TIM: 77 



power of flight has deservedly wmi lr them the name of Sea Swal- 

 lows. They capture their prey <>f -mall li-h \>\ plunging into the 

 water, frequently ilisHp|<earii)K' ami swimming a f.-w feet beneath the 

 surface. They nest in colonies. The nest is usually on the gnuim!. 

 Generally it is simply a slight depression in the sand, shrlN. <>r (Hobbles 

 of a Ix-ach, or in the n.-ar-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. 



Mg un.lt-r 13-00. 



1. Kntire top of the head jct-hlaek. 

 .1. Hill black, or in.wtly l>hi.-k. 



a. Feet black or blackish. 



a*. Under parts black or blackish 77. BLACK TERN. 



o. Under part* white; bill black .... 63. GILL-BILLED TERM. 

 a 1 . Under part* white; bill black, broadly tipped with yellow. 



ABOT'S T*RN. 



b. Ki-et yellii wish or orange. 



i. Outer tail-feathers jmn- wliite; ouu-r web of first primary black. 



7-. 1 . I:EATE TEEX. 

 t*. Inner web of outer tail-feather gray ; outer web of flrt primary 



gray 69. FOKCTER'B TERN. 



B. Bill mostly or entirely yellowish, reddish, bniuui.-li, or orange. 



a. Under partu tinged witli grayish ; outer web of outer Uiil-feather 

 gray ; inner web white. 



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



70. COMMON TERN. 

 a*. Bill without a distinct black tip ; tursus generally under -7". 



71. ARCTIC TERN. 



b. Under part* pure white ; inner web of outer Uil-feather gray ; outer 

 web white tu*. F..RHTER' TERN. 



2. Forehead white; lore* black; crown jet-black. 



A. Wing under 8-00; back pearl -gray 74. LEAKT TERN. 



//. Wing over 8-00; back grayish l>r<>wn ..r blaek'mh. 

 a. Back grayish brown ; a white 8trij)e from the forehead over the eye. 



76. BRIDLED TERN. 

 A. Back blackish ; white of forehead not reaching oner the eye. 



75. BOOTY TERN. 



8. Forehead or crown white or gray'wh, sometimes xpevkled with black ; 

 lore* not entirely black. 

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



a. Outer tail-feather eiitinh pun- white. 



o. Bill over 1-75. tip|H-d with yellow'u.h ... 67. CABOT'* TERN. 

 A Bill under l-7', witlmut \ .!!.. tip . 72. KOCEATE TERN 



b. Outer tail-feather not pure white. 



A. Inner web of outer Uil-feather darker than outer web ; outer web 



