XEMA SABINII : FORK-TAILED GULL. 353 



common in New England, but the circumstances of 

 its presence can hardly be stated without qualification. 

 There is probably no month in the year when the bird 

 may not be found with us, unless it be in the depth of 

 winter. It is commonly seen late in the summer, and 

 its numbers increase in the fall. It resides all the sum- 

 mer in Maine, yet we have no authentic record of its 

 breeding there. It would appear to belong most prop- 

 erly to the category of spring and fall migrants, its 

 presence in summer being chiefly during the latter part 

 of that season, as in the cases of various Sandpipers, 

 which, like this Gull, have a high north breeding range. 

 Individuals are commonly seen into the winter months, 

 and great numbers appear from the south in April. 

 During the migrations the pretty birds fairly swarm by 

 thousands. 



FORK-TAILED GULL. 

 XEMA SABINII (Sab.) Leach. 



Chars. Adult : white, including inner primaries, most of seconda- 

 ries, and greater coverts ; head enveloped in a slate-colored 

 hood, succeeded by a velvety-black collar ; mantle slaty-blue, 

 extending quite to the tips of the tertiaries ; whole edge of the 

 wing, and first five primaries, black, their extreme tips, and the 

 outer half of their inner webs to near the end, white ; bill black 

 tipped with yellow ; feet black. Length, 13.00-14.00; wing, 10.00- 

 n.oo; bill, i. oo ; tarsus, 1.25; tail, $.QQ, forked an inch or more. 

 The changes of plumage are correspondent with those of C. Phil- 

 adelphia. In the young the tail is simply emarginate. 



This very elegant little Gull is probably not so rare 

 as is commonly supposed. For many years it remained 

 one of the least known of the North American repre- 



