115-196.
Udvardy, M. D. F. 1963. Zoogeographic study of the Alcidae. Pages
85-111 _in_ J. L. Gressitt, ed. Pacific Basin biogeography, a
symposium. Pac. Sci. Congr. Proc. 10.
U.S. Bureau of Sport Fisheries and Wildlife. 1973. Semidi Islands
wilderness report. Semidi Islands, National Wildlife Refuge.
(Unpublished report)
U.S. Department of Commerce. 1964. United States Coast Pilot, No.
9, Pacific and Arctic Coasts, Cape Spencer to the Beaufort Sea.
Coast and Geodetic Survey, Washington, D.C. 330 pp.
Walker, E. P. 1923. Definite breeding record for the Aleutian tern
in southern Alaska. Condor 25:113-117.
Willet, G. 1914. Birds of Sitka and vicinity, Southeastern Alaska.
Condor 16:71-91.
Willet, G. 1918. Bird notes from Forrester Island, Alaska. Condor
20:85.
Williamson, F. S. L., and L. S. Peyton. 1963. Interbreeding of
glaucous-winged herring gulls in the Cook Inlet Region, Alaska.
Condor 65:28.
Status and Distribution of Breeding Seabirds of Southeastern Alaska,
British Columbia, and Washington
by
David A. Manuwal
College of Forest Resources
University of Washington
Seattle, Washington 98195
and
R. Wayne Campbell
Provincial Museum
Victoria, British Columbia, Canada
Abstract
Current breeding seabird population estimates,
nest-site preferences, and population changes
are reviewed for southeastern Alaska,
British Columbia, and Washington. There are
19 species of seabirds and a minimum of
216,566 pairs breeding in British Columbia
and Washington. There are limited data on
breeding populations for southeastern Alaska.
Species diversity ranges from 17 species in
Alaska to 15 species in British Columbia and
14 species in Washington. Eighty percent of
all British Columbia seabirds breed on the
east coast of Queen Charlotte Islands and
the northwest coast of Vancouver Island.
The three most numerous species in British
Columbia are the fork-tailed storm-petrel,
_Oceanodroma furcata_ (31.3%); Cassin's
auklet, _Ptychoramphus aleuticus_ (24.6%); and
ancient murrelet, _Synthliboramphus antiquus_
(12.5%). In Washington, 74% (43,274 pairs) of
the seabird population resides on the Olympic
coast; the remaining 26% are in the San Juan
Island area. About 54% of this population
consists of the common murre _(Uria aalge)_ and
rhinoceros auklet _(Cerorhinca monocerata)_.
The rhinoceros auklet and glaucous-winged gull
_(Larus glaucescens)_ make up 97% of the total
seabird population of the San Juan Islands.
About 68% of all seabirds on the northeastern
Pacific coast are nocturnal, burrow or rock
crevice-nesting species. Currently available
population data are inadequate to determine
significant changes in population density for
most species. Suggested topics for future
research are presented.
The purpose of this paper is to discuss the known distribution,
habitat, abundance, and status of breeding seabirds of the Alexander
Archipelago in southeastern Alaska, the Province of British Columbia,
Canada, and the State of Washington.
Even though several studies of the breeding biology of several
seabird species in this area have been published, there have been few
published surveys of known breeding colonies. In British Columbia the
most extensive work has been done by the British Columbia Provincial
Museum and the University of British Columbia (Drent and Guiguet 1961).
Gabrielson and Lincoln (1959) summarized the available literature
on Alaskan birds up to about 1958. Since then, no extensive surveys
have been conducted in southeastern Alaska. The U.S. Department of
the Interior (1972), in its environmental impact statement for the
Trans-Alaska Pipeline, presented additional information on the seabirds
of other parts of Alaska. In Washington, there are no published
comprehensive surveys except those of Kenyon and Scheffer (1961) and
unpublished surveys by the U.S. Fish and Wildlife Service and the
University of Washington.
Table 1. _Taxonomic distribution of marine birds breeding
along the Pacific Coast of Washington, British Columbia, and
southeastern Alaska._
------------------------------------------------------------------------
Regions
---------------------------------------
British Southeastern Total
Family Common name Washington Columbia Alaska forms
------------------------------------------------------------------------
Hydrobatidae Storm-petrels 2 2 2 2
Phalacrocoracidae Cormorants 3 3 1 3
Haematopodidae Oystercatchers 1 1 1 1
Laridae Gulls and terns 2 2 3 4
Alcidae Auks, murres, puffins 6 7 9 9
Total 14 15 16 19
------------------------------------------------------------------------
Taxonomic Distribution of Marine Birds
There are 19 species of seabirds that breed along the Pacific coast
of southeastern Alaska, British Columbia, and Washington (Table 1).
Southeastern Alaska has the largest number (17) of species. Errors
in species identification are most likely with the Larus gulls,
particularly in southeastern Alaska where the herring gull _(L.
argentatus)_ and glaucous-winged gull _(L. glaucescens)_ breed in mixed
colonies (Patten and Weisbrod 1974). A similar situation exists in
Washington where the western _(L. occidentalis)_ and glaucous-winged
gulls intergrade (Scott 1971). Brandt's _(Phalacrocorax penicillatus)_
and double-crested cormorants _(P. auritus)_ are often difficult to
identify from the air. This would be a problem in Washington and the
southwest coast of Vancouver Island, where the two species are locally
sympatric.
Southeastern Alaska
The area under consideration is the 400-km-long Alexander Archipelago
(Fig. 1). This complex pattern of islands, bays, and inlets is
characterized by extremely high precipitation and typical cool marine
temperatures. Average annual precipitation in the Sitka area is 245.4
cm (1931-60), and the average annual temperature is 6.3°C (U.S. Weather
Bureau 1974). As a consequence of this cool, humid environment, most
of the islands are densely covered with conifers, chiefly Sitka spruce
_(Picea sitkensis)_ and hemlock _(Tsuga heterophylla)_, and an almost
impenetrable shrub cover composed of salmonberry _(Rubus spectabilis)_,
elderberry _(Sambucus callicaipa)_, devil's club _(Echinopanax
horridus)_, and three species of _Vaccinium_ (Heath 1915).
[Illustration: Fig. 1. Map of southeastern Alaska showing major seabird
breeding colonies: 1--North Marble Island; 2--Forrester Island.]
There are 16 species of marine birds breeding in the Alexander
Archipelago. The major seabird breeding colonies are located at Glacier
Bay and at St. Lazaria, Hazy, and Forrester islands (Fig. 1; Table
2). Published surveys of these colonies are available only for St.
Lazaria (Willett 1912) and Forrester islands (Heath 1915; Willett
1915). Several authors have reported on seabirds from surrounding areas
(Grinnell 1897, 1898, 1909; Swarth 1911, 1922, 1936; Patten 1974).
There have been no surveys of seabirds of southeastern Alaska since
before the 1940's (J. G. King, Jr., personal communication). However,
since census data are available for only two colonies, we discuss them
in more detail.
Table 2. _Population estimates of seabirds breeding on St.
Lazaria and Forrester islands, southeastern Alaska_ (data from
Willett 1912 and 1915).
St. Lazaria Island Forrester Island
----------------------------------------------------------------------
Number Percent Number Percent
Bird species of pairs of total of pairs of total
----------------------------------------------------------------------
Fork-tailed storm-petrel 2,000 8.0 10,000 6.0
Leach's storm-petrel 20,000 80.0 50,000 30.0
Pelagic cormorant 150 0.6 150 0.0
Black oystercatcher 4 0.0 50 0.0
Glaucous-winged gull 300 1.2 8,000 4.8
Herring gull 220 0.0
Common murre 300 1.2 20,000 12.0
Pigeon guillemot 150 0.6 300 0.0
Ancient murrelet 20,000 12.0
Cassin's auklet 2,000 1.2
Rhinoceros auklet 75 0.0 20,000 12.0
Horned puffin 12 0.0 1,100 0.7
Tufted puffin 2,000 8.0 35,000 21.0
Total 24,991 166,820
The studies by Willett (1912, 1915) and Heath (1915) provide some
base-line information on species composition and abundance with which
future studies on St. Lazaria and Forrester islands can be compared
(Table 2). The somewhat greater species diversity on Forrester Island
is primarily due to its greater size and more suitable soil type for
ancient murrelets _(Synthliboramphus antiquus)_ and Cassin's auklets
_(Ptychoramphus aleutica)_, species that are absent on St. Lazaria.
Storm-petrels (_Oceanodroma_ spp.) are the most numerous species on
both islands, but there are proportionately more storm-petrels (88%)
on St. Lazaria than on Forrester (36%). On the other hand, there are
many large, burrowing alcids on Forrester Island. Nearly a third of the
birds on Forrester are rhinoceros auklets _(Cerorhinca monocerata)_,
tufted puffins _(Lunda cirrhata)_, and horned puffins _(Fratercula
corniculata)_.
The species composition of seabirds breeding on other islands is
similar to that found on Forrester and St. Lazaria islands but less
abundant. In Glacier Bay, for example, the only population data
available are those provided by Patten (1974) for North Marble
Island: pelagic cormorants, _Phalacrocorax pelagicus_ (30 pairs);
black oystercatchers, _Haematopus bachmani_ (8); herring gulls (7);
glaucous-winged gulls (500); common murres, _Uria aalge_ (18); pigeon
guillemots, _Cepphus columba_ (60); horned puffins (4); and tufted
puffins (30).
At the present time, it is impossible to draw any conclusions about
changes in population density and distribution for most of the seabirds
breeding in southeastern Alaska. Adequate data are available only for
St. Lazaria and Forrester islands where Willet and Heath provided the
only early extensive census data for this part of Alaska.
British Columbia
The rugged British Columbia coastline is characterized by 930 km of
islands and inlets (Figs. 2, 3). With the exception of the inner
southern portion, this coast is mostly uninhabited. The physical
characteristics of the offshore islands are similar to those found off
the Washington coast. Descriptions of some of these islands and the
15 species of breeding seabirds on them have been given by Drent and
Guiguet (1961), Guiguet (1971), and Summers (1974).
A detailed analysis of British Columbia seabirds is not presented here
since a more thorough analysis is in preparation by R. W. Campbell
and R. H. Drent (manuscript). Instead, we present seabird population
estimates available for the Province up to the summer of 1975; Tables 3
and 4 summarize these estimates for the five major portions of coastal
British Columbia. The coast of British Columbia contains a myriad of
small islands where there may be small numbers of breeding seabirds.
Many of these have not been censused and are too numerous to include in
Tables 3 and 4.
[Illustration: Fig. 2. Map of northern British Columbia showing sites
of major seabird breeding colonies: 1--Skedans Island; 2--Limestone
Island; 3--Agglomerate Island; 4--Bischoff Island; 5--Ramsey Island;
6--Alder Island; 7--Rankins Island.]
[Illustration: Fig. 3. Map of southern British Columbia showing sites
of major seabird breeding colonies: 1--Triangle Island; 2--Cleland
Island.]
More than half of the breeding seabirds in British Columbia are found
on the east coast of the Queen Charlotte Islands, and the fork-tailed
storm-petrel _(Oceanodroma furcata)_ comprises more than half of
that total. However, new unpublished data (K. Vermeer) for Triangle
Island and the northwest coast of Vancouver Island indicate that
the population figures in Table 3 for this area are underestimates.
Nevertheless, these two regions have nearly 80% of all the breeding
seabirds in the Province. This results from the very large populations
of the rhinoceros auklet and tufted puffin on Triangle Island and the
fork-tailed storm-petrel, ancient murrelet, and Cassin's auklet on
various islands on the east coast of the Queen Charlotte Islands (Table
3).
Continuing surveys of breeding seabirds are being conducted by
personnel of the British Columbia Provincial Museum and the Canadian
Wildlife Service.
Washington State
_General Environment_
For this report, we have distinguished two major geographical areas in
Washington where breeding seabirds are found--the western coast of the
Olympic Peninsula and the San Juan Islands, including the Strait of
Juan de Fuca.
On the Olympic Peninsula, seabirds breed on the offshore rocks,
islands, and precipitous cliffs from Copalis Beach to Cape Flattery
(Fig. 4). The offshore rocks and islands throughout this area (except
Tatoosh Island) are now included in the Washington Islands National
Wildlife Refuge. Most of the larger rocks and islands have dense
stands of salmonberry, salal, and grasses, and a few support stands of
stunted conifers (Fig. 5); most are inaccessible to man. The adjacent
coast is dominated by the Olympic rain forest where the mean annual
precipitation is about 337.1 cm (U.S. Weather Bureau 1956, 1965_a_,
1965_b_).
Because the San Juan Islands lie northeast of the Olympic Peninsula and
east of Vancouver Island (Fig. 6) they are in a rain shadow; however,
because of highly variable topography and aspect, most islands have a
diverse assemblage of plant communities (Franklin and Dyrness 1973).
Exposed south-facing slopes are occupied by grassland vegetation and
frequently by scattered trees, usually _Pseudotsuga menziesii_ and
_Arbutus menziesii_. Most of the seabird colonies are located on rather
small exposed islands with short, grassy, shrubby vegetation. In
general, these islands are not suitable for burrowing species.
Table 3. _Species composition, population estimates, and
distribution of seabirds in British Columbia._[5][6] (+ =
Present.)
Southwest Northwest West coast
Straits of coast of coast of of Queen
Georgia and Vancouver Vancouver Charlotte
Bird species Juan de Fuca Island Island Island
Fork-tailed storm-petrel + + 1,050
Leach's storm-petrel 10,000 + 1,800
Double-crested cormorant 1,058 0 0 0
Brandt's cormorant 370 0 0
Pelagic cormorant 2,174 336 3,350 1,456
Glaucous-winged gull 10,123 6,870 600 412
Common murre 16 3,000 0
Pigeon guillemot 1,029 204 250 358
Ancient murrelet 0 0 200
Cassin's auklet + 50,000 +
Rhinoceros auklet 1,200 + 10,000
Tufted puffin 1 154 20,000 190
Total 14,385 19,150 77,200 15,466
East coast Prince Rupert
of Queen to Queen Percent
Charlotte Charlotte Total of
Bird species Island Island birds total
Fork-tailed storm-petrel 97,100 + 98,160 31.3
Leach's storm-petrel 180 750 12,730 4.1
Double-crested cormorant 0 0 2,116 >1.0
Brandt's cormorant 0 0 370 >1.0
Pelagic cormorant 496 12 9,998 3.2
Glaucous-winged gull 866 540 29,534 9.4
Common murre 0 0 3,016 1.0
Pigeon guillemot 1,458 1,650 5,978 1.9
Ancient murrelet 42,150 4 42,354 13.5
Cassin's auklet 26,500 450 76,950 4.6
Rhinoceros auklet 300 200 11,700 3.7
Tufted puffin 0 42 20,388 6.5
Total 169,050 3,648 313,294 81.2
Table 4. _Breeding seabird population estimates for British
Columbia_[7][8]
---------------------------------------------------------------------------
Population Percent
Geographic location estimate of total
---------------------------------------------------------------------------
Straits of Georgia and Juan de Fuca 14,385 9.2
Southwest Coast of Vancouver Island 9,575 6.1
Northwest Coast of Vancouver Island 38,600 24.6
West Coast of Queen Charlotte Island 7,733 4.9
East Coast of Queen Charlotte Island 84,530 54.0
Prince Rupert to Queen Charlotte Strait 1,824 1.2
Total 156,647 100.0
[Illustration: Fig. 4. Map of the Olympic Peninsula of Washington State
showing sites of major seabird breeding colonies: 1--Protection Island;
2--Carroll Island; 3--Destruction Island.]
In the Strait of Juan de Fuca, the two most important sites are Smith
and Protection islands. Both are composed of glacial deposits and
heavy sod that has developed under dense grassy vegetation (Fig. 7).
Consequently, these two islands support most of the burrowing seabirds
in the region. Unfortunately, both islands have historically been
subjected to much human disturbance (Richardson 1961; Manuwal 1974).
The existing information on seabird colonies in both the coastal and
San Juan Island areas has been largely derived from aerial surveys by
the U.S. Fish and Wildlife Service. These surveys are inherently biased
toward surface-nesting species such as gulls and cormorants. Population
estimates for guillemots, auklets, storm-petrels, and puffins are
less accurate. Some additional information obtained by direct island
visitation has been provided by Kenyon and Scheffer (1961), Richardson
(1961), Thoresen and Galusha (1971), G. Eddy (unpublished data), and D.
A. Manuwal (unpublished data). Although other accounts of Washington
seabirds are available, the references listed above are specifically
oriented toward population assessment.
_Olympic Peninsula_
Despite the large number of offshore rocks, islets, and islands
along the Pacific coast of Washington, significant seabird colonies
are present only on about 30 islands. Since Table 5 summarizes the
population estimates for 12 species of seabirds breeding on 24 major
sites, it represents only the majority and not the total number of
breeding seabirds on the Pacific coast of Washington. About 74% of the
entire Washington seabird population resides on the coastal rocks and
islands.
Major colony sites with more than 2,500 breeding pairs are Grenville
Arch, Willoughby Rock, Destruction Island, Cake Rock, Carroll Island,
and Bodelteh Island. More intensive censusing, especially of nocturnal
burrowing species will undoubtedly raise the population estimates for
these and other islands off the coast. About 54% of the total coastal
population is composed of the common murre and rhinoceros auklet.
[Illustration: Fig. 5. Photograph of Destruction Island off the coast
of Washington.]
[Illustration: Fig. 6. Map of the San Juan Archipelago showing sites
of major seabird breeding colonies: 1--Viti Rocks; 2--Colville Island;
3--Smith Island.]
_San Juan Islands_
There are about 86 actual or potential seabird colony sites in this
area; 25 (30%) are now considered important. Eleven islands are under
Federal protection as National Wildlife Refuges. Part of Protection
Island is owned by the Washington State Game Department to protect the
largest rhinoceros auklet colony in the State. Most colony sites are
on small islands with poorly developed soil which prevents burrowing
species from using them. Consequently, the dominant species are surface
nesters (such as gulls and cormorants) and rock-crevice nesters (like
the pigeon guillemot). In all, about 31,000 seabirds of 7 species breed
in the San Juan Island area. Breeding seabird population estimates for
49 of the 86 nesting sites are given in Table 6. Even though this does
not represent all the colonies, it covers the most important islands
and those islands where there appears to be potential for seabird
breeding.
[Illustration: Fig. 7. Photograph of Smith Island in the Strait of
Juan de Fuca, Washington. The glacial deposits are evident from the
composition of the cliff faces.]
Table 5. _Estimated breeding seabird populations of the outer
coast of Washington_.[9] (Unpublished data from U.S. Fish and
Wildlife Service and University of Washington)
-----------------------------------------------------------------------
Species
-----------------------------------------------------------------------
Storm-petrels Cormorants
-----------------------------------------------------------------------
Fork- Uniden- Double-
Breeding site tailed Leach's tified crested Brandt's Pelagic
-----------------------------------------------------------------------
Copalis Rock -- -- 15 -- -- --
Point Grenville -- -- -- 60 30 80
Grenville Arch -- -- -- 30 20 --
Flat Rock -- -- 30 -- -- --
Split Rock -- -- -- 100 -- --
Willoughby Rock -- -- -- 80 40 15
South Rock -- -- -- -- -- 40
Abbey Islet -- -- -- -- -- 30
Destruction Island -- -- -- -- -- --
Middle Rock -- -- -- -- -- 25
North Rock -- -- -- -- -- --
Alexander Island -- -- -- -- -- 50
Rounded Island -- -- -- -- -- 25
Giant's Graveyard -- -- -- -- -- 10
Quillayute Needles -- -- -- 50 50 50
James Island -- 30 -- -- -- 40
Cake Rock -- 500 -- -- -- 150
Sealion Rock -- -- -- 70 -- 30
Carroll Island -- 3,100 -- -- -- 100
Ball Rock -- -- -- -- -- 50
White Rock -- -- -- -- -- 100
Ozette Island -- -- -- -- -- --
Bodelteh Island 1,900 -- -- -- -- 100
Tatoosh Island -- 25 -- -- -- 100
Total 1,900 3,655 45 390 140 995
-----------------------------------------------------------------------
-----------------------------------------------------------------
Species
-----------------------------------------------------------------
Gulls
-----------------------------------------------------------------
Black Glaucous-
oyster- winged Common Pigeon
Breeding site catcher Western western murre guillemot
-----------------------------------------------------------------
Copalis Rock -- 30 -- -- --
Point Grenville -- 165 40 1,100 --
Grenville Arch 1 60 -- 3,000 4
Flat Rock -- -- 60 300 --
Split Rock 1 150 -- 2,100 4
Willoughby Rock -- 150 -- 3,000 --
South Rock -- -- 50 -- --
Abbey Islet 3 -- 50 -- --
Destruction Island 12 350 -- -- 25
Middle Rock -- -- 25 -- 50
North Rock -- -- 25 -- --
Alexander Island 5 -- 225 -- --
Rounded Island -- 25 -- -- 1
Giant's Graveyard -- -- -- 150 --
Quillayute Needles -- -- 150 900 --
James Island -- -- 150 750 40
Cake Rock -- -- 600 300 12
Sealion Rock -- -- 250 -- --
Carroll Island 3 -- 550 -- --
Ball Rock 7 -- 150 -- --
White Rock -- -- 75 250 --
Ozette Island 1 -- 15 -- --
Bodelteh Island 2 -- 300 -- 5
Tatoosh Island -- -- 1,500+ 100 20
Total 35 930 4,215 11,950 161
-----------------------------------------------------------------
-------------------------------------------------------
Species
-------------------------------------------------------
Auklets
-------------------------------------------------------
Tufted
Breeding site Cassin's Rhinoceros puffin Total
-------------------------------------------------------
Copalis Rock -- -- -- 45
Point Grenville -- -- -- 1,475
Grenville Arch -- -- 3 3,118
Flat Rock -- -- -- 390
Split Rock -- -- -- 2,355
Willoughby Rock -- -- 25 3,310
South Rock -- -- -- 90
Abbey Islet -- -- 10 93
Destruction Island -- 10,940 350 11,677
Middle Rock -- -- -- 100
North Rock -- -- -- 25
Alexander Island -- -- 1,550 1,830
Rounded Island -- -- -- 51
Giant's Graveyard 50 150 -- 360
Quillayute Needles -- -- 350 1,550
James Island -- -- 20 1,030
Cake Rock -- 50 1,000 2,612
Sealion Rock -- -- 5 355
Carroll Island 25 250 2,400 6,428
Ball Rock -- -- 750 957
White Rock -- -- 100 525
Ozette Island -- -- -- 16
Bodelteh Island -- -- 750 3,057
Tatoosh Island 25? 25? 30 1,825
Total 100 11,415 7,343 43,274
-------------------------------------------------------
Table 6. _Breeding seabird population estimates for the San Juan
Islands and Strait of Juan de Fuca, Washington, 1973-75_.[10]
A: Double-crested
B: Pelagic
C: Black oystercatcher
D: Glaucous-winged gull
E: Pigeon guillemot
F: Rhinoceros auklet
G: Tufted puffin
------------------------------------------------------------------
Species
------------------------------------------------------------------
Cormorants
----------
Breeding site A B C D E F G Total
------------------------------------------------------------------
Bare Island -- 50 1 120 + -- 2 173
Barren Island -- -- -- -- -- -- -- 0
Battleship Island -- -- -- -- -- -- -- 0
Bird Rocks 30 -- + 320 -- -- -- 350
Cactus Island -- -- 1 -- -- -- -- 1
Castle Island -- -- -- -- 30 -- -- 30
Colville Island -- 40 1 1,000 -- -- -- 1,041
Danger Island -- -- -- 125 7 -- -- 132
Decatur Island -- -- -- -- -- -- -- 0
Eliza Island -- -- -- 3 1 -- -- 4
Eliza Rock -- -- -- 1 -- -- -- 1
Flat Top Island -- -- -- -- + -- -- +
Flower Island -- 17 -- 90 -- -- -- 107
Goose Island -- -- -- 60 -- -- -- 60
Gull Rock -- -- + 125 7 -- -- 132
Gull Reef -- -- -- -- -- -- -- 0
Hall Island -- -- 1 275 -- -- -- 276
Harbor Rock -- -- -- -- -- -- -- 0
Iceberg Island -- -- -- -- -- -- -- 0
Johns Island -- -- 1 -- -- -- -- 1
Long Island -- -- 8 80 -- -- -- 88
Low Island -- -- 1 75 17 -- -- 93
Lummi Rocks -- -- -- 4 -- -- -- 4
Matia Island -- -- -- -- + -- -- +
Mummy Rocks -- -- -- 55 -- -- -- 55
Minor Island -- -- -- 100 -- -- -- 100
O'Neal Island -- -- -- -- -- -- -- 0
Patos Island -- -- -- 20 + -- -- 20
North Peapod Island -- -- 1 220 2 -- -- 223
South Peapod Island -- -- 1 75 2 -- -- 78
Pearl Island -- -- -- -- -- -- -- 0
Pointer Island -- -- -- 58 2 -- -- 60
Protection Island 3 110 3 1,500 30 9,200 35 10,881
Puffin Island -- -- 1 350 15 -- -- 366
Ripple Island -- -- -- -- -- -- -- 0
Sentinel Island -- -- -- -- 10 -- -- 10
Sentinel Rock -- -- 1 -- -- -- -- 1
Skip Jack Island -- -- -- 75 20 -- -- 95
Smith Island -- 20 6 10 30 600 -- 666
Speiden Island -- -- -- -- -- -- -- 0
South Sister Island 2 11 1 131 -- -- -- 145
Middle Sister Island -- -- 1 22 -- -- -- 23
North Sister Island -- -- 2 412 3 -- -- 417
Viti Rocks 29 80 1 387 1 -- -- 498
Waldron Island -- -- -- -- 2 -- -- 2
Williamson Rocks -- 67 1 346 2 -- -- 416
Whale Island -- -- 1 70 -- -- -- 71
White Rock -- -- + 125 13 -- -- 138
Yellow Island -- -- -- -- -- -- -- 0
Total per species 64 395 34 6,234 194 9,800 37 16,758
Percent of total
population 0.4 2.3 0.2 37.2 1.2 58.5 0.2 100.0
------------------------------------------------------------------
The major colony sites with more than 250 breeding pairs are located
at Protection and Smith islands, Bird Rocks, Colville Island, Hall
Island, North and South Peapod rocks, Puffin Island, North Sisters,
Viti Rocks, and Williamson Rocks (Fig. 6). Glaucous-winged gulls are
the predominant species on all these islands except Protection and
Smith islands, where there are large colonies of rhinoceros auklets.
Rhinoceros auklets (65%) and glaucous-winged gulls (32%) make up 97% of
the total San Juan Islands seabird population.
Nest-site Preferences
Food supply and availability of nest sites are two critically important
factors influencing the distribution and abundance of seabirds. Whereas
information on general diet composition is known for most seabird
species, we know little about the availability of favored seabird prey.
The dynamics of seabird food chains is reviewed elsewhere in these
proceedings.
The nest-site preferences for seabirds of the northeast Pacific Ocean
are given in Table 7, and Table 8 indicates the proportion of seabirds
that belong to specific nest-site categories. These preferences, in
conjunction with knowledge of the physical characteristics of seabird
habitat, permit a partial explanation of the present distribution and
abundance of seabirds. For example, if we compare the San Juan Island
habitats with those of the Washington coast, it is apparent that
there are more cliff-nesting species on the coast. This reflects the
physical characteristics of the two habitats. There are few cliffs in
the San Juan Islands, and those that exist are very unstable. Colony
sites in the San Juan Islands are typically on low, flat islands.
Glaucous-winged gulls are the most abundant nesting species there.
Coastal islands, on the other hand, are either covered by dense
vegetation or are large monolithic chunks of rock with few available
flat areas. Population estimates for the Washington coast are heavily
biased toward surface nesters, since most of the data have been
gathered by aerial surveys. Consequently, the burrow and rock crevice
categories are underestimated. The aerial survey is appropriate for
only about 43% of the birds nesting on the Washington coast.
Table 7. _Nest-site preference for seabirds breeding from Cape
Fairweather, Alaska, to the Columbia River, Washington._
Nest-site type Bird species
Burrow-rock crevice
Diurnal Pigeon guillemot
Horned puffin
Tufted puffin
Nocturnal Fork-tailed storm-petrel
Leach's storm-petrel
Kittlitz's murrelet
Ancient murrelet
Cassin's auklet
Rhinoceros auklet
Open nests
Flat or slope Double-crested cormorant
Brandt's cormorant
Glaucous-winged gull
Herring gull
Western gull
Black oystercatcher
Cliff face Pelagic cormorant
Common murre
Black-legged kittiwake
Tree branch Marbled murrelet
Northern and southern British Columbia provide another good example of
habitat availability as revealed through seabird population estimates.
The population data are more comprehensive and have largely been
gathered by island visitations. The islands in the northern portion
are heavily vegetated and many have well-developed soil into which
storm-petrels, auklets, and murrelets can burrow. Indeed, 96% of the
seabird population consists of nocturnal, burrow-nesting species. In
southern British Columbia, however, there are more open-nest species,
particularly glaucous-winged gulls and cormorants.
Overall, 68% of the breeding seabirds found along the northeastern
Pacific coast are nocturnal and nest in burrows or rock crevices (Table
8). The most conspicuous nesting birds such as gulls, cormorants, and
murres, comprise only 22% of the total population. Consequently, our
current estimates of breeding seabirds still underestimate the more
secretive, nocturnal, burrow-nesting species.
Table 8. _Proportional nest-site preferences of Pacific coast
seabirds.[11]_
Estimated number of pairs
British Columbia Total
San Juan Washington
Site Northern Southern Islands coast Population
Burrow-rock crevice
Diurnal 1,849 11,334 231 7,504 20,918
Nocturnal 90,347 30,600 9,800 17,070 147,817
Open nests
Flat or slope 909 15,101 6,298 5,755 28,063
Cliff face 982 5,525 395 12,945 19,847
Total 94,087 62,560 16,724 43,274 216,645
Percent of population
British Columbia Total
San Juan Washington
Site Northern Southern Islands coast Percent
Burrow-rock crevice
Diurnal 2.0 18.1 1.4 17.3 9.7
Nocturnal 96.0 48.9 58.6 39.4 68.1
Open nests
Flat or slope 1.0 24.2 37.6 13.3 13.0
Cliff face 1.0 8.8 2.4 30.0 9.2
Population Changes
The available data are inadequate to detect changes in population
distribution and density for most species (Table 9). In Washington,
for instance, limited unsubstantiated information suggests an overall
decline of the double-crested cormorant and tufted puffin in the
San Juan Island area. Likewise, there seems to be an increase in
glaucous-winged gulls there. In British Columbia, Drent and Guiguet
(1961) were able to detect changes in some species. For example, they
noted increases in the double-crested cormorant, pelagic cormorant,
and glaucous-winged gull. No change was observed in the tufted puffin.
Since then, the Brandt's cormorant has established a colony in Barkley
Sound (Guiguet 1971). The data in southeastern Alaska are inadequate
for all species except, perhaps, the Cassin's auklet which Gabrielson
and Lincoln (1959) reported to be declining throughout Alaska. In
short, no definitive statements can now be made concerning changes in
seabird population numbers.
Species Accounts
Fork-tailed Storm-petrel _(Oceanodroma furcata)_
Storm-petrels are especially difficult to census because they are
nocturnal, and the burrows and rock crevices where they breed are
often difficult to locate, especially in mixed-species colonies.
The census data are inadequate to determine whether there have been
changes in population density and distribution. Indeed, the biology of
this species is perhaps the least known of the North Pacific colonial
seabirds. In southeastern Alaska, this species is outnumbered by at
least 5 to 1 by the Leach's storm-petrel _(Oceanodroma leucorhoa)_. The
reasons for this are poorly understood. There is some evidence that the
numbers of breeding fork-tailed storm-petrels on Forrester Island may
fluctuate drastically from one year to the next (Gabrielson and Lincoln
1959).
Leach's Storm-petrel _(Oceanodroma leucorhoa)_
Of the two subspecies of this petrel (_O. l. leucorhoa_ and _O. l.
beali_), only _O. l. beali_ is found in southeastern Alaska. The
_leucorhoa_ subspecies is more northerly in distribution. Where
both fork-tailed and Leach's storm-petrels are sympatric, Leach's
predominates; however, this relationship becomes more unpredictable in
British Columbia and Washington. This species is undoubtedly widespread
in the forested islands of the Alexander Archipelago.
Double-crested Cormorant _(Phalacrocorax auritus)_
The double-crested cormorant apparently does not breed in southeastern
Alaska since Willett (1912), Gabrielson and Lincoln (1959), and S.
Patten (personal communication) do not report breeding colonies
for the area. The largest populations occur in southern British
Columbia principally in the Gulf Islands, where 71% of all breeding
double-crested cormorants are found (Table 10). According to Jewett
et al. (1953), this species was less common in Puget Sound than
was Brandt's cormorant, but is certainly not the case today (D. A.
Manuwal, unpublished data). The only common cormorants in the San Juan
Islands are the pelagic and double-crested species. The double-crested
cormorant seems to have declined in numbers on both coastal and inland
waters. On the basis of his observations, R. W. Campbell believes that
this species is increasing in British Columbia.
Table 9. _Distribution and status of marine birds breeding
along the Pacific coast of Washington, British Columbia, and
southeastern Alaska._ (X = known to breed in the region;? = data
insufficient; + = evidence indicates an overall increase in size
of population; - = evidence indicates an overall decrease in size
of population; 0 = no population change.)
-----------------------------------------------------------------------------
British
Washington Columbia
---------------- ---------------
Family and species Common name Presence Status Presence Status
-----------------------------------------------------------------------------
Hydrobatidae
_Oceanodroma furcata_ Fork-tailed X ? X ?
storm-petrel
_O. leucorhoa_ Leach's storm-petrel X ? X -
Phalacrocoracidae
_Phalacrocorax auritus_ Double-crested X - X -
cormorant
_P. penicillatus_ Brandt's cormorant X ? X 0
_P. pelagicus_ Pelagic cormorant X ? X +
Haematopodidae
_Haematopus bachmani_ Black oystercatcher X ? X +
Laridae
_Larus glaucescens_ Glaucous-winged gull X + X +
_L. occidentalis_ Western gull X ? X ?
_L. argentatus_ Herring gull
_Rissa tridactyla_ Black-legged
kittiwake
Alcidae
_Uria aalge_ Common murre X ? X -
_Cepphus columba_ Pigeon guillemot X ? X +
_Brachyramphus
marmoratus_ Marbled murrelet X ? X ?
_B. brevirostris_ Kittlitz's murrelet
_Synthliboramphus
antiquus_ Ancient murrelet X ?
_Ptychoramphus aleuticus_ Cassin's auklet X ? X ?
_Cerorhinca monocerata_ Rhinoceros auklet X ? X +
_Fratercula corniculata_ Horned puffin
_Lunda cirrhata_ Tufted puffin X - X 0
Total species 14 15
-----------------------------------------------------------------------------
---------------------------------------------------------------------
Southeastern
Alaska
----------------
Family and species Common name Presence Status
---------------------------------------------------------------------
Hydrobatidae
_Oceanodroma furcata_ Fork-tailed X ?
storm-petrel
_O. leucorhoa_ Leach's storm-petrel X ?
Phalacrocoracidae
_Phalacrocorax auritus_ Double-crested
cormorant
_P. penicillatus_ Brandt's cormorant ?
_P. pelagicus_ Pelagic cormorant X ?
Haematopodidae
_Haematopus bachmani_ Black oystercatcher X ?
Laridae
_Larus glaucescens_ Glaucous-winged gull X ?
_L. occidentalis_ Western gull
_L. argentatus_ Herring gull X ?
_Rissa tridactyla_ Black-legged X ?
kittiwake
Alcidae
_Uria aalge_ Common murre X ?
_Cepphus columba_ Pigeon guillemot X ?
_Brachyramphus
marmoratus_ Marbled murrelet X ?
_B. brevirostris_ Kittlitz's murrelet X ?
_Synthliboramphus
antiquus_ Ancient murrelet X ?
_Ptychoramphus aleuticus_ Cassin's auklet X -
_Cerorhinca monocerata_ Rhinoceros auklet X ?
_Fratercula corniculata_ Horned puffin X ?
_Lunda cirrhata_ Tufted puffin X ?
Total species 16
---------------------------------------------------------------------
Brandt's Cormorant _(Phalacrocorax penicillatus)_
Brandt's cormorant is the least abundant of the three cormorant species
that nest in the study area. Washington is at the northernmost edge
of the breeding distribution of this species. Only one more northerly
colony exists, on Sartine Island off Vancouver Island (Vermeer et
al. 1976). Brandt's cormorant comprises about 85% of the cormorant
population in Oregon (U.S. Fish and Wildlife Service, unpublished
data). However, in Washington it is only about 9% and in British
Columbia 3% of the total cormorant population.
Table 10. _Estimated seabird populations breeding
from Cape Fairweather, Alaska, to the Columbia River,
Washington._[12][13][14] (? = present in unknown
numbers; - = inadequate data.)
-----------------------------------------------------------------------------
Northern Southern San Juan Washington Total all
British British Islands coast regions
Columbia Columbia
Bird species Population Population Population Population Population
-----------------------------------------------------------------------------
Fork-tailed
storm-petrel 49,080 ? 0 1,900 50,980
Leach's
storm-petrel 1,365 5,000 0 3,655 10,020
Double-crested
cormorant 0 1,058 64 390 1,512
Brandt's cormorant 0 185 0 140 325
Pelagic cormorant 982 4,017 395 995 6,389
Glaucous-winged gull 909 13,858 6,234 4,215 25,216
Western gull 0 ? 0 930 930
Common murre 0 1,508 0 11,950 13,458
Pigeon guillemot 1,733 1,256 194 161 3,345
Ancient murrelet 21,177 0 0 0 21,177
Cassin's auklet 13,475 25,000 0 100 38,575
Rhinoceros auklet 5,250 6,000 9,800 11,415 27,065
Horned puffin 0 0 0 0 0
Tufted puffin 116 10,078 37 7,343 17,574
Total 94,087 67,960 16,724 43,194 216,566
--------------------------------------------------------------------------
-----------------------------------------------------------------------------
Northern Southern San Juan Washington Total all
British British Islands coast regions
Columbia Columbia
Bird species Percent Percent Percent Percent Percent
-----------------------------------------------------------------------------
Fork-tailed
storm-petrel 52.2 - - 4.4 23.5
Leach's
storm-petrel 1.5 8.0 - 8.5 4.6
Double-crested
cormorant - 1.7 >0.1 >0.1 >0.1
Brandt's cormorant - >0.1 - >0.1 >0.1
Pelagic cormorant 1.0 6.4 2.4 2.3 3.0
Glaucous-winged gull 1.0 22.2 37.3 9.8 11.6
Western gull - - - 2.2 >0.1
Common murre - 2.4 - 27.7 6.2
Pigeon guillemot 1.8 2.0 1.2 >0.1 1.5
Ancient murrelet 22.5 - - - 9.8
Cassin's auklet 14.3 40.0 - >0.1 17.8
Rhinoceros auklet 5.6 >0.1 58.6 26.4 12.5
Horned puffin - - - - -
Tufted puffin >0.1 16.1 >0.1 17.0 8.1
---------------------------------------------------------------------------
Comparing information in Jewett et al. (1953) with the current
situation, it is apparent that there has been a drastic change in the
distribution and probably in the numbers of this species in Washington.
Today, there are no Brandt's cormorant colonies in the San Juan Islands
or Strait of Juan de Fuca. Yet Jewett et al. (1953) reported colonies
at Bellingham Bay and on Lopez and Matia islands. We have observed
juvenile Brandt's cormorants in the San Juan Islands during the summer.
This species may be particularly susceptible to human disturbance,
since all three areas listed above are heavily used in the summer for
recreation.
Pelagic Cormorant _(Phalacrocorax pelagicus)_
The distribution of breeding colonies of the pelagic cormorant is
strongly determined by the availability of the steep cliffs on which it
constructs its nest. This is the only common cormorant in southeastern
Alaska. Throughout its extensive range, this species is generally found
breeding in small numbers. Nothing is known about fluctuations in its
numbers in Alaska.
This species is common in both British Columbia and Washington; nesting
sites are of the same type as those in Alaska except in the San Juan
Islands, where 200-300 birds nest on cliff faces composed of glacial
deposits. Here, there is frequent nest loss due to slippage off the
cliff face; this loss is especially severe on Smith and Protection
islands. There do not appear to be any changes in the distribution
of pelagic cormorants, but an accurate assessment of abundance is
impossible from the data currently available.
Glaucous-winged Gull _(Larus glaucescens)_
The glaucous-winged gull is the characteristic gull of southeastern
Alaska and British Columbia. In Washington, it is the dominant gull
in the San Juan Island area but interbreeds with the western gull on
the Washington outer coast from Tatoosh to Copalis Beach (Scott 1971).
In Alaska, it is widely distributed and locally abundant on Forrester
Island, St. Lazaria, and throughout Glacier Bay (S. Patten, personal
communication). The biology of this species has been extensively
studied in the southern part of its range, especially by Vermeer (1963)
and James-Veitch and Booth (1954). The only study of the breeding
biology of this species in southeastern Alaska is by Patten (1974) for
Glacier Bay. Glaucous-winged gulls are apparently increasing in British
Columbia (R. W. Campbell, unpublished data) and in Washington (T. R.
Wahl, personal communication). This increase is undoubtedly a result
of the proximity of breeding colonies to garbage dumps and commercial
fishing fleets in both Canada and the United States. Little is known
about changes in populations of gulls in southeastern Alaska.
Western Gull _(Larus occidentalis)_
The western gull is the common breeding gull of the Washington outer
coast; however, there is increased interbreeding with glaucous-winged
gulls northward from Destruction Island to Tatoosh Island. The
percentage of glaucous-winged gulls steadily increases until Vancouver
Island and the Strait of Juan de Fuca, where western gulls are rare.
Population estimates of gulls on the outer coast of Washington are
derived primarily from aerial flights. This makes identification of
gulls difficult, and in view of the amount of interbreeding, it is
probably impossible to classify many of the breeding gulls as to
species. Western gulls appear to be increasing in the Grays Harbor area
(G. D. Alcorn, personal communication).
Herring Gull _(Larus argentatus)_
The herring gull is typically found in inland Alaska but can be found
uncommonly along the coast of southeastern Alaska, where it often forms
mixed colonies with glaucous-winged gulls. These two species apparently
hybridize where they are sympatric (Williamson and Peyton 1963; Patten
and Weisbrod 1974; Patten 1974).
Black-legged Kittiwake _(Rissa tridactyla)_
The black-legged kittiwake is found only in the northern portions of
southeastern Alaska. It apparently is a common breeding bird in Glacier
Bay National Monument (S. M. Patten, Jr., personal communication). No
population estimates are available for this species other than that it
is locally abundant.
Common Murre _(Uria aalge)_
Common murres are common in southeastern Alaska and the coast of
Washington but breed only in small numbers in British Columbia and are
absent in the San Juan Islands. Since this species usually prefers
cliffs or the tops of inaccessible rocks, they are probably limited
by island topography in British Columbia, and are most certainly so
limited in the San Juan and Gulf Island groups.
In Alaska, common murres breed in unknown numbers in Glacier Bay and in
large numbers on St. Lazaria, Forrester, and the Hazy islands. No data
on population changes are available for any of the three regions.
Pigeon Guillemot _(Cepphus columba)_
The pigeon guillemot is common throughout the region from Cape
Fairweather to Washington. Even though it is not truly colonial, it
may be locally abundant where there are suitable nest sites. Since
these nest sites are usually difficult to find, population estimates
are seldom accurate, usually being conservative. It is evident that
guillemots appear to be small in number when compared with other
seabirds nesting at major colony sites in the north Pacific region
(Table 10). This disparity may be exaggerated by the difficulty of
censusing guillemots.
Marbled Murrelet _(Brachyramphus marmoratus)_
Since the marbled murrelet has been found to nest in coniferous forests
(Binford et al. 1975), traditional census techniques are unsuitable.
This species is common in southeastern Alaska (Gabrielson and Lincoln
1959), in British Columbia (Drent and Guiguet 1961), and in Washington
(Jewett et al. 1953).
Kittlitz's Murrelet _(Brachyramphus brevirostris)_
The difficulties in assessing breeding populations of Kittlitz's
murrelet are the same as those for the marbled murrelet. This species
nests on the ground at high elevation near the coast (Bailey 1973).
The largest concentrations are in the vicinity of Glacier Bay National
Monument (Gabrielson and Lincoln 1959). They are not found breeding in
Washington or British Columbia.
Ancient Murrelet _(Synthliboramphus antiquus)_
Ancient murrelets appear to be locally common throughout southeastern
Alaska. Their presence is probably strongly dependent upon a suitable
soil in which to excavate burrows. The only available population
estimates are those by Willett (1915) for Forrester Island (Table 1).
Censusing this species is especially difficult because its burrows are
easily confused with those of Cassin's auklet. There are no studies of
this species in southeastern Alaska; however, it has been well studied
in the Queen Charlotte Islands to the south by Sealy (1975).
Cassin's Auklet _(Ptychoramphus aleuticus)_
A synthesis of literature and unpublished observations led Gabrielson
and Lincoln (1959) to conclude that Cassin's auklet has greatly
decreased in numbers and is not abundant anywhere in Alaska. They
also concluded that the colony on Forrester Island (Table 1) was the
only well-documented colony in southeastern Alaska. Fishermen in the
southeastern Alaska area occasionally see this species (M. E. Isleib,
personal communication), but it is apparently still uncommon though
more widespread than just Forrester Island. The nocturnal habits
and burrowing in dense vegetation makes censusing this species very
difficult. Nothing is known about the ecology of this species in Alaska.
Rhinoceros Auklet _(Cerorhinca monocerata)_
Rhinoceros auklets seem to be found breeding only on islands where
there is a well-developed soil in which to excavate their extensive
burrows. From the limited evidence available, it appears that the
largest rhinoceros auklet populations probably are to be found in
southeastern Alaska. Willett (1912) found a very large population on
Forrester Island (Table 2), and the species has been found in the
summer in the Barren Islands east of Kodiak Island (E. P. Bailey,
personal communication). More intensive surveys of the Alexander
Archipelago will probably reveal other populations of this species.
This species is less common in British Columbia than either Alaska or
Washington. A possible reason for this is lack of suitable nesting
areas. In Washington, the two largest colonies are at Protection Island
in the Strait of Juan de Fuca and Destruction Island on the outer
coast. Smaller numbers exist on other coastal islands and on Smith
Island in the Strait of Juan de Fuca. The Smith Island colony is an
interesting one since it appears that early human disturbance in the
late 19th or early 20th century eliminated the species from the island.
In their discussion of Smith Island, Jewett et al. (1953) made no
mention of auklets, only of puffins and guillemots. Couch (1929) did
not record the species in 1925. The colony now numbers about 600 pairs.
Horned Puffin _(Fratercula corniculata)_
Although the horned puffin is one of the most abundant seabirds in
other parts of Alaska, it is much less abundant in the southeastern
portion. In addition to the information discussed by Sealy (1973),
it now appears that this species may breed as far south as Triangle
Island, British Columbia (K. Vermeer, personal communication; D. A.
Manuwal, personal observation). Here, as on Forrester Island, it is
greatly outnumbered by the tufted puffin. No data are available on the
breeding or status of this species in the study area.
Tufted Puffin _(Lunda cirrhata)_
The tufted puffin is found breeding on scattered islands throughout the
region. The largest known colonies are on Forrester Island, Alaska,
Triangle Island, British Columbia, and Carroll Island, Washington. It
is notably absent from most of the gulf and San Juan Islands. Even
though puffins have apparently never been numerous in the San Juan
Islands, their population has noticeably declined during the past
35 years. For example, Jewett et al. (1953) reported a colony of 50
pairs on Bare Island in 1937, but in 1973 only 2 pairs were counted
(D. A. Manuwal, unpublished data). Likewise, in 1915 there were more
than 250 pairs on Smith Island, but by 1916 there were only 75 pairs
(Jewett et al. 1953). The decline is attributed to rapid erosion of the
glacial-deposit cliffs. There are no puffins on Smith Island today,
and the largest colony in the Puget Sound area is the 35 pairs on
Protection Island (D. A. Manuwal, unpublished data).
Discussion
The total minimum estimate of the breeding seabird populations of
British Columbia and Washington is 216,500 pairs (Table 10). No
comprehensive estimates are available for breeding seabirds of
southeastern Alaska. It is likely, however, that the number of breeding
seabirds in the Alexander Archipelago may be equal to (or exceed)
the populations of both British Columbia and Washington. Data are
desperately needed from that area. Of the total seabird population in
the study area (Table 10) 43% reside in northern British Columbia. The
Washington State population represents 28% of the total. Fork-tailed
storm-petrels comprise almost 25% of all the breeding seabirds in the
area under consideration. The Cassin's auklet is the next most numerous
species (18% of the total).
It is apparent that current data are, for the most part, inadequate
for assessing anything but catastrophic changes in seabird breeding
colonies. This inadequacy is due to inadequate censusing because of
excessive reliance upon aerial surveys; in the past, this has often
been a result of insufficient funding.
Of the several threats facing seabird populations, none may be as
important as oil pollution. A general review of this subject is
presented elsewhere by Vermeer and Vermeer (1975). It is apparent
from this review that the most vulnerable species are those that dive
beneath the sea surface, including all the alcids and cormorants
breeding along the coast that are discussed in this paper. This
group makes up almost 60% of all the breeding seabirds in this area.
Unfortunately, our knowledge of several of these species is scanty and
our current census techniques are unsuitable for most of these birds.
Studies of the changes in seabird numbers have been made in other
oceans. For example, in Great Britain (Bourne 1972_a_, 1972_b_; Harris
1970), eastern Canada (Nettleship 1973), and the Atlantic coast of the
United States (Kadlec and Drury 1968), two major trends seem apparent.
First, there is an overall decline in alcid and tern numbers. The
decline in auks may be due to their extreme vulnerability to oil
pollution (Bourne 1972_a_, 1972_b_; Vermeer and Vermeer 1975). The
Atlantic puffin, however, may be suffering the additional effects of
gull cleptoparasitism (Nettleship 1972). Secondly, there seems to
be an increase in gull populations on both sides of the Atlantic,
particularly the herring gull and black-legged kittiwake.
Compared with the Atlantic coast of North America and northern Europe,
the data base for seabird populations of the Pacific coast is poor.
The fragmentary evidence now available indicates that there may be
small population increases in the western and glaucous-winged gulls
and range extensions of the Brandt's and double-crested cormorants and
of the rhinoceros auklet (Scott et al. 1974). Whether these changes
represent actual population increases or displacements remains unclear.
The remote locations of most of the large Pacific seabird colonies
may provide unofficial protection from human interference. Intensive
surveys are needed to establish base-line inventories in these areas.
As a consequence of this first comprehensive review of the status of
breeding marine birds of the northeast Pacific coast of North America,
we recommend the following future research topics as necessary for the
conservation of this great international resource.
• Seabird colony census techniques should
be refined since almost 68% of the seabirds
in this area are nocturnal and nest in burrows.
The present reliance on aerial censusing,
although economical, is inadequate to
census most breeding seabird populations;
more on-site surveys are needed. For surface-nesting
species and diurnal, burrowing
species, studies on species specific activity
cycles are needed so that census data
can be corrected for birds not observed at
the colony. For nocturnal, burrowing
species seasonal burrow occupancy rates
must be determined so that burrow counts
can be corrected for inactive burrows.
• Comprehensive surveys should be made
every 3-5 years.
• In 1980 a coordinated breeding bird survey
of the entire Pacific coasts of Mexico,
Canada, and the United States should be
conducted.
• Specific islands where key populations
exist should be carefully monitored for
subtle changes in population density or
species composition.
• Increased study of the breeding biology of
seabirds should be carried out so that base-line
reproductive characteristics can be
determined.
• Detailed studies of the effects of human
disturbance should be made, especially for
species that breed near large coastal cities
or marine recreation areas.
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Expedition. Univ. Calif. Publ. Zool. 7:9-172.
Swarth, H. 1922. Birds and mammals of the Stikine River Region of
northern British Columbia and southeastern Alaska. Univ. Calif.
Publ. Zool. 24:194-314.
Swarth, H. 1936. Origins of the fauna of the Sitkan District.
Alaska. Proc. Calif. Acad. Sci. Ser. 4, 15:59-78.
Thoresen, A., and J. Galusha. 1971. A nesting population study of
some islands in the Puget Sound area. Murrelet 52:20-23.
U.S. Department of the Interior, Interagency Task Force. 1972.
Environmental setting between Port Valdez, Alaska, and west coast
ports. Final Environmental Impact Statement, Vol. 3.
U.S. Weather Bureau. 1956. Climatic summary of the United
States--supplement for 1931 through 1952, Washington.
Climatography of the United States 11-39. 79 pp.
U.S. Weather Bureau, Environmental Data Service. 1965_a_. Climatic
summary of the United States--supplement for 1951 through 1960,
Oregon. Climatography of the United States 86-31. 96 pp.
U.S. Weather Bureau, Environmental Data Service. 1965_b_. Climatic
summary of the United States--supplement for 1951 through 1960,
Washington. Climatography of the United States 86-39. 92 pp.
U.S. Weather Bureau, Environmental Data Service. 1974.
Climatological Data, Alaska Annual Summary 1974, 60:13.
Vermeer, K. 1963. The breeding ecology of the glaucous winged gull
_(Larus glaucescens)_ on Mandarte Island. B.C. Occas. Pap. B.C.
Prov. Mus. 13. 104 pp.
Vermeer, K., D. A. Manuwal, and D. S. Bingham. 1976. Seabirds
and pinnipeds of Sartine Island, Scott Island group, British
Columbia. Murrelet 57(1):14-16.
Vermeer, K., and R. Vermeer. 1975. Oil threat to birds on the
Canadian west coast. Can. Field-Nat. 89:278-298.
Willett, G. 1912. Report of George Willett, Agent and Warden
stationed on St. Lazaria Bird Reservation, Alaska. Bird-lore
14:419-426.
Willett, G. 1915. Summer birds of Forrester Island, Alaska. Condor
19:15-17.
Williamson, F. S. L., and L. Peyton. 1963. Interbreeding of
glaucous-winged and herring gulls in the Cook Inlet region,
Alaska. Condor 65:24-28.
FOOTNOTES:
[5] Data are minimum estimates of pairs and do not include breeding
sites with less than 100 birds.
[6] Does not include the black oystercatcher, marbled murrelet, and
western gull.
[7] Estimates only for colonies of 100 or more birds.
[8] Estimates are in number of pairs.
[9] Estimates are number of pairs.
[10] Estimates are numbers of pairs.
[11] Data for southeastern Alaska were inadequate to enable estimates
of breeding pairs.
[12] Population estimates are minimum and represent numbers of pairs.
[13] Does not include the following species for which population
estimates are lacking: black oystercatcher, herring gull, black-legged
kittiwake, marbled murrelet, Kittlitz's murrelet.
[14] Data for southeastern Alaska were inadequate to enable estimates
of breeding pairs.
THE BIOLOGY AND ECOLOGY OF MARINE BIRDS IN THE NORTH
Trophic Relations of Seabirds in the Northeastern Pacific Ocean and
Bering Sea
by
David G. Ainley
Point Reyes Bird Observatory
Stinson Beach, California 94970
and
Gerald A. Sanger[15]
National Marine Fisheries Service
Marine Mammal Division
Seattle, Washington
Abstract
Literature on the diets of seabirds is reviewed
for 70 species found in five subarctic
oceanographic regions of the northeastern
North Pacific Ocean and Bering Sea. Species
inhabiting estuaries and sheltered bays are
not included. The diets of cormorants, marine
ducks, alcids, and marine raptors are best
known; less information is available for loons,
grebes, petrels, and gulls. Enough is known,
however, to broadly characterize the diet of
each species. Less than 7% of all species feed
on one type of prey, about 60% feed on two or
three types, and the rest feed on four or more
types. Only 12% of all species feed on eight
or more types of prey. Most seabirds (77%)
feed as secondary and tertiary carnivores.
Where overlap in diet exists, seabirds
partition resources through use of different
feeding methods, selection of different-sized
prey, and zonation of habitat. Species that
have specialized diets are probably more
susceptible than others to local environmental
catastrophes. Species whose feeding methods are
highly adapted for exploitation of resources
in polar and subpolar habitats are not adapted
for coping with oil pollution. Competition
between birds and man for marine resources can
sometimes benefit seabirds and at other times
harm them. More research is needed on seabird
feeding relations so that the ecological roles
played by marine birds can be defined and
placed in perspective. Such work should be
conducted at the community level, year-round,
and should be so conducted as to facilitate
comparison with biological oceanographic data.
The ecology, morphology, and much of the behavior of a seabird species
are definable in terms of the food resources it exploits year-round and
the spatial and temporal relations between food and breeding sites.
This general point unifies such important reports as those by Kuroda
(1954), Bédard (1969_a_), Ashmole and Ashmole (1967), Ashmole (1971),
Spring (1971), and Sealy (1972). More concretely, information on
trophic relations of seabirds is useful in several ways. In conjunction
with biological oceanographic data, it can provide insight into
geographic location, marine habitat, depth, time of day, and general
method of food capture by seabirds. Collected over several years, it
can provide a basis for understanding annual differences in seabird
breeding phenology and success. Finally, supplemented with data on how
much seabirds eat and excrete, it is necessary for an understanding
of the energetic and ecological roles played by the birds in the
functioning of marine ecosystems.
Several studies that describe trophic relations within seabird
communities have helped to define the principals of community
organization pertaining to the exploitation of available food resources
and have given clues to food-chain pathways. Trophic relations
have been described for breeding communities in the Barents Sea
(Uspenski 1958; Belopol'skii 1961), in the tropical Pacific Ocean
(Ashmole and Ashmole 1967; Ashmole 1968), in the North Sea (Pearson
1968), and in the Chukchi Sea (Swartz 1966). The last-named study
pertained most directly to the geographic region discussed in this
paper, but several other studies have provided sound information on
segments of communities in the northeastern North Pacific and Bering
Sea. These include the work on three species of auklets (_Aethia_,
_Cyclorrhynchus_) in the Bering Sea (Bédard 1969_a_); investigations
on cormorants and other fish predators in British Columbia by Munro
(1941), Munro and Clemens (1931), and Robertson (1974); studies of
murres in Bristol Bay by Ogi and Tsujita (1973); observations on
several species near the Pribilof Islands by Preble and McAtee (1923);
work on diving species off Oregon by Scott (1973); and studies of
murrelets by Sealy (1975).
A review of available reports reveals three obvious gaps in the
emphasis placed in seabird food studies. First, few studies have ever
considered in detail the trophic relations of seabird communities
during the winter or nonbreeding season. Partial exceptions are the
works by Cottam (1939) and others on marine diving ducks, species that
are seabirds only during the winter, and by several researchers (Munro
and Clemens 1931; Munro 1941; Robertson 1974) on seabirds in British
Columbia. Divoky (1976) studied diets of pack-ice gulls during the
nonbreeding season, but those species are not included in the present
analysis because they rarely are found south of the Bering Strait.
Second, no study has considered the trophic relationships of an entire
seabird community, i.e., not just breeding species but also nonbreeding
species. In the rather broad communities considered here, 50-70% or
more of the birds breed in another part of the world. To say that these
nonbreeding species have no significant impact on resource exploitation
or on organization and evolution among breeding members would be naive.
Finally, few investigators have attempted to fit birds into an entire
ecosystem, including lower trophic level origins as well as fish,
marine mammals, and man.
The reasons for these gaps in study emphasis are readily apparent:
the inconvenience of marine research during the winter when weather
is stormy, the need for costly study platforms (boats), and the
difficulties in organizing the specialized community of biologists
required for such tasks. A less obvious but important reason is that
oceanographers and fishery biologists have overlooked seabirds as
important members of marine ecosystems.
Diets of Seabirds in Western North America
Relatively good information exists for most pelecaniformes of
the region. A notable exception is the brown pelican _(Pelecanus
occidentalis)_, an endangered species. This is unfortunate because
dietary information is important for understanding the species'
ecology. Observations in eastern North America (Palmer 1962) and Peru
(Murphy 1936) indicated that their diet consisted of fish that occur
at the surface. The larger cormorants are piscivorous, particularly
on schooling fishes that occur at moderate to great depths (Table 1).
The smaller cormorants feed more heavily on benthic fish and decapod
crustaceans. Cormorants apparently feed only during daylight and
then only for short periods because their wettable plumage loses its
buoyancy. Thus they remain relatively close (50 km) to nesting and
loafing areas.
Table 1. _Food of cormorants in different localities_ (x = major
prey, o = minor prey and * = incidental prey species)
-----------------------------------------------------------------------
Key:
A_Amphipod
B: Isopod
C: Decapod
D: _Clupea_
E: _Engraulis_
F: Salmonid
G: Argentinid
H: _Porichthys_
I: _Otophidium_
J: _Boreogadus_
K: _Microgadus_
L: _Gasterosteus_
M: _Sebastes_
N: Hexagrammid
O: Cottid
P: Agonid
Q: Embiotocid
R: _Chromis_
S: _Oxyjulis_
T: Stichacid
U: Pholid
V: Gobiid
W: _Ammodytes_
X: Pleuronectid
Y: Bothid
CRUSTACEAN
Location Diet A B C D E F G H I J K L M
-----------------------------------------------------------------------
Double-crested cormorant
_(Phalacrocorax auritus)_[16]
Alaska Peninsula (Palmer 1962) o o o x x x
SE Alaska (Bailey 1927) x
Mandarte Island (Robertson 1974) * * * * *
Vancouver Island (Munro and
Clemens 1931) x
Oregon (Palmer 1962) x * * x
Farallon Island (PRBO,
unpublished data) * *
Brandt's cormorant _(P.
penicillatus)_[17]
Vancouver Island (Robertson,
unpublished data) x
Vancouver Island (Munro and
Clemens 1931) x
Washington (Jewett et al. 1953)
Yaquina Head (Scott 1973) x o o
Farallon Island (PRBO,
unpublished data) * o * * x x x
San Diego (Hubbs
et al. 1970) *
Pelagic cormorant
_(P. pelagicus)_[18]
Cape Thompson (Swartz 1966) x x
Pribilof Island (Preble
and McAtee 1923) x
Alaska (Palmer 1962) x x x
SE Alaska (Heath 1915) x x
Mandarte Island (Robertson 1974) x
Vancouver Island
(Munro and Clemens 1921) x x x
Washington (Jewett et al. 1953) x x
Netarts, Oregon (Gabrielson and
Jewett 1940) * * x
Yaquina Head (Scott 1973) o o
Farallon Island (PRBO,
unpublished data) x x
Red-faced cormorant _(P. urile)_
Pribilof Islands (Preble and
McAtee 1923) x
-----------------------------------------------------------------------
-----------------------------------------------------------------------
CRUSTACEAN FISH
Location Diet N O P Q R S T U V W X Y
-----------------------------------------------------------------------
Double-crested cormorant
_(Phalacrocorax auritus)_[16]
Alaska Peninsula (Palmer 1962) o x
SE Alaska (Bailey 1927)
Mandarte Island (Robertson 1974) * o x x
Vancouver Island (Munro and Clemens 1931)
Oregon (Palmer 1962) * x * *
Farallon Island (PRBO, unpublished data) * x * * *
Brandt's cormorant _(P. penicillatus)_[17]
Vancouver Island (Robertson,
unpublished data) o x
Vancouver Island (Munro and Clemens 1931)
Washington (Jewett et al. 1953) x
Yaquina Head (Scott 1973) * o o o
Farallon Island (PRBO, unpublished data) * o * * *
San Diego (Hubbs et al. 1970) * o o * x
Pelagic cormorant _(P. pelagicus)_[18]
Cape Thompson (Swartz 1966) x x
Pribilof Island (Preble and McAtee 1923) x x
Alaska (Palmer 1962) x x x x x x
SE Alaska (Heath 1915) x
Mandarte Island (Robertson 1974) * * x x
Vancouver Island (Munro and Clemens 1921) x x x
Washington (Jewett et al. 1953) x x
Netarts, Oregon (Gabrielson and Jewett 1940) x
Yaquina Head (Scott 1973) x
Farallon Island (PRBO, unpublished data) x x
Red-faced cormorant _(P. urile)_
Pribilof Islands (Preble and McAtee 1923) x x x x x
-------------------------------------------------------------------------------
Table 2. _Food of marine ducks and geese (x = major prey, o =
minor prey, and * = incidental prey species_).[a]
Key:
A: Amphipods
B: Decapods
C: Barnacles
D: Mussels
E: Rock clams
F: Razor clams
G: Oysters, Scallops
H: Littorinids
I: Chitons
------------------------------------------------------------------------
|PLANTS
| |CRUSTACEANS
| | |MOLLUSCS
| | | |ECHINODERMS
Diet[19] | | | | |FISH
Location | |A|B|C|D|E|F|G|H|I| | |FISH EGGS
------------------------------------------------------------------------
=Geese= x
(_Branta_ spp.)
=Emperor goose= x
_(Philacte canagica)_
=Oldsquaw= o * * * * * * * o
_(Clangula hyemalis)_
=Harlequin duck= * x x o * * o o * *
_(Histrionicus histrionicus)_
=Steller's eider= o x * * * * o * * * *
_(Polysticta stelleri)_
=Common eider= * * x * o * o o * o *
_(Somateria mollissima)_
=King eider= * * o * x * o o * x *
_(S. spectabilis)_
=Spectacled eider= x * x o * * * *
_(S. fischeri)_
=White-winged scoter= * * * * o x * x o * * o o
_(Melanitta deglandi)_
=Surf scoter= o * * * x * * x o * * * o
_(M. perspicillata)_
=Black scoter= o * * o x * * x * * * *
_(M. nigra)_
=Red-breasted merganser= x
_(Mergus serrator)_
------------------------------------------------------------------------
Information on diets of marine ducks (Table 2) is more nearly complete
than for most other seabirds. These birds fall into four groups
with some overlap: species feeding on plants (_Branta, Philacte_,
_Anas_-type, and _Somateria fischeri_); those feeding on benthic
crustaceans (_Clangula hyemalis_, _Histrionicus histrionicus_,
_Polysticta stelleri_, _S. mollissima_); those feeding on benthic
molluscs (_Somateria_ spp. and _Melanitta_ spp.); and those feeding
on fish (_Mergus serrator_, _Clangula hyemalis_, and _Melanitta
deglandi_). A study by Perthon (1968), one of the few on a seabird's
diet during most of a year, showed a seasonal change in diet for _S.
mollissima_ in Norway. In general, waterfowl seem to specialize in
their diets much more than other seabirds and, for that reason, are
perhaps more restricted in their distributions. Some marine ducks
are known to dive to considerable depths (reviewed by Kooyman 1974),
but usually they occur in shallow waters where plants and sessile
invertebrates are readily available.
The summer diet of the pigeon guillemot _(Cepphus columba)_ is the best
known among seabirds in the region being considered here (Table 3).
Only in the extreme southern part of its range (i.e., the California
Channel Islands) is there no information available on its diet. The
species feeds on organisms, mostly fish, from rocky habitat and
apparently can dive to considerable depths (Follett and Ainley 1976).
Because so much is known about guillemot diets during summer, a study
of the winter diet would be valuable.
The diets of other alcids are known well enough to at least
characterize them broadly. The larger species, murres, tufted and
horned puffins (_Lunda cirrhata_, _Fratercula corniculata_), and the
rhinoceros auklet _(Cerorhinca monocerata)_, feed heavily on fish,
mainly species that school in midwater (Table 4). To a great degree,
these birds are opportunistic, feeding rather heavily at times on
cephalopods and crustaceans, particularly nektonic forms. Morphological
differences between the two murre species suggest that thick-billed
murres _(Uria lomvia)_ feed on benthic organisms much more than do
common murres _(U. aalge)_, and that the latter species is more
piscivorous (Spring 1971); however, field data on diets are barely
adequate to confirm this. Ogi and Tsujita (1973) analyzed the stomach
contents of murres drowned in salmon gill nets but did not separate the
two species. For the present paper we considered them to be mostly _U.
aalge_, since this species predominates in the region of the food study
(Bartonek and Gibson 1972). Adult murres sometimes eat different items
than they feed to their chicks (Spring 1971; Scott 1973). The smaller
alcids, ancient and marbled murrelets--_Synthliboramphus antiquus_ and
_Brachyramphus marmoratus_--(Table 5) and auklets (Table 6), feed on
macrozooplankton: crustaceans, and fish and squid larvae. Little is
known about the food or feeding ecology of Kittlitz's murrelet _(B.
brevirostris)_. Its diet is probably similar to that of the other
murrelets, especially the marbled murrelet, its allopatric congener,
but the diets of the other murrelets differ somewhat (Bédard 1969_b_;
Sealy 1975). The Kittlitz's murrelet's shorter bill suggests that it
feeds more on invertebrates. Alcids feed in deep or shallow water,
depending on food distribution. Some alcid species can be found at
great distances from land, particularly in winter (Hamilton 1958; Scott
et al. 1971).
Information on the diets of other seabirds in the region is fragmentary
and sometimes rather anecdotal. A little is known about the feeding
habits of loons (_Gavia_ spp.) and grebes (_Podiceps_ spp. and
_Aechmophorus occidentalis_), especially off British Columbia (Table
7). The larger of these birds feed mainly on inshore fish, but as
species become progressively smaller, there is a tendency toward eating
crustaceans. Work by Madsen (1957) in Denmark, indicated that loons and
grebes tend to take prey near or on the bottom. Much more information
is available on these birds' diets at their freshwater breeding sites
but this provides only partial insight into what they might eat in
marine habitats.
Information is especially poor for albatrosses and petrels (order
Procellariiformes) (Table 8). Yet, based on sheer numbers alone,
members of this diverse group are easily among the most ecologically
dominant of the region (Sanger 1972; Ainley 1977). The Laysan
albatross _(Diomedea immutabilis)_ seems to be a squid specialist; the
black-footed albatross _(D. nigripes)_, northern fulmar _(Fulmarus
glacialis)_, scaled petrel _(Pterodroma inexpectata)_, and the
fork-tailed and Leach's storm-petrels (_Oceanodroma furcata_ and _O.
leucorhoa_) appear to be large, medium, small, and tiny versions,
respectively, of surface-feeding generalists that eat whatever
they can find, including live and dead fish, squid, coelenterates,
crustaceans, and other organisms. The shearwaters (_Puffinus_ spp.)
feed to an unknown degree on schooling fish, squid, and crustaceans
that occur near the surface. For these very abundant shearwaters,
that, unfortunately, is close to the extent of our knowledge both for
the North Pacific, where they winter, and the South Pacific, where
they breed. Most petrels remain in oceanic habitats, but shearwaters,
particularly the sooty shearwater _(Puffinus griseus)_, and sometimes
fulmars feed close to, if not within, the inshore neritic habitat. A
much better understanding of the diets of this group is sorely needed.
Table 3. _Food of the pigeon guillemot_ (Cepphus columba) _in
different localities (x = major prey, o = minor prey, and * =
incidental prey species)_.
Key:
A: Amphipod
B: Isopod
C: Decapod
D: Petromyzontid
E: Chimaerid
F: Clupeid
G: Osmerid
H: Gadid
I: Gasterosteid
J: Scorpaenid
K: Cottid
L: Agonid
M: Embiotocid
N: Bathymasterid
O: Clinid
P: Cryptacanthodid
Q: Cebidichthyid
R: Stichaeid
S: Pholid
T: Ammondytid
U: Bothid
V: Pleuronectid
----------------------------------------------------------------------------
|CRUSTACEAN
| |OCTOPUS
Diet | | |FISH
Location |A|B|C| |D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V
----------------------------------------------------------------------------
Cape Thompson o o
(Swartz 1966)
Pribilof Island o o o
(Preble and McAttee 1923)
Mandarte Island o o * o x o o * o * o o o o o o
(Drent 1965; Koelink 1972)
Vancouver Island o o o
(Munro and Clemens 1931)
Olympic Peninsula o o o o
(Thoresen and Booth 1958)
Yaquina Head o o o o o
(Scott 1973)
Farallon Island o o * x x * o o o o
(Follett and Ainley 1976)
----------------------------------------------------------------------------
Knowledge on the food of gulls, shorebirds, and related species is
surprisingly scanty in view of all that is known about their breeding
biology and social behavior. Little is known about the marine food of
phalaropes, but by inference from their association with storm-petrels,
plankton-feeding whales, and convergence lines (Martin and Myers
1969), their tiny size, and their method of feeding (picking at
minuscule items on the water surface), one can guess that they feed
on zooplankton and detritus. Skuas _(Catharacta skua)_ and jaegers
(_Stercorarius_ spp.) apparently eat what they can find at the surface,
as well as whatever they can steal from gulls and terns. Almost all the
literature on their feeding (Bent 1946) dwells on accounts of their
stealing from other birds. That spectacular behavior would seem to be
so energetically costly, though, that it is probably less important
than we have been led to believe. Rather surprisingly, the question
of what foods the gulls and terns eat in the eastern North Pacific
is difficult to answer from the literature (Tables 9 and 10). Some
information exists for five of the larger larids at isolated places,
but little is known about food elsewhere in their respective ranges,
and the diets of the seven smaller gulls and the terns are practically
unknown. Studies on gull diets in the Atlantic region (e.g., Spaans
1971; Harris 1965) provide information on what to expect from the same
species in the Pacific, but that information must be considered only in
general terms because, the birds being somewhat opportunistic, their
diets differ greatly from one locality to another (Ingolfsson 1967). A
few observations are available for arctic terns _(Sterna paradisaea)_
in Alaska, but little information exists for other terns (Table 10).
Bent (1921) noted that Aleutian terns _(S. aleutica)_ sometimes
associate with arctic terns during feeding.
Finally, we must include raptors, particularly the peregrine _(Falco
peregrinus)_ and bald eagle _(Haliaeetus leucocephalus)_, because they
are important predators on the smaller seabirds (White et al. 1971,
1973). Peregrines have, in fact, been observed feeding on storm-petrels
far at sea (Craddock and Carlson 1970).
Trophic Relations Within Seabird Communities
We have compared and summarized in general terms the food partitioning
by species in five rather broad oceanographic regions and their
subdivisions in the northeastern North Pacific and Bering Sea, based
on the specific details on diets presented in Tables 1 through 10.
The five broad regions, defined oceanographically by Dodimead et al.
(1963) and Favorite et al. (1976) and modified by Sanger (1972), are
shown in Fig. 1. The five oceanographic regions (domains) were divided
further into inshore neritic, offshore neritic, and oceanic habitats
(Sanger and King, this volume). We did not include estuarine habitats
or sheltered bays in the analysis.
[Illustration: Fig. 1. Schematic oceanographic domains of the subarctic
Pacific regions (defined by Dodimead et al. (1963) and Favorite et al.
(1976) and modified by Sanger (1972).)]
Table 4. _Food of murres and puffins in different
localities (x = major prey, o = minor prey, and * = incidental
prey species)._
KEY:
CRUSTACEAN
A - Euphausiid
B - Amphipod
C - Isopod
D - Decapod
E - POLYCHAETE
F - CEPHALOPOD
CRUSTACEAN POLYCHAETE CEPHALOPOD
LOCATION A B C D E F
--------
=Common murre= _(Uria aalge)_[20]
Cape Thompson o o o o o
(Swartz 1966)
Pribilof Islands x o o
(Preble and McAtee 1923)
E. Bering Sea x o
(Ogi and Tsujita 1973)
Forrester Island o o
(Heath 1915)
Vancouver Island o o
(Robertson, unpublished
data)
Olympic Peninsula
(Cody 1973)
Yaquina Head x o
(Scott 1973)
Farallon Islands x o
(PRBO, unpublished data)
=Thick-billed murre=
_(U. lomvia)_[21]
Cape Thompson o o o
(Swartz 1966)
Pribilof Islands x x
(Preble and McAtee 1923)
Hooker Island x o
(Demme 1934, _in_
Dement'ev et al. 1968)
NE Canada x o o o
(Tuck and Squires 1937)
=Tufted puffin=
_(Lunda cirrhata)_[22]
Cape Thompson *
(Swartz 1966)
Forrester Island
(Heath 1915)
Langara Island
(Sealy 1973_a_)
Washington
(Jewett et al. 1953)
Olympic Peninsula
(Cody 1973)
Farallon Island
(PRBO, unpublished data) x
=Horned puffin=
_(Fratercula corniculata)_
Cape Thompson o
(Swartz 1966)
Alaska
(Bent 1946)
Forrester Island
(Heath 1915)
=Rhinoceros auklet=
_(Cerorhinca monocerata)_
NW Pacific (Kozlova 1961; x
Komaki 1967)
Forrester Island
(Heath 1915)
Langara Island
(Sealy 1973_a_)
Destruction Island
(Richardson 1961)
Olympic Peninsula
(Cody 1973)
So. California (Linton x
1908; Grinnell 1899)
---------------------------------------------------------------
KEY:
FISH
G - Clupea
H - Sardinops
I - Engraulis
J - Salmo
K - Onchorhynchus
L - Hypomesus
M - Thaleichthys
N - Mallotus
O - Boreogadus
P - Microgadus
Q - Theragra
R - Lycodes
S - Gasterosteus
T - Sebaste
U - Triglops
V - Myoxocephalus
W - Cottid
X - Cymatogaster
Y - Embiotocid
Z - Chirolophis
AA - Stichaeid
BB - Ammodytes
CC - Pleuronectid
DD - Liparid
FISH A B C D
LOCATION G H I J K L M N O P Q R S T U V W X Y Z A B C D
--------
=Common murre= _(Uria aalge)_[20]
Cape Thompson x o o o x
(Swartz 1966)
Pribilof Islands o
(Preble and McAtee 1923)
E. Bering Sea x x x
(Ogi and Tsujita 1973)
Forrester Island x
(Heath 1915)
Vancouver Island x o
(Robertson, unpublished
data) x x o o
Olympic Peninsula
(Cody 1973) x x o x o o o
Yaquina Head
(Scott 1973) x o o * x o o
Farallon Islands
(PRBO, unpublished data)
=Thick-billed murre=
_(U. lomvia)_[21] x o o o o o x o
Cape Thompson
(Swartz 1966)
Pribilof Islands
(Preble and McAtee 1923)
Hooker Island
(Demme 1934, _in_
Dement'ev et al. 1968) o x * x * o x o o o
NE Canada
(Tuck and Squires 1937)
=Tufted puffin= x
_(Lunda cirrhata)_[22] *
Cape Thompson
(Swartz 1966) x
Forrester Island
(Heath 1915) x
Langara Island x
(Sealy 1973_a_) x x x x
Washington o
(Jewett et al. 1953) x o x
Olympic Peninsula x
(Cody 1973) x o
Farallon Island
(PRBO, unpublished data)
=Horned puffin= x o
_(Fratercula corniculata)_ o x
Cape Thompson
(Swartz 1966)
Alaska
(Bent 1946) x
Forrester Island
(Heath 1915)
=Rhinoceros auklet=
_(Cerorhinca monocerata)_ x o x x
NW Pacific (Kozlova 1961;
Komaki 1967) x
Forrester Island
(Heath 1915) x
Langara Island
(Sealy 1973_a_) o x
Destruction Island o
(Richardson 1961) x x o
Olympic Peninsula
(Cody 1973) x
So. California (Linton
1908; Grinnell 1899)
-----------------------------------------------------------------------------
Table 5. _Food of ancient and marbled murrelets (x = major prey,
o = minor prey, and * = incidental prey species)._
Column Headings:
CRUSTACEAN
A - Euphausiid
B - Thysanoessa
C - Euphausia
D - Mysid
E - Acanthomysis
F - Amphipod
G - Gammarid
H - Carid shrimp
I - Decapod
J - Larvae
CRUSTACEAN
Location DIET A B C D E F G H I J
------------------------------------------------------------------------------
=Ancient murrelet= _(Synthliboramphus antiquus)_[23]
Commander Islands (Dement'ev et al. 1968) x x
Amchitka Island (White et al. 1971, 1973) x x x x
Langara Island (Sealy 1975) x x x * * *
=Marbled murrelet= _(Brachyramphus marmoratus)_[24]
SE Alaska (Grinnell 1897)
Langara Island (Sealy 1975) x x *
Vancouver Island (Munro and Clemens 1931) x
Olympic Peninsula (Cody 1973)
Column Headings:
SQUID
K - Larvae
FISH
L - Engraulis
M - Osmerid
N - Scorpaenid
O - Cymatogaster
P - Stichaeid
Q - Ammodytes
R - Larvae
SQUID FISH
Location DIET K L M N O P Q R
-----------------------------------------------------------------------------
=Ancient murrelet= _(Synthliboramphus antiquus)_[23]
Commander Islands (Dement'ev et al. 1968)
Amchitka Island (White et al. 1971, 1973) x
Langara Island (Sealy 1975) o o x
=Marbled murrelet= _(Brachyramphus marmoratus)_[24]
SE Alaska (Grinnell 1897) o
Langara Island (Sealy 1975) * * * x *
Vancouver Island (Munro and Clemens 1931) x x
Olympic Peninsula (Cody 1973) x x
Table 6. _Diets of auklets in different localities (x = major
prey, o = minor prey, and * = incidental prey species)._
Table Headings
CRUSTACEAN
A - Euphausiid
B - Thysanoessa
C - Mysid
D - Stylomysis
E - Amphipod
F - Parathemisto
G - Phronema
H - Gammarid
I - Copepod
J - Calanus
K - Carid shrimp
L - POLYCHAETE
SQUID
M - Larvae
FISH
N - Cottid
O - Larvae
Location Diet A B C D E F G H I J K L M N O
=Cassin's auklet=
_(Ptychoramphus aleuticus)_
Forrester Island (Heath 1915) x x x
Olympic Peninsula (Cody 1973) x x
Farallon Islands (Manuwal 1974) x x x x x o x
=Parakeet auklet=
_(Cyclorrhynchus psittaculus)_
Chukhotsk Peninsula (Portenko 1934,
_in_ Dement'ev et al. 1968) x x x x x
Aleutian Islands (Bent 1946) x
St. Lawrence Island (Bédard 1969_a_) x x o x x o o * o o o
=Crested auklet=
_(Aethia cristatella)_[25]
W. Bering Sea (Portenko 1934,
_in_ Dement'ev et al. 1968) x x
Commander Islands (Stejneger 1885) x
Amchitka (White et al. 1973) x x x x x
St. Lawrence Island. (Bédard 1969_a_) x x x o o x x *
Pribilof Islands (Preble and McAtee 1923) x x
=Least auklet= _(A. pusilla)_
Commander Islands (Stejneger 1885) x
Aleutian Islands (Bent 1946) x
St. Lawrence Island (Bédard 1969_a_) o o * o o o x x x
=Whiskered auklet= _(A. pygmaea)_
Commander Islands (Stejneger 1885) x x *
Table 7. _Diets of loons and grebes in different localities (x =
major prey, o = minor prey, and * = incidental prey species)._
Table Headings:
CRUSTACEANS
A - Euphausid
B - Amphipod
C - Mysid
D - Decapod
E - POLYCHAETE
FISH
F - Anguilla
G - Clapea
H - Sardinops
I - Salmo
J - Thaleichthys
K - Atherinops
Location A B C D E F G H I J K
=Common loon= _(Gavia immer)_
Alaska (Palmer 1962) * * o o
Vancouver Island (Munro and Clemens 1931) x
Denmark (Madsen 1957) *
=Yellow-billed loon= _(G. adamsii)_[26]
Alaska (Cottam and Knappen 1939) * *
Alaska (Bailey 1922)
=Arctic loon= _(G. arctica)_[27]
Vancouver Island (Palmer 1962) x
Vancouver Island (Robertson, unpublished data) x
California (Palmer 1962)
Denmark (Madsen 1957) * o
=Red-throated loon= _(G. stellata)_[28]
Oregon (Palmer 1962)
No. Atlantic (Palmer 1962)
Denmark (Madsen 1957) * o
=Western grebe= _(Aechmophorus occidentalis)_
Vancouver Island (Munro 1941) o * x
Vancouver Island (Robertson, unpublished data) x
Puget Sound (Phillips and Carter 1957) x
Washington (Chatwin 1956) * x
California (Palmer 1962) o * x x
=Red-necked grebe= _(Podiceps grisegena)_
Pribilof Islands (Preble and McAtee 1923) o
Vancouver Island (Wetmore 1924)
Vancouver Island (Munro 1941) x o
E. No. America (Wetmore 1924) o * o
=Horned grebe= _(P. auritus)_[29]
Pribilof Islands (Preble and McAtee 1923) x o
W. No. America (Wetmore 1924) x x *
Vancouver Island (Munro 1941) x x
Denmark (Madsen 1957) o o o
=Eared grebe= _(P. nigricollis)_[30]
W. No. America (Wetmore 1924) * x *
Vancouver Island (Munro 1941) x x o
Denmark (Madsen 1957) x *
Table Headings:
FISH
L - Zoarchid
M - Gadid
N - Fundulus
O - Gasterosteus
P - Sebastes
Q - Cattid
R - Cymatogaster
S - Stichaeid
T - Ammodytes
U - Gobiid
Location L M N O P Q R S T U
=Common loon= _(Gavia immer)_
Alaska (Palmer 1962) o o o
Vancouver Island (Munro and Clemens 1931)
Denmark (Madsen 1957) o x * o
=Yellow-billed loon= _(G. adamsii)_[26]
Alaska (Cottam and Knappen 1939) o x
Alaska (Bailey 1922) x
=Arctic loon= _(G. arctica)_[27]
Vancouver Island (Palmer 1962)
Vancouver Island (Robertson, unpublished data)
California (Palmer 1962) x
Denmark (Madsen 1957) * x x * x *
=Red-throated loon= _(G. stellata)_[28]
Oregon (Palmer 1962) x
No. Atlantic (Palmer 1962) x x o
Denmark (Madsen 1957) * x o * * o
=Western grebe= _(Aechmophorus occidentalis)_
Vancouver Island (Munro 1941) x
Vancouver Island (Robertson, unpublished data) x
Puget Sound (Phillips and Carter 1957) * o o o
Washington (Chatwin 1956)
California (Palmer 1962) x *
=Red-necked grebe= _(Podiceps grisegena)_
Pribilof Islands (Preble and McAtee 1923)
Vancouver Island (Wetmore 1924) x
Vancouver Island (Munro 1941) x
E. No. America (Wetmore 1924) o x
=Horned grebe= _(P. auritus)_[29]
Pribilof Islands (Preble and McAtee 1923)
W. No. America (Wetmore 1924) o o
Vancouver Island (Munro 1941) o o *
Denmark (Madsen 1957) o
=Eared grebe= _(P. nigricollis)_[30]
W. No. America (Wetmore 1924) o
Vancouver Island (Munro 1941)
Denmark (Madsen 1957) o
Table 8. _Diets of albatrosses and petrels in different
localities (x = major prey, o = minor prey, and * = incidental prey
species)._
Key:
CRUSTACEAN
A: Euphausiid
B: Amphipod
C: Copepod
D: Decapod
E: Larvae
F: Barnacle
FISH
G: "Fish"
H: _Engraulis_
I: Myctophid
J: _Sebastes_
K: _Ammodytes_
L: Carrion, fish offal
M: Fish eggs
-----------------------------------------------------------------------------
|CRUSTACEAN
| |COELENTERATE
| | |ECHINODERM
| | | |CEPHALOPOD
Location Diet |A|B|C|D|E|F| | | |
---------------------------------------------------------------------
=Black-footed albatross= _(Diomedea nigripes)_
No. Pacific (Palmer 1962) x
Aleutian Islands (Cottam and Knappen 1939) o x o
California (Miller 1936, 1940) o o x
=Laysan albatross= _(D. immutabilis)_
No. Pacific (Palmer 1962; Bartsch 1922;
Fisher 1904) x
=Northern fulmar= _(Fulmarus glacialis)_
Pribilof Islands (Preble and McAtee 1923) o x
Alaska (Gabrielson and Lincoln 1959) x x
Oregon (Gabrielson and Jewett 1940) x
No. Atlantic (Hartley and Fisher 1936;
Einarsson 1945; Fisher 1952) x
=Flesh-footed shearwater= _(Puffinus carneipes)_
Australia (Oliver 1955; Serventy et al. 1971) x x
=Pink-footed shearwater= _(P. creatopus)_
California (Murphy 1936; Ainley,
personal observation) x
E. Pacific (Cottam and Knappen 1939) x
=Buller's shearwater= _(P. bulleri)_
SW Pacific (Falla 1934; Serventy et al. 1971) x x
Peru (Murphy 1936) x
=Sooty shearwater= _(P. griseus)_
Aleutian Islands (Sanger, personal
observation) x x
British Columbia (Martin 1942; Sealy 1973_a_) x
Oregon (Gabrielson and Jewett 1940) x
California (Ainley, personal observation) x
Peru (Murphy 1936) x x
SW Pacific (Oliver 1955; Serventy et al. 1971) x x
=Short-tailed shearwater= _(P. tenuirostris)_
Bristol Bay (Bartonek, personal communication) x
Alaska (Cottam and Knappen 1939) x x x
No. Pacific (Palmer 1962; Kuroda 1955) x x
Australia (Serventy et al. 1971) x x
Bass Strait (Sheard 1953) x
=Mottled petrel= _(Pterodroma inexpectata)_
Pacific Ocean (Imber 1973)
E. No. Pacific (Kuroda 1955)
=Fork-tailed storm-petrel=_(Oceanodroma furcata)_
Pribilof Islands (Preble and McAtee 1923)
SE Alaska (Heath 1915) x
British Columbia (Martin 1942)
California (Ainley, personal observation)
=Leach's storm-petrel= _(O. leucorhoa)_
SE Alaska (Heath 1915) x
California (PRBO, unpublished data) x x x
So. California (Palmer 1962) x
No. Atlantic[31] (Palmer 1962) x x x
---------------------------------------------------------------------