576 KEPORT OF STATE GEOLOGIST. 



Alaskan coast of Bering Sea it is rare, and there is no record of its 

 presence along the shore of the Arctic Ocean (Nelson, Cruise of the 

 Corwin, p. 108). It has been noted as breeding at Ft. Yukon, along the 

 Nelson Eiver, and at York Factory on Hu'dson's Bay (Mcllwraith, 

 Birds of Ontario, p. 50). 



SUBFAMILY STERNIN^E. TERNS. 



7. GENUS STERNA LINN^US. 

 a 1 . Wing more than 9.00. 



6 1 . Both webs of outer tail feathers white. S. dougalli Montag. 17 



6 2 . Both webs of outer tail feathers not white. 



c 1 . Outer tail feathers with inner web dusky ; outer web white. 



S. fosteri Nutt. 15 

 c 2 . Outer tail feathers with inner web white; outer web dusky. 



S. hirundo Linn. 16 

 a 2 . Wing under 7. S. antillarum Less. 18 



Subgenus STERNA. 



15. (69.) Sterna forsteri NUTT. 



Forster's Tern. 



Adult in Summer. Tail deeply forked; whole top of head black; 

 other upper parts pearl gray; outer web of the outside pair of tail 

 feathers white; inner web grayish or dusky toward the end; tips of 

 secondaries., rump,, sides of head, and lower parts white; bill dull 

 orange, the tip blackish; edges of eyelids, black; legs and feet, orange 

 red. Adult in Winter. Similar, but top of head grayish; patch 

 around eye, and over ear coverts black; tail not so deeply forked. 

 Immature. Above, including head, brownish, back and crown nearly 

 uniform; tail feathers (except the outer web of the outer pair) tipped 

 with dusky; bill dusky. 



Length, 12.00-15.00; wing, 9.50-10.30; tail, 5.00-7.70; depth of 

 fork, 2.30-5.00; bill, 1.50-1.65. 



EANGE. America, from Brazil to Virginia on Atlantic coast, to 

 Manitoba in the interior. Breeds locally from Gulf of Mexico north- 

 Vard. Winters from Gulf coast southward. 



Nest, a collection of marsh vegetation, placed upon drift or on the 

 ground. Eggs, 3, varying from pale greenish to warm brownish drab, 

 spotted with different shades of brown, 1.78 by 1.23. 



Most places this tern is a rare migrant, but during the fall it is 

 exceedingly abundant on Lake Michigan. Mr. B. W. Evermann noted 

 it in Vigo County April 28 and May 19, 1888. Several specimens 

 have been taken on Lake Maxinkuckee (Ulrey and Wallace, Proc. 1. 

 A. S., 1895, p. 149). Mr. Charles L. Cass noted one in Steuben 



