NESTING SEABIRDS OF THE GULF OF ALASKA 



63 



murre is better adapted for deep diving and 

 the capture of benthic fishes and pelagic and 

 benthic invertebrates. Having greater lati- 

 tude for food selection, the thick-billed murre 

 would have a greater tolerance for ecological 

 perturbations affecting the available food 

 supply. The common murre has an advantage 

 when pelagic fishes are available but cannot 

 switch to the other foods as readily as can the 

 thick-billed murre. The low density of pelagic 

 fishes in high arctic areas probably also ac- 

 counts for the greater success of the thick- 

 billed murre at higher latitudes relative to 

 common murres. 



Belopol'skii (1961) presented data from 

 East Murman which indicates that the com- 

 mon murre restricts its diet almost entirely to 

 a small number of fish species. Swartz (1966) 

 found strong indications that there were sig- 

 nificant differences in the food preferences of 

 the two species of murres. Thick-billed murres 

 made much greater use of invertebrates. 

 Bedard (1976) asserted that it is well known 

 that the common murre is quite partial to zoo- 

 plankton. So again the issue is not clear-cut. 



The situation is, of course, much more com- 

 plex than I have portrayed it. Nonetheless, I 

 think that it offers potential for use as a tool 

 in assessing population change and perturba- 

 tions in the food supply which should be 

 studied quite closely. 



Pigeon Guillemot (Cepphus columba) 



Gabrielson and Lincoln (1959) noted that 

 the pigeon guillemot was one of the most 

 regularly observed birds in Alaskan waters. It 

 is found everywhere throughout the northern 

 and western Gulf of Alaska area, with only a 

 few understandable and relatively small 

 blanks, such as in the silty waters of Upper 

 Cook Inlet. Because it obviously lacks the 

 breeding murres' need for close contact with 

 its nearest neighbors, it is able to exploit the 

 available nesting habitat to the fullest. It 

 seems that literally every bit of suitable nest- 

 ing habitat is normally occupied. 



Because of the dispersed way in which it 

 breeds and because it does much of its feeding 

 in the onshore zone (which is hazardous for 

 boats) the pigeon guillemot is an almost im- 

 possible species to inventory by standard 

 methods. 



There is no evidence that the pigeon guille- 



mot has been greatly affected by any major 

 perturbation. Because of its choice of nesting 

 habitat, it is probably subject to the attack of 

 only one egg predator, the rat. Because of its 

 loose social structure and the way it selects 

 nesting sites, eggs and young do not sustain 

 loss from panic flights. Its dispersed distribu- 

 tion should insure that man-made impacts 

 such as oil spills will have limited impact. 



The population levels of the pigeon guille- 

 mot are probably relatively very stable. The 

 widespread introduction of the rat to most of 

 its nesting range undoubtedly had impact, 

 but this impact has gone undocumented. It 

 would be interesting to follow the response of 

 guillemot populations on islands where rats 

 had been totally removed, if that ever be- 

 comes more than a dream. 



Marbeled Murrelet (Brachyramphus 

 marmoratus) 



The marbled murrelet apparently breeds 

 throughout most of the northern and western 

 Gulf of Alaska. This apparently is a necessary 

 condition because to date, at least in this part 

 of Alaska, we can only guess where and under 

 what conditions this murrelet breeds. 



In some relatively sheltered waters like 

 Prince William Sound, where marbled murre- 

 lefcs were estimated to number about 250,000 

 in 1972 (Isleib and Kessel 1973), they are the 

 most abundant seabirds. We know from 

 Dixon (1908) and Grinnell (1910) that this has 

 been so in Prince William Sound since the be- 

 ginning of the century. We know also that the 

 type specimens came from there as well 

 (Stresemann 1949), which is not necessarily 

 an indication of abundance but is suggestive 

 of their abundance relative to species not 

 collected. 



Gabrielson (Gabrielson and Lincoln 1959) 

 found marbled murrelets common near Yaku- 

 tat, in Prince William Sound, in Resurrection 

 Bay, and at Kodiak, and reported seeing them 

 at the C his well Islands and at Chignik and 

 Pavlof Bay on the Alaska Peninsula. Caha- 

 lane (1943, 1944) found them to be common in 

 Kupreanof Strait, and along the Alaska 

 Peninsula north of Katmai Bay. Murie (1959) 

 found them all along the Alaska Peninsula. 

 My own field notes from 1973 indicate that 

 the only place where they were common along 

 the Alaska Peninsula was at Wide Bay. 



