178 NORTH AMERICAN FAUNA 61, FISH AND WILDLIFE SERVICE 



should be based on a precise observation, or on specimens of 

 breeding birds. 



Hartert (1920) and Stejneger (1885) reported both species 

 nesting on the Commander Islands, usually in separate colonies, 

 according to Stejneger, though he once found both species nest- 

 ing on the same cliff. 



Xema sabini: Sabine's Gull 

 Xema sabini woinesenskii 



Friedmann (1935) reports a specimen from Kodiak, taken by 

 Bischoff, July 25, 1868, and Gabrielson observed one there on 

 August 10, 1945. Osgood (1904) apparently did not observe it at 

 the base of Alaska Peninsula, but he records a specimen taken 

 by McKay at Lake Aleknagik. Hanna obtained a specimen at 

 Nushagak, May 31, 1911. 



These birds undoubtedly nest on Alaska Peninsula, however. 

 At Ugashik River, May 27 to 29, 1936, they were common on 

 the tide flats, in pairs, obviously preparing to nest. This area 

 is identical in character with the nesting habitat of this species 

 noted at Hooper Bay in 1924. It is probable that Sabine's gull 

 nests farther west — at Port Heiden and Port Moller for example. 

 We could not examine those areas thoroughly, but, on May 22, at 

 least one bird, in immature plumage, was seen offshore opposite 

 Nelson Lagoon, and Jaques (1930) reports an adult at Port 

 Moller on May 23, 1928. 



There is no evidence that these birds nest to the west of Nelson 

 Lagoon, although they have been observed much farther west. 

 On May 18, 1936, one was seen at False Pass, Unimak Island. 

 On May 11, 1925, I saw one at Urilia Bay, and McGregor (1906) 

 obtained a specimen on Unimak Island, August 14, 1901. In June 

 1937, the natives of Atka Island obtained a specimen, which they 

 presented to us — this specimen is the westernmost record in the 

 Aleutians. 



Hartert (1920) records a specimen of an adult male from the 

 Commander Islands, which apparently is the only record for 

 those islands. 



Sterna hirundo: Common Tern 

 Sterna hirundo hirundo 



The only record of this bird is a brief statement by Wetmore in 

 his field report of 1911: "I saw several common terns 50 miles 

 off Tigalda Island, June 4." 



