^1914^] THAYER AND BANGS — BIRDS 11 



Rhodostethia rosea (Macgillivray). 



In the summer of 1905 the Russian ornithologist, Dr. ButurUn, 

 found a large breeding colony of Ross's gull in the Island Delta of 

 Kolyma. In the season previous to Mr. Koren's visit to the 

 region, that of 1911, the bird was abundant all summer, and bred 

 in large numbers in some swamps north of the town of Nijni 

 Kolymsk, and a native gave him two specimens which he had shot 

 that summer and had mounted himself. 



During the season of 1912 Mr. Koren searched the whole coast 

 from Kolyma to Chaun Bay, not only without finding a breeding 

 colony, but not even seeing stray individuals of the species, save 

 on May 3, 1912, when he shot one fine specimen at Nijni Kolymsk. 



It would seem therefore that Ross's gull does not breed regularly 

 from year to year in any one place in this vast region. The reason 

 probably is that the colony of breeding birds is very impatient of 

 any molestation, and if too much disturbed one season seeks a new 

 spot the next. 



Sabine's gull (Xema sahini (Sabine)) was not observed on the 

 Arctic coast of Siberia. It was last seen, as the expedition sailed 

 northwest, on July 25, 1911, off the mouth of the Yukon. Mr. 

 Koren, however, examined a skin in the possession of a native at 

 Nijni Kolymsk. 



Sterna paradisaea Briinnich. 



Common along the whole Arctic coast of Siberia, and up the 

 Kolyma River at least to Nijni Kolymsk. 



Stercorariidae. 



Stercorarius pomarinus (Temm.). 



The pomarine jaeger is much more common south of Bering 

 Strait than northward. It was observed onlv a few times on the 



