MARINE BIRDS IN THE ALEUTIAN ISLANDS, ALASKA 



37 



nest with kittiwakes and murres and are often 

 found with red-faced cormorants. By far the 

 densest concentration of cormorants occurs in 

 the Near Islands, especially at Attu, where an 

 estimated 77,000 birds were seen in 1970. In 

 the Aleutians as a whole, red-faced cor- 

 morants outnumber pelagic cormorants, and 

 double-crested cormorants make up only a 

 very small percentage of the breeding 

 population. 



Parasitic Jaeger (Stercorarius parasiticus) 



The distribution of jaegers is poorly known 

 because investigators have spent little time 

 ashore on most islands. Murie (1959) found 

 jaegers on a number of islands, and most of 

 the data in Fig. 5 are his. Population esti- 

 mates are available only for Amchitka (25 

 pairs; White et al. 1977) and Buldir (30-40 

 pairs; G. V. Byrd, unpublished data). 



Glaucous-winged Gull (Larus glaucescens) 



Glaucous- winged gulls no longer nest on 

 islands where foxes occur except where 

 islands in lakes are available. Most colonies 

 are on offshore rocks or islets and range in 

 size from a few pairs to over 200 pairs, and 

 occasionally more. They are found throughout 

 the Aleutians, but the largest known colonies 

 are at Bogoslof (500 pairs) and Buldir (250 

 pairs). 



Black -legged Kittiwake and Red-legged 

 Kittiwake (Rissa tridactyla and 

 R. brevirostris) 



Black-legged kittiwakes breed locally in 

 every major island group, usually mixed with 

 murres and cormorants. The large colonies 

 contain over 25,000 birds, but colonies of less 

 than 50 pairs also occur. Red-legged kitti- 

 wakes breed only on Buldir and Bogoslof. 

 They are remnants of a previously more wide- 

 spread population. 



Arctic Tern and Aleutian Tern (Sterna 

 paradisaea and S. aleutica) 



Terns breed locally in each island group. 

 Both species occur at Attu, Amchitka, Adak, 

 and Umnak, but only arctic terns are found at 

 Nizki. Factors limiting distribution are un- 

 known. Colonies vary in size from less than 10 

 pairs to 100 pairs. 



Common Murre and Thick-billed Murre 

 (Uria aalge and U. lomvia) 



Like kittiwakes, murres are abundant 

 locally. A pure colony of either species is al- 

 most unknown, although one species often 

 makes up more than 90% of a colony. Com- 

 mon murres may have been reduced by foxes, 

 since they tend to use sites with less slope 

 than those used by thick-billed murres. At 

 Bogoslof and the Baby islands, the birds use 

 inland, gently sloping areas because there are 

 no foxes. The presence of the lichen (Caloplaca 

 spp.), which according to Tuck (1960) is in- 

 dicative of bird roosts, on several extensive 

 cliff areas suggests that either murres or kitti- 

 wakes, or both, formerly used areas they do 

 not use now. 



Pigeon Guillemot (Cepphus columba) 



This species has been noted near almost 

 every island that has been visited. Nesting 

 under beach boulders and driftwood, the birds 

 only occasionally are found in large concentra- 

 tions (near Great Sitkin more than 4,000 birds 

 were seen in 1971). Murie et al. (1937) summed 

 up the distribution of pigeon guillemot accu- 

 rately: "Each island has its meager quota of 

 these birds, nesting unobtrusively among the 

 rocks but never assembled in any really large 

 groups." Estimates of populations may be ex- 

 tremely inaccurate because the diurnal 

 rhythm of the pigeon guillemot is unknown. 



Marbled Murrelet and Kittlitz's Murrelet 

 (Brachyramphus marmoratus and 

 B. brevirostris) 



Nests of neither species have been located 

 in the Aleutians, but nesting of both is sus- 

 pected at Adak, Unalaska, and Unimak, 

 where specimens of Kittlitz's with brood 

 patches or eggs in the oviduct have been col- 

 lected in nearshore waters. Courtship has 

 been recorded in marbled murrelets (Byrd et 

 al. 1974). 



Ancient Murrelet (Synthliboramphus 

 antiquus) 



The distribution of this species is very 

 poorly known, since it is nocturnal near nest- 

 ing colonies. Murie (1959) wrote, "This is one 

 of the species that undoubtedly has greatly 

 declined in recent years, as a result of increase 



