2l6 SWIMMERS. 



While flying, the Tern exhibits uncommon watchfulness; 

 beating the air with a steady wing, and following the track of 

 the vessel with an easy flight, this bird may be observed, with 

 quick eye and raovmg head, minutely scanning the haunts and 

 motions of its finny prey. At the approach of winter it retires 

 south of the limits of the Union. 



In America this Tern is chiefly confined to the Eastern Pro- 

 vince, and is a common bird throughout its range. 



FORSTER'S TERN. 

 Sterna forsteri. 



Char. Above, pearl gray, paler on the wings and tail ; crown and 

 nape black ; beneath, white ; bill orange, the terminal third blackish ; 

 legs and feet orange; claws black. Length I2 to 15 inches. 



In winter the head and neck are white, the nape is tinged with gray, 

 and on the side of the head is a broad black band. 



Nest. On a marshy margin of lake or stream, or on a grassy island; 

 loosely made of reeds and sedges, and lined with grass. 



Eggs. 2-3 ; varying from pale buff or olive to olive brown, marked 

 brown and pale lilac; average size about 1.80 X 1.25. 



Nuttall wrote in a note to the Common Tern that the bird 

 described by Richardson as Sterna hirundo appeared to be a 

 distinct species, distinguished by the pearl-gray tail and other char- 

 acters, and he proposed for this probable new species the name 

 of Sterna forsteri, in honor of the eminent naturalist and voyager 

 who first suggested these distinctions. Having been recognized by 

 naturalists as a valid species, the name thus proposed has been 

 adopted for it. 



In appearance, as in manners, the bird is very similar to the 

 Common Tern, though the present species displays a decided pre- 

 ference for a grass-covered nesting site, and is inclined to remain 

 near fresh water. 



It is a rare bird along the Atlantic coast, excepting at Cobb's 

 Island, off Virginia, but is abundant on the inland waters of the 

 west, north to Manitoba. A number nest every year on the St. 

 Clair Flats, Ontario; but the only examples that have been taken 

 in Canada to the eastward of that point were obtained at Lake 

 Mistassini, Quebec, and on Prince Edward's Island. 



In winter the flocks range southward as far as Brazil. 



