TERNS. 



T7 



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

 lows. They capture their prey of small fish by plunging into the 

 water, freciuently disappearing and swimming a few feet l)encath 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 liead jot-black. 



A. Bill black, or mostly black. 



a. Feet black or blackish, 



a». Under parts black or blackish 77. Black Tern. 



a*. Under parts white ; bill black . . . . C3. Gill-iulleu Tekn. 

 a*. Under parts white; bill black, broadly tipped with yellow. 



67. Cabot's Tern. 



b. Feet yellowish or oratijre. 



J*. Outer tail-feathers [lure white ; outer web of first primary blnck. 



72. Roseate Tern. 



J>. Inner web of outer tail-feather gray ; outer web of first primary 



pray 69. Forstek's Tern. 



B. Bill mostly or entirely yellowish, reddish, brownish, or oranjre. 



a. Under parts tinged witli grayish ; outer web of outer tail-feather 

 gray ; inner web wliite. 



a». Bill broadly tipped with blackish ; tarsus generally over •70. 



70. Common Tern. 

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



71. Arctic Tern. 



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

 web white 69. Forsteu's Tern. 



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



^. Wing under 8^00; back pearl -jrruy 74. Least Tern. 



B. Wing over 8^00; back grayish brown or blackish. 



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. 



7r). 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 (iure white. 

 a'. Bill over 1'75, tipped with yellowish 

 a*. Bill under 1^75, without a yellow tip 



b. Outer tail-feather not pure white. 



6». Inner web of outer tail-feather darker than outer web ; outer web 



. . 67. Cabot's Tern. 

 72. Roseate Tern (Iin.). 



