38 



P. C. SEKORA, G. V. BYRD, AND D. D. GIBSON 



of the blue-fox industry." The leading of 

 downy young to sea by the adults is a very 

 noisy process and foxes could easily take 

 large numbers. Also, these murrelets nest in 

 fairly shallow burrows which foxes could dig 

 out easily. Birds were recorded near islands in 

 every group during surveys from 1972 to 

 1975, but workers seldom went ashore to de- 

 termine if they were nesting. In Fig. 12, the 

 only basis for designating most of the areas 

 marked as colonies is the presence of birds 

 during breeding season (15 May-1 July). 



Cassin's Auklet (Ptychoramphus aleuticus) 



This is another species that was more com- 

 mon before the fox was introduced. Cassin's 

 auklet now seems to occur only locally, but 

 these nocturnal birds are probably often over- 

 looked. They are known only from Buldir, 

 Umnak, and the vicinity of Oglodak. 



Parakeet Auklet (Cyclorrhynchus psittacula) 



This auklet, which nests under beach 

 boulders, in burrows, and in rock crevices, 

 seems to use a greater variety of breeding 

 sites than do the other auklets. The largest 

 known colony is at Chagulak, where an esti- 

 mated 10,000 were seen in 1972. Smaller colo- 

 nies are found as far west as Buldir. 



Crested Auklet, Least Auklet, and Whiskered 

 Auklet (Aethia cristatella, A. pusilla, 

 and A. pygmaea) 



Aethia nest primarily in rock crevices of 

 talus slides. Such habitat occurs locally in 

 each major island group except the Near 

 Islands. Least auklets outnumber crested 

 auklets in the Aleutians, and whiskered auk- 

 lets are far less common than either. Esti- 

 mates of populations are probably grossly in- 

 accurate because of the difficulty both in esti- 

 mating the number of birds in the milling 

 flocks observed and in interpreting the esti- 

 mates after they are obtained. 



Horned Puffin and Tufted Puffin (Fratercula 

 corniculata and Lunda cirrhata) 



Horned puffins favor rock crevices in talus 

 slides and cliff faces for nesting, whereas 

 tufted puffins are primarily burrow nesters. 

 The historical distribution of the two species 

 was probably based on availability of nesting 



sites, so tufted puffins were more widespread 

 and numerous. However, in areas where ex- 

 tensive talus slopes are available, horned 

 puffins reached high densities. Predation by 

 introduced foxes may have altered the distri- 

 bution of tufted puffins, which now nest pri- 

 marily on fox-free islets just offshore from the 

 larger islands where foxes occur. The distribu- 

 tion of horned puffins may not have been 

 altered significantly, since they are relatively 

 free from fox predation in their rock crevices. 



Recommendations 



A complete survey of the Aleutian Islands 

 has not been done. This should be done, by 

 methods that will provide accurate population 

 estimates. Life history information is needed 

 on almost all species, and data should be 

 gathered on selected populations to determine 

 trends. Information on winter distribution 

 should also be compiled. The effects of intro- 

 duced predators should be evaluated quanti- 

 tatively, and if control measures are needed, 

 effective, humane methods should be devised 

 and implemented. 



Acknowledgments 



The authors are grateful to the following 

 Fish and Wildlife Service personnel who 

 helped collect previously unpublished data 

 used in this paper: E. P. Bailey, C. S. Craig- 

 head, C. P. Dau, M. H. Dick, G. J. Divoky, R. 

 Martin, J. L. Trapp, G. W. Watson, and C. M. 

 White. Most of the data were collected from 

 the deck of the Aleutian Islands National 

 Wildlife Refuge research vessel Aleutian 

 Tern. Captain George Putney is acknowl- 

 edged for his peerless seamanship and con- 

 stant encouragement; he also contributed ob- 

 servations of birds. 



The maps were adapted from a master sup- 

 plied by Elaine Rhode, Public Affairs Office, 

 U. S. Fish and Wildlife Service, Anchorage; 

 she also suggested the use of squares to dis- 

 play data. C. M. White graciously made his in- 

 press manuscript available. W. B. Emison, 

 R. J. Gordon, and J. L. Trapp kindly made 

 their field notes available, and Trapp helped 

 compile data. Most of the funds for the sur- 

 veys in 1971-75 were provided by the U. S. 

 Fish and Wildlife Service. 



