NESTING SEABIRDS OF THE GULF OF ALASKA 



61 



poise Rock in Hinchinbrook Entrance, Bar- 

 well Island/Cape Resurrection, the Chiswell 

 Islands, the Barren Islands, and Chisik 

 Island. 



For some reason, the islands of the Kodiak- 

 Afognak Archipelago do not host any known 

 major murre colonies. There is also a rather 

 large gap between the Chisik Island colony 

 and the next major colony at Oil Creek west of 

 Puale Bay. Directly west of Oil Creek is an- 

 other colony at Cape Unalishagvak. Both of 

 these latter colonies are Class V and they are 

 the first colonies of this size to be encountered 

 in the Gulf of Alaska. West of these colonies 

 the next large colony is at Atkulik Island. To 

 the south, midway between the last-named 

 colonies, lies the major composite murre 

 colony in the Semidi Islands. These sites 

 make up the only Class VI colony in the Gulf 

 of Alaska. Westward, the next major colony, 

 a Class V, is at Spitz Island south of Mitro- 

 fania Island. In the Shumagin Islands one 

 Class V colony is at Karpa Island, and lesser 

 colonies with large murre components are 

 found at the Haystacks, Castle Rock, and 

 Bird Island. Only minor murre colonies are 

 found between the Shumagin Islands and the 

 end of the Alaska Peninsula. 



Gabrielson and Lincoln (1959) were aware 

 only of the colonies at Cape Resurrection 

 (which Gabrielson considered to be large), at 

 the Chiswell Islands, and at Chisik Island for 

 the area from Cook Inlet east. Gabrielson 

 visited the Barren Islands on 13 June 1940 

 and apparently did not notice the present 

 murre colonies, both Class IV, at East Amu- 

 tuli (an island which he visited) and Nord 

 Island. 



Gabrielson (Gabrielson and Lincoln 1959) 

 found a few small colonies at Kodiak, mostly 

 on small offshore islands. Gabrielson found 

 common murres to be abundant in the Semidi 

 Islands and stated that there were no notable 

 colonies in the Shumagins, although on his re- 

 turn to the Shumagins in 1949 he did find a 

 fairly large colony at the Haystacks. That size 

 description would fit the colony that is there 

 now. He obviously did not see the other colo- 

 nies. Rausch (1958) reported murres from 

 Middleton Island. 



There is quite a difference between the dis- 

 tribution of murres as we know it today and 

 the way Gabrielson and Lincoln pictured it. 



Why does this difference exist? There are two 

 possible answers: either the number of colo- 

 nies has increased, or the coverage of colony 

 locations has improved. The latter case, at 

 least, is established. I must confess to being 

 puzzled by the way Gabrielson was able to 

 move about close to what are now known to be 

 sizeable colonies without seeing them, those 

 in the Barren Islands and the Shumagin Is- 

 lands in particular. Perhaps this represents 

 the vague outlines of yet another population 

 change. 



The center of abundance for murre distribu- 

 tion in the Gulf of Alaska today is from Paule 

 Bay west to eastern Shumagin Islands. The 

 Semidi Islands are the heartland of this area 

 of maximum abundance. We have no defini- 

 tive data on species composition of these colo- 

 nies. Common murres undoubtedly dominate 

 in most of the colonies; the only ones where we 

 know of a sizeable thick-billed murre compo- 

 nent are in the Shumagin Islands. 



Thick-billed Murre (Uria lomvia) 



Thick-billed murre population information 

 cannot be separated from that of the common 

 murre on the basis of existing data. A direct 

 assessment of present-day status is not pos- 

 sible. After reviewing what we know about 

 their distribution, I suggest a way to examine 

 the question indirectly. 



The thick-billed murre is found in colonies 

 with the common murre from Middleton Is- 

 land westward; Rausch (1958) noted about 

 400 murres at Middleton Island and observed 

 that the thick-billed murre outnumbered the 

 common murre by several times. Isleib and 

 Sowl (FWS, unpublished data) saw a thick- 

 billed murre mixed with common murres at 

 Porpoise Rock in July 1972. Isleib and Kessel 

 (1973) expressed the opinion that small num- 

 bers of thick-billed murres will be found in 

 most common murre colonies in the northern 

 Gulf of Alaska when it is possible to survey 

 these colonies in detail. Karpa Island had a 

 significant component of thick-billed murres 

 in June 1973, and they constituted 40% of the 

 colony at the Haystacks (L. W. Sowl, unpub- 

 lished data). 



Bent (1963) reported that many thick-billed 

 murre eggs have been taken by collectors at 

 Round Island in the Shumagin Islands. Ball 

 and Bannister (1869) reported a thick-billed 



