FAMILY LARID&. GULLS AND TERNS. 43 
Outer web of outer tail feather, darker than inner web; back, pearl gray; breast 
and underparts, pearl gray ; bill, in adults, entirely red; tarsus, usually less than .70. 
Sterna paradisea. Arctic Tern. 
See No. 46. 
Back, black; a white stripe from forehead, extending over the eye; breast, white; bill, 
in adults, black. Sterna fuliginosa. Sooty Tern. 
See No. 49. 
Back, sooty or grayish brown; a white stripe from forehead, not reaching above the 
eye; bill, black. Sterna anethetus. Bridled Tern, 
See No. 50. 
Back, sooty brown; underparts, sooty brown. Anous stolidus. Noddy Tern. 
See No. 53. 
* Group 5. Wing, 11 to 13 inches long. 
Bill, black, not tipped with vellow ; feet, blackish: back, pearl gray ; bill, comparatively 
short and stout. Gelochelidon nilotica. Gull=billed Tern. 
See No. 39. 
Bill, black, not tipped with yellow; feet, black; back, black or sooty. 
Sterna fuliginosa. Sooty Tern. 
See No. 49. 
Bill, red, tipped with black; feet, orange red; back, pearl gray or gray and buff. 
Sterna hirundo. Common Tern. Wilson’s Tern. 
See No. 45. 
Bill, black, tipped with pale yellow ; feet, dark; bill, comparatively long and slender. 
Sterna sandvicensis acuflavida. Cabot’s Tern. 
See No. 39. 
* Group 6. Wing, 13 to 17 inches long. 
Bill, orange or yellowish; tarsus, less than 1.50; inner web of outer primary, usually 
with more or less white. Sterna maxima. Royal Tern. 
See No. 41. 
Bill, red or reddish; tarsus, over 1.50; inner web of outer primary, usually without 
white. Sterna caspia. Caspian Tern. 
See No. 40. 
Bill, black, tipped with yellow. Sterna sandvicensis acuflavida. Cabot’s Tern. 
See No. 39. 
* Group 7. Wing, over 17 inches long. 
Bill, red or reddish. Sterna caspia. Caspian Tern. 
See No 40. 
* For directions for measurement, see page 9. 
