Subfamily Sternine
Terns.
Terns are littoral; never, I believe, pelagic. They inhabit the shores of bodies of both fresh and salt water, but are more abundant on the bodies of both fresh and salt water, but are more abundant on the seacoast than in the interior. Their principal characters, as compared with the with the Gulls, are mentioned under the subfamily Larinæ. Their TERNS. power of flight has deservedly won for them the name of Sea Swallows. They capture their prey of small fish by plunging into the water, frequently disappearing and swimming a few feet beneath the surface. They nest in colonies. The nest is usually on the ground. Generally it is simply a slight depression in the sand, shells, or pebbles of a beach, or in the near-by seaweed, moss, or grasses. Sometimes it is scantily lined with bits of grass, seaweed, moss, etc., but these are frequently wanting.
I. Wing under 13.00.
KEY TO THE SPECIES. 1. Entire top of the head jet-black.
A. Bill black, or mostly black. a. Feet black or blackish. a¹. Under parts black or blackish a2. Under parts white; bill black 77. BLACK TERN. 63. GULL-BILLED TERN. 67. CABOT'S TERN. as. Under parts white; bill black, broadly tipped with yellow. b. Feet yellowish or orange. 61. Outer tail-feathers pure white; outer web of first primary black. 72. ROSEATE TERN. 62. Inner web of outer tail-feather gray; outer web of first primary gray 69. FORSTER'S TERN.
B. Bill mostly or entirely yellowish, reddish, brownish, or orange. a. Under parts tinged with grayish; outer web of outer tail-feather gray; inner web white. a¹. Bill broadly tipped with blackish; tarsus generally over 70. 70. COMMON TERN. a2. Bill without a distinct black tip; tarsus generally under 70. 71. ARCTIC TERN. b. Under parts pure white; inner web of outer tail-feather gray; outer web white 2. Forehead white; lores black; crown jet-black.
A. Wing under 8.00; back pearl-gray.
B. Wing over 8.00; back grayish brown or blackish. 69. FORSTER'S TERN. 74. LEAST TERN. a. Back grayish brown; a white stripe from the forehead over the eye. 76. BRIDLED TERN. b. Back blackish; white of forehead not reaching over the eye. 75. SOOTY TERN. 3. Forehead or crown white or grayish, sometimes speckled with black; lores not entirely black.
A. Wing pearl-gray, over 9.00. a. Outer tail-feather entirely pure white. a¹. Bill over 1.75, tipped with yellowish a. Bill under 1.75, without a yellow tip b. Outer tail-feather not pure white. 67. CABOT'S TERN. 72. ROSEATE TERN (Im.). b. Inner web of outer tail-feather darker than outer web; outer web TERNS. mostly or entirely white; a black space generally on the side of the head inclosing the eye 69. FORSTER'S TERN (Im.). 62. Outer web of outer tail-feather darker than inner web; tarsus over 70 70. COMMON TERN (Im.). b3. Outer web of outer tail-feather darker than inner web; tarsus under 70 B. Wing blackish, over 9.00. a. Under parts blackish b. Under parts white 71. ARCTIC TERN (Im.). 75. SOOTY TERN (Im.). 76. BRIDLED TERN (Im.). 77. BLACK TERN (Im.). 4. Crown silvery gray; lores black; rest of plumage sooty 79. NODDY. C. Wing under 9.00 II. Wing over 13.00.
A. Wing 15.00 or over; outer primary mostly gray. 64. CASPIAN TERN. B. Wing under 15.00; inner half of inner web of first primary white. 65. ROYAL TERN. a b C d e FIG. 61. First primaries of adult Terns, seen from below. (a) Caspian Tern; (b) Royal Tern; (c) Common Tern; (d) Arctic Tern; (e) Roseate Tern. 63. Gelochelidon nilotica Hasselq. GULL-BILLED TERN; MARSH