The cover image was created by the transcriber and is placed in the public domain.

WILDLIFE RESEARCH REPORTS

This series comprises reports of research relating to birds, mammals, and other wildlife and their ecology, and specialized bibliographies on these, issued for wildlife research and management specialists. The Service distributes these reports to official agencies, to libraries, and to researchers in fields related to the Service's work.

Library of Congress Cataloging in Publication Data

Conservation of marine birds of northern North America.

(Wildlife research report: 11)

Supt. of Docs. no.: I 49.47/4:11

1. Sea birds—North America—Congresses. 2. Sea birds—Northwest, Pacific—Congresses. 3. Birds, Protection of—North America—Congresses. 4. Birds, Protection of—Northwest, Pacific—Congresses. 5. Birds—North America—Congresses. 6. Birds—Northwest, Pacific—Congresses. I. Bartonek, James C. II. Natural Resources Council of America. III. United States. Fish and Wildlife Service. IV. Series.

QL681.C59333.9'5 79-607005

Use of trade names does not imply U.S. Government endorsement of commercial products.

CONSERVATION OF MARINE BIRDS OF NORTHERN NORTH AMERICA

CONSERVATION OF MARINE BIRDS OF
NORTHERN NORTH AMERICA
Papers from the International Symposium
held at the Seattle Hyatt House,
Seattle, Washington, 13-15 May 1975

Edited by

James C. Bartonek and David N. Nettleship

• Sponsored by
• Natural Resources Council of America
• National Audubon Society
• National Wildlife Federation
• U.S. Department of the Interior, Fish and Wildlife Service

UNITED STATES DEPARTMENT OF THE INTERIOR
FISH AND WILDLIFE SERVICE
Wildlife Research Report 11
Washington, D.C. • 1979

Dedicated to the Memory
of

Robert D. Bergman, Leonard A. Boughton, and J. Larry Haddock, Wildlife Biologists of the Fish and Wildlife Service, and Robert Johnson, Pilot of the Office of Aircraft Services, all of the U.S. Department of the Interior, who perished in the Gulf of Alaska on 30 September 1974 while conducting aerial surveys of marine birds,

and to

Einar Brun, Professor of Zoology in Tromsø University and a contributor to these proceedings, who perished in the Vega Sea on 13 July 1976 when returning from making aerial surveys of marine birds.

Contents

Foreword

The international symposium "Conservation of Marine Birds of Northern North America" was convened because of a growing awareness that not all was well with our marine birds. The symposium provided a forum for scientists, governmental administrators, conservationists, and laypeople to discuss the diverse topics and issues that we must all understand if we are to act both responsively and responsibly to assure that marine birds will not be lost through our neglect.

The symposium was cosponsored by the Natural Resources Council of America, National Audubon Society, National Wildlife Federation, and the U.S. Department of the Interior, Fish and Wildlife Service; additional support was provided by the Canadian Wildlife Service, the International Association of Game, Fish, and Conservation Commissioners, the Pacific Seabird Group, the Sierra Club, the Smithsonian Institution, the Wildlife Management Institute, and the Wildlife Society.

Persons interested and knowledgeable in the many and varied aspects of marine bird conservation were invited to participate in this symposium. There were 139 registered and several score of unregistered participants in attendance. Major topics treated were: (1) socioeconomic considerations and conservation of marine birds; (2) the marine environment of birds; (3) status of marine bird populations on land and sea; (4) the biology and ecology of marine birds in the North; (5) conflicts between the conservation of marine birds and uses of other resources; (6) programs and authorities related to the conservation of marine birds; and (7) conservation of marine birds in other lands.

The objective of the symposium was to identify problems and the needed information and programs necessary for the conservation of marine birds of northern North America. For the purpose of this symposium the term "northern North America" referred to the coasts of Washington, British Columbia, Alaska, Yukon Territory, and Northwest Territories and the adjacent North Pacific and Arctic Oceans. "Marine bird" was defined as being any bird using marine or estuarine waters. Speakers were asked to describe the status of information or the state of the art as it pertained to their topic within the limitations set by the objective of the symposium. Examples from other regions and of bird species not found in the regions of concern were to be used for comparative purposes when little pertinent information was known for regions or species of concern. Speakers were asked to identify the gaps in the knowledge and methodology that are most critical to their topic.

I believe that this symposium was particularly successful in that it provided a timely forum for many scientists who were about to embark on studies of marine birds in those areas of Alaska and California being considered for outer continental shelf oil and gas exploration and development. These published proceedings may be of lesser importance from that standpoint because some data, particularly those on populations, are out of date. However, I believe that the proceedings will long be of importance to biologists and administrators alike in charting their respective courses to ultimately assure conservation of this valuable avian resource.

Many people from many organizations and agencies worked hard to put together the symposium in the relatively short time of about 8 months. Nathaniel P. Reed was the person primarily responsible for bringing this symposium to fruition. The Steering Committee was composed of Daniel A. Poole, John S. Gottschalk, David N. Nettleship, Amos S. Eno, C. Eugene Knoder, Warren G. King, Louis Clapper, Robert Hughes, Fred G. Evenden, James C. Bartonek, and me. James C. Bartonek, Warren G. King, David N. Nettleship (Co-chairmen), C. Eugene Knoder, David A. Manuwal, William H. Drury, and Spencer G. Sealy served on the Program Committee. David A. Manuwal and Terence R. Wahl arranged trips for persons to observe pelagic birds off the Washington coast and other birds on Skagit Flats. C. Eugene Knoder handled financial matters. John A. Sayre and Richard Bauer made arrangements for facilities and entertainment. Elaine Rhode prepared the program and abstracts for printing. John Pitcher kindly contributed the artwork used in this publication as well as that used in the program and abstracts.

George Reiger made general introductions to the symposium; Spencer G. Sealy, Daniel W. Anderson, and I served as Session Chairmen; and James C. Bartonek served as General Chairman. Elvis J. Stahr was guest speaker at the symposium banquet.

Most credit for the success of this symposium goes to the 52 persons who as authors, coauthors, or summarizers of sessions presented much meaningful information in their presentations, during recorded discussions, and during many informal occasions. I wish to make special recognition of Ian C. T. Nisbet for his skillful summary of the symposium.

Editorial assistance in preparing the proceedings was provided by Judith Brogan.

Harvey K. Nelson
Chairman of Symposium and
Director of Wildlife Resources

Introduction

Migratory birds make up a resource that is shared by many people of many nations. Public awareness of marine birds—their manifold values, ecological requirements, and problems—is prerequisite to their protection. I am proud that the Fish and Wildlife Service can further this needed awareness by publishing these proceedings of the international symposium "Conservation of Marine Birds of Northern North America."

Lynn A. Greenwalt, Director
Fish and Wildlife Service

MARINE ENVIRONMENT OF BIRDS

[Long-term Climatic and Oceanographic Cycles Regulating Seabird Distributions and Numbers]

by

M. T. Myres

Department of Biology, University of Calgary
Calgary, Alberta, Canada T2N 1N4

Abstract

Seabird ornithologists have generally paid little attention to the possible roles played by long-term climatic cycles or air-ocean interactions on population changes at established colonies or on the processes of colony establishment or extinction. Yet, a rapidly expanding literature in the physical sciences suggests that seabird numbers are not naturally stable at particular colonies for any great length of time. It is suggested that the establishment of new colonies at one end of the range may counter the decline of colonies at the other end. Perhaps these changes in small marginal colonies are important, and they may be more indicative and significant (when detected and explained) than are much larger changes in numbers in bigger reproductive units in the center of a species' range. Fluctuations in seabird numbers must in future be first considered as possible responses either to short-term, or turnarounds in longer term, natural climatic or oceanographic cycles, or to trends ranging in length from a few years to at least several decades.

During the last 30 years extensive literature in the fields of physical and biological oceanography has accumulated that is not readily accessible to the nonprofessional student of seabirds and not as widely understood by career seabird ornithologists as it should be. This literature in oceanography and marine fisheries is as extensive in Russian and Japanese together as in the main languages of Western Europe combined; this abundance compounds the problem of becoming familiar with it if, as a student of seabirds, one's interest in the literature is initially somewhat marginal. Nevertheless, to achieve the best possible appreciation of the oceanographic influences affecting seabirds, particularly in the north Pacific Ocean and its adjacent embayment seas, it is necessary to make the effort.

Because of the rigor of carrying out their primary duties while at sea, only a very few North American and European oceanographers or fishery biologists have found time to interest themselves in seabirds and then, with a few notable individual exceptions, only as an off-duty pastime. The reason is not far to seek. It is far less important to examine the ecology of organisms at the next highest level of the food chain to the ones that are the primary concern than it is to examine the next lowest level (the food of the fishes or, in the case of phytoplankton, the physical and chemical environment in which the organisms grow best).

Seabirds are at the very top of the marine food chain, and they are not wholly aquatic in any case since they mainly travel through the air rather than the water and reproduce on land rather than in the sea. Only with the relatively recent recognition that seabirds contribute to the recycling of nutrients back into the ocean to an important degree, have seabirds gained a new scientific constituency.

At about the same time, governments have begun to recognize that seabirds are relatively easily examined indicators of the presence of unseen chemical pollutants in coastal seas, perhaps primarily for the very same reasons that they were previously so largely ignored; namely, that they are at the top of the food chains (and so accumulate the most-persistent and least-degradable pollutants) and that the on-land failures in their reproductive biology are readily visible.

During the last 10 years, it has become evident that yet another fundamental science is even more basic to the achievement of a balanced and in-depth understanding of the influence of the environment upon seabirds—the combined field of astrophysics, geophysics, and climatology. New developments in this field (when they are not published in Nature or Science) appear in journals that are less familiar to seabird ornithologists than those in which the fishery biologists and biological oceanographers publish their findings.

Unfortunately, important advances in understanding the dynamics and energy transport mechanisms of both the atmosphere and the water masses of the oceans are not being picked up by students of seabirds because of the natural lag in communication that occurs between disparate disciplines. Only in the last few years have oceanographers and climatologists been invited to address gatherings of ornithologists, and the modesty with which they have sometimes done so has limited the impact of their offerings.

At this symposium, it was left to a biologist with no pretentions in either physics or mathematics to demonstrate the need for seabird ornithologists to understand basic environmental processes well beyond their usual range of interests. I did so with a series of slides taken from this "other" literature, and I had intended to include in the published version of this paper an extensive bibliography, subdivided into category groupings, so that seabird ornithologists could make their own selection of the points in the spectrum at which they most needed information.

Unfortunately, limitations upon space in this volume, daily additions to the exploding literature, and my own inability to keep up with understanding this have forced me to omit any references and not to attempt to expound detailed specific physical mechanisms.

Thus unencumbered here, I shall briefly outline instead what I perceive to be some of the significance for seabird ornithology and conservation of the rapidly expanding understanding of the oceans, the air-sea interface, atmospheric dynamics, and influences upon the world's climate of extraterrestrial events.

Small-scale or Short-term Influences

There is no need to dwell on the well-known events that could be mentioned under this heading. Seabird ornithologists are familiar with the fact that the atmosphere is the medium of seabirds both when searching the ocean for feeding areas and when on migration, and also a violent enemy, as when particular storms cause occasional "wrecks" of seabirds inland from coastlines. As a refinement of the former, Manikowski of Poland suggests that seabirds respond to the passage of weather systems, so that their distribution over the open ocean may be constantly changing. Whereas some species may attempt to avoid the stormy conditions of low-pressure areas (cyclonic conditions), others more highly specialized for exploiting the aerodynamic properties of wind over a moving water surface may possibly, instead, try to avoid large high-pressure regions (anticyclonic conditions with little or no wind). My student, Juan Guzman, is attempting to determine whether this may be so; if it is, it might be possible, for example, to predict some things about the distribution patterns and population structure of southern hemisphere shearwaters while they are visiting the oceans of the northern hemisphere during the nonbreeding season.

In comparison with the "wrecks" brought about by storms, which are of short duration and not usually very serious, seabird ornithologists are also familiar with relatively brief and localized disasters caused by changes in the ocean itself. The best-known example is a slight change in the boundary of an ocean current (or other shift in the position of a distinctive water mass) that results in the failure of food fishes to appear as they normally would, close to breeding sites of conspicuous colonial seabirds, such as the periodic shift in the El Niño off the west coast of South America. A scarcely studied refinement of this type of event would be the effects of less-pronounced oceanic changes that might reduce the planktonic food supply of nocturnally active, burrow-nesting seabirds. In such instances, the effects might also be a breeding failure for only one or two seasons; in all probability such events occur, but whether they are as likely to be detected by us is problematical. However, the populations of most seabirds are probably already adapted to survive short-term crises of this type because, having long adult life spans, reproductive adults that fail to raise young one year may mostly live to succeed in doing so in the next or succeeding year, when the oceanic "anomaly" has disappeared. What constitutes an "anomaly" will be considered again shortly.

A third critical condition for seabirds may be local or widespread, temporary or final, or some combination of these. A single local spill, or outfall, of a chemical pollutant will be short term if we can take steps to alleviate the consequences or stem the flow. Alternately, we may consider it to be long term if we take the view that it is one additional act of violence resulting from the "progress" of Industrial Man, and that it is never going to shift into reverse gear. We may say that the effect on seabird populations of spills of oil products or chemical pollutants in coastal waters of a region will be a "final solution" for any that become wholly extinct before the oil wells go dry or the industries fail. On the other hand, the effect will have been merely a perturbation of the population if the species survives and outlives these activities. Recent upturns in populations of peregrine falcons (Falco peregrinus) and pelicans (Pelecanus sp.) in certain places where environmental controls have been enacted give us hope that crises of several years' duration can be withstood by at least those species that once were common in relation to their respective food sources or available safe breeding habitats. The really critical features to document are the means whereby abandoned breeding sites are reoccupied and the time it takes.

It must never be forgotten that we know almost nothing about the ecology of subadult or nonreproductive adult seabirds during the years they are at sea unconfined by membership in a breeding unit and that we know almost nothing about the activities of pelagic seabirds in the nonbreeding season. These birds may be far from land and hard to study, but what happens during those phases of their lives is basic to the composition of the colony and condition of the birds when breeding. A start would be to learn everything that is known and is being discovered about the oceans by oceanographers and, thus forearmed, go looking for the seabirds with certain questions clearly in mind.

Detecting the Effects of Long-term Cycles

A scientist's working life lasts only a few decades, and few studies of seabirds by a single author or agency have been continued for longer than 5-10 years on any one problem. Further, while we as individuals may live to be equally active in a certain field of research 20 years hence, our collective conscience and collective muscle consist of several levels of government that tend to exhibit 4- or 5-year changes of direction and priorities. Certainly, the civil service may live on as an inertial recorder of collective experience. Certainly, too, those who live under one form or another of dictatorship or, as in some Canadian provinces, where conservative patterns of voting occur, may experience a continuity of research and development and conservation policies that exceed the 4- to 5-year turnaround pattern that is most common. Yet, even these more continuous systems may come to an end quite suddenly because of economic or political happenstance.

The point of this digression is to show that seabird ornithologists must not rely on government programs to provide continuous data over a long period of years—not, at least, in most countries. Monitoring the biological circumstances of seabirds is not the same as recording the temperature regularly by machine at a weather station, since this activity is unlikely to be terminated unless the society collapses altogether. We may know that in some countries the amateur naturalist exists in such numbers that records of seabirds will continue to be made whatever the circumstances. Nevertheless, planning of censuses that will be repeated every 10 years is best assured if government and career biologists combine with the amateur element, so that any one of them can continue the work if any other element should be incapacitated. At any one time, either the amateur or the government or the university personnel may be the prime mover, and each of these forms now exists in various countries.

What the scientific literature in the fields of the geophysical, atmospheric, and oceanographic disciplines demonstrates is that natural climatic oscillations probably range in length from the 11-year sunspot cycle through several decades (or a human lifetime) to several hundred years. So, when our children are the new trustees of seabird colonies 20 or 40 years hence, they must interpret their data using the full range of physical as well as biological data that we can leave for them. Indeed, the information is, I believe, already available over a long enough period (since 1940 at least) to allow some speculative interpretations of what may have been happening to our seabird populations, whether or not we knew or had any evidence of it.

I have already suggested that extraterrestrial events, particularly the 11-year sunspot cycle, are increasingly believed to influence the atmosphere of this planet. The Chinese and Japanese have remarkably precise records of the northern limits of certain agricultural crops at particular times, the phenology of flowering, and the freezing of lakes. These demonstrate long-term trends in overall climate in eastern Asia that extend over hundreds of years. The climate of Japan is influenced by the high-pressure area in winter over mainland East Asia. There is evidence that severe ice conditions in the Bering Sea during the early 1970's may have been due to an eastward shifting of this high-pressure area. Again, the water mass of the Kuroshio Extension and the West Wind Drift takes several years to travel across the Pacific Ocean, and there is an established temperature variation that travels like a slow wave with it. Off Japan, the Kuroshio Current periodically develops meanders which slow the speed of the eastward flow. Cold and warm "pools" of water approach the west coast of Canada and the western United States from time to time.

Ocean currents are driven by the atmospheric motion above them, which consists of several convective cells between the equator and each pole. The outcome is zonal winds, such as the trade winds and the westerlies. However, as the influence of the sun on the atmosphere is variable, the input of heat and the extent of the major high-pressure areas vary, as does the path of the jet stream. The recent droughts in northern Africa and unusually heavy rains in Australia are both linked to a southward shift of the Intertropical Convergence Zone in the atmosphere and a "corrugation" of the wind circulation from a more normal zonal (latitudinal) path. These shifts in the atmospheric circulation are almost certainly transmitted also to the ocean currents and the marine ecosystem, with the influence being felt for a long period of years.

One of the oceanic domains of the North Pacific is the transitional domain, which lies east-west where the West Wind Drift impinges upon the coasts of British Columbia and Washington State. It is precisely in this sector that there was a well-documented "temperature anomaly" in 1957-58. Since an anomaly implies something completely out of the ordinary, I seriously question the appropriateness of the term for an event that may or may not be recurrent (at the time it was a pronounced variation from the oceanographic records accumulated up to that time, but the period had not been a very long one). It is no coincidence that the numbers of albatrosses recorded at Ocean Weather Station "Papa" was higher during this warm-water "anomaly" than subsequently (indeed, an 18-year record of the seabirds recorded at "Papa" also exhibits other interesting fluctuations from the base-line data in certain years).

Recent analyses of sediments from off the coast of California have demonstrated long-term fluctuations in sardine populations extending back at least 1,800 years, with increases lasting 20-150 years and spaced 20-200 years apart. The number of anchovies declined steadily. Yet until now, El Niño events have been treated as anomalies in that region as well as off the coast of Peru. Just as we recognize that different species of fish follow the warm water north on such occasions, we must also recognize the rather distinct seabird species assemblage that is trapped, as it were, in the Gulf of California. Clearly, like the termination point of the West Wind Drift at about the 45-55° parallel, the coast of Baja California and southern California State, from the 25-35° parallel where the California Current begins to swing away from the coast to the west as the North Equatorial Current, is another zone of instability.

I think that it is no accident that the southern limit of several northern species of North Pacific seabirds ends in southeastern Alaska or northern British Columbia, and that the northern limit of the ranges of several other species occurs in Washington State or southern British Columbia. Indeed, the west coast of Vancouver Island is not rich in species, and several of those that exist are not present in great numbers. This is a region of rather more variable conditions than elsewhere, and species evidently find that it is difficult to colonize and it quickly becomes unsuitable again. Since 1940, indeed, there has been a parallel decline in the annual mean sea-surface temperature at a number of coastal recording stations in British Columbia, and this seems to have been a rebound from a less well-documented rise in sea-surface temperatures during the 20 years before that, which culminated in a peak around 1940. Salinity has likewise trended downwards during the last 30 years. The seabird colony size data before 1960 are so nonquantitative that it is impossible to be sure what changes in seabird populations and breeding sites may have taken place in response to these physical changes.

The lesson is that we must now examine all future census and distribution data with trends in sea-surface temperature and salinity in mind as two of several likely factors influencing them. We must no more ignore data outside our own field than a salmon ecologist might.

Conclusions

We know little of the accuracy of censuses of seabird numbers made between 1850 and 1950. There has been a tendency to assume that numbers of seabirds at long-established colonies have been relatively unchanging, even though the expansion of some species into previously unrecorded breeding sites in low numbers is well documented. Contraction of breeding ranges, likewise, has most commonly been attributed to the influence of man. Recent literature from the physical sciences, on the contrary, suggests that seabird numbers at particular colonies are most unlikely to have been stable for any great length of time, at least at high or middle latitudes and particularly at points where boundaries between currents impinge on continental coasts. Indeed, some early estimates of colony sizes may not have been as much in error as we may have assumed, neither when apparently too large nor when apparently unlocated by previous visitors.

The halving of a large colony over a period of 20 to 50 years in the middle of the range of a species and the establishment and disappearance of smaller breeding groups at opposite extremes of the range (both latitudinally and longitudinally), may equally reflect natural long-term climatic or oceanographic changes and may naturally be reversed at some time in the future, perhaps within half a century. The implication for conservation of seabird colonies that are at the contracting end of a species' range is that cultural rather than biological criteria may be the best determinants.

[Sea Ice as a Factor in Seabird Distribution and Ecology in the Beaufort, Chukchi, and Bering Seas]

by

George J. Divoky[1]

U.S. Fish and Wildlife Service
Fairbanks, Alaska

Abstract

Arctic sea ice has a variety of effects on seabirds. Although the decrease in surface area available for feeding and roosting is probably the major restrictive effect, also important are productivity of water covered by ice and the reduced prey abundance in nearshore areas due to ice scour. The most important benefit that sea ice provides to seabirds is the plankton bloom that occurs in the ice in the spring. In the Beaufort and Chukchi seas this bloom supports an under-ice fauna that is an important food source for seabirds.

Sea ice is a major factor in the distribution and ecology of many of the birds treated in this symposium. Sea ice is defined here as ice formed by the freezing of seawater and includes both free floating pack ice and the more stable shorefast ice. Since icebergs are composed of ice of land origin, they are not discussed.

Before discussing the specific relationship of birds and sea ice in the Beaufort, Chukchi, and Bering seas, I list the general effects that arctic ice can have on seabirds. For purposes of discussion these effects can be divided into negative effects, or disadvantages, and positive effects, or advantages.

General Effects of Ice on Birds

Negative Effects

Sea Ice Decreases the Surface Area of Water

The decrease in the surface area of water is the simplest and most immediate effect that sea ice has on birds. Ice acts as a barrier that restricts the availability of food in the water. Surface feeders are the most severely affected since, in general, ice cover of 50% reduces the possible feeding area by half. The effect on diving species is not as severe since, if open water is scattered throughout the ice, diving species still have access to much of the prey in the water column and benthos. When open water is scarce, however, diving species can become concentrated in the available water, resulting in intense competition for available prey. In certain situations the open water is used only as a migratory pathway, but open water is necessary for birds that must roost or feed.

Sea Ice Reduces Primary Productivity in the Water Column

Ice inhibits phytoplankton blooms in the water column, thus decreasing the biological productivity of ice-covered waters. This inhibition occurs in two ways:

• By decreasing light penetration of the water column.—Much of the sunlight reaching the ice is reflected by the ice and by snow on the ice. The amount of light reaching the water depends on the angle of the light, thickness of ice, and amount of snow cover. When the layer of under-ice algae forms, it absorbs light and further reduces the amount of light reaching the water (Bunt 1963). This reduction in light reduces the depth of the euphotic zone.

• By increasing the stability of the water column.—Increased stability of the water column reduces the upwelling of nutrient-rich waters into the euphotic zone. Ice stabilizes the water column primarily by preventing wind-driven movement of surface waters and by forming a layer of meltwater at the surface in the spring and summer (Dunbar 1968).

Sea Ice Reduces Benthic and Intertidal Biota

Benthic flora and fauna can be reduced by the presence of ice in two ways: In shallow water ice can freeze to the bottom for much of the year and prevent the establishment of plant and animal populations; and when ice floes are pushed together, they form underwater ice keels that can scour the bottom when the ice moves. Both of these events not only act directly to decrease benthic populations but also disturb the sediment, making it less suitable for colonization. In areas with heavy ice scour, sessile benthic populations can be greatly reduced, although motile species may move into scoured areas during the ice-free period in summer. In addition to preventing the establishment of sessile benthic animal populations, ice scour also prevents the establishment of beds of kelp and eelgrass (Zostera marina), thus decreasing the diversity and productivity of arctic inshore waters. Both kelp and eelgrass beds are important feeding sites for birds in areas south of the region affected by ice scour.

Sea Ice Allows Terrestrial Predators Access to Breeding Sites

The formation of ice between the mainland and offshore islands allows the arctic fox (Alopex lagopus) and other predators access to the islands used by breeding birds. Foxes can become permanently established on islands that have food sources during the period when birds are absent from the island. Often, however, there is little to attract foxes to the islands other than breeding birds. Because moats form around many islands before the breeding birds arrive, foxes are primarily a problem when moat formation is incomplete or when the breakup of ice is late. Arctic foxes are found on the pack ice throughout the summer and thus can visit islands that are separated from the mainland by open water but are adjacent to the pack ice.

Advantages

Sea Ice Provides a Matrix and Substrate for an Ice-associated Plankton Bloom and an Associated Under-ice Fauna

The first detailed studies on the blooms of diatoms that occur in the lower levels of ice were done by Appollonio (1961). The importance of this bloom in the energy budgets of arctic and subarctic seas has only recently been realized (Alexander 1974; McRoy and Goering 1974). In areas where ice is present throughout the year, the plankton bloom supports a population of under-ice invertebrates. These populations have been little studied but apparently consist primarily of copepods and amphipods (Mohr and Geiger 1968). Feeding on the invertebrates associated with the ice are two species of fish, polar cod (Arctogadus glacialis) and arctic cod (Boreogadus saida). Andriashev (1968) used the term cryopelagic to describe such fish, which are found in the midwater zone but also are associated with ice during some part of their life cycle.

The underside of multi-year ice has numerous ridges and pockets that provide a heterogeneous environment for the under-ice fauna. This environment is protected from disturbance from currents and wave action by ice keels acting as barriers, which also provide shelter from predators in the same manner as a coral reef. The overall effect of the under-ice flora and fauna is to increase the diversity of surface waters in arctic seas by creating an inverted benthic biota.

Sea Ice Provides Hauling Out Space for Marine Mammals

The mammals that inhabit the ice in the Chukchi and Bering seas and their adaptations to the pack ice environment were discussed by Fay (1974). Many of these species frequently haul out on the ice, where they provide food in the form of feces, placentas, and carcasses.

Sea Ice Provides Roosting Sites

Ice provides a hard substrate that allows seabirds to leave the water to roost. This allows such species as the Larus gulls, which typically roost on hard substrates, to occur in large numbers well offshore.

Sea Ice Reduces Wind Chill

The unevenness of the upper surface of the ice reduces the speed of winds directly over the ice, thus providing a microhabitat and reducing the amount of wind chill for birds sitting on and next to the ice.

Sea Ice Decreases Wave Action

Ice floating on the water reduces the surface disturbance of the water. Although swells pass through areas with much ice cover, waves do not. In addition, surface waters on the lee side of ice floes and cakes usually have little surface disturbance. Surface feeders may be able to locate prey more easily because of these reductions in surface disturbance.

Specific Effects of Ice on Birds in the Western Arctic

The retreat of the pack ice each spring and the formation of new ice each fall greatly affect a large area of the Arctic Ocean off the coast of Alaska and much of the Bering Sea. Specific ways in which birds are affected by ice in the western Arctic are discussed on a seasonal basis. All observations are my own, unless otherwise stated.

Winter

Chukchi and Beaufort Seas

From late November to mid-April, ice cover of the Chukchi and Beaufort seas is almost complete. The only areas where birds can be expected to winter in these seas are the chronic lead systems. Such lead systems are found off Wainwright and Point Barrow and south of the Point Hope-Cape Thompson area (Shapiro and Burns 1975). Only the black guillemot (Cepphus grylle) is known to regularly winter offshore from Wainwright and Point Barrow (Gabrielson and Lincoln 1959; Nelson 1969). In the Point Hope-Cape Thompson area, glaucous gulls (Larus hyperboreus), the common murre (Uria aalge), and the thick-billed murre (U. lomvia) occur throughout the winter (Swartz 1967). It is likely that black guillemots are also found in this area.

The lack of chronic lead systems in the Beaufort Sea precludes the presence of wintering seabirds. The one species that may be found wintering in the Beaufort is the Ross' gull (Rhodostethia rosea). Ross' gull is believed to winter primarily in the Arctic Ocean (Bailey 1948). The number of sightings that have been obtained in both the eastern and western Arctic indicate that the species may winter over much of the Arctic Ocean. It may thus be expected to occur in both the Chukchi and Beaufort seas during winter.

Ice cover—not prey abundance—plays the major role in severely limiting bird numbers in the Arctic Ocean in winter. Prey is known to be abundant in parts of the Arctic Ocean during the period of ice cover. In the Chukchi Sea, Eskimos fishing through the ice can catch 23 kg of arctic cod per person per day (D.C. Foote, unpublished data). Eskimos jig for the fish at considerable depths, and the cod do not appear to be as common directly below the ice as they are in summer. The effects of new ice (which forms on the underside of the ice during the winter) on the under-ice fauna are not known. The abundance of amphipods in ice-covered waters in winter is demonstrated by the experience of the Greeley Expedition in the eastern arctic. They discovered that any scrap of food thrown into a lead was quickly consumed by amphipods. Nets were made to catch the amphipods and the availability of this food source played a major part in the survival of the expedition (Schmitt 1965).

Aside from the food found in leads in the ice, the only food available to birds in the Beaufort and Chukchi seas in winter is carrion and the feces of mammals found on the pack ice. The presence of the arctic foxes on the pack ice during the winter demonstrates the availability of scavenging opportunities on the ice. Arctic foxes on the pack ice live on feces and the remains of seals killed by polar bears (Ursus maritimus). Polar bear and seals are both common in the Beaufort and Chukchi seas in winter, but no scavenging seabirds are found there in the winter. It was thought that the ivory gull (Pagaphila eburnea) was associated with marine mammals during the winter, but they are now known to winter at the Bering Sea ice edge, where they feed on fish and crustaceans (Divoky 1976). The only birds associated with polar bear kills in the Chukchi Sea in March are ravens, Corvus corax (T. J. Ely, Jr., personal communication).

Bering Sea

Ice begins to cover the northern Bering Sea in November and reaches its maximum by February, when it usually extends as far south as the edge of the continental shelf, and covers nearly 75% of the surface of the Bering Sea (Lisityn 1969). Coverage can vary greatly from year to year. In certain years Bristol Bay may be completely covered and in others ice is found only in the northern part of the Bay. Almost all ice in the Bering Sea is first-year ice. This ice tends to be flat on the top and underside and in general lacks the extensive keels and pressure ridges found on multi-year ice.

The Bering Sea ice has a number of large-scale features of importance to birds. The "front" is a zone of ice south of the consolidated pack that is composed of small floes, ice pans, and brash ice. This zone is prevented from forming large floes by the action of swells from the open water to the south. The front continually changes in width. When winds are from the south, it is compressed into a narrow band; when winds are from the north, it is a broad zone composed of bands of ice interspersed with open water.

Polynias (areas of open water) are found immediately south of the large islands in the northern Bering Sea. They are formed by the southward movement of ice caused by the prevailing winds. This movement causes ice to be pushed away from the south side of islands, leaving areas of open water. Large polynias are associated with St. Lawrence, St. Matthew, and Nunivak islands and with the south side of the Seward Peninsula (Shapiro and Burns 1975).

The most biologically active area of the Bering Sea in winter is the ice front. Studies of primary productivity in April show that production at the surface in the ice front is high (1.98 mg C/m³ per h). Surface waters directly under the pack ice have much lower production (0.29 mg C/m³ per h), and that in the water south of the ice is lower yet. At this time production within the ice is very high (more than 5 mg C/m³ per h) (McRoy and Goering 1974). Because this phytoplankton bloom is trapped in the ice, it is not available to grazers. Thus, before the spring melt the ice front is the only area where a large quantity of phytoplankton is available to higher levels of the marine food chain.

The winter distribution of birds in the Bering Sea correlates well with the findings on primary productivity. Densities south of the ice and the continental shelf average less than 10 birds/km². At the ice front during one cruise in March, densities exceeded 500 birds/km². Densities at the ice front increase from south to north; they drop in the region where the ice front grades into more consolidated pack ice, and are less than 0.1 bird/km² in the consolidated pack.

The most numerous species at the ice front are common and thick-billed murres, which constitute more than 90% of all birds seen. Irving et al. (1970) were the first to report on the large number of murres at the ice front. Feeding flocks of 25,000 individuals have been observed at the front, in which densities were as high as 10,000 birds/km². No other diving species is common at the ice front. The parakeet auklet (Cyclorhynchus psittaculus) is seen on most cruises, but only during a small percentage of observation periods and always in low numbers. Black guillemots are common north of the ice front and stragglers are occasionally seen at the front. Pigeon guillemots (Cepphus columbus), least auklets (Aethia pusilla), and crested auklets (A. cristatella) are irregular visitors to the front.

Surface feeding species commonly found at the ice front include the northern fulmar (Fulmarus glacialis) and five species of gulls. The fulmar is common south of the ice and is found only in the southern portion of the front. Three species of Larus are found at the ice front. The most common is the glaucous-winged gull (Larus glaucescens); the glaucous gull is less frequently seen. The slaty-backed gull (L. schistisagus), a species that breeds in Asia, is most common west of St. Matthew Island (McRoy et al. 1971). The black-legged kittiwake (Rissa tridactyla) is common in open water south of the ice but is also found throughout the entire width of the front. The ivory gull is unique in that it is found only at the ice front in winter. In addition to these species, the fork-tailed storm-petrel (Oceanodroma furcata) is a regular but uncommon visitor to the ice front in winter. Densities of surface feeding species at the ice front are low when compared to the high densities of murres, and do not regularly exceed 10 birds/km².

The primary food consumed by birds at the ice front is pollock (Theragra chalcogramma). An amphipod (Parathemisto libellula) and the euphausiids are less important. Examination of the stomach contents of birds and fish show that large feeding flocks are usually associated with schools of pollock feeding on P. libellula and euphausiids.

The habitat of the consolidated pack in the Bering Sea is markedly different from that at the ice front. Whereas the front is characterized by bands of ice interspersed with open water and ice coverage rarely exceeding 4 oktas (4/8), the consolidated pack consists primarily of large expanses of unbroken ice. Small leads are formed by the shifting of the ice caused by currents and wind. Ice coverage is usually 7 to 8 oktas. The southern part of the consolidated pack, which grades into the ice front, has frequent leads. Most of the species found at the ice front can be found in the southern part of the consolidated pack, but murres are most common. Their numbers decrease, however, in the more northerly pack, where leads are less frequent. Black guillemots, in contrast, increase with increasing ice cover, and reach their greatest abundance in the small leads constantly forming and refreezing deep within the ice. Because they exploit this habitat, they are dependent on the formation of lead systems. I have often seen leads a quarter mile wide refrozen to the point where new ice covered all but a small patch of open water; black guillemots were frequently crowded into this open water. Before the lead closes completely the guillemots must fly to an open lead. When winds are light and temperatures low, lead systems fail to form as rapidly as usual, and when they do they refreeze quickly, causing a loss of the preferred habitat of wintering black guillemots. A severe winter in the White Sea in 1965-66 decreased the amount of open water and caused an increased black guillemot mortality (Bianchi and Karpovitsch 1969). On a windless day in March I conducted bird observations in the Bering Sea ice where no leads or open water were encountered. The only bird seen was a black guillemot flying over the ice. In situations such as this, where black guillemots are prospecting for open water, they may use the "water sky" and steam fog associated with leads as visual aids. "Water sky" is the reflection of the dark water in the clouds over the lead, and contrasts sharply with the "ice sky." The presence of "water sky" allows birds to detect open water from a distance of many miles.

Aside from birds found in and near island-associated polynias, only murres and black guillemots are regularly found on the consolidated pack ice in winter.

The polynia associated with islands in the consolidated pack provide refuge(s) for seabirds. Fay and Cade (1959) found the polynias south of St. Lawrence to be most important to oldsquaws (Clangula hyemalis). King eiders (Somateria spectabilis), common eiders (S. mollisima), and oldsquaws are common in the St. Matthew Island polynias (McRoy et al. 1971). Because these polynias are in shallow-water areas, they provide feeding opportunities for benthic feeding species.

Spring

Chukchi and Beaufort Seas

In April and May a lead system develops from the Bering Strait north to Cape Lisburne and then northeast to Point Barrow. The lead is a flaw lead that occurs between the shorefast ice and the free-floating pack. It is a major migration route for a number of species of birds, primarily eiders. East of Point Barrow in the Beaufort Sea, no similar well-defined large lead exists. Consequently, there is a greater chance of bird mortality occurring in the Beaufort Sea than in the Chukchi Sea because the early migrants are unable to find open water. In 1960, 10% of all the king eiders that migrate through the Beaufort Sea died during a late freeze (Barry 1968). Additional records of eider mortality due to late breakup or sudden freezes were presented by Palmer (1976).

In late May, rivers that empty into the northern Chukchi and Beaufort seas begin to flow. The shorefast ice is still present at this time and the rivers flow over the ice. For large rivers, such as the Colville and the Sagavanirktok, the area of ice covered by water is considerable. Openings in the ice develop sometime after the river runoff starts and the river water drains through the ice.

This river overflow plays an important role in the breeding biology of certain island nesting species, since the overflow surrounds islands and prevents arctic foxes from reaching the islands. The overflow also allows birds to sit in the water near breeding sites. It is not known whether river overflow contains prey items available to birds. After the overflow drains through the ice, the shorefast ice that has been covered with river overflow decomposes quickly, and patches of open water occur early in areas just seaward of major river deltas. For this reason the largest breeding colonies on barrier islands in the northern Chukchi and Beaufort seas are all found near the mouths of large rivers. Islands away from rivers become isolated from the pack ice by moats, which are caused by the absorption of solar radiation by the islands and the melting of the ice immediately adjacent to them. Moat formation is not as predictable and uniform as river overflow.

Bering Sea

When the ice in the Bering Sea begins to melt in April, the edge of the pack does not recede northward as is frequently thought. Rather, there is a general decomposition of ice throughout the pack. The leads that are constantly forming in the ice no longer freeze. As melt continues and ice becomes rotten, leads form with increasing frequency. This manner of ice decomposition is important to birds. The leads that form deep in the pack ice provide feeding and roosting areas near the large seabird colonies found north of the ice edge, and are used by certain tundra-nesting ocean migrants such as eiders, red phalaropes (Phalaropus fulicarius), and jaegers (Stercorarius spp.). If ice decomposition is retarded by persistent low temperatures, the initiation of breeding may be delayed at northern Bering Sea colonies and for some tundra species.

At the time of decomposition the large standing stock of phytoplankton present in the pack ice is released into the water. No information is available on fish and invertebrate populations that are associated with the decomposing ice. The quantity of organic carbon released is considerable, although it is not known what fish or invertebrate populations are supported by this plankton as soon as it is released. For birds breeding in areas where ice is present in the initial stages of breeding, the phytoplankton released by the disintegrating ice could play an important part in the birds' energy budgets.

Summer

Chukchi and Beaufort Seas

In the northern Chukchi and Beaufort seas the nearshore marine environment is dominated by sea ice in June and July. In June the coastal areas are characterized by a snow-free tundra teeming with nesting waterfowl and shorebirds next to an expanse of sea ice almost completely devoid of bird life. In areas where river outflow does not occur, the use of nearshore waters usually begins when a moat forms along the shoreline. Amphipods and other invertebrates are found in this moat, especially at stream mouths. Limited but regular use of the moat occurs, primarily by loons (Gavia spp.), oldsquaws, and arctic terns (Sterna paradisaea).

As the snow on top of the shorefast ice begins to melt, ponds form on top of the ice. As melt proceeds, these melt ponds merge into long, parallel channels and may cover well over 50% of the ice surface. Only when thaw holes form and the melt ponds are connected to the water under the ice is food present in the channels. Amphipods are then seen swimming in these channels. Bird use of these channels is not extensive.

It is usually late July before the nearshore ice begins its rapid decomposition. Ice in the lagoons is the first to melt. Ice seaward of the barrier islands decomposes more slowly because of the presence of keels and pressure ridges. As the ice melts, the in-ice algal bloom is released into the water. These algae are important because they provide at least 25 to 30% of the productivity in coastal waters and allow the biological growing season to begin before the open-water plankton bloom occurs (Alexander 1974). In nearshore areas close to Barrow, large populations of mysids and amphipods are associated with the decomposing ice. At least in certain areas, these ice-associated zooplankton populations are a major food source for nearshore migrants, especially red phalaropes, arctic terns, and Sabine's gulls (Xema sabini).

The effects of ice scour on the shoreline and the nearshore bottom of the Chukchi and Beaufort seas is demonstrated by the absence of sessile benthic fauna and flora. The effect this absence has on birds is seen in the feeding habits of nearshore birds. Oldsquaws and eiders, which frequently feed on molluscs, feed instead on motile benthos species such as mysids, amphipods, and isopods. The emperor goose (Philacte canagica) is absent from the northern Chukchi and Beaufort seas, apparently due to the absence of eelgrass beds. Ice scour is the major cause of the absence of eelgrass in northern Alaska (C. P. McRoy, personal communication).

The offshore ice in the Chukchi decomposes more rapidly than that in the Beaufort, largely because Bering Sea water enters the Chukchi through the Bering Strait (Coachman and Barnes 1961). By late July the Chukchi is usually ice free as far north as Icy Cape. In the Beaufort, however, ice decomposition occurs slowly through June and July, and only in August does a definite strip of open water develop between the shore and the edge of the pack ice. The amount of open water varies greatly from year to year. In certain years the Beaufort is not navigable due to the lack of open water.

Aerial censusing in June and July shows that bird densities on the offshore ice are extremely low. In August and September, when shipboard censusing can be conducted, densities on the pack ice in both seas are about 10 birds/km². Unlike the Bering Sea, where densities south of the ice are much less than on the ice, bird densities south of the ice in the Beaufort and Chukchi seas are slightly higher in the open water south of the ice, averaging about 20 birds/km². In the Chukchi the principal species encountered on the ice are the black-legged kittiwake and the thick-billed murre. In the Beaufort, red phalaropes, oldsquaws, and glaucous gulls are the most common species.

Numerous arctic cod are associated with the underside of the summer pack ice. Shipboard censusing in the ice is complicated when cod are stranded on ice floes, as the ice shifts under the weight of the ship. Gulls, arctic terns, and jaegers gather behind the ship to feed on these fish; mixed flocks of more than 100 birds are common. In the absence of a ship to provide the disturbance needed to make large numbers of cod available, these birds are dependent on locating the fish in the surface waters next to ice floes. Because cod frequently swim over underwater ice shelves they are highly visible from above and should be easily accessible to aerial feeders.

Fall

Chukchi and Beaufort Seas

By the time ice formation begins in late September or early October, most seabirds have left the Arctic on their southward migration. The principal exception is the oldsquaw, which does not begin its migration until September. Some oldsquaws remain in nearshore waters until they are driven out by the formation of new ice. In contrast to the spring mortality, there are few records of extensive bird mortality in the fall due to lack of open water. One instance was reported for 1975, when nearshore waters froze early and flightless eiders were seen sitting on the ice near Pt. Lay in the Chukchi Sea. The birds were in a weakened condition, apparently due to their inability to obtain food (W. J. Wiseman, personal communication).

In the offshore waters the species associated with the pack ice in September are the same as those in August. In late September, however, ivory and Ross' gulls become the most common species at the ice edge in the Chukchi. Glaucous gulls and black guillemots are also associated with the advancing ice edge (Watson and Divoky 1972). Except for the Ross' gull, which apparently winters in the arctic basin, these species remain with the ice as it advances into the Bering Sea.

Bering Sea

Little is known about bird distribution in the Bering Sea during ice formation because cruises in rapidly forming ice are potentially hazardous. It is not known if the large numbers of birds found at the ice edge in March are present in December and January.

Discussion

The principal effect of the arctic pack ice is to lower biological productivity and bird densities in the areas it covers. Unlike the antarctic pack ice, which supports a large biomass of pagophilic species, the number of pagophilic species supported by the arctic pack ice is small. Only the ivory gull, Ross' gull, and black guillemot have specific adaptations to the ice environment. The Ross' gull and guillemot winter in the pack ice, and the ivory gull is associated with ice throughout the year. The total biomass of these species is low. Other species which are regularly associated with the arctic pack, such as murres and black-legged kittiwakes, are also found in large numbers away from the ice. In addition, these species are usually associated with ice for limited periods during the year—murres primarily in winter and spring and kittiwakes primarily in summer.

The difference in the antarctic and arctic pack ice systems is largely due to the antarctic pack ice being surrounded by ocean, whereas the arctic pack ice is, in general, surrounded by land. The high productivity associated with the antarctic pack ice is due primarily to the mixing that occurs at the edge of the pack ice. There is little opportunity for mixing to occur next to the arctic pack ice, except where it is next to large expanses of boreal waters. This occurs in the Bering Sea in winter and spring, in the North Atlantic, and to a minor extent in the Chukchi Sea in summer and fall (Dunbar 1968). The limited geographic range and seasonal nature of high productivity at the arctic pack ice edge has been a major factor in preventing a well-developed pagophilic avifauna.

The importance of the in-ice algal bloom and its associated under-ice fauna is not yet clear. It is probably most important in areas such as the Beaufort Sea, where productivity in the water column is low. Although considerable numbers of seabirds are regularly found in the summer pack ice feeding on arctic cod and zooplankton associated with the ice, bird densities south of the ice are usually greater than those in the ice. The only species that appear to depend on the ice-associated fauna for much of their food are the three pagophilic species mentioned above.

References

Alexander, V. 1974. Primary productivity regimes of the nearshore Beaufort Sea, with reference to potential roles of ice biota. Pages 609-632 in J. C. Reed and J. E. Sater, eds. The coast and shelf of the Beaufort Sea. Arctic Institute of North America, Arlington, Virginia.

Andriashev, A. P. 1968. The problem of the life community associated with the antarctic fast ice. Pages 147-155 in R. I. Currie, ed. Symposium on antarctic oceanography. Scott Polar Research Institute, Cambridge.

Appollonio, S. 1961. The chlorophyll content of arctic sea ice. Arctic 14:197-200.

Bailey, A. M. 1948. Birds of arctic Alaska. Colo. Mus. Nat. Hist. Popular Ser. 8. 317 pp.

Barry, T. W. 1968. Observations on natural mortality and native use of eider ducks along the Beaufort Sea coast. Can. Field-Nat. 82(2): 140-144.

Bianchi, V. V., and V. N. Karpovitsch. 1969. The influence of abnormal ice-cover of the White Sea and Murman in 1966 upon birds and mammals. (In Russian, English summary.) Zool. Zh. 48(6):871-875.

Bunt, J. S. 1963. Diatoms of antarctic sea ice as agents of primary production. Nature (Lond.) 199:1255-1257.

Coachman, L. K., and C. A. Barnes. 1961. The contribution of Bering Sea water to the Arctic Ocean. Arctic 15:147-161.

Divoky, G. J. 1976. The pelagic feeding habits of Ivory and Ross' Gulls. Condor 78:85-90.

Dunbar, M. J. 1968. Ecological development in polar regions: a study in evolution. Prentice-Hall, Englewood Cliffs, N.J. 119 pp.

Fay, F. H. 1974. The role of ice in the ecology of marine mammals of the Bering Sea. Pages 383-399 in D. W. Hood and E. J. Kelly, eds. Oceanography of the Bering Sea. Univ. Alaska Inst. Mar. Sci. Occas. Publ. 2.

Fay, F. H., and T. J. Cade. 1959. An ecological analysis of the avifauna of St. Lawrence Island, Alaska. Univ. Calif. Publ. Zool. 63:73-150.

Gabrielson, I. N., and F. C. Lincoln. 1959. The birds of Alaska. The Stackpole Company, Harrisburg, Pennsylvania, and Wildlife Management Institute, Washington, D.C. 922 pp.

Irving, L., C. P. McRoy, and J. J. Burns. 1970. Birds observed during a cruise in the ice-covered Bering Sea in March 1968. Condor 72:110-112.

Lisityn, A. P. 1969. Recent sedimentation in the Bering Sea (Transl. from Russian.) Israel Program for Scientific Translations, Jerusalem. 614 pp.

McRoy, C. P., and S. R. Goering. 1974. The influence of ice on the primary productivity of the Bering Sea. Pages 403-421 in D. W. Hood and E. J. Kelly, eds. Oceanography of the Bering Sea. Univ. Alaska Inst. Mar. Sci. Occas. Publ. 2.

McRoy, C. P., S. W. Stoker, G. E. Hall, and E. Muktoyuk. 1971. Winter observations of mammals and birds, St. Matthew Island. Arctic 24:63-65.

Mohr, J. L., and S. R. Geiger. 1968. Arctic Basin faunal precis-animals taken mainly from arctic drifting stations and their significance for biogeography and water-mass recognition. Pages 297-313 in J. E. Sater, coordinator. Arctic drifting stations. Arctic Institute of North America.

Nelson, R. K. 1969. Hunters of the northern ice. University of Chicago Press, Chicago, Ill. 429 pp.

Palmer, R. S. 1976. Handbook of North American birds. Vol. 3. Yale University Press, New Haven, Conn. 560 pp.

Schmitt, W. L. 1965. Crustaceans. University of Michigan Press, Ann Arbor. 204 pp.

Shapiro, L. H., and J. J. Burns. 1975. Major late-winter features of ice in northern Bering and Chukchi seas as determined from satellite imagery. Univ. Alaska Geophys. Inst. Rep. 75-78.

Swartz, L. G. 1967. Distribution and movements of birds in the Bering and Chukchi seas. Pacific Sci. 21:332-347.

Watson, G. E., and G. J. Divoky. 1972. Pelagic bird and mammal observations in the eastern Chukchi Sea, early fall 1970. U.S. Coast Guard Oceanogr. Rep. 50:111-172.

FOOTNOTES:

[1] Present address: Point Reyes Bird Observatory, 4990 State Route 1, Stinson Beach, California 94970.

STATUS OF MARINE BIRD POPULATIONS

[Distribution and Status of Marine Birds Breeding Along the Coasts of the Chukchi and Bering Seas]

by

James C. Bartonek[2]

U.S. Fish and Wildlife Service
Fairbanks, Alaska

and

Spencer G. Sealy

University of Manitoba
Winnipeg, Manitoba, Canada

Abstract

The Alaska coast fronting on the Chukchi and Bering seas, exclusive of the Aleutian Islands, supports seven complexes of marine bird colonies numbering more than 1 million birds each, nine colonies of 100,000 to almost 1 million birds, and many smaller colonies. Colonies are found on most headlands and islands and are dominated numerically by alcids and kittiwakes (Rissa sp.). Estuarine habitats (mainly the lowlands of northern Seward Peninsula, Yukon-Kuskokwim delta, and the north side of the Alaska Peninsula) are extremely important for breeding and migrating marine waterfowl, shorebirds, gulls (Larus sp.), and terns (Sterna sp.). Information on population size and distribution of breeding marine birds within this area is extensive for only a few of the more heavily hunted species of waterfowl. Except for the intensive and systematic censusing of a few colonies in this region, population data on cliff-, burrow-, and crevice-nesting birds are such that all but gross changes in numbers may go unnoticed, and if noticed they could not be measured.

Habitats for breeding marine birds are found along much of the 4,100-km coastline of Alaska that fronts on the Chukchi and Bering seas. Seasonal sea ice and an extensive outer continental shelf are dominant features that contribute to the productivity of these marine waters, which sustain populations of fishes, birds, and mammals that are of considerable and diverse values to man (Kelley and Hood 1974).

Our purpose in this paper is to describe the distribution, abundance, and relative status of some of the nearly 100 species of marine birds breeding within this region and the information base from which the descriptions are derived. Although the selection is admittedly arbitrary, we discuss mainly the colonial nesting species because they are generally in greater jeopardy from lost breeding habitat and from catastrophes than are the species that are widely dispersed or solitary in nesting. Because we believe matters affecting the conservation of marine birds will be geographically oriented, we discuss the status and distribution of breeding birds on that basis, rather than by the more traditional taxonomic approach. We use the terms "colony" and "colonies" somewhat loosely and interchangeably to include any aggregation of birds of the same or different species nesting in proximity to each other, even those on the same island or headland, although populations may be miles apart and occupy different kinds of habitats. The nature of this paper and the scale of our maps do not allow for detailed resolution of each colony's location (for the most part this information is not available), but rather facilitates a general impression of status.

Most place-names used by us are shown in Fig. 1; the others may be located by referring to Orth's (1967) gazetteer on Alaska.

Information Base

There is no adequate catalog of marine bird colonies and other avian habitats for the Bering-Chukchi region or for Alaska as a whole. King and Lensink (1971) described the waterfowl populations and major lowland habitats of the State and listed only a few of the many colonies of cliff-nesting birds. LeResche and Hinman (1973) identified a few additional colonies, provided fragmentary information on composition and abundance at some of these sites, and delineated areas of wetland habitats on maps in their statewide atlas on wildlife. General and occasionally site-specific information on the location, but rarely on population size and composition, of colonies can be gleaned from the 321 species accounts presented by Gabrielson and Lincoln (1959) and from the general works by Bent (1919, 1921, 1922, 1923, 1925, 1927, 1929), Dement'ev and Gladkov (1951), Dement'ev et al. (1951, 1952), Palmer (1962), Fisher (1952), Tuck (1960), and others. The birds on the Asiatic side of these waters, which are not treated in this paper, were described by Portenko (1973).

Information on the status of waterfowl in the region is generally more detailed than that for most other groups of birds because waterfowl have been the object of systematic surveys since the late 1940's as part of the continent-wide effort to manage populations for sport hunting. Because the emphasis of these surveys has been directed toward the species of ducks important to hunters in the "lower 48" States, data are not adequate to measure changes in populations for most sea ducks and marine geese nesting in this region. These surveys have, however, enabled biologists to delineate waterfowl habitats and make reasonable estimates of populations for some of the more abundant and conspicuous species (King and Lensink 1971; U.S. Fish and Wildlife Service [FWS] 1973c; U.S. National Park Service [NPS] 1973).

Chukchi Sea Coast

A disproportionate percentage of ornithological investigations in arctic Alaska have centered about Barrow, where ornithologists were attracted because of the propensity of vagrant birds to collect there and because of the above average facilities, conveniences, and transportation afforded first by the whaling station, then by the military, and later by a research laboratory. Recent petroleum development near Prudhoe Bay has resulted in a somewhat commensal eastward shift in ornithological studies.

Bailey (1948), Gabrielson and Lincoln (1959), and Pitelka (1974) reviewed much of the published information on arctic avifauna, including that of the Chukchi coast. Selkregg [1975] mapped various avian habitats, ascribed either relative or absolute values for the population size of certain groups of birds, and included a selected bibliography that did not entirely duplicate those provided by the other reviewers. Watson and Divoky (1975) described the avifauna of Alaska's Beaufort Sea coast, which is much the same as that of the Chukchi coast from Point Barrow south to Cape Lisburne (both coasts are of low relief).

Intensive studies near Barrow have done much to characterize the behavior, productivity, and ecological requirements of calidridine sandpipers (Pitelka 1959; Pitelka et al. 1974; Holmes 1970, 1971) and, to partly explain the cyclical relationships between jaegers (Stercorarius spp.) and their prey (e.g., Pitelka et al. 1955; Maher 1974). Quantitative estimates of certain bird populations at Cape Thompson (Swartz 1966; Williamson et al. 1966), Little Diomede (Kenyon and Brooks 1960), and on the coastal lowlands of the Seward Peninsula (King and Lensink 1971; U.S. NPS 1973), and for black guillemots (Cepphus grylle) throughout the region (Divoky et al. 1974) are among the best data on status of marine birds for any locality in Alaska. Grinnell (1900a) described the birds he observed in the Kotzebue Sound area.

Fig. 1. Place-names in the region of the Chukchi and Bering seas.

Cursory aerial surveys conducted by J. C. Bartonek, J. G. King, and D. R. Cline (U.S. FWS 1973a; U.S. NPS 1973; this paper) in 1972 and 1973 provided information on the location and relative size of most, if not all, colonies of cliff-nesting marine birds between Point Barrow and the Bering Strait, including those at Cape Lisburne, at Motherhood Point, Nine-mile Point, Cape Deceit, Towalevic Point, Sullivan Bluff, all on the northern base of the Seward Peninsula, and at Fairway Rock. The relative size of populations of most species was probably underestimated because the burrow-and crevice-nesting species were largely unseen.

Bering Sea

Aside from work by Gabrielson and Lincoln (1959) and the early but understandably incomplete accounts by Nelson (1883, 1887) and Turner (1886), no comprehensive description of the avifauna of the Alaskan coast of the Bering Sea exists. Many studies adequately describe local avifauna, and some of them are exemplary assessments of the status of populations.

Most of the coastline suitable for cliff-nesting marine birds and most of the smaller nearshore islands from the Bering Strait south to the tip of the Alaska Peninsula were reconnoitered piecemeal from aircraft between 1970 and 1973 by J. C. Bartonek, J. G. King, D. R. Cline, C. D. Evans, and M. L. Plenert (U.S. FWS 1973a, 1973b; this paper). In late June 1973 Bartonek, Cline, and Plenert made brief reconnaissances on foot of King, Besboro, and Shaiak islands. Bartonek and J. G. Divoky, traveling by boat and occasionally on foot, reconnoitered colonies at Cape Seniavin, a portion of the Walrus Islands group, Shaiak Island, and the coastline from Cape Peirce around Cape Newenham to Security Cove (U.S. FWS 1973a, 1973b; this paper). Although these cursory surveys (especially those from aircraft) tended to identify nesting sites of cliff-nesting birds while missing sites used by burrow-and crevice-nesting species, information was obtained on the location and relative size of many previously unreported colonies.

The mainland and island colonies in Norton Sound have received little notice in the published literature. Bailey (1943, 1948), although working mainly at Little Diomede and in Arctic and Lopp lagoons on the north side of the Seward Peninsula, mentioned the birds at Wales Mountain and Tin City. Nelson (1883, 1887) traveled throughout the region studying the avifauna and the anthropology of Eskimos. Grinnell (1900b) at Nome, McGregor (1902) along the Koyuk River, Hersey (1917) and Turner (1886) near St. Michael, and Cade (1952) at Sledge Island provide fragmentary examples of the area's marine bird populations. Colonies at King, Besboro, Egg, and Sledge islands, near York Mountains, and at Bluff were described in proposals for new National Wildlife Refuges (U.S. FWS 1973a).

Sealy et al. (1971) reviewed the literature and discussed the various zoogeographic relationships among the avifauna of St. Lawrence Island. Fay and Cade (1959) estimated numbers and biomass of all birds on St. Lawrence Island but did not identify locations and sizes of particular populations; consequently, replication of their estimates is precluded. An exemplary study by Bédard (1969) identified the locations and sizes of all populations of crested auklets (Aethia cristatella), least auklets (A. pusilla), and parakeet auklets (Cyclorrhynchus psittacula) on the island. Sealy (1973) identified breeding sites of horned puffins (Fratercula corniculata) there and throughout the species' range. Thompson (1967) listed the birds observed at Northeast Cape and on nearby Punuk Islands.

Annotated accounts have been published on the breeding avifauna of St. Matthew, Hall, and Pinnacle islands by Elliott (1882), Hanna (1917), Bent (1919), and Gabrielson and Lincoln (1959). Klein (1959) presented quantitative data on the birds he observed incidental to his study of reindeer (Rangifer tarandus).

The avifauna of the Yukon-Kuskokwim delta, which is rich both in numbers and diversity, has been treated extensively in the literature. Nelson (1883, 1887), Turner (1886), Conover (1926), Brandt (1943), Gabrielson and Lincoln (1959), Williamson (1957), Kessel et al. (1964), Harris (1966), Dau (1972), and Holmes and Black (1973) all described the avifauna in the same general area of the delta, i.e., the eroding portion in the general vicinity of Hooper and Hazen bays. The avifauna of the aggrading portion of the Yukon delta and of the Kuskokwim's mouth have not been accorded similar attention. Populations of waterfowl nesting on the delta and their wintering affinities were described by King and Lensink (1971) and U.S. FWS (1973c).

Studies of particular species of marine birds on the delta (again, all in the general vicinity of Hooper and Hazen bays) were reported by Hansen and Nelson (1957) and Shepherd (1960) for black brant (Branta bernicla), by Headley (1967) and Eisenhauer and Kirkpatrick (1977) for emperor geese (Anser canagica), by Dau (1974) and Mickelson (1975) for spectacled eiders (Somateria fischeri), by Petersen (1976) for red-throated loons (Gavia stellata), and by Holmes (1970, 1971, 1972) for dunlins (Calidris alpina) and western sandpipers (C. mauri).

Birds of Nunivak Island were reported by Swarth (1934), but the importance of the island to marine birds was not put into proper perspective until the Nunivak National Wildlife Refuge was evaluated for designation as a wilderness area (U.S. FWS 1972).

The Pribilof Islands have served as a focal point for ornithological investigations of the Bering Sea in much the same way that Barrow has for the Arctic. The avifauna of the Pribilofs has been described by Coues (1874), Elliott (1882), Palmer (1899), Hanna (1918), Preble and McAtee (1923), Gabrielson and Lincoln (1959), Kenyon and Phillips (1965), and a host of others that mainly added new species to the record list. Although most of these ornithologists marveled at the numbers of birds, information is lacking from which most changes in populations can be noted. (An exception is the record of common and thick-billed murres, Uria aalge and U. lomvia, which formerly nested in such abundance on Walrus Island that annually several tons of eggs were gathered for consumption by residents of the islands [Palmer 1899], but were greatly reduced in numbers by the summer of 1973, when J. C. Bartonek, J. G. King, G. J. Divoky, and D. T. Montgomery observed only a few thousand murres on a small portion of the island. Most of the suitable nesting sites, especially the flat areas often used by common murres, were occupied by Steller's sea lions, Eumetopias jubata, which, apparently because of reduced hunting pressure, occupied the island and displaced the murres.)

For some unexplained reason the numerous and large marine bird colonies along the north side of Bristol Bay appear to have been largely overlooked until recent years (Bartonek and Gibson 1972). Gabrielson and Lincoln (1959) summarized the few observations by Osgood (1904) and Turner (1886) in this area, but obviously were unaware that, in aggregate, these colonies rival those of the Pribilofs. Dick and Dick (1971) made an exemplary study of marine birds and their numbers at Cape Peirce and on nearby Shaiak Island. Murie (1959) provided annotated remarks on marine birds of Amak Island, but not of nearby Sealion Rocks.

Status and Distribution

Seven groups of colonies of cliff-, burrow-, and crevice-nesting birds are found on the headlands and islands in the coastal region, each numbering more than 1 million birds; nine colonies range downward to 100,000 birds; and a host of others range downward to 1,000 birds (Fig. 2). Un-estimated numbers of other marine birds nest on the lowlands about Kotzebue Sound, the Yukon-Kuskokwim delta, and Bristol Bay, but are not shown in Fig. 2. The occurrence at colonies of 20 of the nearly 100 species of marine birds is shown in Fig. 3; their relative numbers at these sites are not shown because data are generally lacking.

Fig. 2. Relative numbers of marine birds at colonies in different localities, without regard to species composition or breeding status.

Fig. 3. Location of known breeding populations of some marine bird species without regard to size of population.

Chukchi Sea

The largest colonies of seabirds in the Chukchi Sea are those on Little Diomede Island, Cape Lisburne, Cape Thompson, and Fairway Rock. Smaller colonies are in Kotzebue Sound along the northern base of the Seward Peninsula. These colonies are largely dominated by thick-billed and common murres and black-legged kittiwakes (Rissa tridactyla) and on the islands in the Bering Strait also the crested, least, and parakeet auklets. Horned puffins, tufted puffins (Lunda cirrhata), pelagic cormorants (Phalacrocorax pelagicus), and glaucous gulls (Larus hyperboreus) make up the remaining majority. For the whole area there are probably fewer than a hundred birds each of black guillemots and pigeon guillemots (Cepphus columba) occupying colonies. Dovekies (Alle alle) are occasionally sighted in this area, but only as stragglers from their normal range.

Part of the mystery surrounding the nesting location of Kittlitz's murrelet (Brachyramphus brevirostris) was solved when Thompson et al. (1966) discovered a downy chick in the Kukpuk River drainage nearly 45 km by river from salt water. Other nesting sites of the Kittlitz's murrelets in this region were reported for Wales Mountain (Ford 1936; Bailey 1943, 1948) and the Cold Bay area (Bailey 1973) (Fig. 3).

Only the colonies at Cape Thompson have been censused systematically throughout a breeding season. During one of three years of varying census efforts, Swartz (1966) estimated that about 400,000 birds of nine species occupied the cliffs. Whereas the Cape Thompson colonies received considerable attention because of Swartz's efforts, the colonies that extend along nearly 35 km of headlands southward from, but mainly at, Cape Lisburne have received little if any attention by either early or recent ornithologists in the Arctic, even though they support perhaps twice the number of birds. Also perplexing is why Chamisso and Puffin islands with their several thousand nesting horned puffins and lesser numbers of other seabirds were designated as the Chamisso National Wildlife Refuge in the early 1900's when none of the many larger and more species-diverse colonies in the area received comparable recognition by and protection through refuge designation.

The lowlands on the north side of the Seward Peninsula produce fall flights of sea ducks that average 49,200 oldsquaws (Clangula hyemalis), 51,000 eiders (mostly common eiders, Somateria mollissima), and 26,700 scoters (mostly black scoters, Melanitta nigra) (King and Lensink 1971). Small populations of black brant and emperor geese breed in what outwardly appears to be excellent habitat, and King and Lensink (1971) speculated that subsistence hunting by local Eskimos is responsible for suppressing these populations.

Bering Sea

The largest concentration of nesting seabirds in the Bering Sea and perhaps in the entire North Pacific is that on St. George Island. Colonies that rank somewhere below that at St. George are along the coast from Cape Newenham to Cape Peirce, in the Walrus Islands (Round, High, Crooked, and Summit islands, The Twins, and Black Rock), at Cape Mohican on Nunivak Island, St. Matthew Island, Southwest Cape of St. Lawrence Island, and King Island.

The Pribilofs have the unique distinction of being the primary nesting site of red-legged kittiwakes (Rissa brevirostris). They are also interesting from the zoogeographic standpoint in that they are the northernmost stronghold of red-faced cormorants (Phalacrocorax urile); guillemots are conspicuous by their absence, and larid gulls are conspicuously scarce nesters.

St. Matthew Island and associated Hall and Pinnacle islands, and all but Walrus Island of the Pribilofs, are sites of nesting northern fulmars (Fulmarus glacialis). Nesting fork-tailed or Leach's storm-petrels (Oceanodroma furcata and O. leucorhoa) have been found nowhere in this region, although both are commonly observed at sea and both nest throughout the Aleutians.

Most colony sites identified in Fig. 2 are dominated by common or thick-billed murres (or both) and black-legged kittiwakes. Glaucous gulls (generally north of the Yukon-Kuskokwim delta), glaucous-winged gulls (Larus glaucescens) (generally to the south of the delta), and pelagic cormorants occupy almost every rocky prominence along the entire coast (most of these sites are not shown in Figs. 2 and 3). Double-crested cormorants (Phalacrocorax auritus) nest at a few island and inland locations in the Bristol Bay area. The small auklets are largely restricted to islands in the Bering Sea; the parakeet auklet is the only one occasionally found in mainland colonies.

The marine birds of the Yukon-Kuskokwim delta lowlands, although largely uncounted, in their aggregate probably exceed the numbers at any individual site identified in Fig. 2. This is not particularly surprising since the delta has nearly 70,000 km² of habitat (King and Lensink 1971) in contrast to the generally small parcels of habitat occupied at the sea-cliff and island sites.

King and Lensink (1971) estimated that fall flights of sea ducks originating on the delta averaged 292,300 oldsquaws, 51,000 eiders (mostly common and spectacled eiders with lesser numbers of Steller's eiders, Polysticta stelleri), and 157,000 scoters (primarily black scoters). They also estimated that half of the 150,000 black brant and most of the 150,000 emperor geese in Alaska's fall flight originate there. Although no counts have been made, we believe that the delta's lowlands support easily more than half of Alaska's nesting dunlins, black turnstones (Arenaria melanocephala), rock sandpipers (Calidris ptilocnemis), western sandpipers, and substantial percentages of red phalaropes (Phalaropus fulicarius), northern phalaropes (Lobipes lobatus), and red-throated loons.

The north side of the Alaska Peninsula (including the wetlands, uplands, and estuaries) is perhaps more important to marine birds as a staging, feeding, and resting area than as a nesting habitat. The importance of Izembek Lagoon to black brant and emperor geese during fall and spring is a classic example. King and Lensink (1971) estimated that the fall flight of sea ducks originating from the Peninsula averages 53,400 oldsquaws, 1,700 eiders, and 74,400 scoters. Breeding geese are scarce throughout the area.

Conclusions and Recommendations

Most of the major breeding habitats of marine birds in the Chukchi and Bering seas are known, but imprecisely identified as to location and size. With few exceptions, the populations of birds using these habitats are described only by the subjective and ambiguous descriptors of abundance such as "abundant, common, occasional, and rare," which makes measurement of change impossible.

We recommend that first and foremost a catalog of habitats used by birds be developed to aid resource administrators, developers, and biologists (all of whom should be "conservationists") in identifying critical habitats. We believe that such a catalog would preclude many problems because birds and their habitats could be considered at the planning stage rather than only at the operational stage. Such a catalog would also be useful to students of ornithology who are seeking locations suitable for particular studies.

Nowhere in this region have studies of marine birds been of sufficient duration to enable changes in populations (from whatever cause) to be characterized. Since some species of marine bird are known not to breed before at least 3 or more years of age, meaningful information on survival and recruitment in populations cannot be obtained by studies of less than 10 years. We therefore recommend that long-term studies be initiated at as many places as possible, but at least at one site on the Yukon-Kuskokwim delta; at a mainland colony site that has predominantly murres, kittiwakes, puffins, and cormorants; and at an island site that also has small auklets. Although the nesting distribution of the Kittlitz's murrelet remains an enigma, we regard it less of a conservation issue and more of an ornithological challenge. Consideration of logistics and support facilities must, of course, be included in the site selection process. Most of the areas suggested for these studies also merit recognition and protection by being designated as a National Wildlife Refuge, a National Park or Monument, or a State Game Sanctuary.

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