FAUNA OF THE ALEUTIAN ISLANDS AND ALASKA PENINSULA 41 



Family PROCELLARIIDAE 

 Puffinus tenuirostris: Slender-billed Shearwater 



Attu: A-la-mach 

 Russian, Commander Islands: "Tschornij Glupisch" (Stejneger) 



In summer, the slender-billed shearwater is distributed widely 

 over the North Pacific and throughout the Bering Sea. On the 

 Gulf of Alaska, we observed them often, singly or in small groups. 

 Some of the birds that we thought to be slender-billed shearwaters 

 may have been the sooty shearwater, P. griseus. 



At Kodiak Island, however, P. tenuirostris has been identified, 

 and we obtained a specimen there in 1936. Shearwaters, believed 

 to be this form, were noted May 10, 1936, near the entrance to 

 Cook Inlet; one was noted near Barren Islands on May 11; they 

 were numerous between Sutwik Island and Cape Kumlik on May 

 14, and there was a flock at the entrance to Chignik Bay. On 

 May 15, a few were seen near Xagai Island, in the Shumagins; 

 on August 29, some were noted near Simeonof Island in this 

 group, and some were noted between that point and the main- 

 land; next day, between Kupreanof Harbor and Chignik, more 

 were sighted. Again, on September 1, we passed through dense 

 masses of shearwaters north of Karluk, in Shelikof Strait. These 

 birds occur also on the north side of Alaska Peninsula and were 

 seen as far east as the entrance to Bristol Bay. 



Slender-billed shearwaters occur all through the Aleutian 

 Islands, with their center of abundance apparently at the eastern 

 end of the chain, among the Fox Islands. Unimak Pass is a 

 favorite feeding place, with large concentrations also observed 

 in other places as far as the western end of Umnak Island. 



Many published accounts describe the hordes of shearwaters 

 observed at various times. Arnold (1948), during an hour and a 

 half, June 9, 1944, recorded 160,000 shearwaters in Unimak Pass. 

 Probably the most outstanding was the flock noted by Scheffer 

 in Umnak Pass on September 3, 1938. He says, in his field report: 



In the Pass we saw the greatest concentration of shearwaters that we have 

 ever seen in the Aleutians. Captain Sellevold remarked that it was the 

 greatest in his experience. The Pass is 3 miles wide. We estimated that 

 the raft of birds extended for 25 miles by 2 miles wide, or an area of 50 

 square miles. From 5:30 a. m. to 8:00 a. m. the ship passed through 

 dense masses of the birds, about half of them on the water and half 

 flying back and forth ... At 5 p. m. the birds had thinned out by more 

 than half. 



Apparently this bird is much less abundant to the westward, 

 though in 1941 Gabrielson saw "thousands" at Attu and "several 



