upper parts. The scapulars are broadly banded with 

 black, two bands on each feather, and the feathers of the back and 

 coverts are more or less barred or spotted with black. The under 

 parts are white. 



When the young bird attains its full growth, a partial molt, in- 

 volving most of the contour feathers, begins early in September. 

 The feathers of the fore back are now heavily tipped with dusky, 

 forming an interscapular dusky patch ; the scapulars are variegated 

 with hastate dusky markings and the tertials are doubly banded with 

 dusky near the tips; the rectrices are mottled with dusky near the 

 tips, more so centrally and less so laterally; and the lesser wing 

 coverts are mottled with dusky. This might be considered the first 

 winter plumage though it is more properly a transition stage from 

 the juvenal plumage for it soon disappears by wear, fading, or 

 molt. Later in the fall young birds assume the pearl gray mantle 

 and can be distinguished from adults only by the dusky in the 

 lesser wing-coverts and the mottled tails. A complete molt in early 

 spring renders old and young indistinguishable in March. Some 

 birds retain the mottled crown until May. 



Adults have two complete molts — the prenuptial in February and 

 March, producing the full nuptial plumage, and the postnuptial in 

 August and September, producing the adult winter plumage with 

 the white-streaked crown, the pearl gray mantle and wing-coverts, 

 and the pure gray tail. Adults usually have white foreheads and 

 more white in the crown than young birds; they also have larger 

 bills. The postnuptial molt of adults begins before the end of the 

 breeding season, sometimes as early as June, with the appearance of 

 white feathers in the black crown. The outer primaries are molted 

 last. 



