22 Birds of Colorado 



Distribution. — Breeding far north in north-east Asia, and Arctic 

 America from Alaska to Greenland, irregularly south in winter through 

 the United States to the Bermudas. 



Sabine's Gull occasionallystrays to Colorado during the fall migration. 

 There are about half a dozen well authenticated records both from 

 the plains and the mountains. W. G. Smith obtained a male at Love- 

 land, October 12th, 1889, and H. G. Smith about the same time saw 

 one in the flesh in Denver, killed October 1st ; Carter obtained a specimen 

 from an Alpine lake above 10,000 feet near Breckenridge, September 

 26th, 1886, and Aiken another at Manitou Park, Teller co., about 

 8,000 feet, October 12th, 1897 (Cooke). James Cowie shot one out 

 of a flock of six on a lake near Boulder, September 15th, 1907, 

 which is now in the Museum of the University of Colorado (Henderson). 

 There is a young female in the Colorado College Museum, collected by 

 J.G . Frey at Salida, September 26th, 1908 ; and another in the Museum 

 at Denver, taken by Hersey, October 31st, 1896, at Barr, where it 

 is also not infrequent on migration in March. 



Genus STERNA. 



Bill long, pointed and compressed, both mandibles of equal length ; 

 wings very long and pointed, the outer primary the longest ; tail strongly 

 forked, always for more than the length of the tarsus, the outer feathers 

 elongated, attenuated and pointed, sometimes to a considerable extent ; 

 tarsus short, less than the middle toe and claw ; toes fuUy webbed. 



A large genus of world-wide distribution on the seas and inland 

 waters ; about ten species in the United States. 



Key of the Species. 



A. Outer web of the outer tail-feather white, inner grey. 



S. forsteri, p. 22. 



B. Outer web of the outer tail-feather grey, inner white. 



a. Dark band on the inner web along the shaft of the primaries 



broader, occupying about half the web. S. hirundo, p. 24. 



b. Dark band on the inner web narrower, about a quarter the 



width of the web. S. paradisaea, p. 24. 



Forster's Tern. Sterna forsteri. 



A.O.U. Checklist no 69 — Colorado Records — Ridgway 73, p. 188 ; 

 Allen & Brewster 83, p. 198 ; Morrison 89, p. 147 ; Cooke 97, pp. 19, 

 51, 193 ; Felger 02, p. 294 ; 09, p. 278 ; Dille 03, p. 74. 



Description. — Adult in sunxmer — Top of the head black ; upper-parts 

 pearl-grey ; below white ; rump white, tail becoming a httle dusky 



