TERNS. It 



power of flight has deservedly won for them the name of Sea Swal- 

 lows. They capture their prey of small flsh 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. 



» 



KEY TO THE SPECIES. 



I. "Wing under 13-00. 

 1. Entire top of the head jet-black. 

 A. Bill black, or mostly black. 

 li. Feet black or blackish. 



fli. Under parts black or blackish 77. Black Tebn. 



of. Under parts white ; bill black .... 63. Gull-billed Teeit. 

 o'. Under parts white; bill black, broadly tipped with yellow. 



67. Cabot's Tehn. 

 b. Feet yellowish or orange. 

 bK Outer tail-feathers pure white ; outer web of first primary black. 



72. EosEATE Tehw. 

 i^. Inner web of outer tail-feather gray ; outer web of first primary 



gray 



69. Fokstee's Tekn. 



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. 



a'. Bill broadly tipped with blackish ; tarsus generdly over -70. 



70. Common TsEif. 

 a^. Bill without a distinct black tip ; tarsus generally under •70. 



71. Aeotio Teen. 



b. Under parts pure white ; inner web of outer tail-feather gray ; outer 

 web white 69. Foestee's Teen. 



2. Forehead white; lores black; crown jet-black. 



A. Wing under 8"00 ; back pearl-gray 74. Least Teen. 



J3. "Wing over 8*00 ; back grayish brown or blackish. 



a. Back grayish brown ; a white stripe from the forehead over the eye. 



76. Beidled Tern. 

 6. Back blackish ; white of forehead not reaching over the eye. 



75. Sooty Teen. 



3. Forehead or crown white or grayish, sometimes speckled with black; 

 lores not entirely black. 



A. "Wing pearl-gray, over 9-00. 

 u. Outer tail-feather entirely pure white. 

 ffli. Bill over 1-75, tipped with yellowish ... 67. Cabot's Tekn. 

 cfl. Bill under 1-75, without .a yellow tip - 72. Eoseate Tebn (Im.). 



b. Outer tail-feather not pure white. 



Ji. Inner web of outer tail-feather darker than outer web ; outer web 



