Black-headed Gull
It could be readily distinguished from the Common Tern, which it closely resembles when on the wing, by its grating monotonous note, which very closely resembles one frequently uttered by the Loggerhead Shrike" (B. B., and R.). 70. Sterna hirundo Linn. COMMON TERN; WILSON'S TERN; SEA SWALLOW (see Fig. 7). Ad. in summer. -Whole top of the head black; back and wings pearl-gray; inner border of inner web of outer primaries white, except at the tip (Fig. 61, c); throat white; breast and belly pale pearl-gray; tail white, the outer webs of the outer feathers gray or pearl-gray; bill red at the base, the end third black; feet orange-red. Ad. in winter.-Similar to the above, but front part of the head and under parts white: bill mostly black. Im.-Similar to the preceding, but the back more or less washed or mottled with light brownish; lesser wing-coverts slaty gray, and tail much shorter. L., 15.00; W., 10-25; T., 5-50; Tar., 75; B., 1.40.