by
LeRoy W. Sowl
U.S. Fish and Wildlife Service
1011 East Tudor Road
Anchorage, Alaska 99507
The history of ornithological field work in the Gulf of Alaska dates back to 20 July 1741 and Bering's discovery of Alaska. In spite of this long history, the record is fragmentary and often seemingly contradictory. The coming of the tanker terminal at Valdez and the pending development of oil and gas resources on the outer continental shelf threaten massive change for seabirds in the Gulf of Alaska. Often overlooked, however, is the fact that man has already effected a change in status for many of these birds. In this paper I examine the scanty, general record from the exploratory period, roughly 1741 to 1935, and the somewhat more comprehensive record of the reconnaissance period, 1936-74, and attempt to develop a basis for better understanding of the change in seabird status that has already taken place. This paper should be treated as a verbal model which can be improved as our knowledge of seabirds in the Gulf of Alaska is expanded.
From the perspective of history, 1970 should prove to have been a momentous year for Alaska and its seabirds. Two events, the construction of the Trans-Alaska Pipeline and the passage of the National Environmental Policy Act (NEPA) merged head on in 1970 with the decision that Section 2c of NEPA applied to the proposed pipeline. The systematic appraisal of potential environmental impacts required by Section 2c quickly exposed the inadequacy of the existing data base in many areas. With respect to seabirds in the Gulf of Alaska, it was apparent that there had never been any effort to develop a synthesis of the information accumulated over 230 years. The data gaps which were uncovered were appalling.
While the Trans-Alaska Pipeline impact statement had provided shock therapy, it was not the only influential event on the horizon. Two local disturbances had already preceded the pipeline. These were Project Chariot at Cape Thompson and the Amchitka Island test program. Now in quick succession the Wilderness Act and native land claims added new urgency to the need for solid resource information. More recently, the outer continental shelf minerals leasing program has made the quick development of base-line information even more essential.
All of the new activity in Alaska's coastal waters has the potential to affect seabirds in one way or another. We must remember, however, that man's activities have been affecting seabirds for a long time. We cannot accurately assess the effect of a tanker terminal at Valdez or offshore oil activity without first developing some understanding of the current status of seabirds in the context of the historical record.
Seabird work in Alaska can be divided roughly into three periods. The first is the early historical or exploratory period; it extended from Georg Steller's 1741 visit to Kayak Island to 1935. This was literally a period of exploration and the collection of information was dependent upon interest and opportunity. The second is the reconnaissance period; during this period investigators were dispatched to a particular area to gather general information for management application. This period begins with Murie's extensive investigations of the Alaska Peninsula and the Aleutian Islands; I see it extending from 1936 to 1975. In 1975 the need for data became so acute that it was necessary to enter the third period, one of intensive data gathering. Knowing where the big seabird colonies were located and knowing their general species composition was no longer adequate. The current intensive data-gathering effort in the waters over oil and gas leasing areas is a partial response to the recognition of this inadequacy.
In this paper I draw some tentative conclusions relative to the status of the 26 species of primary seabirds (Fisher and Lockley 1954) breeding in, or which may have bred in, the northern and western Gulf of Alaska area. This area extends from Cape Fairweather, 59°N 138°W, westerly along the coast to Ikatan Bay, 55°N 163°W, at the end of the Alaska Peninsula. These bird species tend to be colonial, but not exclusively so. Two birds which are primary seabirds, the mew gull (Larus canus) and Bonaparte's gull (L. philadelphia), have not been included because they tend to be more riverine than marine in habit. Several marine ducks have been excluded because they are secondary seabirds.
Information from the early exploratory period is summarized under the next section. The more detailed information from the reconnaissance period is discussed in the species accounts.
The history of ornithological field work in the Gulf of Alaska goes back 235 years to 20 July 1741. On that day Bering's surgeon/naturalist, Georg W. Steller, spent a scant 10 h ashore on Kayak Island. He collected a single bird. This bird, later named for Steller, reminded him of a plate of the blue jay by Make Catesby, the colonial-era predecessor of Audubon, in Volume 1 of the Natural History of Carolina, Florida, and the Bahama Islands (Stejneger's annotated translation of Steller's journal in Golder 1925). Collection of the bird confirmed for Steller that the first Russian Expedition had reached America.
Steller was an accomplished naturalist, but his overbearing and superior manner had apparently sorely irritated Bering and his officers long before the expedition reached Kayak Island. The seamen made little effort to go ashore anywhere in Alaska and Steller was blocked from doing so as well. In addition to Kayak Island, he was able to go ashore only on Nagai Island, first with a water party on 30 August and again the next day. He noted that "all sorts of waterbirds in abundance were seen." These included two kinds of cormorants, auks, ducks, gulls, divers, pigeon guillemots (Cepphus columba), tufted puffins (Lunda cirrhata), and horned puffins (Fratercula corniculata).
Stejneger's comment on the identity of the cormorants is interesting because, based on his experience, he assumed them to be pelagic and double-crested cormorants (Phalacrocorax pelagicus and P. auritus). He gave no thought to red-faced cormorants (P. urile) which are now common there.
Steller noted on 6 September off Bird Island in the Shumagin Islands, that "when we were out to sea about half a mile we were especially astonished at the untold numbers of seabirds which we saw on the northern side of the island." These birds were listed as cormorants, auks, horned puffins, fulmars (Fulmarus glacialis), pigeon guillemots, black oystercatchers (Haematopus backmani), and a pied diver which Stejneger assumed was an ancient murrelet (Synthliboramphus antiquus).
On 15 September when Bering's vessel, the St. Peter, was south of Amukta Pass, Steller recorded observing "river gulls." The observation is not as interesting as Stejneger's comment (Golder 1925) concerning it. Stejneger stated that no true river gulls lived in the Aleutians and these must, therefore, have been another small gull with red feet. He thought they must have been the red-legged kittiwake (Rissa brevirostris), which "inhabits the Aleutian Islands from Bering Island to Sannak."
Thirty-seven years after Bering's voyage, Captain James Cook sailed into the Gulf of Alaska, arriving off Kayak Island on 11 May 1778. Cook was not accompanied by an able naturalist. His surgeon, William Anderson, did have some experience gained on earlier voyages in preparing skins and taking notes, but he had contracted tuberculosis and became so ill that even his notes ceased after 8 June, while the expedition was in Cook Inlet.
Cook was under orders to keep a careful record of everything he saw. One of the results was that he had birds collected even though he had no naturalist to do the work. Several birds were collected in Prince William Sound while Cook's vessels were at anchor in Port Etches. These included two marbled murrelets (Brachyramphus marmoratus—type specimens), a black oystercatcher, a surfbird (Aphriza virgata), a surf scoter (Melanitta perspicillata), and a red-breasted merganser (Mergus serrator—type specimen), along with several forest birds (Stresemann 1949).
The watch journals of Cook and his officers provide some additional information. Captain Charles Clerke (Beaglehole 1974) remarked in his log on the passage out of Prince William Sound through Montague Strait on 20 May that "it had almost become tautology to mention whales and seals and innumerable sea fowl that so confoundingly kept their distance."
Between the Trinity Islands and Chirikof Island on 18 June, Cook's men collected a single tufted puffin. Later Cook passed close to the Semidi Islands and the Shumagin Islands and directly through the Sandman Reefs. Beaglehole's version of this part of the voyage makes no mention of seabirds.
There is a gap of 87 years during which there is almost no hint of published material bearing on the status of seabirds in the Gulf of Alaska. In 1865 the Russo-American Telegraph Expedition touched this area. Dall and Bannister (1869) provide us with a few scraps garnered during that expedition, primarily by Bischoff. The glaucous-winged gull (Larus glaucescens) was described as the most common species from California northward. Bischoff's collections at Kodiak indicate that the horned and tufted puffins were collected with ease. He was able also to collect an Aleutian tern (Sterna aleutica—type specimen) along with an egg.
Dall (1873) noted in 1872 that the black-legged kittiwake (Rissa tridactyla) was common at Round Island and Delarof Harbor, Unga Island, in the Shumagins. The inference is that it was more common at these two places than elsewhere. The Arctic tern (Sterna paradisaea) was abundant in the Shumagin Islands and particularly at Range Island in Popoff Strait. Dall expressed the opinion that the horned puffin was very abundant in the Shumagins and appeared to fill the niche of the tufted puffin, which he did not see there. The only other bird which he thought to be very common was the pigeon guillemot. He did not note the common murre (Uria aalge) at all.
In 1908 the second of three Alexander Expeditions conducted field work in the Prince William Sound area. From Dixon (1908) and Grinnell (1910) we can derive some basis for assessing status in a very general way. The most common seabird noted was the marbled murrelet. Glaucous-winged gulls and black-legged kittiwakes were common; the glaucous-winged gull was the more common. Horned puffins were judged to be slightly more common than tufted puffins by both authors. The northern end of Montague Strait appears to have been the center of abundance for puffins. Dixon noted that on 16 July 1908 there were swarms of puffins in the channel along Green Island. Pigeon guillemots were common along the rocky coasts. Parakeet auklets (Cyclorrhyncus psittacula), common murres, and ancient murrelets were noted only in very small numbers.
After the Alexander Expeditions there was another doldrum in which little was done. During this lull in activity, a note by Townsend (1913) appeared which compared the numbers of crested auklets (Aethia cristatella) at Yukon Harbor, Big Koniuji Island, to the least auklets (A. pusilla) of St. George Island, stating that the crested auklets were more numerous. He sailed into the Yukon Harbor anchorage on the evening of 1 August and observed that crested auklets "were present in myriads. The surface of the water was covered with them, and the air was filled with them."
The formal record available to researchers is very shallow for this exploratory period. With a few exceptions it was compiled by non-scientists, primarily explorers and egg and skin collectors.
This paper should be viewed as a conceptual model. While I attempted to be as objective as possible, subjectivity was unavoidable. Many of the tentative conclusions are based on very little data. Each improvement will make it a better management tool. Because of the space limitations, it is not possible to go into a detailed tracking of my reasoning for each species. In an attempt to overcome this handicap, I am including some examples of the sorts of reasoning that went into the process.
In 1973 I led a Fish and Wildlife Service (FWS) reconnaissance survey team that was delineating seabird colonies along the Alaska Peninsula. In the Shumagin Islands we entered or crossed Koniuji Strait twice (on 11 and 12 June) without even suspecting the presence of a horned puffin colony. A third passage through the strait (13 June) was not so uneventful. The water and the air were filled with horned puffins. This led to the discovery that the 430-m mountain on the southeastern corner of Big Koniuji was also covered with horned puffins, clear to its top. The minimum estimate of the birds that were visible was 140,000. Even this number of birds would make this the largest horned puffin colony ever discovered. David Spencer (personal communication) had noted similar swarms of horned puffins in this strait in 1956 while flying sea otter surveys in the area. In 1975 a field camp was established at Yukon Harbor, with study of this colony as one of the prime objectives of the investigators. As far as these investigators could tell no such large colony existed there, even though the nesting habitat was still there, unaltered. This sort of event, one of the banes and vagaries of estimating seabird numbers, is not rare.
In 1973, when FWS personnel delineated the colony on the southwestern end of Bird Island in the Shumagins, there were estimated to be 43,000 kittiwakes, 24,000 murres, and 6,000 cormorants present; no tufted puffins were seen about the colony. The last time (in 1970) one of the observers, Edgar Bailey, had visited the colony with Robert Jones, there was an extremely large colony of tufted puffins which Jones (E. Bailey, personal communication) estimated at more than 1 million birds. We made a particular effort to visit Jude Island, between the Shumagin Islands and the Pavlof Islands, because David Spencer (personal communication) had reported once having seen the air over the island filled with an extremely large number of tufted puffins. However, there were no puffins at this colony either.
Let us examine the facts in context. On 8 June we had visited High Island where we had attempted to collect puffin eggs for pesticide analysis, but had been able to find only one egg. Also, there were only 6,000 tufted puffins where George Putney, master/engineer of the Aleutian Tern, had seen much larger numbers in 1972. These two facts could easily be related to explain the current situation because it was still early in the breeding season. The horned puffin observations in Koniuji Strait (11-13 June) were in keeping with this conclusion also—an indication that these birds had not yet settled down to a full breeding effort. The erratic comings and goings of common puffins (Fratercula arctica) early in the season have been well documented (Lockley 1962). It is an easy step to extend this reasoning to the absence of birds at Bird Island on 11 June, even though fresh signs of the characteristic evidence of tufted puffin occupancy were missing. Jude Island provides a different clue, however. There were 3,000 pigeon guillemots, an unheard-of concentration, apparently occupying abandoned tufted puffin burrows on 15 June. Also, on 7 June we had made a very interesting observation that had no special significance at the time: murres on Spitz Island were occupying little parapets created by mashing down the mouths of puffin burrows which filled the slope above the cliff portion of their colony.
After looking at all of the observations cited above, I conclude that tufted puffins were greatly reduced in numbers on these sites in 1973 and that they had been absent from the burrows used by the murres and pigeon guillemots for more than the current breeding season. What causes these sorts of changes? I do not know.
One reason for year-to-year change may be local movements of colonies. Black-legged kittiwakes nest at several places in lower Orca Inlet, Prince William Sound. Counts made at these sites in 1972 and 1974 yielded almost identical totals but the numbers of birds varied between individual sites. This may be an indication that all of these sites are part of one large composite colony and that, at least in this colony and for this species, the birds shift at will.
The best record of population flux involving two species has been summarized by Peterson and Fisher (1955). In 1872 and 1873 the murres observed on Walrus Island in the Pribilofs were almost entirely common murres. In 1890 common and thick-billed murres (Uria lomvia) were evenly matched in number. By 1901 the colony was almost exclusively dominated by thick-billed murres. In 1911 and 1914 the few thick-billed murres present were almost lost among the then dominant common murres. In 1940 thick-billed murres dominated again. When Peterson and Fisher visited the island in 1953, the situation was again reversed and common murres had almost completely replaced the thick-billed murres. These changes are even more impressive because of the number of birds involved, between 1 and 2 million in 1953. There are more tenuous indications that somewhat the same thing may occur between two other congener pairs, the pelagic and red-faced cormorants and the black-legged and red-legged kittiwakes. The causative factor, or factors, is not readily apparent. One possibility is long-term climatic fluctuation.
Dement'ev and Gladkov (1966) provide an example of abrupt and massive change. Before 1876, the pelagic cormorant abounded on the Commander Islands. During the winter of 1876-77, the birds were decimated by an unknown epizootic disease. By spring only a few individuals remained alive. The record shows that by 1882 they were already becoming common again. Red-faced cormorants were apparently not reduced in number because Dement'ev and Gladkov (1966) state that they were common in "the second half of the last century and the beginning of this." Did they flourish only while the pelagic cormorants were reduced in number?
Bowles (1908) gives another indication of naturally induced population impact. He noted large numbers of dead seabirds on Washington beaches and the ocean "rather plentifully dotted with sick birds ..." He examined some birds and found "many hundreds" of tapeworms in every bird. His conclusion was that their intestines were so solidly packed with tapeworms that starvation was "an absolute certainty."
Some apparent disruptions are long term. In the Gulf of Alaska there is a hiatus in the distributions of a number of small seabirds that are active around their colonies only at night. Repeatedly, the northern Gulf of Alaska shows up as an area of reduced population, as a boundary between subspecies, or as a limit to a range. This same area has a noticeable lack of total darkness during a substantial portion of the breeding season.
The nocturnal habit no doubt evolved because it was advantageous to concentrate on the breeding grounds only under the cover of darkness, when diurnal predators were at a great disadvantage. Cody (1973) states that Cassin's auklet (Ptychoramphus aleuticus), which is strictly nocturnal around its colonies, avoids these colonies on brightly moonlit nights. He sees this as an apparent response to gull predation. At higher latitudes the small alcids have overcome this disadvantage by swamping predators through their sheer numbers. In the Gulf of Alaska I suspect that few of the small seabirds, except possibly the fork-tailed storm-petrel (Oceanodroma furcata), have ever achieved great enough numbers to offset the impact of extended daylight.
Past disruptions of seabird populations are both natural and man-induced; however, the documentary record is much too fragmentary to allow us to fully appreciate what has occurred or what the long-term effect has been. To give some perspective to the problems associated with assessing change and attempting to understand it, some of the indicators of natural and unnatural change and flux in seabird populations are reviewed here.
The flux in bird numbers can be related to the time of day, season of the year, and atmospheric conditions on a short-term basis. This sort of flux or apparent flux can easily be explained. The underlying cause of some of the longer term flux is not so easily arrived at. Murie (1959), Gabrielson and Lincoln (1959), and Sowl and Bartonek (1974) have noted some of the man-induced changes. These are also explored to some extent in the species accounts as they are found to apply.
I sometimes refer to a colony size class when discussing the existing data rather than to an actual population estimate. The size classes used are defined as follows:
The Dictionary of Alaska Place Names (Orth 1967) is the reference for those who wish to locate some of the less obvious sites. The Coast Pilot, No. 9 (U.S. Department of Commerce 1964) is another useful reference.
Petrels of a number of species can be found in the Gulf of Alaska, some of them in great numbers. Only the northern fulmar breeds there.
The fulmar is common in the offshore waters of the northern Gulf of Alaska throughout most of the year (Isleib and Kessel 1973). Most authors, including Clark (1911), one of the earlier ones, who commented on the distribution of fulmars farther out in the Gulf, have considered them to be abundant. Nichols (1927) raised one of the few voices of apparent dissent; he noted that in 1926 he encountered the largest number of fulmars (about 800) on 11 July in Shelikof Strait after he had left the Gulf. During the summer, fulmars are very common seaward of Montague Island, particularly to the northeast of Patton Bay and in the approaches to Montague Strait. Data derived from FWS surveys in July and August 1972 showed an estimated 10,000 fulmars in a stretch of waters 19 km wide along the east side of Montague Island (Isleib and Kessel 1973).
Over the Portlock Banks and in Stevenson Entrance, fulmars sometimes concentrate in very large numbers, either by themselves or in company with sooty shearwaters (Puffinus griseus). In August 1973, FWS observers crossing Perenosa Bay saw large numbers of tube-nosed birds moving northeastward across the Bay. Although these appeared to be predominantly shearwaters, there were also many fulmars. There was a general movement of birds through Shuyak Strait from Shelikof Strait into the Gulf of Alaska. It was not determined whether the fulmars were moving with the shearwaters or on a regular feeding flight. Fulmars are often found close to Afognak Island in the area between Sea Lion Rocks and Sea Otter Island. Gabrielson and Lincoln (1959) reported seeing swarms of fulmars in Marmot Strait and around the small islands on the north side of Afognak in early August. Murie (1959) noted fulmars in Shelikof Strait and again around the Shumagin Islands. There is nothing in this record to indicate any change in their distribution at sea recently.
The Semidi Islands support the Gulf of Alaska's largest fulmar breeding population, a Class V colony (U.S. Bureau of Sport Fisheries and Wildlife 1973). Gabrielson and Lincoln (1959) considered it to be one of the four largest colonies in Alaska.
Gabrielson (1940) was told by Captain Sellevold of the marine vessel Brown Bear that he thought the birds nested on Sea Otter Island in Perenosa Bay. Gabrielson also learned that they probably nested on Sea Lion Rock at the head of Marmot Strait. In August 1973 I observed fulmars in close proximity to Sea Lion Rock. More recently, small numbers of apparently breeding fulmars have been found in the Barren Islands (L. W. Sowl, personal observation and Edgar Bailey, unpublished FWS report, Anchorage, Alaska). Although no other colonies are known or suspected, the evidence suggests the possible existence of some.
Peterson and Fisher (1955), on noting dark fulmars between St. Paul and St. George when only the light morph was present on any of the colonies in the Pribilofs, expressed no surprise. They offered the opinion that a round trip of 960 km to one of the dark morph colonies in the Aleutians just might be within the operating range of a fulmar on a 4-day vacation from nest-tending duties. Using this as a general yardstick, it appears that the rich foraging grounds over the Portlock Banks might also be within the range of breeding fulmars from the Semidis. The trip up Shelikof Strait and on to Portlock Bank by way of Shuyak Strait is only slightly longer than the one from Chagulak to St. Paul. The feeding grounds off Montague Island would require a 1,600-km round trip from the colonies in the Semidi Islands. Birds from the Barren Islands and any colonies around Shuyak Island could easily reach the Montague Island grounds, but why would they cross the Portlock Banks to do so?
Fulmar colonies may be found in the Chiswell Islands. It is also a possibility that the existence of colonies on islands along the north coast of Afognak Island will be verified and that others will be found in the vicinity of Shuyak Island. Gabrielson and Lincoln (1959) expressed the opinion that there is almost certainly a colony on Sutwik Island. If there is one, however, I did not see it on one quick trip around the island in 1973.
Gabrielson (1940) expressed surprise at the size of the Semidi Island breeding colony. Gabrielson and Lincoln (1959) considered 1911 to be the first time breeding fulmars were found in the Shumagins. They apparently based this on two eggs collected there that year and documented in a plate in Bent (1964). Other than Gabrielson's opinion, there is nothing to indicate a major change in fulmar status during this century. If there has been a change in status, it has probably been in the direction of increasing populations.
The fork-tailed storm-petrel probably breeds throughout the Gulf of Alaska. It is abundant at sea during the summer in most offshore waters. Murie (1959) described it as the dominant petrel in the Bering Sea and the North Pacific.
In view of its wide distribution and apparent abundance very little is known about the fork-tailed storm-petrel's breeding colonies. Friedmann (1935) recorded specimens and eggs from Kodiak dating back to 1843. Murie (1959) noted them as nesting on Sanak Island and stated that they almost certainly nested in the Shumagins and on other islands along the Alaska Peninsula. David Roseneau (Isleib and Kessel 1973) found this storm-petrel "breeding by the 10,000's" on East Amatuli Island in the Barren Islands in June 1965. This was subsequently verified in 1974 by Edgar P. Bailey (unpublished report, FWS, Anchorage, Alaska).
On 2 July 1972, responding to a tip by James W. Brooks (personal communication), M. E. Isleib and I anchored at Fish Island in the Wooded Islands. We did not locate any storm-petrel burrows, but a steady flow of storm-petrels passed over the boat throughout the darkest part of the night. Surveys conducted at about that time provided an estimate of 19,000 fork-tailed storm-petrels in Prince William Sound, primarily in or close to Montague Strait, and in coastal waters on the east side of the Sound's outer islands. In this area Isleib (personal communication) has noted a general movement of fork-tailed storm-petrels westward around Montague Island and into Prince William Sound through Montague Strait each morning and a corresponding countermovement each evening. I conclude that in 1972 there was a Class IV colony in the Wooded Islands, numbering between 19,000 and 38,000 birds. Additional colonies will be discovered in a similar manner as more systematic searches are made.
No colonies were discovered during the 1973 reconnaissance survey of the islands south of Alaska Peninsula. Working primarily inshore, FWS investigators encountered very few storm-petrels during the day. On the night of 14 June, the FWS vessel, Aleutian Tern, responded to a Mayday call and was either in transit or participating in rescue operations from 2245 to 0420 h on the morning of 15 June. During this period numerous fork-tailed storm-petrels were encountered, particularly off Cape Wedge on Nagai Island. After we anchored in Eagle Harbor on Nagai, more storm-petrels were heard about the vessel.
At about this same date, National Marine Fisheries Service enforcement officers flying fisheries patrols observed storm-petrels in abundance south of the Shumagin Islands (James Branson, personal communication). These observations support the belief that there are probably substantial undiscovered colonies in the Shumagin Islands.
Fork-tailed storm-petrels are abundant summer residents in the northern Gulf of Alaska and the estimate by Isleib and Kessel (1973) is that populations using the waters off the North Gulf Coast probably number in the millions. Certainly the same estimate is valid for the rest of the Gulf area west of the Chugach Islands.
The status of these birds relative to their historical abundance cannot be derived from the existing information. There is strong suspicion that the introduction of fox on many of the islands in the area during the early part of this century probably caused a reduction in their numbers. Murie (1959) said that experience taught him that wings left from fox kills or remains of storm-petrels in fox droppings could be accepted as evidence of the presence of a colony. Gabrielson and Lincoln (1959) reported that E. P. Walker visited the Wooded Islands in 1922 searching for a storm-petrel colony that had been reported to exist there in 1918. He could not find it even though he searched diligently. This apparent disappearance was attributed to the introduction of fox.
There is another factor to consider, however. The limited number of specimens now available from the Gulf of Alaska indicates that separate subspecies occupy the eastern and western Gulf of Alaska. The accepted boundary is somewhere in the vicinity of Prince William Sound. This is an indication that there has been a hiatus in this area of rather long duration. I have speculated that this sort of break may be in some way related to the length of day and a period during the summer when there is little darkness to cover activities near the colony. Thoresen (1964) and Cody (1973) have both reported that western gulls (Larus occidentalis) assemble in Cassin's auklet colonies on moonlit nights to prey on arriving adults. It is likely that other nocturnal species would provoke the same sort of hunting tactic. A light-related predation factor implies that the predators rely on sight. Avian predators are indicated.
Even less well understood than the breeding distribution of the fork-tailed storm-petrel is that of Leach's storm-petrel.
Bendire (1895) quotes notes from Chase Littlejohn, who found Leach's storm-petrel to be an abundant breeder on unspecified small islands near Sanak in 1894. It greatly outnumbered the fork-tailed storm-petrel. On his visit in 1937 Murie (1959) learned that all of the large colonies of seabirds that had once existed there were gone. He attributed this to overfishing and associated perturbation and to the introduction of fox. No systematic assessment of seabirds on Sanak has been attempted since Littlejohn's time.
No Leach's storm-petrel colonies have been encountered during reconnaissance surveys of the Gulf of Alaska. Small numbers have been reported from time to time and while it is very much less abundant than the fork-tailed storm-petrel, I expect that it will be found in small numbers at various places in the Gulf of Alaska when it becomes possible to make more thorough searches. It may occur in remote areas like the smaller islands scattered throughout the Sandman Reefs—possibly even in large numbers. On the basis of the Sanak record, we must assume that this storm-petrel has been greatly reduced in numbers, at least in the western portion of the Gulf.
The white-crested cormorant, the race of the double-crested cormorant residing in the Gulf of Alaska, is principally an inhabitant of the marine environment. This cormorant is a common, but apparently patchily distributed, resident throughout the northern and western Gulf of Alaska.
Gabrielson and Lincoln (1959) thought that it nested only from Kodiak Island westward into the Aleutians. However, it probably breeds from Yakutat Bay westward. Isleib and Kessel (1973) estimated the abundance of the double-crested cormorant along the North Gulf Coast as several thousands, about one-tenth as common as the pelagic cormorant. It is the third most abundant of the four cormorant species nesting in the area. It occurs as scattered inclusions in many colonies throughout the area, and at least in the Shumagin Islands, even occurs in some colonies by itself.
There are no data on which to base an estimate of any change in status. It probably is not much affected by many of the naturally occurring perturbations.
On 22 July 1972, 13 Brandt's cormorants (4 sitting on nests) were found at Seal Rocks in Hinchinbrook Entrance, Prince William Sound (Isleib and Kessel 1973). Two years later I positively identified two individuals in breeding plumage among a mixed group of cormorants in the Chiswell Islands west of Seward. Are these recent range extensions? Possibly, but I propose an alternative explanation.
Palmer (1962) showed the distribution of this cormorant as breeding north to Puget Sound and as a straggler north to Forrester Island, Alaska. This viewpoint is shared by the American Ornithologists' Union (1957), which regards the bird as casual as far north as Forrester Island, where this species was collected by Willet (1918).
Let us look at the other record, the one that is not supported by specimens. Bent (1964) thought of Brandt's cormorant as a breeding resident of Forrester Island. Gabrielson and Lincoln (1959) admonished bird observers to be on the lookout for this particular cormorant in the vicinity of Ketchikan and Prince of Wales Island. Brandt's cormorant also appears on the bird list for the Kodiak National Wildlife Refuge as an accidental visitor.
Early observers like Bent were explorers. They carefully examined and made notes on all the birds they saw because there was always a chance of a new discovery. It is also very probable that Bent paid particular attention to the cormorants when he was at a place like Forrester Island. He would have undoubtedly been very interested in trying to confirm the presence of the now extinct Palla's cormorant (P. perspiculatus), as he must have been aware of Schlegel's (1862-64) list of the birds in the Dresden Museum since Willet (1914) had recently referred to it. The staffs for the Kodiak and Aleutian Islands National Wildlife refuges have included some very careful observers, such as Frank Beals. These men would have noticed the difference if a new bird such as Brandt's cormorant was seen, verified the sighting visually, and then noted it in their field diaries. They would not have bothered to develop the type of proof needed for an undisputable record, but the bird would have appeared in the refuge bird list (as it does).
The outside coasts of the Alexander Archipelago, Kenai Peninsula, and the Islands of the Kodiak Archipelago impose some logistical requirements which discourage all but the most determined birders. Not many have been able to reach more than very limited segments of the entire coast. Given the vast distances involved, few of the FWS vessels passing through the area have had the time to thoroughly examine any cormorant colonies or roosts bird by bird. Even for those who pause, the ever present swells and the constant chop of the summer westerlies make positive identification difficult.
It is possible that Brandt's cormorant has been in the area in small numbers for a long time, either regularly or intermittently. It could have escaped observation because of the conditions described above. This species may be there as a relict, as a pioneer, or only because surplus birds are being pushed into marginal habitat by population pressures on their main range to the south.
The pelagic cormorant is the most abundant of the four cormorants residing in the Gulf of Alaska. It is found throughout coastal Alaska south of the Bering Strait and even in some colonies in the southern Chukchi Sea.
Cormorants have a certain invisibility which is brought about by their universal presence. This blindness appears to have affected everyone, even the earliest observers.
The earliest accounts provide a composite picture of the distribution and abundance of the pelagic cormorant which is very similar to that encountered today. In southeastern Alaska, beginning at the eastern edge of the area under discussion, the pelagic cormorant was pictured as the sole resident cormorant. However, we know from Willet's collection of a Brandt's cormorant at Forrester Island that this might not be quite true. From Yakutat Bay westward into the Aleutians this species coexisted with the double-crested cormorant. In the Western Aleutians there is some disagreement, but in general it appears to have been accepted that the red-faced cormorant occurred there along with pelagic and possibly double-crested cormorants. In the Bering Sea this species coexisted with the red-faced cormorant.
A number of recent authors (Gabrielson 1940, 1944; Murie 1959; and others) have considered the pelagic cormorant to be the most widely distributed and abundant of the four species found in Alaska. Since the modern picture fits, in a general way at least, it would be easy to conclude that the species enjoys an unchanged status. There is just a faint suggestion that this may not be true.
Dement'ev and Gladkov (1966) refer to a great die-off of pelagic cormorants referred to earlier, in the Commander Islands. Stejneger (1885) enlarges on this disaster. It is true that Stejneger visited these islands a relatively short time after the die-off, but he reported that even though the pelagic cormorants were increasing, "people having seen their former multitude think that there is no comparison between the past and the present." Murie (1959) thought that the pelagic cormorant, while numerous, was outnumbered by the red-faced cormorant in the Aleutians. More recently there has been the rapid eastward expansion of the red-faced cormorant. Although it is not possible to determine what the real status of the pelagic cormorant is relative to its past status, I conclude that during this century its status relative to that of the red-faced cormorant has declined.
The red-faced cormorant, in spite of superficial similarities to the pelagic cormorant, just does not look the same to an experienced observer. However, it would have been possible for inexperienced observers in the days before modern optics to overlook the differences. The problem was further compounded by the "invisibility" of the ubiquitous cormorants referred to earlier. Apparent absences or blank spots in their range may not have been real.
Dement'ev and Gladkov (1966), reporting on the Russian record, stated that the red-faced cormorant was common in the Commander Islands during the last part of the 19th century and into the early part of the 20th. Older authors had also reported it from Kamchatka and the Kurile Islands. Now, according to Dement'ev and Gladkov, it is an uncommon breeder on Mednyi Island in the Commander Islands and occurs only as an autumn visitor to some of the southern Kurile Islands.
Turner (1885) reported that the double-crested cormorant was abundant in the Near Islands and that the pelagic cormorant was common, but makes no reference to the red-faced cormorant. One specimen of the latter in the Leningrad Academy of Science was taken at Attu on 16 September 1844 (Gabrielson and Lincoln 1959), which indicates that they were probably present during the period reported on by Turner and, therefore, relatively uncommon. Clark (1911) identified red-faced cormorants only a few times and in the Aleutians only once, near Agattu. Dall (1874) noted two red-faced cormorants collected at Amchitka but he (Dall 1873) apparently did not see any east of Unalaska.
Nelson (1887) apparently found red-faced cormorants breeding on the Siberian and Alaskan mainlands at either side of Bering Strait, but Bailey (1948) searched for some sign of their presence and found none. Nelson (1887) also reported the red-faced cormorant from St. Matthew and St. Lawrence islands in the northern Bering Sea and from St. Michael and Nelson Island on the Alaskan coast. Gabrielson and Lincoln (1959) pointed out that it has not been found breeding north of the Pribilofs since then. Friedmann (1934) provides support for Nelson by reporting red-faced cormorant bones from archeological sites on St. Lawrence. Gabrielson and Lincoln (1959) cited two red-faced cormorants in the Leningrad Academy of Science which were collected in the Pribilofs in 1843. Dall and Bannister (1869) reported them to be plentiful on St. George Island. Baird (1869) also noted their presence in the Pribilofs.
Bent (1964) makes no mention of seeing the red-faced cormorant in the Aleutians. He gives their breeding range as the Bering Sea region, the Pribilof Islands, and perhaps the western Aleutians, the Commander Islands, and the coast of Siberia north of North Cape. The American Ornithologists' Union (1931) gave their breeding range as the Pribilof Islands, the Commander Islands, and Siberia north to North Cape.
Murie (1959) found a colony of between 4,000 and 5,000 red-faced cormorants nesting on Amak Island in 1925. In 1936 he was surprised to find that the red-faced cormorant was the most abundant breeding cormorant in the Aleutian Islands. Pelagic cormorants still appeared to be most numerous, but there were large numbers of nonbreeding birds. In 1936 he located "a good sized colony" of red-faced cormorants at Unga in the Shumagin Islands. He found about 300 birds starting their nests on 16 May.
In August 1946 Gabrielson (Gabrielson and Lincoln 1959) visited the colony at Delarof Harbor, Unga, where several thousand cormorants were observed. From a number of small samples he estimated that the red-faced cormorants outnumbered pelagic cormorants five to two. In 1973 I observed about 2,000 cormorants, mostly red-faced, in this colony. Gabrielson also located them at two other sites in the Shumagins and at Aghiyuk Island in the Semidi Islands.
Howell (1948) noted only double-crested cormorants at Double Island, Kodiak. Shortly after that the leaflet, Birds of the Kodiak Island National Wildlife Refuge (first issued in 1955), listed red-faced cormorants as common summer residents. The red-faced cormorant was next found at Katchemak Bay about 1963. Isleib (Isleib and Kessel 1973) first noticed red-faced cormorants wintering in Prince William Sound in 1969. In July 1972 Isleib and Sowl had found a colony containing 75 nests at Point Elrington at the western approach to Prince William Sound. By 1974 Isleib and Haddock (unpublished data, FWS, Anchorage, Alaska) found them east of the Copper River Delta at Wingham Island.
The relatively rapid expansion of the range and apparent population size of the red-faced cormorant is remarkable. But has this been a real expansion into vast stretches of new territory? The record in the literature which I have summarized shows, I think, something else. We can demonstrate a historical range for the red-faced cormorant that extends on the Asiatic Coast from North Cape, Siberia, south to the Kurile Islands, the entire Aleutian Arc including the Commander Islands, all the Bering Sea islands north to Bering Strait, Norton Sound, Nelson Island, and the islands south of the Alaska Peninsula at least as far east as Kodiak Island. The recently occupied coast from Cook Inlet to the Copper River may represent a real range extension. The breeding range of this species at the present time does not include parts of its historical range west of the Commander Islands or north of the Pribilof Islands.
The fragmentary record appears to show a long-term perturbation in the range and populations of the red-faced cormorant that covers at least 100 years. I believe that we are probably seeing a recovery of lost range and a return to something resembling a former distribution and abundance.
What caused the perturbation? I am not prepared to answer this question, but there are two occurrences which I find suggestive.
It is interesting to note (Dement'ev and Gladkov 1966) that on the Commander Islands the red-faced cormorant was most abundant during the first 50-odd years after the pelagic cormorants had been wiped out in the winter of 1876-77. Perhaps some clues are to be found in the interactions between these similar species.
It does not appear that the introduction of fox could have been a causative factor. The first observations of population expansion were noted almost concurrently with the heyday of the fox-farming industry. Because of its choice of nesting habitat (very steep cliffs), this cormorant would not have been affected by predators except for the one that went into a very rapid population decline at a time that would fit—the Aleut.
Jochelson (1968) and Hrdlicka (1945) summarized references to Aleut clothing in the diaries and reports of early Russian visitors to the Aleutian Islands. Evidently Aleut women sometimes wore a long, robe-like parka made of harbor seal (Phoca vitulina) skins or, for women of high rank, parkas made of sea otter (Enhydra lutra). The men in almost all reports were said to have worn bird-skin parkas; puffins and guillemots appear to have been preferred, but cormorants were sometimes used. It took about 40 puffin skins to fabricate a parka and a man evidently needed from one to three of these garments each year.
Sea otter populations were drastically reduced by Russian hunters. Rats were introduced to the Aleutians very early during the Russian period and must have had a substantial impact on populations of tufted puffins and guillemots. The introduction of fox would have had a further impact on burrow-nesting birds. Turner (1885) noted that Aleuts in the Near Islands kept the fox confined to Attu so that they could keep the fox away from the birds on Agattu. This is evidence of an Aleut recognition of serious competition. Could cormorants, particularly red-faced cormorants, have been preferred sources of fiber? Were Aleuts forced to rely more heavily on cormorant skins as puffin and guillemot numbers were reduced by rats and fox and sea otters by men?
Whatever the cause and effect, the status of red-faced cormorants now appears to be better in the Gulf of Alaska than for at least the last 100 years.
The glaucous-winged gull is apparently one of the more successful seabirds breeding in the Gulf of Alaska. While it is outnumbered (both locally and in total abundance) by the black-legged kittiwake, it is generally the most commonly seen and most uniformly distributed gull in the Gulf of Alaska. Murie (1959) called it the common breeding gull about the Alaska Peninsula. Cahalane (1943, 1944) considered it to be numerous to abundant around Kodiak and in the Shelikoff Strait area. Gabrielson (1944) reported that it could be seen in small numbers everywhere. Most recently, Isleib and Kessel (1973) reported it to be an abundant resident in the north Gulf Coast area. My own experience would confirm these observations.
This gull appears to use a wider variety of nesting sites than some others (Gabrielson and Lincoln 1959). Except where man's activities have created new food sources, there appears to be a close link between the location of glaucous-winged gull colonies and those of murres, kittiwakes, and cormorants. Swartz (1966) found that during the breeding season glaucous-winged gulls at Cape Thompson derived almost all of their food from murre eggs and chicks. I have noted small numbers of these gulls nesting, usually on turf near the tops of cliffs, in most colonies of favored prey species.
The glaucous-winged gull is the principal scavenger throughout much of coastal south-central Alaska. This has sometimes resulted in the development of large concentrations near canneries and, more recently, near dumps.
Two glaucous-winged gull concentrations stand out in the northern Gulf of Alaska. One of these is on Egg Island at the western end of the Copper River Delta. Patten (1976) estimated that this colony contained 10,000-12,000 gulls in 1975. At times it appears to spread onto nearby Hinchinbrook Island. M. E. Isleib (personal communication) has estimated its size as high as 25,000 gulls. The other large concentration is on the Susitna Flats across Cook Inlet from Anchorage. This colony, or colony cluster, may be larger than the one at Egg Island. There are no other known colonies even approaching these in size. Most colonies range between a few pairs and 2,000-3,000.
Glaucous-winged gulls do not appear to have had any great changes in population that can be detected from the literature. There have almost certainly been local fluctuations in the number of breeding birds as food supplies, such as canneries and dumps, have appeared or disappeared in an area. Long-term changes in salmon runs have undoubtedly had an impact as well. One other change, the reduced level of egging, has undoubtedly had an effect also. Along the Alaska Peninsula and in the Shumagin Islands, cannery workers of Filipino heritage and fishermen who have a strong Aleut heritage still harvest gull eggs for food. However, this activity is much reduced from what it must have been.
The herring gull is a resident of Upper Cook Inlet and is found up and down the coast from Prince William Sound to the Alaska Peninsula. Not too much was learned about it during the recent FWS reconnaissance. Williamson and Peyton (1963) reported the interbreeding of herring gulls and glaucous-winged gulls in this area. This interbreeding has resulted in a situation in which assignment of these gulls to one group or another in the field can be rather arbitrary. The result has most often been that field observers tend to lump them with glaucous-winged gulls unless their herring gull characteristics are obvious. Specimens collected by Williamson and Peyton (1963) indicate that herring gulls have the edge in numbers in Upper Cook Inlet.
The black-legged kittiwake is the most abundant gull in the northern and western Gulf of Alaska. Colonies of this species can be found throughout the entire area, and range in size from a few pairs (Class I) to more than 100,000 birds (Class V). They may be found in essentially pure colonies, but are often found sharing colonies with murres.
The center of abundance for breeding black-legged kittiwakes in the Gulf of Alaska is in the Semidi Islands, where Palmer Sekora (U.S. Bureau of Sport Fisheries and Wildlife 1973) estimated that there were 426,000 breeding kittiwakes in 1972. He located kittiwake colonies at eight sites, ranging in size from 1,000 to 109,000 nesting birds. The size of the average colonial site was 27,000 birds. Ten sites were Class IV in size and one was a solid Class V.
The easternmost known colony in the northern Gulf of Alaska is at Wingham Island. Up to 1973, 22 colonies had been located in Prince William Sound. The largest of these contained only 5,636 nests in 1972 (Isleib and Kessel 1973). Class IV or larger colonies are found at Cape Resurrection, the Barren Islands, Chisik Island, Boulder Bay and Cape Chiniak on Kodiak Island, and at Delarof Harbor and the Haystacks in the Shumagin Islands. It is interesting to note that Gabrielson (1940) considered Whale Island to be one of the largest known kittiwake colonies in Alaska. He stated that there were many thousands of pairs extending over a mile or more of cliff. He saw a second site which he did not visit but looked equally large. A photograph in an article by East (1943) also indicated the presence of a large colony. C. J. Lensink (personal communication) estimated that there were about 100,000 kittiwakes in the colony in 1956. When last visited by Vernon Berns (personal communication), this colony contained only 3,000 birds. It is also of interest that Gabrielson (1940, 1944) did not notice either the kittiwakes or the murres now breeding on Nord Island in the Barren Islands or the kittiwakes on East Amatuli Island.
Whale Island and possibly the colonies in the Barren Islands give evidence of local population fluctuations, but for the most part I have not found an indication of a major perturbation over the past 40 years. Before 1936, the record is too fragmentary to allow an assessment.
One of the interesting aspects of kittiwake ecology in the Gulf of Alaska is the common occurrence of breeding failure. David Snarski (December 1943 Quarterly Progress Report, Alaska Cooperative Wildlife Research Unit, University of Alaska) observed breeding failure on colonies in the Tuxedni National Wildlife Refuge in 1970 and 1971 and obtained circumstantial evidence of another failure in 1972. In 1973 all of the breeding cliffs were occupied and nesting was successful. Whatever the cause of these periodic failures, they do not yet appear to have had a permanent impact that we are able to measure.
Red-legged kittiwakes are not now known to breed in the western Gulf of Alaska. Turner (1886) stated that he saw a few at Sanak in 1878. We also have Stejneger's (1885) statement, that "red-legged" kittiwakes nest from Bering Island to Sanak. Friedmann (1937) reported two humeri from Kodiak Island middens. During the summer of 1976, two birds were observed off Kodiak Island by Irving M. Warner (personal communication), and one at 158°W and 54°30'-54°20'N south and east of the Shumagin Islands (Patrick J. Gould, personal communication).
Turner (1885) listed the red-legged kittiwake as abundant and breeding in the Near Islands. Turner (1886) also stated that he had seen quite a number about a cliff back of the village on Akutan Island in 1878. He added that to the westward this kittiwake was more abundant than the black-legged kittiwake. Murie (1959) expressed the opinion that Turner had confused the short-billed gull with the "short-billed" kittiwake. Clark (1911) also reported that he had seen the red-legged kittiwake in small numbers near Unalaska and that they became progressively more common west to the Near Islands. Nelson (1887) reported seeing large numbers of red-legged kittiwakes at Unalaska. Murie (1959) and Gabrielson (1940, 1944) did not see any red-legged kittiwakes in the Aleutian Islands. The species has recently been discovered breeding at Buldir and Bogoslof islands (G. Vernon Byrd, personal communication).
Is it possible that we have here another species which is exhibiting a response to some unknown long-term perturbation? The suggestion that such an event has occurred is faint, but it is there. Do we have in the red-legged and black-legged kittiwakes an example of yet another congener pair that has been affected by some perturbation in which one was affected positively and the other negatively? Clark (1911) reported small numbers of black-legged kittiwakes to go with large numbers of red-legged kittiwakes in the Near Islands, which is the reverse of the current situation.
Gabrielson and Lincoln (1959) attribute to the Arctic tern the most extensive range of any Alaskan water bird. It is found in suitable habitat everywhere north of Tracy Arm in Southeastern Alaska. Murie (1959) stated that he found it nesting at suitable sites everywhere he went. Isleib and Kessel (1973) considered it to be an abundant breeder in Prince William Sound and along the northern Gulf Coast.
The Arctic tern was observed in FWS aerial surveys in Prince William Sound, and surveys in July and August 1972 provided an estimate of 45,000 terns in the Sound (Isleib and Kessel 1973). On the other hand, tern colonies were located only rarely in the FWS colony surveys before 1975. This is, however, a reflection of the equipment and methods used and not of the abundance of terns.
From the fragmentary data available, it is not possible to detect changes in Arctic tern status at the present time. We have to assume that the widespread introduction of fox had at least local impact. Although this tern uses a wide variety of nesting sites, it tends to nest on flat sites where access by mammalian predators is easy.
No Aleutian tern colonies were discovered in the Gulf of Alaska area during FWS colony surveys in the early 1970's. This is again a reflection of the fact that surveys were not designed to locate tern colonies. Aleutian terns were encountered at least twice, once during late March 1972 in Hawkins Cutoff, Prince William Sound, and again when two birds were noted offshore from the Katmai National Monument on 30 May 1973 (L. W. Sowl, personal observations).
The type specimen of the Aleutian tern and a single egg were collected at Kodiak Island on 12 June 1868 by Bischoff (Coues 1874). Fisher (Gabrielson and Lincoln 1959) collected four more eggs in 1882. The bird was not found breeding there until Howell (1948) found a colony of 50 pairs at Bell's Flats in 1944. Walker (1923) found them nesting on the Situk River, Yakutat, in 1917 and shortly thereafter saw them at the Alsek River Flats. He also reported that D. H. Stevenson of the Bureau of Biological Survey had told him that they nested on the Isanotski Islands at the end of the Alaska Peninsula. This latter report was the only one from the Aleutian Island chain for many years. Isleib and Kessel (1973) considered it an uncommon local breeder in the northern Gulf of Alaska. Isleib estimated its population at a few hundred pairs on the Copper River Delta in May 1973 and 300-500 birds in June 1970. He also reported that they appeared more or less regularly near Controller Bay and off the Situk River.
In recent years Aleutian terns have been seen with increasing frequency in many places in western Alaska and the Aleutian Islands. This is probably partly due to the increasing level of field work. At Amchitka Island the several colonies that have been found in recent years are almost certainly exhibiting a response to the removal of fox from the island.
Although there is no way of determining what the past status of the Aleutian tern has been in the Gulf of Alaska area, it has been there in small numbers since it was first discovered on Kodiak. It has probably not been abundant at any time and may have suffered a long-term decline brought about by the introduction of fox.
The common murre is resident in the northern and western Gulf of Alaska from Pinnacle Rock, Kayak Island, westward. East of Cook Inlet colonies are located at Wingham Island, the Martin Islands, Middleton Island, Porpoise Rock in Hinchinbrook Entrance, Barwell 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 another 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 Mitrofania 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 Amutuli (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 return 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 colonies. Rausch (1958) reported murres from Middleton Island.
There is quite a difference between the distribution 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 colonies 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 Islands in particular. Perhaps this represents the vague outlines of yet another population change.
The center of abundance for murre distribution 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 definitive data on species composition of these colonies. Common murres undoubtedly dominate in most of the colonies; the only ones where we know of a sizeable thick-billed murre component are in the Shumagin Islands.
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 possible. 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 Island 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 numbers 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, unpublished data).
Bent (1963) reported that many thick-billed murre eggs have been taken by collectors at Round Island in the Shumagin Islands. Dall and Bannister (1869) reported a thick-billed murre that was taken at Kodiak in 1867.
The Gulf of Alaska is at the periphery of the breeding range of the thick-billed murre. While it probably occurs in mixed colonies with the common murre throughout this area, the thick-billed murre is much less abundant. Occasionally in the Gulf of Alaska, a colony will be occupied predominantly by the thick-billed murre. Gabrielson and Lincoln (1959) noted that the thick-billed murre outnumbered the common murre in many colonies in the Aleutians and that it became progressively more common at higher latitudes.
We have almost no data relative to the species composition of murre colonies in the Gulf of Alaska. Until we do it will not be possible to fully understand the population status of the thick-billed murre. It appears that changes in the species composition of murre colonies in the Bering Sea may be an indicator of perturbation. The data for the Gulf of Alaska are still too fragmentary to provide any indication of whether or not the same indicator would work there. Close monitoring of the Shumagin Islands colonies over a number of years might produce the answer.
Earlier in this paper I noted the dramatic changes in species composition of murre colonies on Walrus Island. Gabrielson and Lincoln (1959) also commented on this well-documented and anything but static situation. Investigators who visited this island during 1976 reported seeing no murres on the island and only small numbers on offshore rocks. James Bartonek (personal communication) said that this situation has prevailed for several years.
There is an indication that a similar population fluctuation and change in species composition of murre colonies have also occurred on St. Matthew Island. Bent (1963) found mostly common murres and few thick-billed murres at St. Matthew. Hanna (1916) saw only thick-billed murres. Later, Gabrielson (1941) found this to be true in 1940.
Dramatic fluctuation in murre populations may be common and, at least in some cases, the two species may be affected differently. Perhaps this phenomenon has potential for providing us with an indicator of some natural perturbations.
Peterson and Fisher (1955) expressed the opinion that thick-billed murres arrived at the nesting ledges later than the common murre and had to take the sites that were left. Tuck (1960) reported data from the western Atlantic showing that thick-billed murres arrive later than common murres. On the other hand, Belopol'skii (1961) reported data showing that the two species arrive on breeding colonies in East Murman simultaneously. At Cape Thompson, Swartz (1966) found that thick-billed murres arrived about a week before common murres. The date of arrival, while perhaps a contributing factor, is probably not decisive. Interspecific competition of another sort is indicated.
In mixed murre colonies where there are large numbers of common murres, this species occupies the choice nesting sites. Thick-billed murres are usually left with the narrower ledges while the common murres occupy the longer, broader ledges (Belopol'skii 1961). The broader ledges have lower chick and egg mortality (Spring 1971). Spring also noted that thick-billed murres are excluded from the centers of mixed colonies. Johnson (1938) found that this contributes to higher losses of eggs to predators and to the loss of other social benefits of occupying the colony center (Johnson 1941).
Kozlova (1961) said that during the occupation of a colony there is a sharp competitive struggle between the two species. In the end thick-billed murres are pushed out to the periphery of the colonies or left with narrow ledges or other equally unfavorable sites. Spring (1971) studied the functional anatomy of both species and concluded that the common murre is more successful in these encounters because it has a more upright gait and greater agility than the thick-billed murre.
It follows that in a portion of their respective ranges, where the two species overlap and where there is an equal chance that either common murres or thick-billed murres will dominate a given colony, the common murre dominates. I conclude from this that where there are dramatic changes in species composition of murre colonies, such as at Walrus Island, it is probably because the common murre has been greatly reduced in numbers at the colony.
Spring (1971) concluded that the common murre is well adapted to pursuit and capture of pelagic fishes and that the thick-billed murre is better adapted for deep diving and the capture of benthic fishes and pelagic and benthic invertebrates. Having greater latitude 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 accounts 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 common murre restricts its diet almost entirely to a small number of fish species. Swartz (1966) found strong indications that there were significant differences in the food preferences of the two species of murres. Thick-billed murres made much greater use of invertebrates. Bédard (1976) asserted that it is well known that the common murre is quite partial to zooplankton. So again the issue is not clear-cut.
The situation is, of course, much more complex than I have portrayed it. Nonetheless, I think that it offers potential for use as a tool in assessing population change and perturbations in the food supply which should be studied quite closely.
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 nesting 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 impossible species to inventory by standard methods.
There is no evidence that the pigeon guillemot 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 distribution should insure that man-made impacts such as oil spills will have limited impact.
The population levels of the pigeon guillemot 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 becomes more than a dream.
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 murrelets 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 beginning 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.