U.S. Department of the Interior

U.S. Fish and Wildlife Service

U.S. Geological Survey

Information and Technology Report

USGS/BRD/ITR–2000-0012

Biology and Conservation of the Common Murre

in California, Oregon, Washington,

and British Columbia

Volume 1: Natural History and Population Trends
Suggested citation:

Manuwal, D. A., H. R. Carter, T. S. Zimmerman, and D. L. Orthmeyer, Editors. 2001. Biology and conservation of the

common murre in California, Oregon, Washington, and British Columbia. Volume 1: Natural history and population

trends. U.S. Geological Survey, Biological Resources Division, Information and Technology Report USGS/BRD/ITR–

2000-0012, Washington, D.C. 132 pp.

Additional copies of this report may be obtained from the National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161 (1-800-553-6847 or 703-487-4650). Also available to registered users from the Defense Technical

Information Center, Attn: Help Desk, 8725 Kingman Road, Suite 0944, Fort Belvoir, VA 22060-6218 (1-800-225-3842 or

703-767-9050).

Front cover photograph: Common murre (Uria aalge californica) in breeding plumage at the South Farallon Islands,

California (U.S. Fish and Wildlife Service, Farallon National Wildlife Refuge).

Back cover photograph: Parent-chick pair of common murres (Uria aalge californica) at sea just minutes after departing

from the colony at Three Arch Rocks, Oregon, 11 July 1989 (Photo by R. W. Lowe).

Technical Report Series

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same peer-review and high quality standards as their journal

counterparts.
Biology and Conservation of the Common Murre

in California, Oregon, Washington, and British Columbia

Volume 1:

Natural History and Population Trends

Editors

David A. Manuwal1, Harry R. Carter2, Tara S. Zimmerman3, and Dennis L Orthmeyer4

1

 University of Washington, College of Forest Resources,

Wildlife Science Group

Seattle, Washington 98195

2 Humboldt State University, Department of Wildlife,

 Arcata, California 95521

3

 U.S. Fish and Wildlife Service, Division of Migratory Birds,

911 N.E. 11th Avenue

Portland, Oregon 97232

4

 U.S. Geological Survey, Western Ecological Research Center,

Dixon Field Station, 6924 Tremont Road,

Dixon, California 95620

Information and Technology Report 2000-0012

January 2002

U.S. Department of the Interior

U. S. Geological Survey

Washington, D. C. 20240
iii

Contents

Page

Contents................................................................................................................................................................................ iii

Executive Summary ........................................................................................................................................................... vii

Chapter 1. Natural history of the common murre (Uria aalge californica) ............................................................... 1

Abstract .................................................................................................................................................................................. 1

Methods.................................................................................................................................................................................. 3

Overview of the biology of the common murre ............................................................................................................... 4

Reproductive ecology .......................................................................................................................................................... 5

Breeding habitat .......................................................................................................................................................... 5

Seasonal and daily colony attendance patterns .................................................................................................... 5

Timing of breeding ..................................................................................................................................................... 7

Egg laying .................................................................................................................................................................... 7

Incubation and hatching ............................................................................................................................................ 8

Chick rearing and colony departure ........................................................................................................................ 8

Demography ........................................................................................................................................................................... 9

Adult and subadult survival ...................................................................................................................................... 9

Proportion of adults that breed ................................................................................................................................. 9

Hatching success ......................................................................................................................................................... 9

Fledging success .......................................................................................................................................................10

Breeding success .......................................................................................................................................................12

At-sea chick rearing ............................................................................................................................................................13

Philopatry, recruitment, and intercolony movements ..................................................................................................14

Colony formation and irregular attendance ...................................................................................................................14

Predators ...............................................................................................................................................................................15

Foraging ecology ................................................................................................................................................................16

Diet ........................................................................................................................................................................................17

At-sea distributions.............................................................................................................................................................18

California ....................................................................................................................................................................18

Oregon .........................................................................................................................................................................19

Washington ................................................................................................................................................................19

British Columbia .......................................................................................................................................................19

Movements...........................................................................................................................................................................20

Acknowledgments ..............................................................................................................................................................22

Literature cited ....................................................................................................................................................................22

Additional references .........................................................................................................................................................30

Unpublished data and personal communications.........................................................................................................32

Chapter 2. Population trends of the common murre (Uria aalge californica) ........................................................33

Abstract ................................................................................................................................................................................33

Methods................................................................................................................................................................................36

Summary of population data .............................................................................................................................................38

California ....................................................................................................................................................................38

Historical background on breeding colonies in California, 1800–1978 ..................................................38

Current population size and distribution of breeding colonies in California .........................................39

Population trends in central California, 1979–1995 ....................................................................................42

Population trends in northern California, 1979–1995 .................................................................................45

Oregon .........................................................................................................................................................................48

Historical background on breeding colonies in Oregon, prior to 1980 ....................................................48

Current population size and distribution of breeding colonies in Oregon ..............................................51

Population trends in Oregon, 1988–1995 ......................................................................................................52
iv

Washington ................................................................................................................................................................54

Historical background on breeding colonies in Washington, 1905–1978 ..............................................54

Current population size and distribution of breeding colonies in Washington ......................................56

Population trends in southern Washington, 1979–1995 .............................................................................58

Population trends in northern Washington, 1979–1995 .............................................................................60

British Columbia .......................................................................................................................................................61

Historical background on breeding colonies in British Columbia, 1900–1979 .....................................61

Current population size and distribution of breeding colonies in British Columbia ............................64

Population trends in British Columbia ...........................................................................................................65

Overall population assessment ...............................................................................................................................66

Current population size and distribution of breeding colonies .................................................................66

Recent and historical population trends.........................................................................................................68

Acknowledgments ..............................................................................................................................................................70

Literature cited ....................................................................................................................................................................71

Additional references .........................................................................................................................................................81

Unpublished data and personal communications.........................................................................................................84

Appendix A. Techniques for aerial and other photographic surveys of common murre (Uria aalge

californica) colonies in California, Oregon, Washington, and British Columbia ........................................87

Appendix B. Histories of common murre (Uria aalge californica) colonies in California, 1800–1978 ...........93

Appendix C. Population data for common murre (Uria aalge californica) colonies in California,

1979–1986 .............................................................................................................................................................. 109

Appendix D. Population data for common murre (Uria aalge californica) colonies in California,

1987–1995 .............................................................................................................................................................. 113

Appendix E. Population data for common murre (Uria aalge californica) colonies in Oregon,

1987–1995 .............................................................................................................................................................. 117

Appendix F. Population data for common murre (Uria aalge californica) colonies in Washington,

1979–1989 .............................................................................................................................................................. 119

Appendix G. Population data for common murre (Uria aalge californica) colonies in Washington,

1990–1995 .............................................................................................................................................................. 121

Appendix H. Summary of regression analyses............................................................................................................ 123

Appendix I. Photographs of selected breeding colonies of common murres in California, Oregon,

Washington, and British Columbia .................................................................................................................... 129

Tables

Number Page

1.1 Reproductive success of first and replacement clutches of the common murre on the South Farallon

Islands, California, 1972–1983 ................................................................................................................................ 8

1.2 Reproductive success of the common murre in the Pacific and Atlantic Oceans..........................................11

1.3 Summary of reproductive and other characteristics of the common murre in California, Oregon,

Washington, and British Columbia. ......................................................................................................................12

1.4 Seasonal projected total number of common murres in the protected marine waters of Washington

and southern British Columbia during 1978–1979 ...........................................................................................19

2.1 Average and maximum sizes for nine breeding colonies of common murres in central California,

1979–1995 .................................................................................................................................................................41

2.2 Average and maximum sizes for eight breeding colonies of common murres in northern California,

1979–1995 .................................................................................................................................................................41

2.3 Summary of museum egg specimens of common murres in Oregon ................................................................51

2.4 Numbers of common murre counted at seven colonies formed in Oregon between 1989 and 1995 .........52

2.5 Average and maximum sizes for 15 selected breeding colonies of common murres in Oregon,

1988–1995 .................................................................................................................................................................52

2.6 Numbers of common murres counted during replicate aerial surveys at 15 selected colonies in

Oregon in 1995 .........................................................................................................................................................53
v

2.7 Summary of most-recent surveys of common murres at colonies in British Columbia, 1977–1997 .........64

2.8 Comparison of counts of common murres at subcolony sites on Triangle Island in 3 years from

1982 to 1989 ..............................................................................................................................................................65

2.9 Total sum of common murres counted and numbers of breeding adults estimated in California,

Oregon, Washington, and British Columbia in 1988–1989 .............................................................................66

Figures

Number Page

1.1 Common murre (Uria aalge californica) in breeding plumage at the South Farallon Islands,

California ...................................................................................................................................................................... 3

1.2 Distribution of the common murre on the Pacific coast of the continental United States and Canada ...... 3

1.3 Breeding colony of common murres in the Upper Shubrick Point study plot at the South Farallon

Islands, California, May 1995 .................................................................................................................................. 5

1.4 Breeding colony of common murres at Puffin Rock near Triangle Island, British Columbia,

16 July 1985 ................................................................................................................................................................ 5

1.5 Reproductive success for first eggs of the common murre in the Upper Shubrick Point study plot at

the South Farallon Islands, California, 1972–1983 ............................................................................................10

1.6 Parent–chick pair of common murres at sea just minutes after departing from the colony at Three

Arch Rocks, Oregon, 11 July 1989 ........................................................................................................................13

1.7 Variation in diet composition of the common murre between three marine habitats and three times

of year in the Gulf of the Farallones in central California, 1985–1988 ..........................................................17

2.1 Distribution of common murre colonies in northern California (Del Norte to Sonoma Counties) ............40

2.2 Distribution of common murre colonies in central California (Marin to Monterey Counties) and

southern California (Santa Barbara County)........................................................................................................40

2.3 Trends in whole-colony counts for six colony complexes of common murres in central California,

1979–1995. ................................................................................................................................................................42

2.4 Trends in whole-colony counts for common murres in central California, 1979–1995 ..............................42

2.5 Changes in whole-colony counts of common murres at selected colonies in northern California,

1979–1995 .................................................................................................................................................................46

2.6 Changes in whole-colony counts of common murres in northern California, 1979–1989, excluding

the Castle Rock colony ............................................................................................................................................47

2.7 Distribution of common murre colonies in Oregon (Clatsop to Curry Counties) .........................................49

2.8 Changes in whole-colony counts for 15 sample colonies of common murres in Oregon, 1988–1995 .....53

2.9 Distribution of common murre colonies in Washington (Clallam to Pacific Counties) ..............................55

2.10 Trends in whole-colony counts for common murres in Washington, 1979–1995, excluding Tatoosh

colonies.......................................................................................................................................................................57

2.11 Trends in whole-colony counts for four colony complexes of common murres in Washington,

1979–1995 .................................................................................................................................................................58

2.12 Trends in whole-colony counts for common murres in southern Washington, 1979–1995 .......................59

2.13 Changes in whole-colony counts for common murres in northern Washington, 1979–1995 ....................61

2.14 Distribution of common murre colonies in northern British Columbia and the southern edge of

Alaska ..........................................................................................................................................................................62

2.15 Distribution of common murre colonies in southern British Columbia .........................................................62

2.16 Changes in whole-colony counts of common murres at breeding colonies in central California (all

colonies), northern California (excluding the Castle Rock colony), Oregon (15 sample colonies),

and Washington (excluding Tatoosh colonies), 1979–1995 ............................................................................68
vii

EXECUTIVE SUMMARY

Over the past 30 years, the common murre (Uria aalge californica) has been recognized as a prominent indicator

of marine conservation issues in California, Oregon, Washington, and British Columbia, especially regarding oil

pollution, certain fisheries, and human disturbance. To assist the effective management of the common murre and

the marine environments in which they live, this summary of available information on the biology and regional

status of the common murre has been sponsored by the U.S. Fish and Wildlife Service (Division of Migratory Bird

Management). In Volume 1 (Chapter 1), the natural history of the common murre is summarized, drawing heavily

on breeding studies from the South Farallon Islands, California, plus a host of detailed breeding studies from the

North Atlantic Ocean. Population trends of the common murre are summarized in Volume 1 (Chapter 2), focusing

on changes in whole-colony counts determined from aerial photographs between the late 1970s and 1995 in

California, Oregon and Washington. Historical data and human impacts to murre colonies since the early nineteenth

century are also summarized. Volume 2 will summarize population threats, conservation, and management.

Information presented in Volume 1 has been obtained and recorded by a large number of researchers and natural

historians over two centuries. From the 1960s to 1995, most work in California, Oregon, and Washington was

sponsored by the U.S. Fish and Wildlife Service, Minerals Management Service, and California Department of

Fish and Game. Important breeding biology studies were conducted at the South Farallon Islands (Farallon

National Wildlife Refuge) by the Point Reyes Bird Observatory, in coordination with the U.S. Fish and Wildlife

Service (San Francisco Bay National Wildlife Refuge). Colony surveys in California were conducted mainly by

the U.S. Fish and Wildlife Service (San Francisco Bay National Wildlife Refuge), U.S. Geological Survey (Western

Ecological Research Center, Dixon Field Station), Humboldt State University, and University of California (Santa

Cruz). Colony surveys in Oregon and Washington were conducted mainly by the U.S. Fish and Wildlife Service

(Oregon Coast National Wildlife Refuge and Washington Maritime National Wildlife Refuges). In British Columbia,

most work from the 1960s to 1995 was sponsored and conducted by the Canadian Wildlife Service and Royal

British Columbia Museum.

Key words: Alcidae, British Columbia, California, common murre, conservation, natural history, Oregon,

populations, seabird, trends, Uria aaige, Washington
ix

Project Sponsor:

U.S. Fish and Wildlife Service

Brad J. Bortner and Tara S. Zimmerman

 Division of Migratory Bird Management

Portland, Oregon

Editorial Assistance:

U.S. Geological Survey

Dennis L. Orthmeyer

Western Ecological Research Center

Dixon Field Station

Dixon, California

Jerry D. Cox

Upper Midwest Environmental Sciences Center

Onalaska, Wisconsin

Publication Costs:

U.S. Fish and Wildlife Service

 Division of Migratory Bird Management

U.S. Geological Survey

Western Ecological Research Center

Apex Houston Trustee Council

California Department of Fish and Game, Office of Spill Prevention and Response

U.S. Fish and Wildlife Service, Ecological Services, Sacramento, California

National Oceanic and Atmospheric Administration

Gulf of the Farallones National Marine Sanctuary
Chapter 1

Natural History of the Common Murre

 (Uria aalge californica)

by

David A. Manuwal1 and Harry R. Carter2

1University of Washington, College of Forest Resources

Wildlife Science Group

Seattle, Washington 98195

2Humboldt State University, Department of Wildlife

Arcata, California 95521

Suggested citation:

Manuwal, D. A., and H. R. Carter. 2001. Natural history of the common murre (Uria aalge californica). Pages 1–32 in D. A.

Manuwal, H. R. Carter, T. S. Zimmerman, and D. L. Orthmeyer, editors. Biology and conservation of the common murre in

California, Oregon, Washington, and British Columbia. Volume 1: Natural history and population trends. U.S. Geological Survey,

Biological Resources Division, Information and Technology Report USGS/BRD/ITR2000-0012, Washington, D.C.

Abstract: This natural history of the common murre (Uria aalge californica) in California, Oregon, Washington,

and British Columbia was summarized from published and unpublished information. This information was

augmented with results from studies conducted in the North Atlantic and Alaska. Substantial information on

breeding biology was obtained at the South Farallon Islands in central California, and additional studies at

Tatoosh Island, Washington, and Triangle Island, British Columbia. Little demographic information was

available from banded populations, except at the South Farallon Islands. At-sea distribution and diet have

been studied widely in California, Oregon, Washington, and British Columbia, but data were available for

only a few years in many locations.

Common murres breed in dense colonies on the surface of rocky islands or on cliff ledges. Breeding sites

are inaccessible to predatory land mammals and have low levels of human disturbance. Murres lay a single,

large, pointed egg on the ground, and can lay a replacement egg if the first egg fails to hatch. The egg is

incubated by both parents for 32–33 days. The chick is attended (brooded for the first few days) and fed by

both parents for its first 23–24 days before it jumps into the ocean accompanied by the male parent. The

parent–chick pair swims away from the colony and the chick is further raised at sea for 1–2 months by the

male. At-sea chick rearing overlaps with the flightless, prebasic molt for male parents, but not for female

parents or subadults.

Egg laying occurs earliest (late April to early June) in California and Oregon, and later (late May to midAugust) in Washington and British Columbia. Colony attendance patterns during the prebreeding period, and

early or late portions of the breeding period, tend to be more variable than between peak egg laying and peak

fledging. In California, murres sporadically attend colonies in winter, and also attend colonies earlier in the

prebreeding period than in Oregon, Washington, and British Columbia. Murres typically return to attend natal

colonies and breed in the same locations each year. Subadult murres visit natal colonies for several years
2 USGS/BRD/ITR–2000-0012

before breeding for the first time at about 4–9 years of age. Annual survival rates range from 87 to 94% for

adults and from 17 to 41% for juveniles.

Mean hatching and fledging success of first clutches at the South Farallon Islands are about 85 and 95%,

respectively. Overall breeding success at this colony averages about 0.8 chicks fledged per pair (i.e., chicks

that depart from the colony per breeding site). Additional chick mortality (not well quantified) occurs after

colony departure and before chicks are independent of parental care and can fly. Harassment and predation by

bald eagles (Haliaeetus leucocephalus) and peregrine falcons (Falco peregrinus) and human disturbance

have reduced breeding success at some colonies.

Murres are abundant at sea near major breeding colonies along the coast of central and northern California

and Oregon during the breeding season, with smaller numbers (but still common) off the coast of Washington

and the western and northern coasts of Vancouver Island, British Columbia. In winter, murres are most

abundant in northern Washington and southern British Columbia, as well as off the coasts of central and

northern California. Murres are uncommon in southern California and northern British Columbia during the

breeding season, but are more common during winter. After departing the colony, large numbers of murres

(including parent–chick pairs, females, and subadults) move northward from Oregon and Washington colonies

to complete at-sea chick rearing and prebasic molt, and winter in Juan de Fuca Strait, Strait of Georgia, Puget

Sound, and along the west coast of Vancouver Island. Murres from British Columbia colonies also may

winter in these areas. Murres return to breeding colonies in Oregon, Washington, and British Columbia in late

winter and early spring. In California, murres are largely resident year-round near breeding colonies, but some

birds disperse to southern California in winter. Insufficient evidence is available to determine whether murres

from Alaskan colonies winter in the area from southern British Columbia to California, although some

Alaskan murres (especially from the Forrester Island colony) are present in northern British Columbia in

summer and winter.

Murres feed in various marine habitats on the continental shelf, from estuarine areas near shore to

offshore areas. Prey varies with season and location, with fish predominating during breeding, and more

euphausiids and squid during winter and prebreeding periods. Common prey species include northern

anchovy (Engraulis mordax), rockfish (Sebastes spp.), Pacific sand lance (Ammodytes hexapterus), Pacific

herring (Clupea harengus), Pacific whiting (Merluccius productus), market squid (Loligo opalescens), and

euphausiids (e.g., Euphausia pacifica, Thysanoessa spinifera).

Key words: Alcidae, at-sea chick rearing, at-sea distribution, breeding, British Columbia, California, colony

formation, common murre, demography, diet, Farallon Islands, foraging, movements, natural history,

nonbreeding, Oregon, predators, seabird, Uria aalge, Washington

The common murre (Uria aalge) is a large, diving

seabird of the family Alcidae that breeds and feeds

widely along the coasts of the northern Pacific and

northern Atlantic Oceans (Figure 1.1). On the Pacific

coast of North America, two subspecies currently are

recognized that breed widely from northwestern Alaska

to central California (American Ornithologists’ Union

1983). Some morphological differences have been noted

between the two Pacific and five Atlantic subspecies,

but much overlap in measurements occurs, museum

specimens examined may be biased, and most

subspecies primarily represent major world populations

of murres in different geographic areas (Salomonsen

1944; Storer 1952; Bédard 1985; Gaston and Jones

1998). In the Pacific Ocean, population sizes of the

northern subspecies (U. a. inornata) in Alaska and

northeastern Asia are much larger than those of the

southern subspecies (U. a. californica) that ranges from

British Columbia to California (Figure 1.2; Byrd et al.

1993). In the nineteenth and early twentieth centuries,

the southern subspecies was often referred to as the

“California murre,” either because it was then considered

to be a separate species (U. californica) or the subspecies

U. a. californica was thought to be restricted to the type

locality at the Farallon Islands, California (Sharpe 1897;

Coues 1903; Salomonsen 1944). Bent (1919) lumped

both Pacific subspecies under Uria troille californica

and referred to them as “California Murres”.

Storer (1952) assigned all breeding murres in

California, Oregon and Washington to U. a. californica

and remarked further that the “breeding birds of Oregon

and British Columbia are both intermediate between U.

a. californica and U. a. inornata, and the amount of

overlap in size between populations is too great to permit

subspecific identification of birds of the mixed

wintering population. Consequently, all wintering birds

taken in British Columbia have been arbitrarily listed

under U. a. inornata.” Several other sources have
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 3

Figure 1.1. Common murre (Uria aalge californica) in breeding plumage

at the South Farallon Islands, California (U.S. Fish and Wildlife Service,

Farallon National Wildlife Refuge).

Figure 1.2. Distribution of the common murre on the Pacific coast of

the continental United States and Canada. Small numbers extend

south into northern Baja California, Mexico.

assigned British Columbia murres to U. a. inornata, but

without additional substantiation (Guiguet 1950, 1972;

Jewett et al. 1953; Gabrielson and Lincoln 1959; Drent

and Guiguet 1961; Tuck 1961; Campbell et al. 1990;

Morgan et al. 1991). Given poor evidence of the

presence of U. a. inornata in British Columbia and little

geographic separation of British Columbia and

Washington colonies, we considered British Columbia

breeding murres to belong to the subspecies U. a.

californica. Small numbers of murres also breed in

southeast Alaska (Sowls et al. 1978). Geographic gaps

are present north of southeast Alaska and between

Forrester Island and British Columbia colonies; thus,

we considered that breeding murres in southeast Alaska

might belong to either subspecies.

In this chapter, we summarize the natural history of

the common murre (U. a. californica) in California,

Oregon, Washington, and British Columbia. Our goal is

to provide a general summary of natural history for this

species, with emphasis on basic aspects of murre biology

in this geographic area. Several detailed summaries of

murre biology are available or in progress (e.g., Tuck

1961; Nettleship and Birkhead 1985; Gaston and Jones

1998; Ainley et al., in preparation). However, these

excellent summaries focused on available published

research that, for the most part, has been more extensive

in the North Atlantic and Alaska and focused on certain

well-studied aspects of natural history. Our intent is to

provide (1) a general summary of published research

with reference to representative studies, (2) information

on aspects of natural history that have not been well

studied, and (3) a collation of scattered unpublished

information on natural history from this geographic area.

We hope this approach will provide a general

background on the natural history of the common murre

and generate additional research in California, Oregon,

Washington, and British Columbia.

Methods

We collated information about the natural

history of the common murre from published and

unpublished sources with emphasis on information from

California, Oregon, Washington, and British Columbia.

In this part of the range of the common murre, extensive

study of the breeding biology and demography has been

conducted only at the South Farallon Islands, California,
4 USGS/BRD/ITR–2000-0012

where the Point Reyes Bird Observatory and U.S. Fish

and Wildlife Service (USFWS) have operated a longterm seabird research and monitoring program since

1972 (e.g., Ainley and Boekelheide 1990; Boekelheide

et al. 1990; Sydeman 1993). Studies of breeding

colonies of murres also have been conducted at Tatoosh

Island, Washington, by the University of Washington

during the 1990s (e.g., Parrish 1995; Parrish and Paine

1996); and Triangle Island, British Columbia, by the

Canadian Wildlife Service and Simon Fraser University

during some years since the 1970s (e.g., Rodway 1990).

In addition, the USFWS, Humboldt State University,

and National Audubon Society initiated studies in 1996

in central California at three colony complexes—Point

Reyes, Devil’s Slide, and Castle–Hurricane (Parker et

al. 1997, 1998, 1999). Many important studies of the

breeding biology of the common murre have been

conducted in northern Europe, eastern Canada, and

Alaska (see summaries in Nettleship and Birkhead 1985;

Murphy and Schauer 1994; Gaston and Jones 1998;

Ainley et al., in preparation). Where necessary, we rely

on studies from other parts of the range of the common

murre to describe known breeding biology and

demography.

During the 1970s and 1980s, several Federal

agencies (especially Minerals Management Service,

National Oceanic and Atmospheric Administration, and

the Environmental Protection Agency) sponsored major

at-sea survey programs conducted by the University of

California, University of Washington, and Ecological

Consulting Incorporated to describe the overall

abundance and distribution of seabirds in California,

Oregon, and Washington in marine habitats (e.g., Wahl

et al. 1981; Briggs et al. 1987, 1992). In British

Columbia, at-sea surveys have been conducted in many

parts of the province in the 1970s and 1980s, mainly by

the Canadian Wildlife Service (e.g., Vermeer et al. 1983;

Morgan et al. 1991). We have relied extensively on

these major sources to describe at-sea distribution and

movements. To describe foraging ecology, diet, and other

aspects of the at-sea biology of the common murre, we

collated information from available studies in this

geographic area and elsewhere in the world.

Overview of the Biology of the

Common Murre

Alcids exhibit a suite of morphological, behavioral,

and life-history traits characterized by wing-propelled

diving, high adult survivorship, delayed maturity, and

a low clutch size of one egg (except for two eggs in the

genera Cepphus and Synthliboramphus). Wingpropelled diving likely evolved in alcids for efficient

exploitation of subsurface marine fish and invertebrates,

which are often abundant during the breeding season,

may be sparse during other times of the year, and can

show a high degree of annual variation. Alcids probably

originated in the North Pacific Ocean (Udvardy 1963;

Bédard 1969, 1985) and radiated extensively, although

there are only 23 extant species within 5 tribes (after

Strauch 1985): (1) Alcini (genera Uria, Alca, and Alle),

(2) Cepphini (genera Cepphus and Synthliboramphus),

(3) Brachyramphini (genus Brachyramphus), (4)

Aethiini (genera Aethia and Ptychoramphus), and (5)

Fraterulini (genera Fratercula and Cerorhinca). Alcids

have been ecologically successful and form a dominant

component of breeding seabird communities in

subarctic and arctic waters in the North Pacific and North

Atlantic Oceans. The common murre and the thick-billed

murre (Uria lomvia) are among the most abundant alcids

that breed and winter throughout most of these northern

waters.

Alcids have strong bills for capturing, carrying, and

holding prey, small wings as a compromise adaptation

for diving and flying, and specialized breeding plumage

(exhibited in most species). Similar to most alcids, murres

exhibit a common “black above and white below” body

plumage of pursuit-diving seabirds with a striking

blackish-brown head plumage during the breeding

season (Figure 1.1). This body plumage type may have

evolved to reduce conspicuousness to potential prey

when feeding in midwater, although the dark back also

may assist thermal regulation along with large body

size for surface breeding or retard feather wear from solar

radiation (Ashmole 1971; Birkhead and Harris 1985;

Cairns 1986). Unlike most alcids but like other species

in the genera Uria, Cepphus, and Brachyramphus,

common murres carry single prey items to their chicks

and have a long bill with large palatal denticles for

capturing, holding, and carrying fish (Bédard 1969).

Although common murres share many similarities with

other alcids, they also have evolved several different

adaptations, largely related to feeding, which have

produced a unique life history pattern. Three main

adaptations are large body size, intermediate pattern of

post-hatching development, and surface breeding in

dense colonies. Common murres are the largest (800–

1300 g) of the extant alcids (Nettleship 1996). The

extinct Great Auk (Pinguinus impennis) and other

extinct alcids were larger but flightless. Large body size

allows murres to exploit deeper water (for fish and

invertebrate prey) than most other alcids. They have

been recorded to dive as deep as 180 m (Piatt and

Nettleship 1985). Chicks are raised partly at the colony

and partly at sea, a pattern intermediate between most

other alcids (Sealy 1973; Gaston 1985; Nettleship 1996;

Gaston and Jones 1998). In contrast, “precocial” alcids
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 5

Figure 1.3. Breeding colony of common murres in the Upper Shubrick

Point study plot at the South Farallon Islands, California, May 1995

(Photo by M. W. Parker).

Figure 1.4. Breeding colony of common murres at Puffin Rock near

Triangle Island, British Columbia, 16 July 1985 (Photo by M. S. Rodway).

(e.g., Ancient Murrelet Synthliboramphus antiquus)

raise their chicks almost entirely at sea, and “semiprecocial” alcids (e.g., Cassin’s Auklet Ptychoramphus

aleuticus) raise their chicks entirely at protected

breeding sites. Common murres often breed “shoulderto-shoulder” in large, dense colonies on the flat or

sloping surface of the ground (Figure 1.3) or on cliff

ledges (Figure 1.4). Most other alcids breed in large or

small colonies where individual breeding sites are

present on cliff ledges, in rock crevices or other cavities,

or in excavated burrows.

Reproductive Ecology

Breeding Habitat

The common murre breeds on the surface of the

ground in colonies on flat, sloping, or cliff habitats on

islands, or occasionally on the mainland, where breeding

sites are inaccessible to mammalian predators and have

low levels of human disturbance. Flat or gently sloping

habitats are used only where mammalian predation is

rare. For example, such habitats on small rock islands

are used extensively for breeding in California, Oregon,

and parts of Washington (Figure 1.3; Boekelheide et al.

1990; Takekawa et al. 1990; Carter et al. 2001).

Mammalian predation or human disturbance often limit

breeding to cliff habitats in certain areas. For example,

in Alaska, where foxes have been introduced to islands

or are present naturally, cliff breeding predominates

(Bailey 1993). Cliff-face and cliff-top breeding occurs

widely and is well known at Tatoosh Island, Washington,

and Triangle Island, British Columbia (Figure 1.4;

Guiguet 1950; Campbell et al. 1990; Parrish 1995;

Carter et al. 2001). In some years, cliff-top subcolonies

at Tatoosh Island were subject to greater egg predation

by glaucous-winged gulls (Larus glaucescens) and

northwestern crows (Corvus caurinus) and greater

harassment by bald eagles (Haliaeetus leucocephalus)

and peregrine falcons (Falco peregrinus) than cliff-face

subcolonies (Parrish 1995, 1996).

In California, Oregon, Washington, and British

Columbia, breeding habitat is very stable and does not

change substantially between years. However, erosion

of breeding habitats has been noted at certain colonies.

At the Double Point Rocks colony in central California,

a small natural arch used by small numbers of breeding

murres fell into the ocean between 1982 and 1985

(Takekawa et al. 1990). At the long-inactive Sea Lion

Rock colony in northern California, breeding by murres

has not been reported since the southern half of the rock

fell into the water sometime before the 1950s (Osborne

1972). Human degradation of breeding habitats has

occurred at several colonies of U. a. californica,

especially at the South Farallon Islands, Whaler Island,

Rockport Rocks, and Tillamook Rock (Carter et al.

2001).

Seasonal and Daily Colony Attendance Patterns

The annual cycle of colony attendance is divided

into three distinct periods, the breeding season, the atsea chick-rearing period, and the nonbreeding or winter
6 USGS/BRD/ITR–2000-0012

season. Like many other seabirds, murres live entirely

at sea, except for breeding-related activities at the

colony, which include breeding-site prospecting and

defense; courtship, pairing, and copulation; egg laying

and incubation; and chick rearing.

During the breeding season, breeding adults (i.e.,

after reaching sexual maturity and breeding for the first

time) obtain a mate and breeding site, lay and incubate

eggs, and brood and feed chicks at the colony. However,

during severe El Niño–Southern Oscillation (hereafter

“El Niño”) conditions, or in response to other factors

(e.g., human disturbance or severe disruption by

predators), many or all murres may abandon colonies

before or after egg laying.

During incubation, steady numbers of birds attend

breeding sites although some daily variation occurs

(Boekelheide et al. 1990; Takekawa et al. 1990). At

Triangle Island, British Columbia, murre numbers

peaked in early evening with another lower peak in the

early morning during the incubation period (Rodway

1990). Lowest numbers occurred around mid-day (1300–

1600 h PDT). The number of murres attending colonies

may decline after the median hatching date if parents

spend more time away from the colony foraging for

chicks. Numbers attending colonies drop sharply as

chicks leave the colony (Boekelheide et al. 1990). This

general pattern of attendance during the breeding

season also has been observed at eastern Canadian and

Alaskan colonies (Tuck 1961; Piatt and McLagan 1987;

Hatch and Hatch 1989).

At some colonies, nonbreeding subadult murres (2–

6 years old) congregate on land in “clubs” adjacent to

breeding areas (Birkhead and Hudson 1977). Attendance

patterns vary more at clubs than breeding areas, both

within and between years, and clubs may not be present

at certain colonies. Virtually nothing is known about

colony attendance patterns of nonbreeding murres (i.e.,

subadults and nonbreeding adults) along the west coast

of the United States and British Columbia.

At the end of the colony chick-rearing period,

successful breeding males and their partly-grown chicks

depart the colony. During the at-sea chick-rearing period,

chicks are fed at sea until independence. Other adults

(i.e., females, failed breeders, and subadults) also cease

colony attendance once male-chick pairs have departed.

However, female adults may linger at breeding sites for

some time, probably to defend the breeding site against

prospecting birds if present (Birkhead and Nettleship

1987a). Adults and subadults undergo a flightless,

prebasic molt at sea within 1–2 months of leaving the

colony and develop a “mottled” or white head plumage

(Birkhead and Taylor 1977). Younger subadults molt

earlier than older birds in captivity and the wild

(Swennen 1977; H. R. Carter and S. G. Sealy, unpublished

data). No colony attendance occurs during the at-sea

chick rearing period, although sporadic attendance of

breeding sites by birds that are not feeding chicks can

occur at the South Farallon Islands for a short period

after the colony has been largely evacuated.

In the nonbreeding season, adults and possibly

subadults may resume colony attendance and perform

breeding-related behaviors such as site or pair-bond

maintenance, or prospecting (Harris and Wanless 1988,

1989, 1990a,b). The degree of colony attendance in the

nonbreeding season varies between geographic areas.

No attendance occurs when murres move to wintering

areas that are disjunct from colonies. A partial

prealternate molt occurs in late fall and winter when

adults and subadults redevelop black head plumage,

although molt in adults and older subadults precedes

younger subadults (Swennen 1977). Almost all murres

attending the South Farallon Islands in December–

March have black heads but a few have mottled heads

(Smail et al. 1972). Thus, few or no younger subadults

visit the colony during winter and stay at sea.

In winter, California colonies are visited

periodically by varying numbers of birds, starting as

early as October and extending through the winter

(Ainley 1976; Sowls et al. 1980; DeGange and Sowls

1981; Boekelheide et al. 1990; Parker et al. 1997, 1998;

Hastings et al. 1998; Carter et al. 2001). At the South

Farallon Islands, much variation in winter attendance

occurs between years because of local prey availability,

weather conditions, and behavioral factors related to

breeding-site attendance (Boekelheide et al. 1990; H.

R. Carter, unpublished data). Fairly regular attendance

begins as early as February but murres do not stay

overnight at breeding sites until April, shortly before

egg laying. In Oregon, murres sometimes attend

colonies as early as mid-December (Bayer and Ferris

1988), but regular attendance does not occur until

March–April. No information is available about winter

colony attendance in Washington and British Columbia

where it may not occur regularly. Murres started

attending the Tatoosh Island colony area in March–

April (Parrish 1995).

In winter, murres often raft in waters around the

South Farallon Islands before landing on the colony

and, at times, rafting occurs without subsequent

landings. Similar behavior also has been noted at

nearshore colonies in central California (M. W. Parker,

unpublished data). In spring, murres often raft in

association with frequent landings on and evacuations
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 7

of the colony, prior to developing regular attendance

during the pre-egg stage (Parrish 1995).

Daily attendance patterns vary depending on the

year, time of year, weather, stage of the reproductive

cycle, and location of breeding colony. Variation mainly

reflects the amount of time spent on the colony for

breeding-related purposes versus time spent at sea. In

Newfoundland, incubation shifts of common murres

averaged 17 h, whereas daytime brooding shifts

averaged 4 h and overnight brooding shifts averaged

12 h (Verspoor et al. 1987). Incubation and brooding

shift durations did not differ between males and females,

females incubated more at night than males, breeding

pairs did not change over at night, and breeding pairs

did not change over at the same time each day. However,

shifts during chick rearing and feeding rates varied

between years in response to differences in food

availability (Birkhead and Nettleship 1987c; Verspoor

et al. 1987). On the South Farallon Islands during 1971–

72, attendance was consistently higher in the morning

than midday throughout winter and spring prior to

breeding and peaked again in the evening (Boekelheide

et al. 1990), although some sites were occupied all day.

In winter, murres were usually absent on days with high

winds or heavy rain, which is a pattern also observed in

the United Kingdom (Birkhead 1978a). Attendance by

thick-billed murres in arctic Canada appears linked to

barometric pressure but high winds are associated with

the approach of low pressure systems (Gaston and

Nettleship 1981). Murres rarely visited colony sites on

the South Farallon Islands on days with large swells,

which were often associated with the passage of storm

systems when air pressure changed radically

(Boekelheide et al. 1990).

Timing of Breeding

In California, the breeding season generally occurs

between late April and early August when prey are

abundant in the California Current upwelling system

(Briggs et al. 1988; Ainley et al. 1990; Boekelheide et

al. 1990; Tyler et al. 1993). On the South Farallon

Islands, first egg dates for 1972–83 were 26 April–23

May with mean dates for first eggs 9 May–9 June

(Boekelheide et al. 1990). The timing of breeding in

Oregon is similar to that in California with egg laying

starting in early to mid-May and peaking in late May to

early June (Scott 1973; R. W. Lowe, unpublished data).

Breeding occurs somewhat later in Washington and

British Columbia with egg laying occurring from late

May to mid-August, reaching a peak in early July

(Jewett et al. 1953; Vallee and Carter 1987; Campbell

et al. 1990; Rodway 1990; Parrish 1995). The later

breeding phenology in Washington and British

Columbia may be partly related to a later availability of

abundant prey resources than farther south in the

California Current upwelling system (Tyler et al. 1993;

Wahl et al. 1993; Murphy and Schauer 1994).

Colony departure begins in late June or early July

in most years at the South Farallon Islands, but did not

occur until late July in 1983 during severe El Niño

conditions (Boekelheide et al. 1990; Takekawa et al.

1990). Peak departure typically occurs in early to midJuly. Colony departure begins in late June and continues

during July in Oregon (Bayer et al. 1991). At Yaquina

Head, Oregon, peak fledging occurred in late July from

1969 to 1971 (Scott 1973). At Tatoosh Island,

Washington, colony departure occurred from late July

to early September 1991 (Parrish 1995). At Triangle

Island, British Columbia, colony departure begins in

mid-August and peaks in late August to early September

(Vallee and Carter 1987; Rodway 1990).

Egg Laying

The breeding site typically is located in a

depression or crack in rock, guano, or soil, and can be

bordered by adjacent rocks (Figure 1.3). On occasion,

birds breed in small caves, under boulders, or under

ledges. The common murre has a large single medial

brood patch and incubates the single egg on the bare

substrate or, at times, between and on top of its feet. No

nest is built, although small stones, feathers, or other

materials can be present at breeding sites. The large egg

(about 108 g or about 11% adult weight; Mahoney and

Threlfall 1981; Nettleship 1996; Gaston and Jones

1998) is often brightly colored (blue or green; at times

white), marked with variable amounts of dark streaks or

blotches, and has a strongly-pointed (“pyriform”) shape.

The pointed shape of murre eggs is often cited as an

apparent adaptation for breeding on narrow rock cliff

ledges by reducing egg loss from accidental

displacement. These eggs roll in a tight circle compared

with more ovate egg shapes, especially during the late

incubation period when the embryo is partly developed

(Tschanz et al. 1969). Even so, many murre eggs roll

away from breeding sites, sometimes accounting for most

breeding failures (Tuck 1961). Other research suggests

that breeding-site characteristics and incubating

behavior also are important adaptations preventing egg

loss (Ingold 1980; Harris and Birkhead 1985; Birkhead

and Nettleship 1987b).

A replacement egg will be laid by some females, if

the first egg is lost. Replacement eggs are about 5–10%

lighter than first eggs (Mahoney and Threlfall 1981;

Gaston and Jones 1998). Replacement eggs were laid

by 32% of Farallon murres that lost first eggs
8 USGS/BRD/ITR–2000-0012

(Boekelheide et al. 1990). Replacement rates of 52%

and 40% have been reported in the United Kingdom

and Alaska, respectively (Birkhead and Hudson 1977;

Byrd et al. 1993; Murphy 1995). Eggs laid and lost

early in the season are more likely to be replaced than

those laid later (Uspenski 1958; Tuck 1961; Gaston

and Nettleship 1981; Harris and Birkhead 1985;

Boekelheide et al. 1990). The interval between loss and

replacement is 14–15 days (range, 13–23 days;

Boekelheide et al. 1990; Murphy 1995). On the South

Farallon Islands, more than 50% of replacement eggs

were laid in only 3 years (i.e., 1973, 1977, and 1981)

between 1972 and 1983 (Boekelheide et al. 1990; Table

1.1). In the latter 2 years, high loss of first eggs occurred

early in the season and favorable conditions for relaying

extended late into the season.

Incubation and Hatching

Both members of a breeding pair incubate the egg.

Incubating birds typically face inwards toward the face

of vertical cliffs, upslope, or rock walls (Figure 1.3),

which allows for effective incubation conditions on

small breeding sites on narrow ledges or within larger

groups of densely-breeding birds on flat surfaces. In

addition, incubating and brooding postures reduce

jostling between neighboring birds and limit access by

avian predators of murre eggs and chicks (e.g., gulls

and corvids). Adults will retrieve eggs that roll a short

distance away from breeding sites and birds occasionally

incubate an egg which is not their own (Tschanz 1959).

The incubation period shows little annual variation in

Newfoundland (Verspoor et al. 1987), but the incubation

period was shorter for later eggs in Alaska (Murphy

1995). From 1973 through 1983, murre incubation

periods at the South Farallon Islands averaged 32–33

days but ranged from 26 to 39 days (Boekelheide et al.

1990). Similar incubation periods were found for

common murres in Alaska (Murphy 1995) and for thickbilled murres in arctic Canada (Gaston and Nettleship

1981). Based on chromosome analyses, a female to male

ratio of 25:17 was found for chicks at about day 20 but

this ratio did not differ significantly from equality (Parker

et al. 1991).

Chick Rearing and Colony Departure

 Common murre chicks are constantly attended by

at least one parent at the breeding site. During the first

few days after hatching, the chick must be brooded

constantly by an adult until it is able to thermoregulate.

Murre chicks, on rare occasions, are brooded and fed by

a nonparent adult or “helper,” often a failed breeder

from a neighboring site whose relationship to the chick

and parents is unknown (Tschanz 1968, 1979; Birkhead

1977a; Birkhead and Nettleship 1984; Wanless and

Harris 1985). Tuck (1961) noted that the greatest source

of chick mortality was exposure during the first 6 days

of life. Murre chicks develop a specialized plumage

and onset of thermoregulation occurs by 10 days

(Johnson and West 1975). Older chicks are not brooded

constantly but attending adults protect the chick from

Table 1.1. Reproductive success of first and replacement clutches of the common murre on the South Farallon Islands, California, 1972–1983

(from Boekelheide et al. 1990; see Figure 1.5).a

First eggs Replacement eggs

HS Lost Addled FS HS Lost Addled FS Breeding success

Year n (%) (%) (%) (%) n (%) (%) (%) (%) (mean + SD)

1972 116 80 17 3 97 1 0 100 0 0 0.8 + 0.4

1973 135 82 18 0 93 9 67 33 0 50 0.8 + 0.4

1974 173 88 9 3 97 3 100 0 0 100 0.9 + 0.3

1975 137 93 4 3 98 1 100 0 0 100 0.9 + 0.3

1976 163 90 9 2 94 3 33 66 0 0 0.8 + 0.4

1977 123 80 15 4 96 11 64 27 9 57 0.8 + 0.4

1978 123 81 15 4 85 2 50 50 0 100 0.7 + 0.5

1979 135 83 8 9 100 5 60 20 20 66 0.8 + 0.4

1980 144 88 9 3 98 5 60 40 0 100 0.9 + 0.3

1981 146 89 8 3 94 9 100 0 0 78 0.9 + 0.3

1982 70 91 7 1 95 2 100 0 0 100 0.9 + 0.3

1983 41 32 63 5 15 3 0 100 0 0 0.1 + 0.2

Totalb 1,506 85 12.2 3.2 95 54 67 30 4 72 0.8 + 0.4

aCodes: HS, hatching success (percent of eggs laid that hatch); Lost (i.e., disappeared before hatch); Addled (i.e., eggs that fail to

hatch although incubated for at least 32 days); FS, fledging success (i.e., percent of chicks hatched that depart from the colony);

Breeding success (i.e., number of fledglings per breeding site).

bMean percent values for 1972–82 (n = 11 years) excluded data in 1983 during severe El Niño conditions; however, total n values

included 1983 data (n = 12 years).
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 9

predators and facilitate chick feeding in dense colonies.

Protection from predators also is afforded by adjacent

birds in the colony that attack nearby potential predators

of murre eggs and chicks (Birkhead 1977a, 1978b).

Immediately after hatch, chicks grasp fish by the head

end and swallow fish head first, avoiding injury from

fish spines (Oberholzer and Tschanz 1968). In the late

incubation and early chick-rearing periods, parent–

chick vocal recognition and chick breeding-site

recognition become strongly developed which

facilitates brooding, feeding, and chick return to the

site if dislodged (Tschanz 1968; Wehrlin 1977).

On the South Farallon Islands, a murre chick spent

an average of 23–24 days at the breeding site before

departing from the colony with an adult (usually the

male) to complete its development at sea (see below;

Boekelheide et al. 1990). Chicks hatching later and

those at colonies at higher latitudes have shorter chickrearing periods (Boekelheide et al. 1990; Murphy 1995).

Reduction in the time spent at the colony before

departure (i.e., chick departure from the colony when

only partly grown) could have evolved in relation to

decreased prey availability around the colony as the

breeding season progresses, increased predation on laterhatched chicks, and reduced time remaining for the

parents to complete a prebasic molt before winter

(Birkhead and Harris 1985; Harris and Birkhead 1985;

Wanless and Harris 1988). Several other selective

pressures such as high wing loading, small prey loadcarrying capacity, chick provisioning rates of breeding

adults, chick growth rates on the colony and at sea, and

availability of prey resources far from the colony also

may have helped forge this life history pattern

(Stettenheim 1959; Sealy 1973; Gaston 1985; Ydenberg

1989; Gaston and Jones 1998).

Demography

Adult and Subadult Survival

The only long-term demographic study of the

common murre in the Pacific Ocean has been conducted

at the South Farallon Islands, California, where a banded

sample of murres has been studied since 1985 (Sydeman

1993). Murres from a large subcolony (n = 2,500

breeding pairs) had an annual survivorship of 94%,

whereas birds from a much smaller, new subcolony (n =

50 breeding pairs) survived at a rate of only 77% . This

difference was attributed to high predation by peregrine

falcons in winter at the latter subcolony. Annual survival

rates for males and females were 99% and 93%,

respectively (Sydeman 1993).

Studies on common murres in the Atlantic Ocean

provide demographic information that may be generally

applicable to Pacific Ocean murres, despite significant

differences in prey resources, hunting of murres in certain

areas of the Atlantic, and various conservation issues.

Band returns at or away from the colony have been used

to determine adult and subadult survival rates in Europe

(Birkhead 1974; Mead 1974; Hudson 1985; Hatchwell

and Birkhead 1991). Adult annual survival rates of

common murres ranged from 87 to 94% in five European

studies. Survival rates of juveniles from the time of

colony departure to breeding age varied from 17 to 41%

in 10 European studies, based mainly on band

recoveries. Many hatching-year juveniles die between

colony departure and during their first autumn

(Birkhead 1974; Stenzel et al. 1988; Bayer et al. 1991).

At the Isle of May, Scotland, survival of post-fledging

murres decreased with later hatching date in 2 of 6 years

studied (Harris et al. 1992). In this study, 12–47% of

chicks survived to at least six months of age, which

indicates that juvenile mortality also may be great in

mid- to late winter.

Proportion of Adults that Breed

Murres breed for the first time between the ages of

4–9, with most birds recruiting between ages 5 and 7

(Hudson 1985; Harris et al. 1994; Halley et al. 1995; W.

J. Sydeman, unpublished data). After reaching sexual

maturity, most murres lay eggs each year, unless unusual

circumstances occur. Harris and Wanless (1995a) found

that 5–10% of adult murres did not breed each year,

owing mainly to mate loss. Sydeman (1993) noted that

banded adults did not breed in 4.5% of years studied at

the South Farallon Islands. During severe El Niño events

in 1982–83 and 1992–93, a large proportion of breeding

adults likely did not attend colonies or attended colonies

without laying eggs in California, Oregon, and

Washington (Boekelheide et al. 1990; Carter et al. 2001).

Extensive colony disturbances by humans or predators

also might increase the proportion of adults that do not

breed, although some birds may delay breeding or move

to and breed at other colonies in response to such

problems (Parrish 1995; Carter et al. 2001).

Hatching Success

Mean “hatching success” (i.e., percentage of eggs

laid that hatch) for first eggs of Farallon murres from

1972 to 1983 was 85% (range, 80–93% in 1972–82),

but was much lower in 1983 (32%) because of severe El

Niño conditions (Table 1.1; Figure 1.5; Boekelheide et

al. 1990). Replacement eggs had lower hatching success,

averaging 67% (range, 0–100% in 1972–82). Of 249

eggs (including first and replacement eggs) that failed

in 1972–83, 58% disappeared, 20% did not hatch (after

39 days of incubation), 8% rolled away from the site,
10 USGS/BRD/ITR–2000-0012

6% were abandoned, 3% were broken, 2% were

depredated by western gulls (Larus occidentalis), 2%

were dislodged during fights or interference with other

murres or Brandt’s cormorants (Phalacrocorax

penicillatus), and 1% were wedged in rocks

(Boekelheide et al. 1990). Losses from eggs rolling away

from breeding sites were rarely observed at the study

plot, whereas predation by western gulls was noted

frequently (Spear 1993). In general, 12.2% of first eggs

(n = 1,506 eggs from 1972 to 1983) and 30% of

replacement eggs (n = 54 eggs from 1972 to 1983) were

lost during incubation (Boekelheide et al. 1990). About

3.2% of all eggs (n = 1,560 first and replacement eggs

from 1972 to 1983) failed to hatch despite being fully

incubated.

For 11 colonies in North Pacific Ocean, Byrd et al.

(1993) reported mean hatching success values per

colony. For first eggs, 11 colonies ranged between 34

and 81%. For replacement eggs, four colonies ranged

between 47 and 65%. For 12 colonies in the Pacific and

Atlantic Oceans, Murphy and Schauer (1994) also

reported mean hatching success values per colony. For

first eggs, 12 colonies ranged between 60 and 85%. For

replacement eggs, eight colonies ranged between 43

and 72% (Table 1.2). Reasons for egg loss vary between

colonies, owing to many different natural and

anthropogenic factors that affect breeding and feeding

(e.g., Harris and Wanless 1988).

A summary of reproductive and other

characteristics of the common murre is presented in

Table 1.3.

Fledging Success

Most chick deaths occur in the few days after

hatching when very small chicks can be dislodged or

roll away from breeding sites, especially if disturbed by

humans. After six days of age, murre chicks are better

able to avoid the detrimental effects of colony

disturbances and are increasingly more capable of

returning to natal sites if dislodged a short distance

(Tuck 1961). In Newfoundland, chicks reaching 13 days

of age had high survivorship until colony departure

(greater than 80%; Burger and Piatt 1990). At the South

Figure 1.5. Reproductive success for first eggs

of the common murre in the Upper Shubrick Point

study plot at the South Farallon Islands, California,

1972–1983 (adapted from Boekelheide et al. 1990;

see Table 1.1). Mean (± 2 standard errors) values

are presented.

Hatching Success

0%

20%

40%

60%

80%

100%

1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983

Percent

Fledging Success

0%

20%

40%

60%

80%

100%

1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983

Percent

Breeding Success

0.0

0.2

0.4

0.6

0.8

1.0

1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983

Number
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 11

Farallon Islands, high “fledging success” (i.e., percent of

hatched chicks that depart from the colony) occurred for

chicks hatched from first eggs between 1972 and 1982

(mean = 95%; 1972–82 range, 85–100%; Table 1.1;

Figure 1.5; Boekelheide et al. 1990). Chicks from

replacement eggs had lower fledging success (mean =

68%; 1972–82 range, 0–100%). Very low success in 1983

(15% for first eggs with no replacement eggs laid)

coincided with severe El Niño conditions and high gull

predation (Boekelheide et al. 1990; Spear 1993).

For 11 colonies in the North Pacific Ocean, Byrd et

al. (1993) reported mean fledging success values per

colony. For chicks hatched from first eggs, 11 colonies

ranged between 67 and 91%. For chicks hatched from

replacement eggs, four colonies ranged between 17 and

83%. For 12 colonies in the Pacific and Atlantic Oceans,

Murphy and Schauer (1994) also reported mean fledging

success values per colony (Table 1.2). For chicks hatched

from first eggs, 12 colonies ranged between 60 and 85%.

For chicks hatched from replacement eggs, eight colonies

ranged between 43 and 72%.

Little quantification of chicks lost during colony

departure has been attempted in available studies. Most

chick losses are from predation by gulls or other avian

species or injury from hitting rocks or ledges as the

chicks jump off cliffs or steep slopes when leaving the

colony (Tuck 1961). Most murre fledging occurs during

evening twilight, which reduces predation during

colony departure and the first few hours at sea.

When breeding on cliffs or steep slopes, fledging

chicks flutter down from a cliff to the water at a steep

angle. From low-lying or flat breeding habitats, chicks

walk to the water, at times accompanied for all or a

portion of the journey by an adult. At the water, they

are met by an adult, usually the male parent (Scott

1990). At Three Arch Rocks, Oregon, chicks are often

accompanied by an adult during their descent from

the rock and immediately dive on reaching the water

(R. W. Lowe, personal observation). Parent–chick

recognition occurs through intense vocalizing at this

time by parents and chicks. Failure to link up with the

male also may contribute to chick losses at this time.

Occasionally, chicks face aggression from nonparental

adults on the water (Fisher and Lockley 1954; Kenyon

1959; R. W. Lowe, personal observation). At the South

Farallon Islands, California sea lions (Zalophus

californianus) also may harass and prey on fledging

murre chicks on occasion (W. J. Sydeman, personal

Table 1.2. Reproductive success of the common murre in the Pacific and Atlantic Oceans (from Murphy and Schauer 1994).a

First Eggs Replacement eggs Breeding

Latitude ) Years success

Colony (

oN of data HS (%) FS (%) HS (%) FS (%) (%) Sourceb

NE Atlantic

Skomer Island 52 4 77 ± 7 88 ± 8 59 ± 13 59 ± 18 71 ± 9 1, 2, 3, 4

Isle of May 56 6 79 ± 2 94 ± 4 55 ± 8 77 ± 7 78 ± 4 5

Stora Karlsöc 57 4 72 71 45 67 80 6

NW Atlantic

Gannet Islands 54 3 85 ± 4 95 ± 0 43 ± 7 72 ± 5 83 ± 3 7

E Pacific

S. Farallon Islandsd 38 12 81 ± 16 89 ± 23 61 ± 36 63 ± 42 77 ± 24 8

N Pacific

Chowiet Island 56 3 69 ± 5 82 ± 6 47 ± 50 17 ± 29 58 ± 8 9

Agattu Island 52 2 76 ± 8 88 ± 10 nd nd 68 ± 16 10

St. George Islande 57 8 73 ± 10 78 ± 19 nd nd 57 ± 17 11

St. Paul Islande 57 9 73 ± 8 79 ± 10 nd nd 57 ± 8 12

Cape Piercee 59 3 60 ± 9 89 ± 5 nd nd 53 ± 6 13, 14

St. Lawrence Island 63 1 68 94 57 50 66 15

Bluff 65 5 65 ± 4 91 ± 3 72 ± 15 82 ± 6 68 ± 10 16

aValues reflect means and standard deviations. Codes: HS, hatching success (i.e., percent of eggs laid that hatch); FS, fledging

success (i.e., percent of chicks hatched that depart from the colony); breeding success (i.e., percent of chicks that depart from the

colony from sites where eggs were laid); nd, no data.

bSources: 1 (Birkhead 1976b); 2 (Birkhead 1980); 3 (Hatchwell 1988); 4 (Hatchwell and Birkhead 1991); 5 (Harris and Wanless

1988); 6 (Hedgren 1980); 7 (Birkhead and Nettleship 1987b); 8 (Boekelheide et al. 1990); 9 (Hatch and Hatch 1990); 10 (Byrd

et al. 1993); 11 (Dragoo and Sundseth 1993); 12 (Climo 1993); 13 (Haggblom and Mendenhall 1991); 14 (Haggblom and

Mendenhall 1993); 15 (Piatt et al. 1988); 16 (Murphy and Schauer 1994).

cAt Stora Karlsö, data were pooled between years.

dValues for the S. Farallon Islands included all 12 years of data from 1972 to 1983 (Boekelheide et al. 1990; see Table 1.1).

eAt St. George Island, St. Paul Island, and Cape Pierce, success was reported per site and thus included first and replacement eggs.
12 USGS/BRD/ITR–2000-0012

communication). Gull predation at some colonies can

be high during fledging. Often, however, the number of

deaths has been difficult to ascertain because of low

light levels.

Breeding Success

For 10 colonies in the North Pacific Ocean, Byrd et

al. (1993) reported mean breeding success values (i.e.,

percent of chicks that depart from the colony from sites

where eggs were laid or fledglings per breeding pair or

site), which ranged between 27 and 77%. For 12 colonies

in the Pacific and Atlantic Oceans, Murphy and Schauer

(1994) also reported mean breeding success values per

colony, which ranged between 53 and 83% (Table 1.2).

Breeding success did not appear to vary much with

latitude. At the South Farallon Islands, relatively high

average success has been found compared to other

locations. Murres averaged 0.8 chicks per site (or about

80%) from 1972 to 1982 (range, 0.7–0.9 chicks per site),

but much lower site success occurred in 1983 (0.1 chicks

per site) during severe El Niño conditions (Table 1.1;

Figure 1.5; Boekelheide et al. 1990).

Breeding success is affected by many natural and

anthropogenic factors, including prey resources within

foraging distances of colonies, predators, other breeding

seabirds at the colony, human disturbance, and

mortality. High breeding success of murres at the South

Farallon Islands in 1972–82 reflected adequate prey

resources and low impacts from natural predators, human

disturbance, and human-caused mortality at sea

(Boekelheide et al. 1990; Takekawa et al. 1990; Carter

et al. 2001). In contrast, heavy predation and disturbance

by eagles and falcons as well as other factors resulted in

lower breeding success at Tatoosh Island, Washington.

(Parrish 1995). Reduced breeding success during severe

El Niño events in 1982–83 and 1992–93 occurred

widely at murre colonies in California, Oregon,

Washington, and British Columbia (Boekelheide et al.

1990; Takekawa et al. 1990; Bayer et al. 1991; Wilson

1991; Carter et al. 2001). Severe El Niño events

apparently resulted in poor prey conditions, which

greatly impacted the proportion of adults that breed

and breeding conditions for adults that laid eggs.

Extensive colony disturbances by humans and

predators also has reduced breeding success at certain

Table 1.3. Summary of reproductive and other characteristics of the common murre in California, Oregon, Washington, and British Columbia.

Attribute Description

Breeding habitat Open slopes and cliffs on islands; cliffs on mainland; occasionally small caves

Colony attendance Regular attendance during breeding season; no attendance during at-sea chick rearing and

prebasic molt; regular but punctuated winter attendance in central and California, rare or not

known in Oregon, Washington, and British Columbia

Breeding site Depression or crack in surface of rock, guano, or soil

Clutch size 1

Brood patch type Single, medial

Replacement clutch Common

Second clutch No

Incubation period mean 32 days (range, 26–39; South Farallon Islands)

Hatching successa mean 86% (range, 80–93; South Farallon Islands)

Nestling period mean 23 days (range, 17–35; South Farallon Islands)

Fledging successarange 85–100% (South Farallon Islands)

Breeding successa mean 0.85 chicks per pair (range, 0.78–0.91; South Farallon Islands)

Colony departure Chick jumps off cliff, flutters, or walks to sea, accompanied by male parent

At-sea rearing period Probably 1–2 months; fed and accompanied by male parent; learns to dive and capture fish before

independence

Prebasic molt 1–2 months between July and November; overlaps breeding for males rearing chicks at sea;

complete; remiges lost rapidly causing flightlessness

Prealternate molt 1 month between December and March; partial; black head plumage attained; flight not affected

Adult diet Mostly fish, some invertebrates, and squid; variable by location, season, and year

Chick diet (at colony) Fish or squid 4–15 cm in length; variable species by location and year

Age at first breeding 4–9 years; mostly 5–7 years

Adult survivalb 94% (South Farallon Islands)

Movements Oregon–Washington populations winter in northern Washington and southern British Columbia;

central and northern California populations resident year-round in California; British Columbia

population probably winters in British Columbia, and possibly northern Washington.

a

 First egg data from 1972 to 1983, excluding years of poor success in 1983 or 1978 (Table 1.1; Boekelheide et al. 1990).

b

 Data for a new subcolony (77%) were excluded.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 13

colonies in the last two decades (Parrish 1995; Carter et

al. 2001).

In addition to the factors noted above, breeding

success probably increases with age, at least up to ages

6–9, as found in the thick-billed murre (Gaston et al.

1994). The size and density of murre colonies or breeding

groups also are known to affect the reproduction of

murres. At Skomer Island, Wales, breeding success was

higher in dense breeding groups than small scattered

groups because of high egg-laying synchrony and lower

exposure to gull predation (Birkhead 1977b, 1978b).

However, consistent negative relations between colony

size and chick growth rate, fledging weight, and

breeding success have been shown at the Pribilof

Islands, Alaska, possibly because of competition and

interference at breeding sites, and possibly competition

for prey (Hunt et al. 1986). Whereas resource depletion

around large seabird colonies has not been well

demonstrated (e.g., Birkhead and Furness 1985),

competition among foraging murres in dense

aggregations might contribute to decreased chick

growth, lower fledging weight, and possibly decreased

post-fledging survival (Gaston et al. 1983; Schneider

and Hunt 1984).

At-sea Chick Rearing

Flightless chicks leave the colony at about one

quarter adult mass, before attaining complete juvenile

plumage. Murre chicks are usually accompanied to sea

by a single adult (Figure 1.6), rarely by two adults (Tuck

1961; Varoujean et al. 1979; Gaston and Nettleship

1981; Harris et al. 1990; Scott 1990). Usually, only males

care for chicks at sea (Scott 1973, 1990; Birkhead 1976b;

Harris and Birkhead 1985). Why male murres guard and

raise chicks at sea has not been well studied and remains

one of the more interesting questions in alcid biology.

Males are slightly larger than females on average

(Gaston and Jones 1998) but differential chick-guarding

or foraging abilities have not been demonstrated.

However, females collected during the early at-sea

rearing period exhibit low body weights, which may

indicate poorer condition by this time (Croll 1990; H.

R. Carter and S. G. Sealy, unpublished data). Females

occasionally may still accompany male-chick groups

(Harris et al. 1990). In 1969–73 near Yaquina Head,

Oregon, Scott (1990) found that chicks were

accompanied by a single adult (86.6%), two adults

(2.3%), one adult and another chick (less than 1%), or

were unaccompanied when observed (10.7%). Of 18

adult murres collected with chicks, 17 were male. In

Barkley Sound, British Columbia, in 1979–80, 32 single

adults that were accompanying chicks at sea were

collected and all adults were male, based on gonad

examination (H. R. Carter and S. G. Sealy, unpublished

data). In two instances, another adult or subadult was

strongly associated with the male–chick pair for a period

of time—one was a female and the other a male (i.e.,

possibly the female parent or both may have been

“helpers”). In 1995, USFWS personnel collected 10

adult murres that were accompanying chicks at sea off

Yaquina Head and all adults were male, based on gonad

examination (R. W. Lowe, unpublished data).

When not feeding, chicks usually remain behind

but within 2 m of an accompanying adult. Adults feed

the chick for 1–2 months after fledging, although chicks

learn to dive and supplement parental feeding in the

latter part of the at-sea rearing period (Oberholzer and

Tschanz 1969; H. R. Carter and S. G. Sealy, unpublished

data). When adults dive for food, they usually surface

within 75 m of the chick. Adults and chicks

communicate frequently by loud calls to facilitate rapid

feeding, prevent separation, and reduce

kleptoparasitism or predation during feedings.

Many dead chicks are washed up on beaches in the

late summer and fall (Stenzel et al. 1988; Bayer et al.

1991; Carter 1996). South of Alaska, the largest numbers

of dead chicks on beaches are found in Oregon, probably

reflecting the large breeding population (Carter et al.

2001), onshore winds, and many accessible beaches.

From June to September 1978–90, an annual average

of 421 (range, 33–1,236) dead hatching-year murres

were recorded on a 7.5-km long beach south of Newport

(Bayer et al. 1991). High mortality of hatching-year

murres also is sometimes recorded along the Washington

coast (U. W. Wilson, personal observation). On 5

September 1979, 39 dead murres were found floating in

Barkley Sound, British Columbia, after an intense

storm; 36 (92.3%) were dependent chicks (none had

yet achieved independence by this date), which suggests

Figure 1.6. Parent–chick pair of common murres at sea just minutes

after departing from the colony at Three Arch Rocks, Oregon, 11 July

1989 (Photo by R. W. Lowe).
14 USGS/BRD/ITR–2000-0012

natal colonies each year at traditional colony locations.

However, under certain circumstances, adult or subadult

murres will attend other locations with suitable breeding

habitats. Under favorable population conditions, murres

may attempt “colony formations” (i.e., the establishment

of colonies at “new” locations or the reestablishment or

“recolonization” of colonies at previously-used

locations). A primary hindrance to murre colony

formations seems to be social factors, especially the

initial process of attracting sufficient numbers of

conspecifics over a period of time to encourage breeding

attempts (i.e., pairing, copulation, and egg laying) at

locations with suitable breeding habitat (Buckley and

Buckley 1980). In addition, colony formations require

adequate prey resources plus relatively low levels of

human disturbance, interspecific interference, and

predation.

Rarely have colony formations been documented

in the Pacific or Atlantic Oceans because of the

infrequency of this behavior and the difficulty of

detecting such events as they occur. With incomplete or

unavailable information on past breeding or lack of

breeding at specific colony sites, it is often impossible

to distinguish between the formation of new colonies

and recolonization events. Though the historical

information is incomplete, it seems that natural

recolonization events have occurred in northern

California and Oregon, but not in central or southern

California (Carter et al. 2001).

Formation of colonies in northern California and

Oregon have been noted mainly within “colony

complexes” (Carter et al. 2001) where murres apparently

expanded from long-used colony sites or subcolonies

to breed on nearby (i.e., within a few kilometers)

unoccupied breeding habitats. Many fewer examples

of colony formation away from nearby existing colonies

are known. However, apparent recolonizations in

Mendocino County, California, and intermittent

formation of small colonies on the west coast of

Vancouver Island, British Columbia, occurred long

distances away from existing colonies.

Murre colony formations in California and Oregon

often have been associated with nesting Brandt’s

cormorants. In fact, murres often breed in association

with nesting Brandt’s cormorants in California, Oregon,

and Washington (e.g., Sowls et al. 1980; Speich and

Wahl 1989; Boekelheide et al. 1990; Carter et al. 1992).

Cormorants may facilitate murre colony formations by

providing added protection to murres from potential

gull and corvid predation, as well as providing stimuli

for murre breeding (McChesney et al. 1998, 1999;

Sydeman et al. 1998; Carter et al. 2001).

greater susceptibility of chicks to inclement conditions

than adults (H. R. Carter and S. G. Sealy, unpublished

data). Overall, many of the deaths of first-year birds

compared to adults (see later) seem to occur before the

end of the at-sea chick-rearing period.

Philopatry, Recruitment, and Intercolony

Movements

Like all alcids studied to date, common murres show

a strong tendency to return to their natal colony to breed

(Hudson 1985). Once having bred, a murre normally

tends to return to the same or adjacent breeding site

each year (Birkhead 1977a; Harris and Wanless 1988;

Harris et al. 1996b), and rarely moves to another colony.

The process of recruitment is not well understood.

Studies in Scotland (Swann and Ramsey 1983; Halley

et al. 1995; Harris et al. 1996a) have shown that (1)

subadults (2–7 years old) visit several parts of their natal

colony before selecting a breeding site for their first

breeding, usually in the same subcolony but rarely close

to their natal site; (2) immatures tend to arrive

progressively earlier as they become older, and are

present more frequently; (3) immatures that previously

visited a colony are more likely to make future visits

and eventually breed at the colony site; and (4) younger

immatures (i.e., 2–3 years old) mostly attended “clubs”

on intertidal rocks. Over 2 years of study, 64–67% of

immatures visited their natal subcolony, and 57% of

murres breeding for the first time did so at their natal

subcolony. For six cohorts, an average of 42–54% of

chicks recruited within their natal group of 50–200

breeding pairs (Harris et al. 1996a).

Little attention has been devoted to banding and

resighting or retrapping murres in the Pacific Ocean.

Intercolony movements have been documented at the

Isle of May, Scotland. During 1987–91, Halley and

Harris (1993) recorded 61 murres (2 adults and 59

immatures) on the Isle of May that had been banded

elsewhere. Only one or two of these birds actually bred

at the Isle of May, which suggests some inter-colony

visitation, but low natal dispersal. Habitat saturation or

loss, mate or site loss, colony increase or decrease, close

proximity of other colonies, or human disturbance may

lead to higher rates of emigration for common murres

(less than 30%) or Atlantic Puffins (Fratercula arctica;

less than 50%) at certain colonies (Harris and Wanless

1991; Lyngs 1993; Harris et al. 1996a).

Colony Formation and Irregular Attendance

 Since adult murres exhibit high breeding-site

fidelity, high philopatry, and high annual survival rates,

adult and subadult murres tend to return to and attend
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 15

Colony formations also can be facilitated with the

use of social attraction techniques. In 1996–2000, murre

decoys and broadcasted murre vocalizations were

successfully used as social attraction methods at Devil’s

Slide Rock, California, to recolonize this previouslyextirpated “colony complex” where murres no longer

bred within 35–40 km of this location (Graham 1996;

Parker et al. 1997, 1998, 1999; Helmuth 1999; Parker

1999; Carter et al. 2001).

Several natural and anthropogenic factors can affect

breeding conditions at an active colony and may

contribute to colony formations by providing impetus

for adults or subadults to attend other breeding habitats.

Colony sites suffering from chronic impacts or persistent

low numbers of attending birds may be abandoned. If

such abandonment has resulted from anthropogenic

factors, these colonies have been referred to as

“extirpated,” even though suitable breeding substrates

remain. Colony extirpation has occurred for many

decades at certain locations in California because of

human disturbance, breeding habitat changes, and

egging (Carter et al. 2001). However, it was not

determined whether any surviving murres moved to

other colonies or no longer bred. More recently,

extirpation or abandonment of several murre colonies

has occurred along the southern Washington coast,

evidently because of a combination of natural and

anthropogenic factors (Wilson 1991; Carter et al. 2001).

Corresponding changes in numbers on adjacent colonies

also has been noted in Washington and California,

suggesting that murres will move, either temporarily or

permanently, to adjacent colonies under certain

circumstances (Carter et al. 2001). However, such

movements and subsequent breeding have not been

verified with banded birds.

Irregular attendance at potential breeding habitats

(and, at times, nonbreeding habitats) also has been

recorded at many locations from California to British

Columbia (Carter et al. 2001). Such attendance was

considered to be sporadic (i.e., attendance interspersed

with periods of absence) during the breeding season

when regular attendance typically occurs at colonies

(see above; McChesney et al. 1998). At potential

breeding habitats, such behavior may reflect attendance

(with or without attempted breeding) at a colony site in

the process of being abandoned, extirpated, colonized,

or recolonized. In Washington, irregular attendance at

several colony sites and nonbreeding habitats may

reflect attempts to change breeding sites, or to continue

breeding at low levels under conditions of population

decline (Carter et al. 2001).

Predators

Common murres usually breed in colonies on

islands or mainland cliffs that are free of mammalian

predators. On flat areas, slopes, or cliffs, murres breed in

dense concentrations which reduce predation of eggs

and chicks by avian predators. Other ecological

adaptations which can reduce predation include large

body size, constant attendance of breeding sites, and

active defense of breeding sites against predators.

However, surface breeding makes murres susceptible to

predation of eggs and chicks by various avian predators.

In California, Oregon, Washington, and British

Columbia, chief predators of eggs and chicks include

western gulls, glaucous-winged gulls, common ravens

(Corvus corax), American crows (Corvus

brachyrhynchos), northwestern crows, and occasionally

brown pelicans (Pelecanus occidentalis; Boekelheide

et al. 1990; Rodway 1990; Spear 1993; Parrish 1995;

Parker et al. 1997, 1998; Thayer et al. 1999; R. W. Lowe,

unpublished data).

In Alaska and Newfoundland, Arctic foxes (Alopex

lagopus) and red foxes (Vulpes vulpes) prey on murres

at some colonies, which can result in colony

abandonment, low reproductive success, delayed

breeding, or reduced breeding attempts (Bailey 1993;

Birkhead and Nettleship 1995). In California, Oregon,

Washington, and British Columbia, adult and subadult

murres are taken alive at or near colonies by peregrine

falcons, bald eagles, other raptors (e.g., red-tailed hawk

[Buteo jamaicensis]), large gulls, and occasionally

marine mammals (Bayer 1986; Paine et al. 1990;

Rodway 1990; Garcelon 1994; Harding 1994; Parrish

1995, 1996; R. W. Lowe, unpublished data; M. W. Parker,

unpublished data). However, some dead murres

discovered in raptor nest remains may have been

scavenged at sea or from shorelines. At some colonies,

disturbances by eagles chasing or capturing murres has

severely impacted breeding murres in Washington and

Oregon in recent years (Speich et al. 1987; Parrish 1995;

Warheit 1997; Carter et al. 2001). In 1999, as much as

half of the Oregon murre population may have been

affected to varying degrees by eagle disturbance,

compared to little if any impact before 1994 (R. W.

Lowe, unpublished data). It is unclear to what extent

such disturbances occurred at these murre colonies in

historical times when both eagle and murre numbers

probably were higher. Current disturbances may reflect

recent use by murres of breeding habitats susceptible to

such disturbances at certain colonies (e.g., cliff-top

habitats at Tatoosh Island) and recent expansion of eagle

populations (Parrish 1995; Carter et al. 2001).
16 USGS/BRD/ITR–2000-0012

Most egg and chick predation in Farallon colonies

was attributed to “specialist” western gulls that nest in

or adjacent to breeding groups of murres (Spear 1993).

These gulls tend to expel other gulls from their territories

and, consequently, gull predation does not necessarily

increase where large numbers of gulls nest near murres,

except during breeding failures and abandonments when

egg loss would likely occur regardless of gull predators.

Murre-specialist western gulls may not be present at

small murre colonies (L. B. Spear, personal

communication).

Foraging Ecology

Common murres forage widely between coastlines

and outer parts of the continental shelf, but are most

common in inshore waters (Brown 1980; Bradstreet and

Brown 1985; Briggs et al. 1987). During the breeding

season, foraging by breeding birds and older subadults

attending colonies becomes restricted to within foraging

distance of colonies, but birds still can forage as far as

200 km away from colonies (Cairns et al. 1990). In

central California, murres tend to forage largely within

about 35 km of breeding colonies (Briggs et al. 1987,

1988; Ainley et al. 1990, 1993; Allen 1994). However,

younger subadults or adults not attending colonies can

be found farther from colonies during the breeding

season. In winter, murres tend to forage farther from

colonies, often at distances that prevent regular colony

attendance. However, winter attendance by birds at

certain colonies reflects foraging within a short distance

from the colony.

Feeding areas, both far from and near shore, are

predictable to some degree since recent studies strongly

link murre at-sea densities to specific oceanographic

features (Brown 1980; Woodby 1984; Schneider et al.

1990). For instance, ocean flow gradients are generated

from coastline and bathymetric features (Casanady

1982; Allen et al. 1983; Schneider et al. 1990) and lead

to prey aggregations at “fronts” between water types.

Smaller fronts in nearshore waters can be related to local

topographic features, tides, and river plumes. However,

many factors contribute to prey abundance, distribution,

and availability at fronts or other locations, such as

locations of spawning areas and habitats of fish prey,

patterns and timing of marine productivity in specific

coastal areas, distance from colonies, and various effects

of human activity (e.g., fisheries, pollutants, and

freshwater outflow from rivers). Because of their ability

to dive to great depths (up to about 180 m; Piatt and

Nettleship 1985), murres have wide access to prey

throughout a large portion of the water column and can

forage along the bottom in many nearshore areas.

However, common murres often forage at midwater

depths, perhaps because of prey abundance, vertical

distribution of prey during daylight hours, underwater

energy expenditure, foraging efficiency, or differing

caloric value of prey (Spring 1971; Bradstreet and

Brown 1985; Birkhead and Nettleship 1987c; Ainley

et al. 1996).

Foraging patterns of breeding murres have been

studied mainly by observing adults feeding chicks at

colonies. To feed chicks, adults typically capture single

prey items (usually 4–15 cm fish, but occasionally squid

and invertebrates) in at-sea foraging areas and fly back

to the breeding site, carrying the fish lengthwise in the

bill. As the chick grows larger, feeding rates and size of

fish may increase or remain the same (Burger and Piatt

1990; Hatchwell 1991; Harris and Wanless 1995b).

Chick feeding rates are largely unaffected by weather,

sea conditions, or chick age but high winds and heavy

seas can affect adult foraging behavior (i.e., increase

foraging time and effort) and reduce the size of fish fed

to chicks (Birkhead 1976a; Slater 1980; Burger and

Piatt 1990; Finney et al. 1999).

The response of breeding murres to prey availability

was studied in the Shetland Islands, Scotland, during

years of high and low prey abundance (Uttley et al.

1994). In both years, murres fed on lesser sand lance

(Ammodytes marinus). Between years, hatching success

was similar, but the rate of chick feeding, chick growth,

fledging weight, and fledging success were all higher

in the year when prey were most abundant. Chick

feeding frequency showed little variation during the

early chick-rearing period at the colony when prey were

more abundant, but increased as the breeding season

progressed and prey were less abundant. When prey

abundance was low, adults spent less time at the colony

and their foraging trips required more than twice as

much time. Murre feeding also was studied concurrently

by using radio telemetry (Monaghan et al. 1994). Low

prey abundance had a dramatic impact on foraging

patterns (1) feeding trips were longer, (2) birds foraged

more than six times farther from breeding sites, (3) birds

spent more than five times as much time diving, and (4)

their estimated energy expenditure was twice as great.

Longer foraging time reduced time at the colony tending

the chick. These changes in time allocation and energy

expenditure could adversely affect chick survival at

the colony and possibly adult survival after breeding.

However, murres may compensate for such changes.

Zador and Piatt (1999) found little difference between

chick feeding rates, chick growth rates, or breeding

success between increasing and declining colonies (with

higher and lower prey availability, respectively) in Cook
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 17

Figure 1.7. Variation in diet composition of

the common murre between three marine

habitats and three times of year in the Gulf of

the Farallones in central California, 1985–1988

(adapted from Ainley et al. 1996). Diet

categories are presented as percent of total

index of relative abundance (after Sanger 1987).

Diet categories are coded: EU, euphausiids;

SQ, market squid (Loligo opalescens); NA,

northern anchovy (Engraulis mordax); PW,

Pacific whiting (Merluccius productus); RK,

rockfish (Sebastes spp.); and OT, other.

Inlet, Alaska, but time spent on the colony was greater

at the increasing colony.

Diet

Diet information for common murres has been

obtained mainly from examination of stomach contents

from birds collected at sea (see summaries in Ainley

and Sanger 1979; Bradstreet and Brown 1985; Sanger

1987; Vermeer et al. 1987). Even though fish are the

primary prey of common murre adults and chicks, adults

can feed on other types of prey with different caloric

values that are less suitable for carrying to and feeding

chicks (e.g., euphausiids). Adults can eat larger fish (less

than 20 cm long) than are fed to chicks with fish size

limited by fish body depth (less than 40 mm; Swennen

and Duiven 1977). Adult diet tends to be more diverse

than chick diet in the breeding and nonbreeding seasons

and, in addition to fish and squid, can include molluscs,

polychaetes, and fish eggs. Diet composition varies

considerably between geographic areas and times of

year, including the proportion of fish and crustaceans

in the diet. Overall, much less information is available

on winter diet than summer diet. Various factors can

affect prey abundance, availability, and location on

short- and long-time scales (e.g., Ainley et al. 1993,

1994; Veit et al. 1997).

In Oregon, northern anchovy (Engraulis mordax)

and rockfish (Sebastes spp.) dominated the diet

throughout the year in 3 years studied, but murres

consumed more euphausiids and mysids (up to about

27% of the diet by volume) in July–August (Wiens and

Scott 1975; Scott 1973, 1990). Matthews (1983) also

found a diverse diet in Oregon that varied between years,

seasonally, and among individuals foraging in the same

area. Individual murres consumed up to seven different

taxa during a single foraging session. The most common

prey items included anchovies, juvenile rockfish, Pacific

tomcod (Microgadus proximus), whitebait smelt

(Allosmerus elongatus), Pacific herring (Clupea

harengus), Pacific sand lance (Ammodytes hexapterus),

speckled sanddab (Citharichthys stigmaeus), market

squid (Loligo opalescens), crab megalops (Cancer spp.),

and euphausiids.

Murre diet was found to vary seasonally (i.e.,

prebreeding, breeding, and winter), spatially (i.e.,

coastal, mid-shelf, and outer-shelf waters), and between

years in coastal waters near murre colonies in central

California (Ainley et al. 1996; Figure 1.7). Diet was

most variable during winter and in El Niño periods.

During the prebreeding season (March–April), diet was

dominated by euphausiids (e.g., Euphausia pacifica

and Thysanoessa spinifera) and juvenile rockfish in

Coast Mid-Shelf Outer-Shelf

PreBreeding 

(Mar-Apr)

Breeding 

(May-Aug)

Winter (SepFeb)

Marine Habitats

Times of Year

EU

1.4%

SQ

1.4%

OT

6.7%

PW

0.6%

NA

34.1%

RK

55.8%

n = 62

EU

14.2%

PW

79.7%

NA

6.1%

n = 40

SQ

6.8% E U

72.5%

P W

2.4%

OT

4.3% RK

14.0%

n = 143

OT

11.0%

RK

36.6%

NA

44.7%

SQ

7.7%

n = 118

RK

7.8%

PW

43.1%

NA

0.2%

E U

49.0%

n = 34

OT

3.4%

RK

96.3%

SQ

0.3%

n = 67

OT

37.9%

NA

57.9%

SQ

4.2%

n = 28

OT

15.5%

RK

2.1%

NA

0.6%

SQ

81.8%

n = 13

RK

59.5%

OT

0.2% EU

17.1%

SQ

23.2%

n = 49
18 USGS/BRD/ITR–2000-0012

outer-shelf habitats. Pacific whiting (also known as

Pacific hake; Merluccius productus) and rockfish were

most important in mid-shelf and coast habitats,

respectively. During the breeding season (May–August),

rockfish predominated in outer-shelf habitats. Pacific

whiting and euphausiids were most important in midshelf habitats, and northern anchovy and rockfish in

coast habitats. In winter (September–February), rockfish,

squid, and euphausiids were important in outer-shelf

habitats, whereas squid and anchovy predominated in

mid-shelf and coast habitats, respectively. Throughout

the year, northern anchovy were important in coast

habitats, and rockfish were important in outer-shelf and

coast habitats. Diet also varied by feeding location, even

within a season, which suggested that if primary prey

species became unavailable, murres switch feeding

locations or change their diet dramatically. Rockfish

and northern anchovy also are the primary prey fed to

murre chicks at the South Farallon Islands (Ainley et al.

1990, 1993). Farther away from colonies in central

California, rockfish, market squid, northern anchovy,

night smelt (Spirinchus starksi), and ling cod (Ophiodon

elongatus) were important prey in gill-net killed murres

in Monterey Bay in spring, summer, and fall, but varied

seasonally and between years (Croll 1990). Euphausiids

were not important prey in spring and squid dominated

during summer 1983. Fish also were the principal prey

in winter in Monterey Bay, although some squid were

taken (Baltz and Morejohn 1977).

In British Columbia, murres have been reported

feeding on Pacific sand lance, Pacific herring, northern

anchovy, Pacific whiting, smelts (Osmeridae), other

small fish, marine crustaceans, and small squids (Munro

and Clemens 1931; Guiguet 1972; H. R. Carter and S.

G. Sealy, unpublished data). Murres are well known to

use estuarine waters to exploit abundant Pacific herring

during spring spawning (e.g., Straits of Georgia) or in

juvenile-herring rearing areas in late summer and fall

(e.g., Barkley Sound; Munro and Clemens 1931;

Robertson 1972; Vermeer et al. 1987; Campbell et al.

1990; H. R. Carter and S. G. Sealy, unpublished data). In

gill-net killed murres in late summer and early fall 1993–

96 in the San Juan Islands, Washington, murres fed

primarily on Pacific herring, Pacific sand lance,

salmonid smolts (Oncorhynchus sp.), and Pacific tomcod

(Wilson and Thompson 1998).

At-sea Distributions

California

Extensive at-sea surveys were conducted monthly

from 1975 to 1978 in southern California and from 1980

to 1982 in central and northern California (Briggs et al.

1981, 1983, 1987; Tyler et al. 1993). Common murres

were present at high densities in shelf–slope habitats

near colonies in central and northern California

throughout the year. During the breeding season,

densities averaged 6–12 birds per km2 but peaked at

20–200 birds per km2 near colonies. Highest average

densities (12–18 birds per km2) were recorded in late

July to September, after departure of chicks and adults

from colonies. Two major factors affect the use of these

foraging areas: the distribution of suitable breeding

habitats and the distribution and abundance of prey. In

California, colonies are present in productive coastal

areas with localized upwelling often located downstream

from coastal promontories. These conditions probably

result in abundant prey resources near colonies most of

the year, allowing for year-round residency in these

areas. Between January and July, small numbers of

murres are found between colony areas in northern and

central California (i.e., southern Humboldt to southern

Sonoma Counties). Densities can increase in this area

in winter (Briggs et al. 1983), apparently because of

wider foraging by murres from northern California and

possibly southern Oregon. In winter, lower densities of

murres are present in offshore habitats in central and

northern California and shelf–slope habitats in southern

California that experience cool, locally upwelled waters.

Very small numbers of murres winter in warmer waters

in the southern part of the Southern California Bight

and northern Baja California, Mexico (Unitt 1984;

Howell and Webb 1995).

During the breeding season in central California,

virtually all murres were observed in waters 200 m or

less in depth and adjacent to shore (less than 35 km

from colonies; Briggs et al. 1988; Ainley et al. 1990). A

large feeding area located 8–25 km northeast of the

Farallon Islands was used regularly from mid-April to

early June. In early spring, murres fed in deep waters at

the shelf edge near the Farallon Islands. However, murres

also are widely present in nearshore waters in the Gulf

of the Farallones during the breeding season, as far south

as northern San Luis Obispo County and as far north as

southern Sonoma County (Bolander and Parmeter 1978;

Roberson 1985). As the season progressed, murres began

to shift toward the shallower coastal waters along the

nearby mainland coast. After fledging, adult-chick

groups dispersed along the coast, both south (e.g.,

Monterey Bay) and north (e.g., Bodega Bay). Late

summer movement of murres into Monterey Bay for atsea chick rearing and prebasic molt are followed with

movement out of the bay into offshore waters in fall

(Croll 1990).
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 19

Table 1.4. Seasonal projected total number of common murres in the protected marine waters of Washington and southern British Columbia

during 1978–1979 (from Wahl et al. 1981).

Spring Summer Fall Winter

Area April–May June July–October November–March

Western Strait of Juan de Fuca 1,400 1,200 110,000 26,000

Eastern Strait of Juan de Fuca 1,100 1,300 24,000 12,000

Admiralty Inlet 40 2 450 1,200

Anacortes-Hales Pass 330 40 9,200 5,800

Georgia Strait-East 7,400 460 9,000 17,000

Georgia Strait-West 1,300 20 70 710

Haro Strait 170 10 7,100 1,600

Rosario Strait 610 3 11,000 11,000

Northern Waters 20 — 1,700 5,300

San Juan Passages 50 40 940 2,700

San Juan’s Bays 10 4 330 200

Canadian Watersa 70 1 280 2,500

Total 12,500 3,080 174,070 86,010

a

 Active Pass, Gulf Islands, Sydney approach.

During El Niño conditions, murres feed closer to

shore during summer and some traditional feeding areas

(i.e., offshore or inshore) may be abandoned when

declines in oceanic productivity result in substantially

fewer prey (Ainley et al. 1990; Croll 1990).

Oregon

At-sea distribution of murres was studied in Oregon

in 1989 and 1990 (Briggs et al. 1992; Tyler et al. 1993).

Murres frequented the shelf-edge banks for most of the

year and near-shore coastal waters were used in late

summer. Numbers of murres peaked during late summer

when adults and dependent chicks concentrated in

coastal waters as they moved north. Shallow waters with

murre concentrations coincided with the mid-shelf

thermohaline fronts associated with the southward edge

of the Columbia River plume (Landry et al. 1989). Murre

densities from boat transects in the early 1970s ranged

from 20 to 60 birds per km2 within 25 km of shore (Wiens

and Scott 1975). These densities were consistent with

those derived by Briggs et al. (1992) in southern Oregon

and from northern Oregon to Grays Harbor, Washington.

In general, few murres are present in Oregon during the

nonbreeding season, with small number off southern

Oregon and moderate numbers off northern Oregon (R.

G. Ford, personal communication).

Washington

On the outer coast, murres feed close to shore and

farther offshore, at times in waters as deep as 1,000–

2,500 m (Wahl 1975; Briggs et al. 1992; Wahl et al.

1993; Thompson 1997). In January, April, May, and

June, murres were found mainly in water depths of 125–

140 m in 1989–90 (Briggs et al. 1992; Tyler et al. 1993).

During the breeding season, murres fed 18–27 km from

known colony sites. From April to May, murres were

found mostly along a narrow strip close to shore where

local densities varied from 24 to 240 birds per km2. In

July, murres were well dispersed over most of the

continental shelf. Off Grays Harbor, murres were found

commonly in shallow nearshore waters (50–100 m)

during summer–fall 1972–88 (Wahl 1975; Wahl et al.

1993). Moderate numbers are found off southwest

Washington between November and January (R. G. Ford,

personal communication).

Peak numbers of murres in the protected marine

waters of Washington are present in August through

mid-October, after adult–chick pairs from Washington

and Oregon colonies have departed from colonies and

moved north (Table 1.4; see below). For example, more

than 200,000 murres were estimated in September 1978

(Manuwal et al. 1979; Wahl et al. 1981). In September

1989–90, murres were present on the outer coast in lower

densities (18–183 birds per km2), but distributed

similarly to July (Briggs et al. 1992). By November,

murre numbers in protected marine waters had declined

substantially, indicating movement northward into

Georgia Strait, British Columbia, or to outer coast areas

off the entrance to Juan de Fuca Strait (Table 1.4).

British Columbia

During outer coast at-sea surveys in 1972 and 1973,

and 1981 to 1990, common murres were common in all

seasons off the west coast of Vancouver Island with a

lower number present farther north off the Queen

Charlotte Islands (Robertson 1974; Vermeer et al. 1983,

1989; Morgan et al. 1991; Vermeer and Morgan 1992).

In spring, murres were present in colder, less saline

inshore waters, but occasionally fed far offshore. Highest

densities occurred in summer–fall in shallow waters (less

than 60 m) on the broad continental shelf, as well as
20 USGS/BRD/ITR–2000-0012

inshore and fiord waters, off southwestern Vancouver

Island between Barkley and Clayoquot sounds. The

movement of thousands of murres into Barkley Sound,

British Columbia, was documented in July–September

1979 and 1980 when this area was used extensively for

at-sea chick rearing and prebasic molt (H. R. Carter and

S. G. Sealy, unpublished data). At this time, murres often

participated in multispecies flocks feeding on schools

of Pacific herring and Pacific sand lance (Porter and

Sealy 1981). In winter (November to March), murres

remained abundant on the continental shelf off

southwest Vancouver Island but few murres were present

in nearshore and fiord waters in Barkley and Clayoquot

sounds (Robertson 1974; Hatler et al. 1978; Morgan et

al. 1991; Vermeer and Morgan 1992; H. R. Carter and S.

G. Sealy, unpublished data). Only small numbers of

breeding and nonbreeding murres remained in nearshore

waters in Barkley Sound in May–June (Carter and Sealy

1984; Vermeer and Morgan 1992).

In late summer, fall, and winter, murres are common

in protected waters and fiords in the Strait of Georgia

often at small fronts and near Pacific herring spawning

grounds (Brooks and Swarth 1925; Munro and Clemens

1931; Edwards 1965; Vermeer et al. 1983; Campbell et

al. 1990). Murres move out of the Strait of Georgia into

either protected waters in Washington or outer coastal

waters off the entrance to Juan de Fuca Strait between

February and May (Vermeer 1983; Campbell et al. 1990;

H. R. Carter and S. G. Sealy, unpublished data).

In northern British Columbia, murres were observed

in all months, but peaked in Dixon Entrance and Hecate

Strait between April and May, and September and

October (Vermeer and Rankin 1984, 1985; Morgan et

al. 1991; Morgan 1997). Inshore waters around the

Queen Charlotte Islands had higher densities in winter

than in summer in 1972–73 and October 1976 than

from May to June 1977 (Robertson 1974; Vermeer et al.

1983).

Movements

Common murre movements from specific colonies

in California, Oregon, Washington, and British

Columbia are poorly known because few banding

programs have occurred at colonies. Large numbers of

murres (2,820; 94.6% chicks) were banded at Cape

Lookout and Three Arch Rocks, Oregon, from 1930 to

1940 (Storer 1952; Tuck 1961; Bayer and Ferris 1987).

Most (73%; n = 53) band recoveries of hatching-year

birds occurred north of colonies in Oregon and

Washington. Band recoveries began in August in

Washington and September in British Columbia. No

band recoveries of hatching-year murres occurred in

Oregon after September. In central California, murres

have been banded annually at the South Farallon Islands

since 1985 and sporadically in the 1970s (Sydeman

1993; Sydeman et al. 1997). In addition, many murres

that were oiled and cleaned have been banded and

released (Sharp 1996). Almost all band recoveries have

occurred on the South Farallon Islands (e.g., Sydeman

1993) or on beaches in central California (U.S.

Geological Survey, Bird Banding Laboratory,

unpublished data).

A broad picture of murre movements can be

ascertained from at-sea surveys, colony attendance

patterns, and observations of parent–chick pairs at sea

from California to British Columbia. Hundreds of

thousands of murres are present along the outer coast of

Washington and southern British Columbia between

the Straits of Juan de Fuca and Clayoquot Sound in

July–September (Manuwal 1981; Wahl et al. 1981;

Speich et al. 1987; Vermeer et al. 1987, 1992; Campbell

et al. 1990; Morgan et al. 1991; Thompson 1997; H. R.

Carter and S. G. Sealy, unpublished data). These large

numbers exceed estimates of breeding population sizes

in Washington and British Columbia (Carter et al. 2001).

Thus, it is clear that a substantial northward movement

of Oregon murres (700,000 breeding birds) occurs into

this area, as also indicated with the limited banding

data noted above. In Barkley Sound, British Columbia,

parent–chick groups and other murres arrived in large

numbers in July 1979 and 1980, at least a month before

chicks depart from the Triangle Island and Cleland Island

colonies farther north along the west coast of Vancouver

Island (H. R. Carter and S. G. Sealy, unpublished data).

Thus, most birds likely originated from Oregon where

departure from colonies usually occurs between late

June and late July, earlier than at Washington colonies

(see above). Small chicks recorded in Barkley Sound in

late August and September probably originated from

British Columbia or Washington colonies.

Some adult–chick pairs from Triangle Island also

move into Queen Charlotte Strait. On 2 September 1999,

a concentration of 390 common murres and 130

rhinoceros auklets was observed off the Murray

Labyrinth, in the south mouth of Schooner Channel, on

the eastern side of Queen Charlotte Strait (G. W. Kaiser,

personal communication). Unlike smaller groups farther

at sea, these birds were flightless and included many

chicks noticeably smaller than adults. From October to

March, large numbers remain in northern Washington

and southern British Columbia, although local

movements occur within this area (see above). No

evidence exists of a major movement of murres from

Alaska into southern British Columbia or northern

Washington between July and September, when murres
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 21

are rearing chicks and undergoing the flightless prebasic

molt in Alaska, or from October to March, when murres

are present in high numbers in southern Alaska (e.g.,

Forsell and Gould 1981; Gould et al. 1982).

Breeding murres in California are resident and

remain near colonies throughout the year as evidenced

by (1) high at-sea densities near colony areas throughout

the year (see earlier); (2) extensive winter attendance of

monitored plots in breeding areas at the South Farallon

Islands (Boekelheide et al. 1990; Sydeman et al. 1997;

Hastings et al. 1998); (3) winter attendance at many

other colonies in central and northern California (Ainley

1976; DeGange and Sowls 1981; Parker et al. 1997,

1998; Carter et al. 2001); and (4) at-sea chick rearing

and prebasic molt occurring near colony areas (Stenzel

et al. 1988; Boekelheide et al. 1990; Croll 1990; Carter

1996). Year-round residency of common murres has been

demonstrated with banded birds in the Baltic Sea (Olsson

et al. 2000). However, some northward movement of

murres from northern California may occur after colony

departure or after completion of prebasic molt. At-sea

densities, total population estimates, and distribution

of murres in California in winter are largely consistent

with summer numbers if adjusted for colony attendance,

populations of subadult murres, changes in local at-sea

distribution, and survey error. In fact, the overall mean

density for northern and central California combined in

July (5.14 ± 12.52 birds per km2) was higher than in

December (3.54 ± 7.71 birds per km2; Tyler et al. 1993).

Limited banding data support little or no movement of

murres away from central California (see above).

Higher winter at-sea numbers in northern California

after December may indicate some limited movement

of murres from Oregon in January and February in certain

years, although colony attendance, populations of

subadult murres, changes in at-sea distribution, and

survey error also may be involved (Briggs et al. 1983,

1987; Tyler et al. 1993). Such movement may occur as

Oregon murres move south and return to colony areas

but before regular attendance at colonies. However, if

substantial northward movement of northern California

murres occurs in early fall, higher numbers in December

may simply reflect return of northern California murres.

Smail et al. (1972) considered that some northern murres

(U. a. inornata) were killed in the 1971 San Francisco

oil spill; this conclusion was based on morphometric

comparisons using data in Storer (1952) but there is

now doubt over their approach (Warheit 1995).

Movements of large numbers of murres to central

California from other populations between December

and April are not confirmed with existing data. However,

small numbers of common murres from Alaska (U. a.

inornata ) may be present from southern British

Columbia to California in winter. For instance, small

numbers of thick-billed murres have been noted far south

of major colonies in Alaska in certain years (e.g., Scott

and Nehls 1974; Roberson 1985).

In southern California, moderate numbers of murres

are present in fall and winter and small numbers during

summer (Briggs et al. 1983, 1987; Lehman 1994; Carter

et al. 2001), presumably from central California colonies.

Male–chick groups have been noted in July as far south

as northern Santa Barbara County in some years (Lehman

1994). Murres are most common in Santa Barbara and

San Luis Obispo Counties from July to January (Briggs

et al. 1983, 1987). R. Rowlett (unpublished data),

however, recorded 2,030 murres between 5 and 12 May

1996 off Point Piedras Blancas. Smaller numbers occur

south to San Diego County and northern Baja California

mainly in November–January, with stragglers as late as

June (Unitt 1984; Howell and Webb 1995).

In late summer and early fall (August to October),

common murres from Triangle Island, British Columbia,

probably move south to the northwest or northeast

coasts of Vancouver Island. Small numbers of parent–

chick pairs observed in Kyuquot Sound and Checleset

Bay on northwestern Vancouver Island may originate

from Triangle Island or Oregon and Washington

colonies, depending on observation date (Guiguet

1972; Campbell et al. 1990). By late fall and winter,

these murres may stay in northern Vancouver Island

waters or move south and join large numbers in the

Straits of Juan de Fuca, Strait of Georgia, Puget Sound,

or southwest Vancouver Island. Higher numbers of

murres in Hecate Strait and Dixon Entrance in spring

and fall likely indicate southward movement of some

Alaskan birds, especially from the isolated Forrester

Island colony located just north of Dixon Entrance in

southeast Alaska (Sowls et al. 1978; Vermeer et al. 1983;

Campbell et al. 1990, Morgan et al. 1991; Carter et al.

2001). In early October 1986 and 1997, several adult–

chick pairs were observed in Skidegate Inlet on the east

coast of the Queen Charlotte Islands (S. G. Sealy,

personal communication).

Other winter movements probably occur, especially

by some younger subadults which are known to travel

more widely in winter than adults in Europe (e.g.,

Birkhead 1974; Mead 1974; Olsson et al. 2000). Two

murres banded at the South Farallon Islands have been

recovered off the Washington and Oregon coasts (U.S.

Geological Survey, Bird Banding Laboratory,

unpublished data). Three birds banded in Oregon were

recovered in central California (Storer 1952; Tuck 1961;

Bayer and Ferris 1987).
22 USGS/BRD/ITR–2000-0012

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Acknowledgments

This chapter has benefitted greatly from detailed

reviews and editorial comments of various drafts, or

portions thereof, by D. G. Ainley, D. Bertram, G. V. Byrd,

A. J. Gaston, M. P. Harris, K. Kilbride, R. W. Lowe, G. J.

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provided by T. S. Zimmerman, B. Bortner, and D. L.

Orthmeyer. J. L. Yee helped prepare Figures 1.5 and 1.7.

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Lowe, M. W. Parker, S. G. Sealy, and W. J. Sydeman.

Studies of the common murre in Barkley Sound, British

Columbia, in 1979–80 were funded by grants from the

Natural Sciences and Engineering Research Council of

Canada to S. G. Sealy and Canadian Wildlife Service

Scholarships to H. R. Carter. Photographs were provided

by R. W. Lowe, M. W. Parker, and M. S. Rodway.

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(1993–present), with administrative support from PRBO

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and others. The USFWS also has provided important

base funding to the PRBO for seabird monitoring at the

islands, and has overseen island facilities and all

research and management efforts. The program has been

supported through the efforts of Refuge Biologists R.

W. Lowe, J. E. Takekawa, J. Buffa, and others, with

administrative support from Refuge Managers R.

Johnson, R. Coleman, and M. Kolar.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 23

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Chapter 2

Population Trends of the Common Murre

(Uria aalge californica)

by

Harry R. Carter1, Ulrich W. Wilson2, Roy W. Lowe3, Michael S. Rodway4,

David A. Manuwal5, Jean E. Takekawa 6, and Julie L. Yee7

1Humboldt State University, Department of Wildlife

Arcata, California 95521

2U.S. Fish and Wildlife Service, Washington Maritime National Wildlife Refuge Complex

33 South Barr Road

Port Angeles, Washington 98362

3U.S. Fish and Wildlife Service, Oregon Coast National Wildlife Refuge Complex

2127 S.E. OSU Drive

Newport, Oregon 97365

4Simon Fraser University, Department of Biological Sciences

Burnaby, British Columbia V5A 1S6

5University of Washington, College of Forest Resources

Wildlife Science Group

Seattle, Washington 98195

6U.S. Fish and Wildlife Service, Nisqually National Wildlife Refuge

100 Brown Farm Road

Olympia, Washington 98516

7U.S. Geological Survey, Western Ecological Research Center

Dixon Field Station, 6924 Tremont Road

Dixon, California 95620

Suggested Citation:

Carter, H. R., U. W. Wilson, R. W. Lowe, M. S. Rodway, D. A. Manuwal, J. E. Takekawa, and J. L. Yee. 2001. Population trends

of the common murre (Uria aalge californica). Pages 33–132 in D. A. Manuwal, H. R. Carter, T. S. Zimmerman, and D. L.

Orthmeyer, editors. Biology and conservation of the common murre in California, Oregon, Washington, and British Columbia.

Volume 1: Natural history and population trends. U.S. Geological Survey, Information and Technology Report USGS/BRD/ITR–

2000-0012, Washington, D.C.

Abstract: Population trends for the common murre (Uria aalge californica) were determined from available

whole-colony counts of murres in California, Oregon, Washington, and British Columbia from 1800 to 1995.

From 1800 to 1978, historical counts were sporadic and not standardized. From 1979 to 1995, standardized

whole-colony counts from aerial photographs were conducted in many years in California, Oregon, and

Washington. In contrast, no aerial photographs of murre colonies in British Columbia have been taken and

only a few other whole-colony counts have been conducted. Direct comparisons and statistical treatment of
34 USGS/BRD/ITR–2000-0012

whole-colony counts were conducted using 1979–95 data. Complete data for all colonies were available only

in 1988–89 when the breeding murre population was estimated to be 1.1 million, about 5–8% of the world

population and 13–28% of the Pacific Ocean population. A summary of various natural and anthropogenic

factors affecting murre populations in western North America since 1800, and particularly in 1979–95, also

is provided.

A relatively good history exists for murre colonies in central California. The well-known colony at the

South Farallon Islands may have numbered 1–3 million birds in the early 1800s. Egging and human disturbance

throughout most of the nineteenth century, plus mortality from oil pollution in the early twentieth century,

caused the near extirpation of this colony by the 1930s. Since the 1950s, this colony has grown and, by the

early 1980s, again was the largest colony in central California. Two other large colonies also are present in

central California at the North Farallon Islands and Point Reyes. In the early twentieth century, Prince Island

in southern California was the southernmost breeding colony of U. a. californica, but the colony was

extirpated in about 1912. Hurricane Point Rocks in central California is now the southernmost colony. In

1980–82, the central California breeding population was estimated at 194,000–224,000 breeding birds at nine

active colonies. From 1979 to 1989, this population declined 9.9% per annum (P = 0.002) because of

mortality from gill nets and oil spills, in concert with detrimental effects from the severe 1982–83 El Niño. All

colonies declined significantly and the Devil’s Slide Rock colony was extirpated. In 1989, the population was

estimated at 90,200 breeding birds at 8 active colonies (i.e., 8% of the U. a. californica population). From

1985 to 1995, the population increased 5.9% per annum (P = 0.002), mostly since 1989–90, but had only

partly recovered to 1979–82 levels by 1995. Increase since the late 1980s has occurred despite continuing

anthropogenic impacts and low reproduction during the severe 1992–93 El Niño. The Devil’s Slide Rock

colony did not recover between 1986 and 1995, but breeding has been restored in 1996–2000, using social

attraction techniques.

In northern California, limited historical data indicated that murre colonies were heavily affected by early

settlers in the late nineteenth century, as well as oil pollution in the early twentieth century. Only two colonies

(i.e., Castle and Green Rocks) were specifically known prior to the late 1940s. Detrimental effects apparently

lessened in the mid-twentieth century, allowing substantial population growth over several decades since the

1930s, including many recolonization events prior to the 1970s. Little change in available population numbers

occurred from 1979 to 1989, which suggests a possible leveling of population numbers and little or no longterm detrimental effects from the 1982–83 El Niño. Lower numbers at Castle Rock in 1986 and 1989 appear

related to differences in survey techniques. In 1989, the breeding population was estimated at about 261,400

breeding birds at 11 active colonies (i.e., 24% of the U. a. californica population). The largest colonies were

at Castle Rock, False Klamath Rock, Green Rock, Flatiron Rock, and False Cape Rocks. Colonies had lower

numbers in 1993 indicating short-term abandonment during the severe 1992–93 El Niño, but with few longterm detrimental effects. Recolonization and population increase have continued since the 1970s at the

southern end of this population.

The vast majority of murres in western North America, south of Alaska, now breed in Oregon. Numbers

of murres in the nineteenth and early twentieth centuries were much lower owing to extensive use of coastal

rocks and islands by native peoples, followed by egging and human disturbance by early settlers. However,

the population increased for several decades in mid-twentieth century. By 1988, about 711,900 breeding birds

were estimated at 66 active colonies (i.e., 66% of the U. a. californica population). The largest colonies were

at Shag Rock, Finley Rock, Middle Rock, Gull Rock (Cape Blanco), 270-110, Cat and Kittens, and 219-018.

A sample of 15 colony sites indicated that murre numbers changed little from 1988 to 1995, except for shortterm abandonment during the severe 1992–93 El Niño. Long-term detrimental effects from severe El Niños

in 1982–83 or 1992–93 have not been detected.

Historical accounts indicate that murre populations in Washington increased from 1907 to 1979. In 1979,

about 53,000 breeding birds were estimated at 18 active colonies. The largest colonies were at Split Rock,

Willoughby Rock, Grenville Arch, and Rounded Island. Between 1979 and 1986, a 43.7% per annum (P =

0.006) decline occurred in the number of murres attending breeding colonies in southern Washington. Overall

numbers of murres in Washington declined 13.3% per annum (P = 0.003) from 1979 to 1995. By 1988, about

7,000 breeding birds (i.e., less than 1% of the U. a. californica population) remained. Declines apparently

were related to the 1981 warm water event, the 1982–83 El Niño, and anthropogenic factors (i.e., human

disturbance at colonies and gillnet and oil-spill related deaths). No recovery occurred in southern Washington

from 1984 to 1995 but limited increase in the number of murres attending some colonies in northern Washington

was documented. Increase at Tatoosh Island from 1984 to 1995 involved intercolony movements and intrinsic

growth. The Washington murre population size has recovered little since its decline in the early 1980s, and

remained low through 1995.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 35

Small numbers of murres breed in British Columbia and there is no evidence to suggest they are more

numerous than in 1900. About 8,300 breeding birds (i.e., less than 1% of the U. a. californica population)

were estimated at two active colonies in 1989, although five other small colonies had been active in the 1970s.

The northernmost colony of U. a. californica is at the Kerouard Islands at the southern tip of the Queen

Charlotte Islands. In British Columbia, the vast majority of murres breed at the large colony at Triangle Island

off the northern tip of Vancouver Island. Population trends at Triangle Island have not been well assessed.

Key words: Alcidae, breeding colony, breeding distribution, British Columbia, California, colony disturbance,

colony extirpation, colony formation, common murre, egging, El Niño, gill net, habitat change, oil spill,

Oregon, population size, population trends, predators, seabird, Uria aalge, Washington

Information on populations of the common murre

(Uria aalge californica ) in California, Oregon,

Washington, and British Columbia are of two types,

whole-colony counts of birds, which can be adjusted to

derive estimates of the number of breeding adults at

each colony, and transect counts of birds at sea, which

describe at-sea densities. These two types of population

data serve as primary baseline information for monitoring

and assessing trends in populations of murres in various

geographic areas in western North America (Sowls et al.

1980; Briggs et al. 1987, 1992; Speich and Wahl 1989;

Takekawa et al. 1990; Rodway 1991; Wilson 1991;

Carter et al. 1992, 1995; Byrd et al. 1993; Tyler et al.

1993).

Standardized whole-colony counts include a large

proportion of breeding birds (i.e., each egg or chick had

one or two attending adults) and some nonbreeding

individuals attending the colony. Thus, whole-colony

counts of all colonies in a geographic area constitute a

primary population index wherein most of the

population is counted directly rather than sampled. This

kind of population index increases our ability to measure

trends by greatly reducing potential variation or bias

from sampling. At each colony, this index is related

directly to the number of breeding adults or the total

number of murres (breeding and nonbreeding) attending

the colony, but the exact relation has not been

determined. Estimates of the number of breeding birds

at a colony can be derived from whole-colony counts

with the use of a correction factor k (see Appendix A).

Similarly, estimates of the numbers of nonbreeding birds

can be derived through population modeling. However,

k correction factors and demographic variables used in

population models have been determined in only a few

studies at certain locations and may not apply widely.

We considered trends in sums of standardized

whole-colony counts from aerial photographs for all or

many colonies in a geographic area to best reflect trends

in murre populations over time. Within the range of U.

a. californica, whole-colony counts can be conducted

at all colonies, which reduces the potential for sampling

error (e.g., if one colony were selected for monitoring in

an area). Source colonies of birds also are known for

colony counts but must be interpreted using various

sources of information for at-sea counts. In general,

standardized whole-colony counts are less variable,

more repeatable, and subject to fewer biases than at-sea

counts. However, numbers of murres attending colonies

during the breeding season are subject to variation

because of several factors, especially time of season,

time of day, and colony disruption by human

disturbance or interactions with other seabirds or marine

mammals.

Transect counts of birds at sea also can be

extrapolated over large areas to derive estimates of total

population (i.e., adults and subadults) in a defined

geographic area, but must account for murres attending

colonies. At-sea counts and total-population estimates

provide important data on the density, distribution,

abundance, and movements of murres at sea, which are

important in connection with various conservation

issues. Significantly more baseline population

information useful for monitoring purposes is available

for colonies than for at-sea murre distribution and

abundance.

Since 1979, monitoring of murres in California,

Oregon, and Washington has focused primarily on

standardized whole-colony counts from aerial

photographs of birds attending colonies during the

breeding season. The monitoring is so focused because

(1) most colonies are comparatively small (fewer than

20,000 breeding birds) and are present on small islands

with open habitats that can be aerially photographed

on a regular basis, (2) intensive monitoring of plots

within most colonies is impractical because most

colonies are inaccessible or cannot be accessed without

extensive disturbance to breeding birds, (3) potential

biases are associated with monitoring plots from the

ground (i.e., plot selections, number of plots, variation

between plots, and counting error [Harris et al. 1986;

Mudge 1988; Harris 1989]), and (4) monitoring plots

can involve high cost and effort. The U.S. Fish and
36 USGS/BRD/ITR–2000-0012

Wildlife Service (USFWS) manages and surveys most

murre colonies in Washington and Oregon, and

important colonies in California, within the National

Wildlife Refuge System. In California, however, most

colonies are managed by the California Department of

Fish and Game and the National Park Service, and surveys

have been conducted by a combination of personnel

from the USFWS, Humboldt State University, U.S.

Geological Survey and University of California. Aerial

photographic surveys can be conducted by refuge staff

or other researchers at a reasonable cost in a short period

of time during the breeding season, although the

subsequent counting of photographs requires

substantial effort. In certain other parts of the breeding

range of the common murre, sample plots have been

established as the primary method for monitoring where

deriving accurate whole-colony counts from aerial

photographs of entire colonies is either too difficult,

too costly, or impossible. Overall, researchers have used

a combination of survey and census techniques to

monitor murre populations around the world, with

techniques varying between colonies and geographic

areas (Birkhead and Nettleship 1980; Gaston and

Nettleship 1981). However, standardized or

nonstandardized whole-colony counts at one or more

colonies over several years have been used by many

researchers to describe common murre population trends

in various parts of the Atlantic and Pacific Oceans

(Hudson 1985; Nettleship and Evans 1985; Vader et al.

1990; Byrd et al. 1993). Aerial photographic surveys of

murre colonies at Funk Island, Newfoundland, and

several colonies in eastern Canada have been employed

since 1972 (D. N. Nettleship, personal communication).

Whole-colony counts of murres provide the best

available baseline information for analysis of trends in

the number of murres attending colonies in California,

Oregon, and Washington. Available data sets are

hampered, however, by four main factors: (1) incomplete

or irregular survey coverage (i.e., surveys not conducted

in some years, certain colonies omitted in certain years),

(2) incomplete colony coverage (i.e., poor quality or

incomplete sets of photographs at certain colonies in

certain years), (3) incomplete counting of available aerial

photographs in northern California and Oregon, and (4)

single counts in most years (i.e., variation in wholecolony counts has not been fully assessed). For central

California, Oregon, and Washington, such problems

were limited, have been reduced over the past decade,

and did not greatly affect the use of whole-colony counts

for assessing murre population trends. However, we have

identified and accounted for serious problems in certain

cases. In northern California and British Columbia,

available information was much more limited for

assessing recent trends than in other areas. Under unusual

circumstances, whole-colony counts may not accurately

reflect the actual colony size; for instance, during severe

El Niño-induced weather conditions, large numbers of

murres may not attend colonies during annual surveys.

Such circumstances must be identified and accounted

for in assessments of population trends, using wholecolony count data.

In Alaska, common murres often breed sympatrically

with thick-billed murres (U. lomvia) and it is often

difficult to determine the proportions of each species

(Sowls et al. 1978). This problem does not exist

throughout most of the geographic area of western North

America covered in this chapter. The current southern

limit of breeding thick-billed murres is at Triangle Island,

British Columbia, where up to 70 thick-billed murres

have been recorded attending the colony (Vallee and

Cannings 1983; Rodway 1991).

In this chapter, we have examined population trends

of common murres using available information from

whole-colony counts, primarily from aerial photographs,

in California, Oregon, Washington, and British

Columbia through 1995. In addition, we have reported

estimates of the size of breeding populations of U. a.

californica in different geographic areas. We have not

attempted to collate information on at-sea densities or

total-population estimates, but aspects of at-sea

distribution, abundance, and movements are

summarized in Manuwal and Carter (2001).

Methods

We used a broad framework for assessing murre

population trends within six geographic areas along

the west coast of North America: central California,

northern California, Oregon, southern Washington,

northern Washington, and British Columbia.

Information provided for each area includes summaries

of (1) qualitative and nonstandardized quantitative

historical data from 1800 to 1978 of numbers of murres

attending colonies and known or suspected human

activities at colonies, (2) current breeding population

size and distribution of colonies, and (3) major

population changes identified between 1979 and 1995

(using standardized whole-colony count methods) and

factors known or suspected to be associated with

changes observed. Significant events documented after

1995 were noted where appropriate but data used for

population trend analysis were restricted to the 1979–

95 period.

Historical information on murres at colonies helped

to derive a general concept of long-term colony and
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 37

regional population trends prior to 1979. To summarize

historical information, and without the aid of

computerized databases or search processes, we

consulted all available published and unpublished

sources known to us from prior research as follows:

California (H. R. Carter, see Appendix B), Oregon (R.

W. Lowe), Washington (U. W. Wilson and H. R. Carter),

and British Columbia (M. S. Rodway and H. R. Carter).

To augment historical information, H. R. Carter also

examined egg records in California, Oregon,

Washington, and British Columbia in major museum

collections, including Western Foundation of Vertebrate

Zoology, Camarillo, California (WFVZ); Humboldt State

University, Department of Wildlife Museum, Arcata,

California (HSUWM); Santa Barbara Natural History

Museum, Santa Barbara, California (SBNHM); San

Diego Natural History Museum, San Diego, California

(SDNHM); University of California Berkeley, Museum

of Vertebrate Zoology, Berkeley, California (BMVZ);

National Museum of Natural History, Smithsonian

Institution, Washington, D.C. (USNM); Museum of

Comparative Zoology, Harvard University, Cambridge,

Massachusetts (MCZ); Royal British Columbia

Museum, Victoria, British Columbia (RBCM); and

University of British Columbia Zoology Museum,

Vancouver, British Columbia (UBCZM). Substantial

historical information was rediscovered in these museum

collections.

Annual survey data for each colony in 1979–95

were collated as follows: California (H. R. Carter and J.

E. Takekawa; see Appendices C, D), Oregon (R. W. Lowe;

see Appendix E), Washington (U. W. Wilson; see

Appendixes F and G), and British Columbia (M. S.

Rodway). Regional estimates of the total number of

murres attending colonies during surveys were

determined by summing single representative wholecolony counts from aerial photographic surveys for each

colony within a particular year in central and northern

California and southern and northern Washington (see

Appendix A for survey methods and summary). For these

areas, we summed counts only when all or most colonies

were judged to have been surveyed in a generally

standardized and compatible fashion in the same year.

For Oregon, we summed counts for 15 sample colonies

that were surveyed and counted annually between 1988

and 1995. This sample of colonies is spread along the

entire Oregon coast, but several large colonies are not

included because of extensive counting time required.

Annual sums of whole-colony counts in each geographic

area are presented in Appendix H. In keeping with

seabird colony catalogs (Sowls et al. 1980; Speich and

Wahl 1989; Rodway 1991; Carter et al. 1992), we referred

to specific colonies or subcolonies as they have been

previously defined, which allowed easy cross referencing

between sources.

We also summed whole-colony counts within

“colony complexes” in California and Washington. We

considered a colony complex to be a geographic subunit,

composed of several colonies close together. Such

subunits reflected major geographic assemblages of

breeding murres that resulted from the distribution of

suitable breeding habitat, accounted for the greater

potential for interaction between nearby colonies, and

accounted for inconsistent definitions of what

constituted a colony in seabird colony catalogs (Sowls

et al. 1980; Speich and Wahl 1989; Carter et al. 1992).

We lumped adjacent rocks, islands or mainland cliffs

with groups of breeding murres into colony complexes

when they were within about 5 km of each other. Colony

complex totals are presented in Appendix H.

Regression analysis has been used extensively to

assess avian population trends and is a widely accepted

method of demonstrating and measuring the rate of

population change over a period of time (Sauer and

Droege 1990). We used regression analysis to calculate

rates of population change (percent per annum change

with 95% confidence intervals) for each area within

certain periods and to determine statistical significance

for population trends identified in these periods (see

Appendix H). We conducted linear regression analyses

on single, annual sums of whole-colony counts in

geographic areas over a period of years, only including

standardized and compatible data. Because of

availability of data and previously identified population

changes, we conducted regressions over all years of

available data between 1979 and 1995, as well as on

series of years where our direct inspection of data

indicated a distinct trend (i.e., increasing, decreasing,

or no change). This approach led to the following

regression periods: central California (1979–89, 1985–

95, 1979–95), northern California (1979–89), Oregon

(1988–95), and Washington (1979–86, 1984–95, and

1979–95). Significant regressions (P < 0.050) are

reported in the text and presented in figures. Where

significant trends were not detected, changes in wholecolony counts are discussed in the text and presented in

figures.

For certain objectives, we estimated the number of

breeding adults at a colony and summed colonies to

determine the size of a breeding population. Wholecolony counts of murres can be adjusted with a k

correction factor to convert whole-colony counts to

either “number of breeding pairs” or “number of

breeding individuals” (Nettleship 1976; Birkhead and

Nettleship 1980; Sowls et al. 1980; Takekawa et al.
38 USGS/BRD/ITR–2000-0012

1990; Carter et al. 1992; Sydeman et al. 1997). We

applied a k correction factor to estimate the number of

breeding individuals. Sydeman et al. (1997) calculated

k from data collected between 1985 and 1995 at the

South Farallon Islands in central California. An average

k of 1.671 (SE = 0.026; n = 11) was obtained with

relatively little variation among years (see Appendix

A). A k was not determined for any colony in northern

California, Oregon, or Washington. A very different k

was found for Triangle Island in British Columbia (see

Appendix A). For all estimates of the number of breeding

murres in California, Oregon, and Washington, we used

a constant k correction factor of 1.67. This approach

allowed rough estimation of population sizes for general

comparisons. However, given concerns about potential

variation in k correction factors between different parts

of the breeding range, season, times of day, and years,

we did not apply a k correction factor to whole-colony

count data before examining population trends.

Summary of Population Data

California

Historical Background on Breeding Colonies

in California, 1800–1978

The history of the common murre on the west coast

of North America before 1900 is best documented in

California. Settlement of southern and central California

by the Spanish began in the eighteenth century, much

earlier than European colonization farther north along

the west coast of North America south of Alaska.

Frequent activity by early settlers probably occurred at

many colonies, mainly from the mid-nineteenth through

the early twentieth centuries when rapid immigration

occurred after California was ceded to the United States

by Mexico in 1848. Except at the South Farallon Islands,

little documentation is available. In northern California,

native people may have occasionally visited certain

murre colonies by canoe to obtain eggs or birds until

the late nineteenth century when populations of native

people were reduced to very low levels. Whereas diets

of native people in northern California did not focus on

seabirds, they did feed extensively on marine foods,

which probably included seabirds on occasion (Heizer

and Elsasser 1980). Such food gathering and hunting

activities were limited to accessible offshore rocky stacks

and islets. In central California, visitation of murre

colonies by native people probably was infrequent

because they did not use large ocean-going canoes in

this coastal area. Native people were not known to visit

the South Farallon Islands, which are located far from

shore. Below, we present a brief synopsis of the known

history of murre colonies in California, and we refer the

reader to Appendix B for a detailed account with citation

to historical literature. Given extensive historical

changes in California murre populations, current

population status and trends of murres must be viewed

with these earlier events in mind.

At the South Farallon Islands, the harvest of murres

and their eggs and the human occupation of the islands

for nearly two centuries have greatly impacted the murre

population. In 1818, the Russian sealing station on the

South Farallon Islands (operated from 1812 to 1838)

reported killing birds (probably murres) for meat and

feathers. Egging was first reported in 1827. Commercial

egging began in 1849, was made illegal in 1881, but

continued until at least 1904. From 1850 to 1892,

between 180,000 and 600,000 eggs were harvested

annually, before falling to about 90,000 in 1896. Ainley

and Lewis (1974) estimated that 400,000 birds may

have bred at the South Farallon Islands, based on their

review of egging records. However, our reinterpretation

of historical records suggests numbers of murres were

probably much higher, possibly between 1 and 3 million

breeding birds (Appendix B). Hunting, egging, human

occupation, and disturbance of these small islands, as

well as heavy oil pollution, led to a dramatic decrease

in the size of the murre colony at the South Farallon

Islands. In 1909, the North Farallon Islands were

included in the Farallon Reservation for Protection of

Native Birds (later the Farallon National Wildlife

Refuge). By 1911, there were fewer than 20,000 murres

and very small numbers were reported in 1923, 1930,

and 1933. Several thousands of murres died in the 1937

Frank Buck oil spill at the Golden Gate (Aldrich 1938;

Moffit and Orr 1938). In the 1950s and 1960s, murre

numbers at the South Farallon Islands grew and 6,718

were counted in 1959. In 1969, the South Farallon Islands

were added to the Farallon National Wildlife Refuge.

Additional protection from human disturbance was

provided when the California Department of Fish and

Game prohibited low overflights (although some still

occurred) over the Farallon Islands Game Refuge in

1971. A detailed ground survey in 1972 revealed about

20,000–45,000 birds and the colony continued to

increase to about 30,000–60,000 from 1975 to 1979.

Estimates of population size varied widely owing to

differences in census techniques, the degree of

completeness of surveys, and irregular use of k correction

factors. The increase between 1950 and 1982 reflects

high levels of breeding success, reduction in human

disturbance at the islands (especially since the early

1970s), and low levels of anthropogenic-related deaths

at sea except for the 1971 San Francisco oil spill when

many thousands died (Smail et al. 1972; Carter 1986;

Boekelheide et al. 1990).
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 39

Few other islands in central and northern California

were large enough for occupation by settlers (see

Appendix I), but many colonies were accessible to

people with small boats. Several colonies may have

been extirpated during this period by egging and other

activities. However, only the loss of colonies at Prince

Island (c. 1912) and San Pedro Rock (c. 1908) are well

documented. Egging was documented at other colonies,

including the North Farallon Islands in the 1880s and

1890s, Point Reyes in 1897, and possibly Mendocino

County in 1900. Egging probably occurred at colonies

near settlements at Trinidad and Crescent City. In

addition to egging, extensive disturbance and human

access resulting from construction and operation of the

Ocean Shore Railroad may have contributed to the loss

of the San Pedro Rock colony. Similarly, egg gathering

for private collections may have contributed to the loss

of the Prince Island colony, the only location in southern

California where murre eggs were known to be collected

between 1885 and 1912. Extensive oil pollution in the

early twentieth century probably affected all colonies

in central California. Colonies in northern California

also may have been affected by oil pollution, judging

by observations of oiled murres on beaches in 1909–10

(C. I. Clay, unpublished field notes). Other murre colonies

may have been extirpated by eggers or others before

documentation in the Channel Islands and throughout

the coasts of San Luis Obispo, Monterey, Sonoma and

Mendocino Counties where appropriate breeding

habitats exist. Murres were rarely seen in southern

California before the 1960s until populations in central

California began to increase, with some murres moving

south after breeding (Pyle 1953; Unitt 1984; Lehmann

1994; Manuwal and Carter 2001).

The murre population in northern California seems

to have increased markedly from the 1940s to the late

1970s following earlier decreases that resulted from

activities of early settlers and use of certain islands by

native people. A small colony was reported at Castle

Rock between 1917 and 1935, but the population

increased to 5,000–10,000 breeding pairs in 1956–61

and to 20,000–40,000 breeding pairs in 1970. In 1980,

Castle Rock was included in the National Wildlife

Refuge System. Increases at Castle Rock in the midtwentieth century appear to reflect growth and recovery

following use by native peoples, egging, and the use of

the island for grazing by domestic animals. At Whaler

Island, near Crescent City, breeding was documented in

1928. Since 1939, the island was partly quarried and a

breakwater has connected it to the mainland allowing

easy access by rats and humans, which has prevented

breeding by most seabirds. Murres did not breed at

Flatiron Rock from 1910 to 1934, but 1,000 breeding

pairs were noted in 1969 and many thousands currently

breed there. This colony is close to the long-settled port

of Trinidad and would have been very accessible to

commercial eggers by boat and native people by canoe

(see Appendix I: Figure I-15). In fact, large numbers of

eggs were collected in 1897–1901 from several

unidentified islands, apparently in the Trinidad area,

indicating that higher population levels may have

existed at that time. Nearby Green Rock seemed to be

the only murre colony that existed in the Trinidad area

from 1917 to 1941, with about 2,000 birds noted in

1941. By 1969–70, murres were found at most colonies

where they have been recorded regularly since 1979

(except for Mendocino County), indicating population

increase between the 1940s and late 1960s.

Prior to the 1980s, certain California murre colonies

outside of the Farallon and Castle Rock National

Wildlife Refuges were protected within the Point Reyes

National Seashore (i.e., Point Reyes, Point Resistance,

Millers Point Rocks, and Double Point Rocks), Redwood

National Park (i.e., False Klamath Rock and Sister

Rocks), and Channel Islands National Park (i.e., Prince

Island) in 1968, 1972, and 1980, respectively. Earlier,

Prince Island had received partial protection when

reserved for lighthouse purposes in 1917 and transferred

to the U.S. Navy in 1934. Additional protection for

murre colonies after 1980 in California are mentioned

later in this chapter.

Current Population Size and Distribution of

Breeding Colonies in California

By 1995, 26 murre colonies had been described in

California, including 22 colonies used between 1979

and 1995 and 4 colonies extirpated earlier in the

twentieth century (Appendixes B–D). The colonies

separate into two groups: the northern California group

consisting of 15 colonies in Del Norte, Humboldt, and

northern Mendocino Counties (Figure 2.1); and the

central California group consisting of 10 colonies in

Marin, San Francisco, San Mateo, and Monterey

Counties (Figure 2.2). One colony was previously

reported in southern California (Santa Barbara County)

at Prince Island, a record that represented the southern

breeding limit known for the species in California and

the world (Figure 2.2). Breeding has been confirmed

with observations of eggs or chicks at all colonies in

central California, the extirpated Prince Island colony

in southern California, and most colonies in northern

California (see Appendix B; Sowls et al. 1980,

unpublished data archive; Boekelheide et al. 1990;

Carter et al. 1992, unpublished data archive;

McChesney et al. 1994; H. R. Carter, unpublished data;

M. W. Parker, unpublished data; G. J. McChesney,
40 USGS/BRD/ITR–2000-0012

personal observation). Murres breed regularly at the

South Farallon Islands, Point Reyes, and Castle Rocks

and Mainland colonies where long-term studies of murre

biology and reproductive success are under way (see

Chapter 1; Boekelheide et al. 1990; Parker et al. 1997,

1998, 1999; McChesney et al. 1998, 1999).

The entire breeding population of murres in

California was estimated in 1980, 1982, and 1989 (Sowls

et al. 1980; Briggs et al. 1983; Carter et al. 1992). On

the basis of summed, whole-colony counts for all

colonies, with a k correction factor, we calculated total

populations of 467,100, 514,900, and 351,600 breeding

murres in 1980, 1982, and 1989, respectively. The

central California population held 42, 43, and 26% of

the total in each of the 3 years surveyed, respectively.

The lower percentage in 1989 reflects extensive decline

in central California from 1982 to 1989, and little change

in northern California, except for lower revised estimates

at Castle Rock (see later).

In central California, colonies can be grouped into

six colony complexes—two offshore complexes at the

South and North Farallon Islands (about 20–30 km from

the mainland) and four nearshore complexes (i.e., coastal

rocks within 1 km of the mainland and adjacent mainland

cliffs) at Point Reyes, Points Resistance–Double, Devil’s

Slide, and Castle–Hurricane (Figure 2.2; Appendixes C

and D). The largest colony complex was the South

Farallon Islands where an estimated 102,700 murres bred

in 1982 (Table 2.1). Whole-colony counts at the South

Farallon Islands averaged 38,019 birds per survey from

1979 to 1995, which corresponded to an estimated

63,500 breeding birds (Table 2.1). Two other large colony

complexes were at the North Farallon Islands and Point

Reyes, which averaged 34,600 and 23,000 breeding

birds, respectively, during the same time period.

Breeding on inaccessible mainland points occurs only

at Point Reyes and Castle Rocks and Mainland. Three

smaller colonies (Point Resistance, Millers Point Rocks,

and Double Point Rocks) exist south of Point Reyes

within the Points Resistance–Double complex. Colonies

exist south of San Francisco at the Devil’s Slide complex

(including the Devil’s Slide Rock and Mainland colony

and the long-inactive colony at San Pedro Rock), as

well as at the Castle–Hurricane complex (Figure 2.2).

The southernmost colony in California in 1979–95 was

Hurricane Point Rocks.

Figure 2.1. Distribution of common murre colonies in northern California

(Del Norte to Sonoma Counties).

Figure 2.2. Distribution of common murre colonies in central California

(Marin to Monterey Counties) and southern California (Santa Barbara

County).
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 41

A new colony, “Bench Mark-227x,” was

temporarily established within the Castle–Hurricane

complex in 1996–98 but subsequent breeding did not

occur in 1999–2001 (Parker et al. 1998, 1999;

McChesney et al. 1999; M. W. Parker, unpublished

data). In March–June 1999, 3–9 murres attended but

did not breed at Prince Island, in association with

nesting Brandt’s cormorants (Phalacrocorax

penicillatus; H. R. Carter, unpublished data). Use of the

Bench Mark-227x colony area had not been noted

previously, but murres had been recorded in the vicinity

of Prince Island since 1991 (Carter et al. 1992;

McChesney et al. 1995).

 In northern California, colonies are most often on

offshore rocks within 1 km of the mainland, except for

the small isolated colony at Redding Rock — 7 km

offshore. The largest colony complex in northern

California (and the state) in recent decades was at Castle

Rock, where 142,400 breeding birds were estimated in

1982 (Briggs et al. 1983; Appendix C). However, 1979–

82 counts may have overestimated the size of this dense

colony, which was estimated to be about 100,000 and

107,700 breeding birds in 1986 and 1989, respectively

(Takekawa et al. 1990; Carter et al. 1992). Four other

large colony complexes are found at False Klamath,

Trinidad (including colonies at White Rock, Green

Rock, Flatiron Rock, Blank Rock, and Pilot Rock), Cape

Mendocino (including False Cape Rocks and Steamboat

Rock colonies), and Vizcaino (including Cape Vizcaino

and Rockport Rocks colonies; Table 2.2). Mainland

breeding occurs only at one subcolony on an

inaccessible point at Rockport Rocks. Smaller colonies

are present at Sister Rocks (within the False Klamath

complex) and Redding Rock. By 1995, the

southernmost colony (where breeding was certain) in

northern California was Cape Vizcaino. However, in

1997, breeding was confirmed at three small colonies

(Newport Rocks, Kibesillah Rock, and Goat Island Area)

south of Cape Vizcaino in northern Mendocino County

where attendance had been noted in recent years (Carter

et al. 1992, 1996; see below).

Between 1979 and 1995, murres attended several

rocks in California where breeding was not confirmed

(Sowls et al. 1980, unpublished data; Briggs et al. 1983;

Table 2.1. Average and maximum sizes for nine breeding colonies of common murres in central California, 1979–1995 (see Appendixes C and D).

Mean Mean number of Years Maximum Maximum number Year of

Ranka Colony name countb breeding adultsc of data count of breeding adultsc maximum

1 South Farallon Islands 38,019 63,500 12 61,510 102,700 1982

2 North Farallon Islands 20,717 34,600 12 31,428 52,500 1980

3 Point Reyes 13,755 23,000 13 26,337 44,000 1982

4 Double Point 4,116 6,900 13 8,850 14,800 1980

5 Point Resistance 3,046 5,100 13 4,440 7,400 1980

6 Castle Rocks & Mainland 1,140 1,900 9 2,275 3,800 1980

7 Hurricane Point Rocks 692 1,200 10 1,500 2,500 1981

8 Devil’s Slide Rock & Mainlandd 446 700 11 1,750 2,900 1980

9 Miller’s Point Rocks 256 400 9 713 1,200 1995

a

 Ranked in order of mean colony size.

b

 Only sites with at least five years of data considered suitable for trend analysis were included. Lower quality data for certain

years and colonies were not included.

c Number of breeding adults was obtained by multiplying mean or maximum count by a k correction factor of 1.67, and

rounding to the nearest hundred.

d

 No breeding occurred from 1986 to 1995 (see text).

Table 2.2. Average and maximum sizes for eight breeding colonies of common murres in northern California, 1979–1995 (see Appendixes C and

D)a.

Mean Mean number of Years of Maximum Maximum nunber Year of

Rank Colony name count breeding adults data count of breeding adults maximum

1 False Klamath Rock 26,650 44,500 6 31,801 53,100 1982

2 Green Rock 24,327 40,600 6 32,934 55,000 1980

3 Flatiron Rock 16,799 28,100 8 25,494 42,600 1995

4 False Cape Rocks 8,847 14,800 7 12,426 20,800 1995

5 Cape Vizcaino 4,194 7,000 6 4,950 8,300 1995

6 Steamboat Rock 4,089 6,800 5 5,454 9,100 1989

7 White Rock 2,614 4,400 5 3,277 5,500 1981

8 Redding Rock 923 1,500 6 1,632 2,700 1989

aThe largest colony at Castle Rock was excluded (see text). Symbols and format as in Table 2.1.
42 USGS/BRD/ITR–2000-0012

Carter et al. 1992, 1996; Appendixes C and D). Near

colonies in northern and central California, such

attendance has been noted at Rock R, Sugarloaf Island,

and Martin’s Beach (Figures 2.1 and 2.2; Appendixes C

and D). In addition, such attendance was recorded south

of known breeding areas in Mendocino and Sonoma

Counties at Newport Rocks, Kibesillah Rock, Goat

Island Area, White Rock, and Gualala Point Island

(Figure 2.1; Appendixes C and D). Briggs et al. (1983)

also noted murres on Bruhel Point Rocks (herein referred

to as Newport Rocks). H. L. Cogswell (unpublished field

notes) also noted at least 30 murres “resting on coastside

rock in ocean below sea cliff” at Pillar Point or Moss

Beach on 27 November 1952 and at least 6 murres on “a

small rocky islet offshore” of West Cliff Drive at Santa

Cruz on 23 July 1967 (Figure 2.2).

Carter et al. (1992) classified attendance at Rock R

and Goat Island Area in 1989 as newly-formed colonies

without determining whether eggs were laid. Here, we

reclassified these observations as “attendance without

confirmed breeding.” Breeding was ultimately verified

at Kibesillah Rock, Newport Rocks, and Goat Island

Area on 12-13 July 1997, when about 5–10 chicks and

clumps of other birds in incubation or brooding postures

were observed by telescope from the mainland (G. J.

McChesney, personal observation). In retrospect, these

colonies appearred to be forming during the 1989–95

period. Numbers of murres at Newport Rocks and

adjacent Kibesillah Rock increased from 7 birds in 1993

to 542 birds in 1995 (Carter et al. 1996). Similarly, small

numbers of birds were noted at Goat Island Area in 1989,

1994, and 1995 and at Rock R in 1980, 1989, and 1994

(Sowls et al. 1980; Carter et al. 1992, 1996). From 1989

to 1995, birds were present in clumps or rows, with some

individuals in incubation postures (as seen in aerial

photographs), which suggests possible breeding. In

addition, one murre was observed carrying a fish

(possibly to feed a chick or for courtship) in flight to the

Goat Island Area in June 1989 (Carter et al. 1992;

unpublished survey data). However, breeding probably

was not occurring at Newport Rocks (1993–95) and

Sister Rocks (1989–95), where all birds were standing

and scattered during aerial photographic surveys.

Population Trends in Central California, 1979–

1995

From 1979 to 1982, overall numbers of murres

attending colonies in central California increased

(Figures 2.3 and 2.4; Appendix C; Sowls et al. 1980;

Briggs et al. 1983). This increase was well documented,

mainly at the largest colony at the South Farallon Islands

where boat and ground surveys also documented the

increase (Boekelheide et al. 1990; Takekawa et al. 1990;

Sydeman et al. 1997). At the South Farallon Islands, the

increase reflected part of a long-term increase that began

in the 1950s (Appendix B; Carter 1986; Boekelheide et

al. 1990; Sydeman et al. 1997). No increase occurred at

the nearby North Farallon Islands during that time,

possibly because of total occupation of more limited

available breeding habitat (see Appendix I: Figure I-9)

and lower levels of past human disturbance compared

to the South Farallon Islands. Counts at Point Reyes

and the Points Resistance–Double complex varied, but

also appeared to increased from 1979 to 1982. The

effects of low overflights by aircraft (and possibly close

approach by boats) may have contributed to this

variation in numbers. However, the Gulf of the Farallones

National Marine Sanctuary was created in 1981, which

prohibited low overflights (below 1,000 feet or 305 m)

over the colonies. McChesney et al. (1998) also clarified

that counts in 1979–81 at Point Reyes underestimated

numbers of murres present because of incomplete and

low-quality photographs. Taking this into account, little

change was evident at Point Reyes between 1979 and

1982. Between 1980 and 1982, murre numbers were

reduced at the Devil’s Slide complex and decline was

evident at the Castle–Hurricane complex.

Between 1979 and 1989, all colony complexes in

central California underwent large declines of 8.7 to

28.5% per annum, (0.001 < P < 0.020; Figure 2.3;

Appendix H). The overall population declined 9.9%

per annum (P = 0.002; Figure 2.4; Appendix H). Most

decline occurred between 1982 and 1985, as further

verified with ground-based observations at the South

Farallon Islands (Boekelheide et al. 1990; Takekawa et

al. 1990). Plot observations and ground and boat surveys

at the South Farallon Islands showed low attendance

and low breeding success during the severe El Niñorelated breeding conditions in 1983–84 (Boekelheide

et al. 1990; Takekawa et al. 1990; Sydeman et al. 1997).

Although no aerial photographs were taken in 1983–

84, numbers at colonies in 1985 and 1986 after breeding

conditions had returned to normal were still much lower

than in 1981 and 1982 (Appendix C). By 1986, the

Devil’s Slide Rock and Mainland colony had essentially

disappeared with between 0 and 128 murres in 1986–

87 and 0–5 murres in 1988–95.

Between 1987 and 1990, counts at most colonies

reached their lowest levels compared to 1981–82

(Figure 2.3; Appendix D). The Castle–Hurricane

complex reached the lowest level of all extant colony

complexes (1,047 and 1,093 birds counted in 1988 and

1989, respectively) with loss of subcolonies and only

small groups of birds on several remaining subcolonies.

The small Millers Point Rocks colony (within the Points

Resistance–Double complex) may have been nearly
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 43

Number of murres counted (in thousands)

Central California

0

20

40

60

80

100

120

140

160

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Year

period

1979-1989

1985-1995

r-square

0.883

0.829

p-value

0.002

0.002

Figure 2.4. Trends in whole-colony counts for

common murres in central California, 1979–95

(see Appendix H).

Figure 2.3. Trends in whole-colony

counts for six colony complexes of

common murres in central California,

1979–95 (see Appendix H).

Numbers of murres counted (in thousands)

Year

Point Reyes

0

10

20

30

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Points Resistance – Double

0

5

10

15

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

North Farallon Islands

0

10

20

30

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Devil's Slide 

0.0

0.5

1.0

1.5

2.0

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

South Farallon Islands

0

20

40

60

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Castle – Hurricane 

0

1

2

3

4

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996
44 USGS/BRD/ITR–2000-0012

extirpated during this decline since only 23 birds were

found in 1987. However, this colony grew to 380 birds

by 1990, possibly because of intercolony movements

from nearby colonies within this complex. However, a

remarkable increase occurred at the South Farallon

Islands between 1989 and 1990. In retrospect, this

upswing signaled the end of the decline and the start of

an increase for the central California population. Ground

and boat surveys and plot counts from 1989 to 1995 at

the South Farallon Islands also confirmed the end of

decline by 1990 (Sydeman et al. 1997, 1998).

The decline of the central California population

between 1979 and 1989 and the loss of the Devil’s Slide

Rock and Mainland colony have been attributed mainly

to extensive gill-net and oil-spill deaths, and reduced

productivity related to the severe 1982–83 El Niño

(Carter 1986; Carter and Ainley 1987; Salzman 1989;

Takekawa et al. 1990; Wild 1990; Piatt et al. 1991;

Swartzman and Carter 1991; Carter et al. 1992, 1995;

Ainley et al. 1994; Sydeman et al. 1997; McChesney et

al. 1998, 1999). More than 75,000 murres died in 1979–

87 in central California as a result of gill-net fisheries

(Takekawa et al. 1990). High mortality was attributed

to the consistent spatial and temporal overlap of large

numbers of feeding murres and high gill-net fishing

effort in nearshore waters of Monterey Bay, Gulf of the

Farallones, and Bodega Bay area from 1980–86. Most

severe declines occurred at colonies located nearest areas

of highest gill-net mortality. Two major oil spills occurred

during this period and killed more than 8,000 murres.

In November 1984, the Puerto Rican oil spill occurred

off the Golden Gate, killing 1,500–2,000 murres (PRBO

1985; Ford et al. 1987). Mortality probably was focused

on large colonies at the Farallon Islands and Point Reyes.

In January–February 1986, the Apex Houston oil spill

occurred between San Francisco and Monterey Bay,

killing 6,300–7,500 murres (Page and Carter 1986; Ford

et al. 1987; Page et al. 1990; Siskin et al. 1993). Mortality

probably was spread more widely over all colonies with

greatest impacts at Devil’s Slide Rock and Mainland,

Castle Rocks and Mainland, and Hurricane Point Rocks.

The loss of the Devil’s Slide Rock and Mainland colony

(first noted in June 1986) was associated with this

mortality, although earlier gill-net mortality had reduced

the colony beforehand (Takadawa et al. 1990; Piatt et

al. 1991; Swartzman and Carter 1991). Many smaller

spills also killed thousands of murres between the late

1970s and 1989 (Stanzel et al. 1988; Carter 1997; Nur

et al. 1997).

Low productivity in the 1982–83 El Niño

undoubtedly affected the ability of the central California

population to recover in the late 1980s. However, it was

not possible to detect whether or not increased deaths

of adult or subadult murres resulted during severe El

Niño-induced winter weather conditions in 1982–83.

At this time, high numbers of murres killed in gill nets

were washing up on beaches but the cause of death for

many nonoiled beached birds could not be determined

(Stenzel et al. 1988). A small part of the reported decline

at certain colonies may have been related to (1)

methodological differences between surveys in 1979–

82 and 1985–89, (2) undocumented human disturbances

from low overflights and boats, or (3) depredation at

colonies by peregrine falcons (Falco peregrinus) and

common ravens (Corvus corax ; Sydeman 1993;

McChesney et al. 1998, 1999; M. W. Parker,

unpublished data).

The marked decline in the central California murre

population between 1979 and 1989 far outweighed the

relatively small increase by 1995 after this decline.

Between 1985 and 1995, the total population increased

5.9% per annum (P = 0.002), whereas colony complexes

increased between 4.6 and 7.2% per annum

(0.001 < P < 0.020), excluding the extirpated Devil’s

Slide complex (Figures 2.3 and 2.4; Appendixes C, D,

and H). In 1992, severe El Niño breeding conditions

occurred and murre attendance at the South Farallon

Islands was low (Sydeman et al. 1997). However, wholecolony counts at the South Farallon Islands and Points

Resistance–Double complexes were still higher in 1993

than in 1987–89. The North Farallon, Point Reyes, and

Points Resistance–Double complexes increased after

1990. At the Castle–Hurricane complex, increase was

not noted between 1987 and 1993, but higher numbers

did occur in 1994–95. Overall, increases that began at

the South Farallon Islands in 1990, and later at most

other colonies, were sustained despite interruption by

the severe 1992–93 El Niño. Highest colony complex

counts in the 1993–95 period were still lower than peak

counts in the 1979–95 period (Figure 2.3; Appendixes

C and D). Increases in 1993–95 at the largest complexes

(i.e., South Farallon Islands, North Farallon Islands, Point

Reyes, and Points Resistance–Double) are encouraging,

but natural recovery of the central California population

to 1979–82 levels may require at least another decade

without additional major detrimental effects. Human

disturbance at colonies has been reduced greatly

through additional regulations and enforcement.

However, sporadic disturbance events continue. For

example, extensive disturbance to breeding murres

resulted from low overflights by a U.S. Coast Guard

helicopter responding to the grounding of the M/V

Wayfarer at Point Reyes in 1995 (McChesney et al.

1998; Thayer et al. 1998, 1999).

Funds from the settlement of the Apex Houston oil

spill litigation were used for a restoration project at the
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 45

Devil’s Slide Rock and Mainland colony (Graham 1996;

Parker et al. 1997, 1998, 1999; Helmuth 1999; Parker

1999). Breeding did not occur at this colony between

1986 and 1995. Using social attraction techniques, the

USFWS, Humboldt State University, and the National

Audubon Society restored breeding by small numbers

of murres at this colony in 1996–2000 (i.e., increasing

to 98 breeding pairs by 2000)

The southernmost colony at Hurricane Point Rocks

also did not increase significantly between 1987 and

1995. The increase in the Castle–Hurricane complex in

1993–95 has occurred mainly at the Castle Rocks and

Mainland colony. Both of these colonies are

geographically isolated from other colonies in central

California, were affected greatly during the decline, and

remain susceptible to extirpation. Slow recovery at these

colonies by 1995 may reflect poor breeding success,

immigration, and continued anthropogenic effects

(especially gill-net deaths and human disturbance; Julian

and Beeson 1995; Carter et al. 1998; McChesney et al.

1999; M. W. Parker, unpublished data). Establishment

of the California Islands Wildlife Sanctuary in 1983,

which prohibited disturbance of seabirds and marine

mammals, may have reduced human disturbance at the

Castle–Hurricane and Devil’s Slide colony complexes.

In 1992, the Castle–Hurricane and Devil’s Slide

complexes were provided more protection from human

disturbance through the creation of the Monterey Bay

National Marine Sanctuary that prohibited most

overflights below 305 m (1,000 feet). However,

disturbances from low-flying aircraft still continue.

Depredation by peregrine falcons does not seem to be

seriously affecting these colonies (M. W. Parker,

unpublished data).

In central California, slow population recovery

since 1990, and no recovery at certain colonies, probably

resulted from long-term and extensive anthropogenic

effects, especially mortality from gill nets and oil spills

and human disturbance from 1979 to 1987. Natural

factors (i.e., reduced breeding effort and success during

the severe 1982–83 El Niño) contributed to the decline

and also increased recovery time. Between 1988 and

1995, the effects of deaths from gill-nets and oil-spills

continued, but at reduced levels compared to 1982–88

(Julian and Beeson 1995; Sydeman et al. 1997;

McChesney et al. 1998, 1999). High breeding success

at the South Farallon Islands has occurred throughout

1979–95, except during severe El Niños in 1983–84

and 1992–93 (Boekelheide et al. 1990; Sydeman et al.

1997). Thus, the increase seems mainly a result of

reduced anthropogenic factors. However, continuing

low-level anthropogenic effects from oil pollution, gillnet fishing, and human disturbance may limit recovery.

Reduced breeding effort and success during recent El

Niños (i.e, 1992–93 and 1997–98) also may slow the

rate of recovery. If long-term climate change has caused

a significant reduction of prey resources, this factor also

may have influenced changes observed and slowed

recovery during the 1990–95 period.

Population Trends in Northern California,

1979–1995

From 1979 to 1982, numbers of murres attending

many colonies in northern California increased (Figures

2.5 and 2.6; Appendix C; Sowls et al. 1980; Briggs et

al. 1983). Increases were noted at all colony complexes,

except Trinidad (including Flatiron and Green rocks)

which remained relatively stable despite much variation

at individual colonies. Some methodological

differences between researchers in 1979–80 (Sowls et

al. 1980) and 1980–82 (Briggs et al. 1983) may have

slightly affected survey results reported for these two

periods. In addition, 1981 data quality may have been

lower at several colonies (K. T. Briggs, personal

communication).

Few anthropogenic or natural factors were

documented to affect colonies in northern California at

this time. In 1980, Castle Rock received protection

through designation as a National Wildlife Refuge,

although occasional low overflights may have

continued. Both False Klamath Rock and Sister Rocks

are located within Redwood National Park, which may

have contributed to some disturbance from low

overflights related to park viewing. Variations in

numbers of murres counted at Redding Rock in 1979–

82 (Appendix C) probably reflected disturbance from

U.S. Coast Guard crews servicing an automated light on

this site during the breeding season. This source of

disturbance was first noted in 1979 (Sowls et al. 1980;

unpublished survey data), but probably occurred earlier.

In addition, California sea lions (Zalophus

californianus) “haul out” high up on this rock and may

adversely affect breeding success of murres in some

years (see Appendix I: Figure I-18; H. R. Carter and M.

W. Parker, personal observations). Variable patterns

within the Trinidad complex appear to represent

intercolony movements between five nearby colonies.

In fact, corresponding changes in murre numbers at

Flatiron Rock and Green Rock (i.e., two large and

adjacent colonies in the Trinidad complex) were

recorded between May and July surveys in 1980–82

(Figure 2.5; Appendix C). Reasons for intercolony

movements were not determined, but hundreds of small

dead murre chicks were found on Flatiron Rock on 21

August 1980 (Sowls et al. 1980, unpublished survey

data).
46 USGS/BRD/ITR–2000-0012

Figure 2.5. Changes in wholecolony counts of common murres at

selected colonies in northern

California, 1979–95 (see Appendixes

C and D). At Castle Rock, 1979–82

counts were not considered to be

comparable to 1986–89 counts and

are separated by a dashed line. A

decline between these periods has

not been inferred (see text).

Year

Numbers of murres counted (in thousands)

False Klamath Rock

0

5

10

15

20

25

30

35

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Green Rock

0

5

10

15

20

25

30

35

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Flatiron Rock

0

5

10

15

20

25

30

35

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

False Cape Rocks

0

5

10

15

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Cape Vizcaino

0

5

10

15

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Castle Rock

0

15

30

45

60

75

90

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Sowls et al. (1980) reported four suspected new

colonies in 1979–80 not thought to have been present

in 1969–70 (Osborne and Reynolds 1971; Osborne

1972): Sister Rocks, Blank Rock, Pilot Rock, and Cape

Vizcaino. However, we considered that some or all of

these colonies may have been overlooked in earlier

surveys (i.e., these focused on large colonies) or sporadic

attendance may have reflected intercolony movements

within colony complexes. For instance, murres were

noted by other observers at Blank Rock in March 1965

and at Pilot Rock in 1966–69 (Appendix B). No birds

were reported at Blank Rock in 1979, but small numbers

were present in 1980–81. On the other hand, Cape

Vizcaino was surveyed in August 1969, at a time when

breeding may have been finished. We considered small

numbers of murres attending Sister Rocks in 1980–82

to represent an active colony because about 30

“brooding” birds were reported on 20 June 1980 and

birds were present on 19 May and 25 July 1980 (Sowls

et al. 1980, unpublished survey data). However, no birds

were reported there on 22 May 1979 and breeding has

not been confirmed subsequently.

Overall, the increase in the northern California

population (1979–82) seemed to reflect continuation

of a long-term increase over several decades, owing to a

reduction in levels of human disturbance (Appendix

B). For instance, from 1970 to 1979, murre counts

increased at Castle Rock (i.e., from about 32,000 to

76,000 birds), Green Rock (i.e., from about 20,000 to

25,000 birds), and Flatiron Rock (i.e., from about 5,000

to 15,000 birds). Although counting techniques were

not directly comparable between 1970 and 1979,

substantial increase seemed to have occurred during

this extended period with continued increases through

1982.

Between 1979 and 1989, little change was noted at

many colony complexes in northern California (Figures

2.5 and 2.6). A notable exception was Castle Rock where

numbers were much lower in 1986 and 1989 than in

1979–82 (Figure 2.5; Appendixes C and D). However,

upon inspection of archived aerial photographs (J. E.

Takekawa, H. R. Carter, and K. T. Briggs, personal

communication), there was no visible difference in
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 47

breeding densities or in breeding areas used (Takekawa

et al. 1990). Differences seemed to be related primarily

to different aerial survey methods used at this large

colony (see Appendix I: Figure I-20). In 1979–82, few

photographs were taken per survey and numbers were

estimated roughly within blocks of high-density murres.

In 1986 and 1989, many photographs per survey

provided better viewing of all parts of the colony and

all murres were counted individually. Survey and

counting methods used in 1986 and 1989 were

considered to more accurately reflect colony size

(Takekawa et al. 1990; Carter et al. 1992). The severe

1982–83 El Niño may have caused lower attendance

and breeding success at Castle Rock in 1983, but the

lack of a large or sustained decline at most other colonies

from 1982 to 1986 supports the view that Castle Rock

probably had not declined to a large degree.

In 1983, establishment of the California Islands

Wildlife Sanctuary, which prohibited disturbance to

seabirds and marine mammals, may have reduced human

disturbance at several murre colonies, especially in the

Trinidad and Cape Mendocino colony complexes. In

1989, total numbers in the Trinidad complex were

similar to 1980–81, (Appendixes C and D). Continued

variation in murre numbers occurred at Redding Rock

(i.e., low numbers in 1986 and high numbers in 1989),

probably reflecting continued disturbance by U.S. Coast

Guard personnel. Of interest, Redding Rock was not

specifically identified as “withdrawn for lighthouse

purposes” when the California Islands Wildlife

Sanctuary was created in 1983. The Cape Mendocino

and Cape Vizcaino complexes increased from 1982 to

1989. Most growth within the Cape Vizcaino complex

occurred at the newly recolonized Rockport Rocks

colony where breeding was first noted in 1989.

The northern California population remained

relatively stable from 1979 to 1989 (Figure 2.6;

Takekawa et al. 1990; Carter et al. 1992; Appendix H).

In fact, total whole-colony counts (excluding Castle

Rock) were similar in 1982 (88,962) and 1989 (92,080).

By not considering early survey problems to be

significant at Castle Rock nor examining trends at other

colonies, other sources have indicated that the northern

California population (or Castle Rock colony) declined

greatly between 1979 and 1989 (Ainley et al. 1994;

Jaques and Strong 2001). However, as noted above, the

large change in numbers at Castle Rock between 1982

and 1986 was not visually evident in aerial photographs

(Takekawa et al. 1990). In central California, major

declines between 1982 and 1985–86 were obvious in a

comparison of aerial photographs (Carter and Ainley

1987; Takekawa et al. 1990; McChesney et al. 1998,

1999). We considered data at Castle Rock to be

reasonably comparable within the periods 1979–82 and

1986–89, but not between these periods. Additional

efforts are needed to evaluate comparability of data sets

and trends at Castle Rock, especially reexamining

1979–82 photographs and counting archived aerial

photographs for several years between 1985 and 1995

(Appendixes C and D).

In 1993–95, all colonies were surveyed, but aerial

photographs were counted only at False Klamath Rock,

Flatiron Rock, False Cape Rocks, and Cape Vizcaino

(Carter et al. 1996; Appendix D). Combined murre

numbers at these colonies increased from 1989 to 1995,

Number of murres counted (in thousands)

Northern California

0

10

20

30

40

50

60

70

80

90

100

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Year

Figure 2.6. Changes in whole-colony counts of

common murres in northern California, 1979–89,

excluding the Castle Rock colony (see Appendix

H). Linear regression for the 1979–89 period was

not statistically significant (p > 0.05).
48 USGS/BRD/ITR–2000-0012

despite the severe 1992–93 El Niño when most murres

abandoned colonies, except at Cape Vizcaino. At False

Klamath Rock, little change occurred between 1986

and 1995. By 1995, all four colonies had reached their

highest recorded levels, exceeding peak counts in

1979–82 (Figure 2.5;Appendixes C and D). At Redding

Rock, numbers of murres observed during aerial

photographic surveys have declined from 1989 to 1995,

although photographs have not been counted. This

colony may be extirpated in the near future because of

chronic human disturbance by U.S. Coast Guard

personnel.

Population stability or limited increase in northern

California from 1979 to 1995 may have resulted from

three main factors, this region may be nearing the murre

carrying capacity of available breeding habitat and prey

resources, severe El Niños and other natural events have

not had long-term effects, and anthropogenic effects

have not been extensive. Murres currently use much of

the available and suitable breeding habitat on all large

islands in Del Norte and Humboldt counties, although

breeding densities could increase further (see Appendix

I). The only large islands with substantial breeding

habitat that lack murre colonies north of Cape Vizcaino

are Hunter Rocks, Prince Island (at the Smith River),

and Sugarloaf Island. Although all three islands have

colonies of Brandt’s cormorants, past and present human

disturbance may prevent breeding by murres. In 1912,

Prince Island and Hunter Rocks were assigned to the

Tolowa tribe, and native people periodically visit these

islands. Sugarloaf Island is occasionally visited by

climbers and low overflights occur frequently. Human

disturbance has occurred regularly at Redding Rock,

but has not been well documented (Lowe 1993). During

surveys in May (1980 and 1989), murres were observed

being flushed from Green Rock and False Cape Rocks

by U.S. Coast Guard aircraft flying at or below 152 m

(500 feet) elevation (Sowls et al. 1980; Carter et al.

1992, unpublished survey data). Few predators are

known to affect murres at northern California colonies.

Few peregrine falcons and bald eagles (Haliaeetus

leucocephalus) are present, although numbers of falcons

have been increasing. On several dates in 1980,

extensive egg predation by common ravens was noted

at False Klamath Rock, causing colony disruptions

(Sowls et al. 1980; unpublished survey data). Although

few oil spills occurred in northern California by 1995,

two recent oil spills near Humboldt Bay (1997 Kure

and 1999 Stuyvesant) killed large numbers of murres (P.

R. Kelly, personal communication).

High numbers of breeding birds at colony complexes

at Cape Mendocino and Trinidad Area may have

contributed to the production of source birds that

recolonized the Cape Vizcaino and Rockport Rocks

colonies between 1969 and 1989. Between 1877 and

1942, log loading operations at and around Cottaneva

Wharf, which extended directly onto Rockport Rocks,

probably caused the earlier extirpation of these colonies

(Appendix B). Recolonization and subsequent growth

at the Cape Vizcaino colony complex may have

contributed to the production of source birds for more

recent colony formations at Newport Rocks, Kibesillah

Rock, and Goat Island in the mid-1990s. Such colony

formations in Mendocino County apparently occurred

over several decades of favorable conditions.

Oregon

Historical Background on Breeding Colonies

in Oregon, Prior to 1980

Before the arrival of settlers from Europe and the

United States, native people occupied many locations

along the Oregon coast. Shellfish, fish, seabirds, and

marine mammals were of great importance in the diet of

native people (Berreman 1944; Heflin 1966; Gould

1966, 1976; Zontek 1983; Minor et al. 1987; Lyman

1988, 1989, 1991; Gard 1990, 1992). Large mainland

village sites were associated with offshore rocks (Chase

1873; Schumacher 1877a, 1877b; Berreman 1944; Ross

1977). The pursuit and harvest of these food resources

by native people undoubtedly had great influence on

seabird colonies. Native people may have regularly

visited certain accessible murre colonies (especially near

village sites) by canoe to obtain eggs or birds. All known

colonies are located close to former village sites or

seasonal camps (Figure 2.7). Even colonies 4.8–6.4 m

(3–4 miles) offshore on Orford Reef (i.e., Redfish Rocks,

Colony numbers 270-043 to 270-047; Figure 2.7) could

have been reached by local residents during calm ocean

periods and were probably exploited on occasion for

food.

Some rocks and islands were actually occupied by

native people, at least seasonally. At Goat Island,

shellfish remains were the most common items found in

a large midden (radiocarbon dated to 880 + 70 b.p.),

along with small numbers of bones of marine mammals,

fish, and seabirds (though not murres; Gard 1990, 1992).

Murres probably did not breed on Goat Island during

coastal occupation by native peoples because the entire

island is easily accessible to humans. Seasonal

occupation by people also occurred at an unnamed rock

near Whaleshead Creek, Curry County (Colony number

270-110), where a large murre colony has occurred at

least since the 1950s (see below). At Yaquina Head,

near Newport, archaeological investigations of midden

sites on the mainland included bones of cormorants,
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 49

gulls, albatross, and loons, but not murres. Colony Rock,

just northwest of Yaquina Head (Colony number 243-

015), is connected to the mainland during low tides and

would have been accessible to native people.

Apparently, murres began nesting at this site in the 1940s

or 1950s (see below). Radiocarbon dating of cultural

material from various islands and mainland locations

indicated that coastal rocks and islands were used for

food gathering by native peoples for thousands of years.

Most murre colonies known in 1988 (68%; n = 66) are

considered accessible by climbing and these support

about 90% of the Oregon murre population. Thus, murre

numbers probably were much lower during occupation

by native people and may have been at lowest levels in

recent centuries when settlers arrived.

 After Euro–American settlers arrived, native people

were decimated by disease, then forcibly relocated to

centralized reservations (Gard 1990). The elimination

of subsistence harvest and human occupation on rocks

and islands probably allowed the Oregon murre

population to slowly expand and colonize new locations

over time. As early as 1892, murre eggs were harvested

along the southern Oregon coast by early settlers. Two

local men began a business to harvest murre eggs from

rocks off Humbug Mountain, where “The murre, which

a few years ago was not known to exist north of Cape

Mendocino are now to be found off Humbug by

thousands (Port Orford Tribune, 17 May 1892).” Murre

colonies on Island Rock (Colony number 270-049) and

Figure 2.7. Distribution of common murre

colonies in Oregon (Clatsop to Curry

Counties).
50 USGS/BRD/ITR–2000-0012

Redfish Rocks, west of Humbug Mountain, apparently

were the targets of this harvest. Harvest of murre eggs

on Island Rock and Blanco Reef (probably Redfish

Rocks off Cape Blanco) also occurred by 1901 (Port

Orford Tribune, 11 June 1901), and in 1909 it was

reported that “170 dozen eggs [2,040 eggs] were

collected in one forenoon’s work” (Port Orford Tribune,

9 June 1909). In the late nineteenth and early twentieth

centuries, an average of 700 dozen murre eggs (8,400

eggs) were gathered each year at Island Rock and Redfish

Rocks (Centennial Edition of the Coos Bay Times, 3

May 1947). Thus, thousands of murres evidently bred

on the rocks and islands near Port Orford at this time, a

number sufficient to support commercial harvesting of

eggs for at least a decade.

At the start of the twentieth century, W. L. Finley

(1902; 1905a, 1905b) documented a large colony of

breeding murres at Three Arch Rocks (Colony numbers

219-054 to 219-057), as well as the slaughter of murres

by sport shooters for target practice. Through persistent

urging by Finley, Three Arch Rocks was declared a

Reservation for the Protection of Native Birds (now

known as a National Wildlife Refuge) by Executive

Order of President Theodore Roosevelt in 1907. Over

the years, tremendous numbers of murres have been

reported here, described as “countless thousands” (Ferris

1940), or from “hundreds of thousands” to 750,000

murres (Gabrielson and Jewett 1940). S. G. Jewett (Tuck

1961) considered numbers in the late 1930s and early

1940s to have increased since his first visit to the rocks

in 1914. From 1930 to 1940, R. Ferris banded many

chicks at Three Arch Rocks and Cape Lookout (Colony

numbers 219-061 to 219-063; Bayer and Ferris 1987).

S. G. Jewett (Tuck 1961) also reported large colonies

“on the rocks off Bandon” (Colony numbers 270-015

to 270-020), “off Port Orford” (Redfish Rocks), “off the

mouth of the Pistol River” (Colony numbers 270-085

to 270-087), and “other smaller colonies in between”.

A. Walker (Tuck 1961) reported fewer than 2,500–3,000

on Cape Lookout, large colonies at “Two Arches off

Cascade Head, where two of the three rocks are occupied

by murres” (Colony numbers 219-069 to 219-073),

breeding at “Cape Mears, where some nest on ledges on

the cape and others on an offshore rock” (Colony

numbers 219-044 to 219-051); and breeding at “another

smaller colony on a rock off Falcon Cove” (Colony

number 219-030). Museum egg specimens provided

additional evidence of breeding and numbers of murres

present at several colonies in the first half of the twentieth

century (Table 2.3).

Murre numbers increased during the first half of

the twentieth century, including colony formations.

Murres apparently began breeding on Colony Rock at

Yaquina Head in the 1940s or 1950s. Murres were not

noted breeding in 1899 (Prill 1901; Bayer 1986a), nor

were they recorded during a Portland Audubon Society

field trip in May 1940 (Anonymous 1940). However, a

Portland Audubon Society field trip on 11 May 1952

did report murres from this location, although it was not

clear if they were breeding (Oakes 1952). By 1958,

breeding was confirmed by egg collectors (Table 2.3).

Visual estimates during aerial surveys by the USFWS

from 1966 to 1977 were from 1,800 to 4,800 birds.

The first coastwide survey of murres and other

seabirds in Oregon occurred in the 1960s when the

Bureau of Sport Fisheries and Wildlife (now U.S. Fish

and Wildlife Service) was evaluating the acquisition of

the larger rocks and islands for inclusion in the National

Wildlife Refuge System. On 9–10 July 1964, biologists

conducted an aerial survey along the entire coast and

visually estimated 108,700 murres, which did not

include 300,000 murres previously reported at Three

Arch Rocks (D. B. Marshall, unpublished data). D. B.

Marshall (unpublished field notes) noted that visual

estimates of the murres were probably inaccurate

because “The dense colonies of sea birds, particularly

murres, pose a census problem which I feel is not

satisfactorily resolved.” They did photograph various

colonies to provide a comparison with visual estimates,

but the photos were never counted (D. B. Marshall,

personal communication). The current location of these

photos is unknown.

In 1966–67, Browning and English (1967, 1972)

surveyed 12 rocks and islands and provided estimates

of murres at some colonies, including 225 on North

Coquille Point Rock (Colony number 270-015), 450+

on Cat and Kittens (Colony number 270-019), 1,180 on

Island Rock, 300 on an unnamed rock NW of Island

Rock (Colony number 270-048), and 1,650 on an

unnamed rock at Whaleshead Creek. In 1964, D. B.

Marshall (unpublished data) recorded 1,500 murres at

Island Rock, but there were major differences at other

sites. For example, 12,000 and 18,000 murres were

reported on Cat and Kittens and the unnamed rock at

Whaleshead Creek, respectively. The disparity between

these two surveys may have resulted from the early

survey dates in 1967 (22–23 April) and rough visual

estimates.

In 1967, 28 large islands along the Oregon coast

were included in the National Wildlife Refuge System.

From 1966 to 1977, the Bureau of Sport Fisheries and

Wildlife conducted aerial surveys from fixed-wing

aircraft and visually estimated numbers of murres

attending colonies throughout the Oregon coast. From

1966 to 1974, an average of 122,673 murres was
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 51

Table 2.3. Summary of museum egg specimens a of common murres in Oregon.

Area or Number

colony name of Eggs Dates Sources Notations

Yaquina Head 7 05/30/58 U. G. Kubat Colony Rock

12 06/08/58 U. G. Kubat Three Arch Rocks

15 06/27/40 E. N. Harrison Noted: “thousands of birds were nesting on top

of island as close together as possible”

Cape Lookout 29 06/02/29 A. Walker

3 05/29/32 W. E. Griffee

2 06/05/35 W. E..Griffee Noted: “egg on the bare top of a rock about half

an acre in extent. The 600 or 700 pairs of murres

were closely grouped for protection from the

western gulls, which eat murre eggs whenever

they are exposed.”

8 06/01/41 L. T. Stevens, B. F. Walker

5 06/08/52 U. G. Kubat

26 06/14/53 U. G. Kubat

13 06/05/54 W. E. Griffee, U. G. Kubat

1 06/08/58 U. G. Kubat

Cascade Head Area 54 06/05/35 L. T. Stevens, W. E. Griffee

7 06/15/30 A. and K. M. Walker Two Arches Rock

17 06/19/33 A. Walker Two Arches Rock

40 06/04/34 A. Walker Two Arches Rock

Island Rock 23 06/15/30 J. C. Braly Noted: “between 2,000 and 3,000 murres in

the colony”

Port Orford 3 06/15/30 J. C. Braly Redfish Rocks

Brookings Area 3 07/20 to 22/17 F. J. Smith Egg Island Colony numbers 270-115 to 270-

123

8 5/18 to 19/30 J. T. Fraser Noted: “several hundred murres nested here”

2 06/15/30 J. C. Braly Noted: “several thousands nesting”

109 6/6 to 7/49 L.T. Stevens, L. R. Howsley

1 07/07/49 L.T. Stevens

a

 Specimen information was obtained from Western Foundation of Vertebrate Zoology, Camarillo, California; Santa Barbara

Natural History Museum, Santa Barbara, California; San Diego Natural History Museum, San Diego, California; and National

Museum of Natural History, Washington, D. C.

estimated. In 1975 and 1976, 162,350 and 202,960

murres (respectively) were estimated but numbers of

birds estimated at each site varied significantly. At Three

Arch Rocks, estimates were from 25,000 to 107,000

murres. Even at the small colony at Goat Island, estimates

varied significantly (range, 800–3,000) between years.

Such large variations have not been noted since aerial

photographic survey techniques have been employed,

except during severe El Niños.

The first comprehensive survey of breeding

seabirds in 1979 employed the first use of aerial

photographs at murre colonies in Oregon (Varoujean

and Pitman 1980). A total of 259,993 murres were

counted at 63 colony sites. Unfortunately, count data

from 1979 aerial photographs are considered inaccurate

and were not used for trend analyses because (1) U.S.

Coast Guard Sikorsky helicopters were operated at great

distances from seabird colonies to minimize

disturbance, making photographs difficult to count

accurately and flushing large numbers of murres at

certain colonies; and (2) at 28 (44%) of 63 colonies,

counted photographs were taken on 16 July 1979, by

which date up to 75% of murres had already departed

the colony (based on comparison to other photographs

in May or June 1979). Thus, murre numbers at colonies

in Oregon were probably underestimated using July

1979 data.

Current Population Size and Distribution of

Breeding Colonies in Oregon

By 1995, 75 locations attended by murres had been

documented in Oregon (Figure 2.7; Appendix E). We

have designated these locations as follows: (1) 49

regularly-attended colonies averaging more than 100

birds per count; (2) 14 regularly-attended colonies

averaging fewer than 100 birds per count; (3) 7 recentlyformed (since 1988) and regularly-attended colonies

(Table 2.4), including 6 that are still active and one

colony abandoned in 1991 (Colony number 219-057);

(4) 2 colonies abandoned after 1979 (Colony numbers
52 USGS/BRD/ITR–2000-0012

219-007 and 219-029); and (5) two rocks attended by

small numbers (fewer than 10 birds) without confirmed

breeding. Breeding has been confirmed with

observations of eggs or chicks at all regularly-attended

colonies in 1988–95. The most complete and accurate

survey was conducted in 1988 (R. W. Lowe, unpublished

data). Sixty-six attended locations were identified with

59 surveyed using aerial photography and 7 surveyed

visually by boat. The largest colony (more than 132,000

breeding birds) was located at Shag Rock within Three

Arch Rocks (Colony number 219-056). The Oregon

breeding population was estimated at 711,900 breeding

birds. Although colonies exist within several colony

complexes in Oregon (Figure 2.7), count data were not

available for all colonies within complexes.

Consequently, murre numbers and trends at the colony

complex level in Oregon were not described or assessed.

Population Trends in Oregon, 1988–1995

To measure population trends in Oregon from 1988

to 1995, we analyzed data for 15 sample colonies

surveyed and counted annually during this period

(Table 2.5; Appendix E). This sample of colonies is

spread along the entire Oregon coast. The largest

colonies are not included because of extensive counting

time required. Most colonies (80% of 75 attended

locations in 1988) and most of the Oregon population

(87.5% of 426,278 birds counted in 1988) were not

counted, except in 1988 when all colonies were counted.

In addition, two of the 15 sample locations were not

attended until after 1988 (see below). Analyses of

population trends were hampered by initiation of

standardized aerial photographic surveys of Oregon

murre colonies after major declines in central California

and Washington in 1979–86. Also, trends from 1988 to

1995 for 15 sample colonies might not be representative

of all colonies although obvious differences were not

noted (R. W. Lowe, unpublished data).

In addition to U.S. Fish and Wildlife surveys, murre

colony counts in Oregon were conducted by a private

consulting firm (Briggs et al. 1992) in late June 1989.

Owing to numerous problems (i.e., different survey

techniques and incomplete surveys), data from these

surveys are not discussed in this chapter (see Appendix

A). In 1995, three replicate aerial surveys were

conducted to determine variability in counts over a four

Table 2.5. Average and maximum sizes for 15 selected breeding colonies of common murres in Oregon, 1988–1995 (see Appendix E).

Symbols and format as in Table 2.1.

Colony Mean Mean number of Years Maximum Maximum number Year of

Rank number count breeding adults of data count of breeding adults maximum

1 243-015 15,764 26,300 8 19,147 32,000 1989

2 243-010 12,938 21,600 8 14,377 24,000 1990

3 270-116 6,061 10,100 8 7,588 12,700 1991

4 219-005 5,790 9,700 8 7,199 12,000 1995

5 270-123 2,755 4,600 8 2,968 5,000 1990

6 219-017 2,688 4,500 8 3,145 5,300 1995

7 219-060 2,015 3,400 8 2,506 4,200 1989

8 270-064 2,003 3,300 8 2,389 4,000 1991

9 270-034 1,889 3,200 8 2,317 3,900 1994

10 270-043 1,544 2,600 8 1,888 3,200 1990

11 270-117 1,499 2,500 8 1,918 3,200 1989

12 219-070 790 1,300 8 972 1,600 1988

13 270-122 662 1,100 8 820 1,400 1988

14 270-086 126 200 8 327 500 1988

15 270-085 78 100 8 142 200 1995

Table 2.4. Numbers of common murres counted at seven colonies formed in Oregon

between 1989 and 1995.

Colony number 1988 1989 1990 1991 1992 1993 1994 1995

219-036 0 0 0 0 0 0 Pra 43

219-057 0 157 68 99 0 0 0 0

243-015A 0 0 75 56 33 0 6 73

243-016 0 0 0 0 0 168 119 265

243-017 0 0 8 192 603 783 1,201 1,692

270-016 0 0 0 5 17 0 107 90

270-017 0 0 46 324 795 204 1,180 1,079

Total 0 157 197 676 1,448 1,155 2,613 3,242

aBirds present in small numbers.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 53

week period (Table 2.6). Although a few individual

colony counts did show much variation (i.e., Colony

numbers 219-003, 219-010, 219-026), overall variation

among the 15 colonies was small (Lowe and Pitkin

1996).

The number of murres at sample colonies in Oregon

increased from 1988 to 1990, then declined slightly

before severe El Niño breeding conditions in 1993

(Figure 2.8; Appendix H). In 1993, warm marine waters

persisted along much of the Oregon coast, which

resulted in complete murre reproductive failure. Colony

abandonment began in late May, prior to the annual

aerial photographic survey in early June. Abandonment

of this magnitude had not been reported previously in

Oregon. Murres returned in large numbers in 1994 and

increased further in 1995. The effects of the 1982–83 El

Niño were apparently not as severe as in 1993; however,

reduced breeding success and, possibly, greater adult

and subadult mortality was observed (Hodder and

Graybill 1985; Bayer 1986b; Bayer et al. 1991). Effects

of the 1992–93 El Niño did not result in large changes

in the numbers of breeding murres in Oregon. The

breeding population in Oregon has been relatively

stable from 1988 to 1995 (Figure 2.8; Appendix H).

Seven colony formations occurred during 1988–

95 (Table 2.4). One colony formed in 1989 on Seal Rock

(Colony number 219-057) and persisted until 1991, but

was then abandoned, possibly because of disruptions

from Steller sea lions Eumetopias jubatus that “haul

out” on the rock (R. W. Lowe, personal observation).

Other colonies formed in 1990, 1991, and 1994 when

murre numbers in Oregon reached high levels. One

colony formed in 1993, during the 1992–93 El Niño,

when the number of murres attending colonies was at a

record low. Six of seven new colonies (i.e., except

Unnamed Rock, Colony number 219-036) were

established at rocks nearby (i.e., within 250 m) large

colonies, probably reflecting intercolony movements

within colony complexes. For example, colony

formation at Seal Rock occurred in close association

with the large colony complex at Three Arch Rocks

National Wildlife Refuge. Six of the seven colony

formations (i.e., except Seal Rock) also occurred in

conjunction with newly-formed colonies of Brandt’s

cormorants. Colony formation at Unnamed Rock

(Colony number 219-036) in 1994–95 occurred 5–6

km from the next nearest active murre colony but also

was associated with nesting cormorants. Six new

colonies still existed in 1995 (i.e., except Seal Rock),

despite poor breeding conditions associated with

elevated sea-surface temperatures since 1991 (R. W.

Lowe, unpublished data).

Stable murre populations from 1988 to 1995

coincided with a period of relatively low anthropogenic

effects before and during this period. Between 1982

and 1993, more than 1,200 rocks and islands along the

Oregon coast were protected by acquisition or

conservation agreements by the USFWS. In some cases,

such as Tillamook Rock, human disturbance was

reduced over a period of time and numbers of murres

correspondingly increased. In 1957 the Tillamook Rock

lighthouse was decommissioned. In 1980 access was

limited under private ownership. In 1993 the USFWS

obtained a perpetual conservation agreement for this

site and human access during the breeding season was

Table 2.6. Numbers of common murres counted during replicate

aerial surveys at 15 selected colonies in Oregon in 1995.

Colony

number 23 May 7 June 21 June Mean

219-002 80 67 60 69

219-003 106 118 221 148

219-005 7,488 7,199 7,479 7,389

219-010 0 129 244 124

219-013 2,508 2,694 2,623 2,608

219-014 136 130 120 129

219-017 3,047 3,145 2,649 2,947

219-019 6,549 7,143 7,029 6,907

219-026 7,279 6,132 7,679 7,030

219-027 5,312 5,342 4,462 5,039

219-036 38 43 44 42

219-044 4,428 4,926 4,381 4,578

219-045 7,377 7,079 7,192 7,216

219-060 2,350 1,922 718 1,663

219-062 105 132 139 125

Total 46,803 46,201 45,040 46,014

Deviation

 from 7 June 1.3% ND -2.5% -0.4%

Deviation

 from mean 1.7% 0.4% -2.1% ND

Number of murres counted (in thousands)

Oregon

0

10

20

30

40

50

60

70

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Year

Figure 2.8. Changes in whole-colony counts for 15 sample colonies

of common murres in Oregon, 1988–95 (see Appendix H).
54 USGS/BRD/ITR–2000-0012

prohibited. Numbers of murres attending this site

between 1987 and 1995 far exceeded numbers in the

1970s and peaked in 1995 (see Appendix I: Figure I31). Human disturbance has occurred regularly at many

colonies in Oregon but, to date, this has not resulted in

colony abandonments. Recently, disturbances from lowflying aircraft and close approach by boats were well

documented at Three Arch Rocks (Lowe 1993).

Management actions have now been implemented to

reduce the problem at this colony complex but human

disturbance at other colonies throughout the Oregon

Coast National Wildlife Refuge Complex remains a

primary management concern.

Gill-net fishing has been prohibited in Oregon since

the 1940s and no large oil spills have occurred adjacent

to colonies before or during the 1988–95 study period.

However, death of murres from gill-net fishing and oil

spills in Washington and British Columbia undoubtedly

included large numbers of murres from Oregon colonies

during or after northward movements that occur after

colony departure (Manuwal and Carter 2001). Two

major oil spill events in Washington (i.e., 1988

Nestucca and 1991 Tenyo Maru) killed an estimated

30,000 and a range of 3,740–19,559 murres, respectively

(Ford et al. 1991; Tenyo Maru Oil Spill Natural Resource

Trustees 2000). Given the relative size of the common

murre populations in Washington and British Columbia

prior to and after the Nestucca spill, it is quite likely

that a substantial proportion of the birds killed as a

result of this event were from Oregon breeding colonies.

An assessment of the origin of murres killed in the Tenyo

Maru spill indicated that 39–58% of the adult murres

killed in the spill were from Washington and the

remainder (42–61%) were from Oregon, although a

series of assumptions were used to generate this estimate

(Warheit 1996). Murre deaths also result from gillnet

entanglement in the fall sockeye salmon fishery in Puget

Sound, Washington (Pierce et al. 1994). This fishery

and associated seabird deaths take place when Oregon

birds are typically present (Manuwal and Carter 2001).

In 1997, the Washington Department of Fish and

Wildlife adopted regulations to reduce seabird deaths

in the nontreaty fishery by eliminating early morning

(dawn) fishing and requiring net modifications (Melvin

et al. 1999). In addition, die-offs of large numbers of

chicks after colony departure have been reported for

decades in Oregon (Bayer et al. 1991), but the level of

deaths may have increased since 1990 (R. W. Lowe,

unpublished data).

 Along the north and central coasts, predation and

disturbance by bald eagles have severely affected

breeding murres at some colonies (R. W. Lowe, personal

observation). This was first noted in 1994 and continues

to increase at colony sites from Tillamook Head to

Colony Rock in Newport. The disruption at murre

colonies has been concomitant with increased sightings

of juvenile bald eagles in this area. Most impacts result

from repeated colony disturbance, rather than actual

predation. Juvenile eagles often perch within colonies

and delay murre egg laying. Disruptions during

incubation cause murres to flush, exposing murre eggs

to breakage or predation by gulls and corvids. At Bird

Rocks at Chapman Point (Colony numbers 219-017

and 219-018), continued harassment by eagles

throughout the breeding season has resulted in erratic

colony attendance and complete breeding failure.

Recent effects from various natural and anthropogenic

factors have been localized (e.g., eagle or human

disturbance at specific colonies) or dispersed among

the numerous colonies and large populations (e.g., oilspill and gill-net deaths). Efforts to further reduce

anthropogenic effects are continuing.

Washington

Historical Background on Breeding Colonies

in Washington, 1905–1978

The degree to which native people affected murres

in western Washington before the early twentieth century

is not clear. Despite large populations of native people

and the common use of canoes, the inaccessibility of

many rocks and islands on the Washington coast may

have limited food gathering activities to certain

locations. At some larger islands (i.e., Tatoosh Island),

occupation by native people probably prevented

breeding by murres. Seagull eggs were harvested in June

from colonies at Point Grenville and Cape Elizabeth by

Quinault native people (Olson 1936; Speich et al. 1987).

However, harvesting of gull eggs apparently did not

prevent murre breeding at Willoughby Rock in 1906,

although gull egg harvesting by Ozette native people

may have prevented breeding by murres at White Rock

(Dawson 1907).

In July 1906 and June 1907, most seabird colonies

on islands off the outer coast of Washington were

surveyed by canoe, and 1,736 murres were counted at

seven locations (Dawson 1907, 1908a, 1908b; Dawson

and Bowles 1909). Five of these colonies— Erin,

Grenville Arch, Grenville Pillar or “Radio Stack,”

Willoughby Rock, and Carroll Island— still exist

(Figure 2.9). Eggs or chicks were confirmed only at

Willoughby Rock and Carroll Island (Dawson 1907;

Jones 1909). One egg was collected by Dawson at Carroll

Islet on 21 July 1906 from a colony of about 100 pairs

with “most [eggs] hatched” (SBNHM egg records). Three

eggs in the WFVZ collection were obtained on 20 June
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 55

1907 at “Birdrock,” Washington (WFVZ No. 47,472–

47,474). Another egg collected on 12 June 1910 at

Willoughby Island was from a colony of “500 pairs on

south slope” (SBNHM egg records). No murres were

observed at several other rocks subsequently attended

by murres in historical literature: Erin’s Bride, Split

Rock, Destruction Island, North Rock, Rounded Islet,

Giant’s Graveyard, Quillayute Needles, Cake Rock,

White Rock, Flattery Rocks (including Old Rock, also

known as Bodelteh Islands), Point of the Arches

(including Silversides), and Tatoosh Island. At Carroll

Pillar (adjacent to Carroll Island, also known as

“Paahwoke-it”), 200 murres were recorded, but since

then, only small numbers of murres have been observed

sporadically in 1917 and 1978 (Speich and Wahl 1989;

Appendixes F and G).

On 13–17 July 1959, a combination of aerial and

boat surveys of seabird colonies was conducted along

the Washington outer coast, which recorded 4,450

murres at seven locations plus 550 at sea off Cape Flattery

(Kenyon and Scheffer 1962). The largest colonies were

at Carroll Island and Willoughby Rock (2,000 murres

each, but they were uncertain of exact locations) with

smaller colonies at Tatoosh Island (200) and White Rock

(100). Small numbers (100) were noted at Bodelteh

Islands on 13 July 1959 but none were recorded on 17

July 1959; fewer than 100 murres were noted in 1978–

79 but none between 1980 and 1995 (Speich and Wahl

1989; Appendixes F and G). Murres noted at “Flattery

Rocks” in 1914 may have referred to Bodelteh Islands

or White Rock (Jewett et al. 1953; Speich and Wahl

1989). At Cake Rock, 50 murres were noted on 13 July

1959; small numbers (25–175) were noted in 1967,

1990, and 1992 (Speich and Wahl 1989;Appendixes F

and G). We have considered sporadic observations of

murres at Bodelteh Islands and Cake Rock to reflect

irregular attendance. Various other observations at

several known colonies between 1907 and 1959 indicate

long-term use of many colony sites (Jewett et al. 1953;

Speich and Wahl 1989).

Manuwal and Campbell (1979) summarized data

from USFWS aerial surveys (visual estimates from fixedwing aircraft) conducted in the early 1970s and tabulated

11,950 murres at 11 locations. The largest estimates of

the numbers of murres present were reported at Grenville

Arch (3,000), Willoughby Rock (3,000), and Split Rock

(2,100). Smaller colonies were found at Point Grenville

(1,100), Quillayute Needles (900), James Island (750),

Cake Rock (300), White Rock (250), and Tatoosh Island

(100). Murres have not been otherwise observed on

James Island, but are known to occupy adjacent rocks

now known as Petrel Island ( “Kohchaa[uh]”) and

Figure 2.9. Distribution of common

murre colonies in Washington (Clallam

to Pacific Counties).
56 USGS/BRD/ITR–2000-0012

Gunsight Rock. Quillayute Needles represents a colony

complex with several recent colonies: Huntington

Island, Cakesosta, and Table Rock. In addition, murres

were reported in the early 1970s at Flat Rock south of

Split Rock (300) and Giant’s Graveyard (150; Speich

and Wahl 1989). These observations apparently reflect

irregular attendance or colony misidentification. At

Point Grenville and Giant’s Graveyard, specific islands

attended by murres were not identified.

 Many of Washington’s largest murre colonies are

located on top of flat-topped sea stacks or islands (see

Appendix I: Figures I-33 to I-37). It is impossible to see

all attending birds, and in some cases even to determine

if murres are present, when circumnavigating these

islands by boat. In historical information, it is also

unclear whether all colonies were surveyed, if counts

on adjacent colonies were lumped and reported under

one colony name, or if colonies were properly identified.

In addition, murre attendance at colonies in 1906–07,

1959, and the early 1970s may have been affected by El

Niños (Quinn et al. 1987). Colonization of Tatoosh

Island by 1956 indicates the population may have

expanded in the mid-twentieth century.

Suspected increases may reflect lower levels of

activities by native people along the coast because of

changes in traditional lifestyles. For example, camps of

native people on Tatoosh and Destruction islands were

abandoned. However, the decline of native populations

and the rate of arrival and number of Euro–American

settlers in western Washington was not as pervasive or

extensive as in California and Oregon. Native people

were confined to reservations along most of the outer

coast and early settlers in the 1880s and 1890s tended

to move into Puget Sound or the eastern areas on the

Olympic Peninsula (Evans 1983). Large coastal areas

were included in Mount Olympus National Monument

and Olympic National Forest in the early 1900s. Some

of these areas became part of Olympic National Park in

1938. Much of the outer Washington coast also remained

inaccessible by land until 1931 when the Olympic loop

highway (i.e., Highway 101) was completed. Thus, the

outer coast of Washington was spared from many effects

from early settlers.

Military bombing of Sea Lion Rock (north of

Willoughby Rock) in southern Washington occurred

from 1944 to 1992 (Speich et al. 1987). Carroll Island,

Rounded Island, Sea Lion Rock, and Split Rock also

were practice bombing targets during World War II and

were bombed extensively with heavy ordinance. Several

murre colonies were probably affected by low-flying

aircraft en route to and from Sea Lion Rock and other

target islands, including Willoughby Rock, Split Rock,

and possibly Grenville Arch. Similar problems probably

occurred after World War II. Lighthouse keepers and

associated activities may have prevented breeding at

Tatoosh Island from the late nineteenth century to the

1950s, but rats (Rattusspp.) and cats (Felis catus) were

not introduced (Kenyon and Scheffer 1962). An

accidental fire caused by researchers at Carroll Island

burned the top of the island in 1969, but it is unclear if

murres were affected since they bred on other parts of

the island at that time (M. L. Cody, personal

communication).

Current Population Size and Distribution of

Breeding Colonies in Washington

During 1979–95, murres were recorded at 32

different locations along the outer coast of Washington

(Appendixes F and G). Most counts at these locations

did not provide information on the breeding status of

attending birds. Eighteen locations have been

designated as colonies (Figure 2.9) based on historical

or recent observations of breeding (i.e., eggs or chicks

seen) or regular attendance of rocks with suitable

breeding habitats. As noted above, historical breeding

(pre-1979) had been confirmed only at Carroll Island

and Willoughby Rock (Dawson 1907; Jones 1909;

Jewett et al. 1953). In 1980–82, U. W. Wilson

(unpublished data) observed chicks during the last week

of June and first week of July at Grenville Arch, Split

Rock, Willoughby Rock, and Cakesosta. On 27 August

1985, S. M. Speich collected one egg at Grenville Arch

and four eggs at Willoughby Rock (WFVZ Nos.

149,537–149,541). On 4 September 1985, S. M. Speich

collected an abandoned egg at Split Rock (WFVZ No.

149,536). On 3 June 1987, F. Dobler (unpublished data)

collected several murre chicks near colony departure

that were accidentally killed on Jagged Island. On 19

June 1995, U. W. Wilson (unpublished data) observed

medium-sized chicks on Huntington Island, and noted

several large young on 13 July 1995 at this colony. On

18 July 1995, U. W. Wilson (unpublished data) and G.

Burrell visited Carroll Island and found one abandoned

murre egg. Murres breed regularly at the Tatoosh colony

complex where long-term studies of murre behavior and

reproductive success are under way (Paine et al. 1990;

Parrish 1995). Breeding may have occurred at several

of the other 14 sites but adequate documentation (see

below) to confirm breeding status is lacking.

 To examine population trends, we divided

locations attended by murres into two geographic

sections, southern Washington—with 6 known colonies

in Grays Harbor County—and northern Washington—

with 12 known colonies in Clallam and Jefferson

Counties (Figure 2.9). These areas had been identified
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 57

in previous studies as having different murre population

trends (Wilson 1991; Parrish 1995). No murre colonies

have ever been reported in the inland marine waters of

Washington’s Juan de Fuca Strait, San Juan Islands and

Puget Sound (Speich and Wahl 1989).

Murres were counted annually by the USFWS along

the outer coast of Washington from 1979 to 1995,

except Tatoosh Island which was surveyed aerially only

in 1994–95 (Appendixes F and G). Routine aerial

surveys were not conducted at the Tatoosh Island

complex from 1979 to 1993 because this colony was

not part of the Washington Islands National Wildlife

Refuge (consisting of Flattery Rocks, Quillayute

Needles, and Copalis National Wildlife Refuges). Few

birds (e.g., 200 birds in 1978; Speich and Wahl 1989)

attended Tatoosh colonies (Appendixes F and G) in the

late 1970s. By adding 200 birds to the USFWS 1979

aerial survey total of 31,520 birds for all other locations,

a total count of 31,720 birds for 1979 was derived. By

applying a k correction factor, we estimate the breeding

population for Washington at about 53,000 breeding

birds. Southern and northern Washington accounted for

86% and 14%, respectively.

In late June 1989, murre colony counts in

Washington were conducted by a private consulting

firm (Briggs et al. 1992) but, because of numerous

problems (i.e., different survey techniques and

incomplete surveys), we relied only on data from

standardized USFWS surveys for trend assessments (see

Appendix A). However, if we add 830 birds for Tatoosh

Island (Briggs et al. 1992) to the USFWS total of 3,925

birds (which excluded the Tatoosh Island complex), a

total count of 4,755 murres was derived for 1989, which

corresponded to about 7,900 breeding birds. Certainly,

numbers of murres in Washington were much lower in

1989 than in 1979 (Figure 2.10), and only 28% occurred

in southern Washington.

In 1994 and 1995, breeding population estimates

for murres in Washington were 5,900 and 9,600 breeding

birds, respectively, based on the results of the 5 July

1994 and 25 June 1995 USFWS aerial photographic

surveys (Appendix G), which included the Tatoosh

Island complex. The Tenyo Maru Oil Spill National

Resource Trustees (2000) estimated the 1995 murre

population in Washington at 13,6000 birds by adding a

median count of 5,230 birds from USFWS 1995 refuge

surveys (excluding Tatoosh Island) to a 1995 ground

count of 3,720 murres on Tatoosh Island (Parrish 1996)

and applying a k correction factor of 1.6. The proportion

of Washington murres attending southern Washington

locations was between 1 and 14% in 1994–95.

In southern Washington, colonies occur in

complexes at Point Grenville and Split–Willoughby.

Peak numbers were estimated in 1979 at Point Grenville

(21,400 breeding birds) and in 1982 at Split–

Willoughby (26,300 breeding birds). Between 1979 and

1982, breedings murres were centered at these colonies

in southern Washington. However, all six colonies in

both colony complexes were abandoned or severely

reduced by 1994–95 (see below). In northern

Washington, colonies exist in relatively small

individual colonies and in three colony complexes:

Quillayute Needles, Carroll–Jagged, and Tatoosh

(Appendixes F, G). In 1979–82, relatively small numbers

Number of murres counted (in thousands)

Washington

0

5

10

15

20

25

30

35

40

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Year

period

1979-1995

1979-1986

r-square

0.468

0.745

p-value

0.002

0.006

Figure 2.10. Trends in whole-colony counts

for common murres in Washington, 1979–

95, excluding Tatoosh colonies (see

Appendix H).
58 USGS/BRD/ITR–2000-0012

occurred in northern Washington, but in 1994–95 the

Washington population was centered there.

Many instances of irregular murre attendance at

rocks, often by small numbers, have been documented

in the past (see above), as well as during aerial surveys

from 1979 to 1995 (Figure 2.9). Determining breeding

activity is difficult in Washington because of colony

inaccessibility and poor viewing conditions from

adjacent mainland areas or boats. During surveys in

1979–95, murres were reported at eight locations on

only one survey in 1 year (i.e., Colony number 584 in

1989, 457 in 1986, 426 in 1986, 419 in 1987, 367 in

1985, 294 in 1985, 140 in 1986, and Jagged Pillar in

1991). We suspect that breeding did not occur at these

locations. During this same period, irregular attendance

occurred over 2–3 years at Cake Rock (1990–92) and at

Carroll Pillar (1993–95). At Jagged Pillar, 17 murres

were reported in 1978 and 25 in 1982 (Speich and Wahl

1989). In the past, irregular attendance has been noted

at Carroll Pillar, Cake Rock, Bodelteh Island, Flat Rock,

and Giant’s Graveyard. In addition, irregular attendance

has been reported at “Dahdayla” near Cake Rock (2–30

birds in 1967–69), Half Round Rock (250 murres in

1981), and Quillayute Needle (35–276 birds in 1978–

80). Otherwise, murres were not reported at these

locations (Speich and Wahl 1989; Appendix F). At

Middle Rock, large numbers (range, 450–1,800)

attended irregularly in 1985–86.

Although attended for a few years, breeding is not

suspected at Destruction Island or Colony number 355–

359. Murres were not reported attending Destruction

Island from 1906 to 1987 (Speich and Wahl 1989;

Appendix F). Between 250 and 650 birds were observed

loafing around peripheral rocks annually from 1988 to

1992 (Appendixes F and G). In 1995, 215 murres were

present, but no eggs or chicks were found during ground

visits to the island (U. W. Wilson, unpublished data).

Destruction Island lacks suitable murre nesting habitat

and murres were present in association with nesting

Brandt’s cormorants on the island’s peripheral rocks.

On the Washington coast, small numbers of nonbreeding

murres frequently are seen among nesting Brandt’s

cormorants. Since these cormorants can change their

colony locations, irregular murre attendance at certain

rocks may be due to attraction of murres to Brandt’s

cormorant colonies.

Population Trends in Southern Washington,

1979–1995

Overall numbers of breeding murres in Washington

declined 32.9% per annum between 1979 and 1986 (P

= 0.006; Figure 2.10). Most decline between 1979 and

1986 occurred in southern Washington where steep

downward trends occurred at colony complexes (Figure

2.11), as well as for southern Washington overall (43.7%

per annum, P = 0.006; Figure 2.12). During the period

Numbers of murres counted (in thousands)

Year

Carroll - Jagged

0

1

2

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Quillayute Needles

0

1

2

3

4

5

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Willoughby - Split

0

5

10

15

20

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Point Grenville

0

5

10

15

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Figure 2.11. Trends in whole-colony

counts for four colony complexes of

common murres in Washington,

1979–95 (see Appendix H).
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 59

Number of murres counted (in thousands)

Southern Washington

0

5

10

15

20

25

30

35

40

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Year

period

1979-1995

1979-1986

1984-1995

r-square

0.710

0.743

0.371

p-value

<0.001

0.006

0.035

Figure 2.12. Trends in whole-colony

counts for common murres in southern

Washington, 1979–95 (see Appendix

H).

1979–82, the southern Washington population was

much higher than between 1983 and 1995, when

numbers varied extensively at colonies and colony

complexes (Figure 2.11; Appendix F). Murre attendance

at the Point Grenville complex decreased greatly from

1979 to 1981 before rebounding in 1982. At the

Willoughby–Split complex, both colonies decreased

greatly in 1980 between similar peak numbers in 1979

and 1982. Large differences in the numbers of murres

attending colonies in southern Washington between

1979 and 1982 apparently were related to natural and

anthropogenic factors. In 1981, reduced colony

attendance probably reflected a response to unusually

warm surface waters (similar to moderate El Niños) off

the Washington coast between January and April 1981

(Wilson 1991). Numbers of murres attending colonies

increased in 1982, apparently reflecting the return of

birds that did not breed, remained at sea, or moved

temporarily to other colonies in 1980–81. In addition

to the warm water episode, various human disturbances

such as overflights and military activity occurred along

the Washington coast on a regular basis in the late 1970s

and early 1980s (Speich and Thompson 1987). These

disturbances may have contributed to oscillating

colony attendance. Death of common murres from

entanglement in Washington gill-net fisheries (i.e.,

Willapa Bay, Grays Harbor, Puget Sound) in the 1970s

and early 1980s probably occurred but was poorly

documented.

 In 1983, widespread colony abandonment

occurred in association with severe El Niño conditions

(Wilson 1991). Almost complete abandonment occurred

at the Willoughby–Split complex by 1984–86. Impacts

from chronic colony disturbances and the 1981 warm

water event also may have contributed to this steep

decline. The negative effects of private aircraft

overflights and military practice bombing of Sea Lion

Rock on murre attendance at southern Washington

colonies in 1984–85 was documented by Speich et al.

(1987). Colony attendance was significantly reduced

because of lingering effects of the 1982–83 El Niño

during this study, therefore, the full effect of these

military disturbances on breeding colonies was unclear.

However, such disturbances undoubtedly affected many

murre colonies until military bombing and aircraft

overflights were greatly reduced in 1992. In 1984–85,

disturbance by commercial ground-fishing boats was

noted at Point Grenville and Willoughby Rock (S. M.

Speich, personal communication). Limited increase

between 1984 and 1988 may have reflected the return

of some birds and the recruitment of subadults from

higher populations in 1981–82.

In 1988, numbers of murres attending colonies

again began to dwindle to very low levels during the

1987–88 El Niño (Wilson 1991). From 1988 through

1995, natural and severe anthropogenic factors acted in

concert to affect the murre population. In December

1988, an estimated 30,000 murres were killed off the

outer Washington coast as a result of the Nestucca oil

spill (Ford et al. 1991). Because large numbers of murres

from breeding colonies in Oregon, and possibly British

Columbia, are found along the Washington coast during
60 USGS/BRD/ITR–2000-0012

the fall and winter months (Manuwal and Carter 2001),

these deaths probably involved murres originating from

colonies in Washington and other areas. The proportion

of murres from each area of origin killed by the Nestucca

spill is unknown. Following the July 1991 Tenyo Maru

spill, Warheit (1996) estimated that 39–58% of the adult

murres killed by this spill originated from Washington.

Based on estimates of total mortality (3,740–19,559

murres), the Tenyo Maru Oil Spill Natural Resource

Trustees (2000) concluded that a sizable portion of the

total Washington state murre population (including

nonbreeding adult, subadult, and juvenile birds) may

have been killed in the spill.

Between 1991 and 1994, onboard observer

programs in various Washington gill-net fisheries

documented seabird deaths from entanglements. Further

studies in selected Puget Sound fisheries confirmed that

common murres represented the majority of the total

seabird entanglement (Jefferies and Brown 1993; Erstad

et al. 1994; Pierce et al. 1994). In addition to deaths

from oil spills and gill nets documented in the early

1990s, low colony attendance and reduced breeding

effort occurred in 1993 during the severe 1992–93 El

Niño. By 1994–95, small numbers still attended colonies

in the Point Grenville complex but almost no birds

attended the Willoughby–Split complex. At these low

levels, it is doubtful if any murre breeding was still

occurring in southern Washington.

In summary, numbers of murres attending colony

complexes in southern Washington declined 25.5% per

annum between 1979 and 1995 (P < 0.001; Figure 2.12;

Appendix H). Several types of anthropogenic and

natural factors apparently acted in concert to greatly

affect the population and prevent recovery. These

include severe El Niños, chronic human disturbance,

and direct deaths from oil spills and gillnet

entanglement. These factors presumably resulted in low

colony attendance, reduced breeding success and

recruitment, increased movements within and outside

colony complexes, and deaths at sea. Since the southern

Washington population constituted 86% of the entire

Washington population in 1979–82, this change

represents loss of most of the breeding population of

murres within the state of Washington. Thus, overall

numbers of breeding murres in Washington also declined

13.3% per annum between 1979 and 1995 (P = 0.002;

Figure 2.10). The factors affecting the three largest

colonies (Grenville Arch, Willoughby Rock, and Split

Rock) are largely responsible for the Washington murre

decline. Whereas murre colony attendance during

severe El Niño years is generally reduced (Wilson 1991)

because of changes in the marine food chain (Wooster

and Fluharty 1985), the manner in which anthropogenic

and natural factors acted to contribute to the decline,

and how they may have prevented recovery, are difficult

to determine with available evidence.

Population Trends in Northern Washington,

1979-1995

Between 1979 and 1982, numbers of murres

attending colonies varied extensively at individual

colonies, colony complexes, and overall in northern

Washington (Figures 2.11 and 2.13; Appendixes F, G,

and H). As in southern Washington, widespread colony

abandonment occurred in association with the severe

1982–83 El Niño (Wilson 1991). Colony attendance at

the Quillayute Needles complex returned to 1979–82

levels (excluding 1981) between 1987 and 1995

(Appendix H). This increase may have reflected return

of some breeding birds which had not attended colonies

during surveys in 1983–84 or movements of birds from

other colony complexes. At the Carroll–Jagged

complex, substantial increase and more regular

attendance occurred in 1987–95 than in 1979–86. At

this complex, there was an apparent shift of birds from

Jagged Island to Carroll Island. U. W. Wilson

(unpublished data) considered no birds to be breeding

at Carroll Island in 1995, although egg laying and

breeding-site failure may have occurred prior to surveys.

The lack of recovery at Rounded Island colonies,

located closest to southern Washington, may have

reflected similar conditions as experienced in southern

Washington including a combination of effects from

natural and anthropogenic factors. With the exception

of Navy practice bombing, the same factors affecting

murres in southern Washington also affected the

northern colonies (e.g., severe El Niños and gill-net and

oil-spill deaths).

At Tatoosh Island and associated rocks (Colony

numbers 022, 023, 035), aerial photographic surveys

were not conducted until 1994–95 when moderate

numbers were recorded. Murres have been reported at

this colony since 1956 (Speich and Wahl 1989). Paine

et al. (1990) reported fewer than 1,000 birds during

1956–79, with a sharp increase to 2,000 birds during

the early 1980s. Briggs et al. (1992) reported 830 birds

in 1989. By 1992, islandwide attendance reached 3,871

birds, based on ground counts, ground estimates, and

photographs taken from boats (J. K. Parrish, personal

communication). In 1995, a USFWS aerial count of 1,705

birds was obtained on 27 July, corresponding to an

estimate of 2,800 breeding birds. This estimate is similar

to the 1995 ground-based estimate of 3,270 breeding

birds (J. K. Parrish, personal communication). In

Washington, Tatoosh Island is currently the only murre

colony where murre reproduction has been studied, and
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 61

is the only colony for which there is evidence of

consistent breeding (Parrish 1996). However, murres on

this colony have recently experienced adult deaths and

reduced reproductive success because of predation and

harassment by bald eagles (Parrish 1995; Parrish and

Paine 1996). The peregrine falcon population also has

increased along the outer coast of Washington (Wilson

et al. 2000) and may affect murre colonies (Parrish 1995).

Limited increase in the northern Washington

population occurred after the severe 1982–83 El Niño,

in contrast to a lack of recovery in southern Washington.

Both areas apparently have been subjected to similar

problems (i.e., human disturbance, deaths from gill-net

fishing and oil spills, reduced colony attendance during

El Niños and other warm water events, and possible

impacts from climate change). The large and sustained

increase in murres attending Tatoosh Island indicated

that immigration has contributed to the growth of this

northern Washington colony along with the return of

first-time breeders natal to Tatoosh colonies (Parrish

1995). This rapid increase of the Tatoosh complex and

increase at the Carroll–Jagged complex in the early to

mid-1980s occurred at the same general time as the

marked declines at both southern and other northern

Washington murre colonies.

 Overall, the murre population in Washington

significantly declined between 1979 and 1995, with

the steepest rate of decline occurring between 1979 and

1986. Colony attendance dropped most dramatically

during the severe 1982–83 El Niño. Recovery after this

event has been poor because of the effects of additional

El Niños, continued chronic gill net and oil spill

associated deaths, and disturbance from military practice

bombing and low aircraft overflights through 1992.

Since northern Washington constituted only 14% of

breeding murres in Washington prior to 1983, the small

relative increases in northern Washington from 1984 to

1995 have not significantly changed the status of the

common murre in Washington to date.

British Columbia

Historical Background on Breeding Colonies

in British Columbia, 1900–1979

Historical records for murre colonies in British

Columbia are scarce and mostly anecdotal. Early in the

twentieth century, large colonies were reported on

Triangle Island at the northwest tip of Vancouver Island

and on the west coast of Graham Island in the Queen

Charlotte Islands. Smaller colonies were reported on

the west coast of Vancouver Island at Solander Island

and near Ucluelet (Figures 2.14 and 2.15; Brooks and

Swarth 1925; Taverner 1928). Subsequent breeding was

documented at Triangle Island and near Ucluelet but

not at Solander or Graham Islands.

Triangle Island has been consistently identified as

the main murre colony in British Columbia (Brooks

and Swarth 1925; Drent and Guiguet 1961; Rodway

1991). Breeding was documented as early as 1900 and

has been recorded on all subsequent ornithological

Figure 2.13. Changes in wholecolony counts for common murres in

northern Washington, 1979–95 (see

Appendix H).

Number of murres counted (in thousands)

Northern Washington

0

5

10

15

20

25

30

35

40

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Year
62 USGS/BRD/ITR–2000-0012

Figure 2.14. Distribution of

common murre colonies in

northern British Columbia and

the southern edge of Alaska.

Figure 2.15. Distribution of

common murre colonies in

southern British Columbia.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 63

expeditions to the island (Kermode 1904; Guiguet 1950;

Carl et al. 1951; Drent and Guiguet 1961; Vermeer et al.

1976b; Rodway et al. 1990b; Parrish 1997). A weather

station and lighthouse were abandoned in 1921 (Beebe

1960). Between 24 June and 1 July 1949, murre breeding

was well documented during a collecting trip by the

British Columbia Provincial Museum (now Royal

British Columbia Museum [RBCM]; Guiguet 1950;

Carl et al. 1951; Drent and Guiguet 1961). Drent and

Guiguet (1961) reported 19 eggs collected, although

26 eggs are currently preserved in collections at the

RBCM (numbers E1149, E2025–E2038, E228–E229)

and the UBCZM (numbers 787–795). One adult male

also was “taken off egg” by C. J. Guiguet on 28 June

1949 (RBCM number 9853). In addition, colony size

was estimated to be about 1,500 breeding pairs, but egg

laying had just commenced (Drent and Guiguet 1961).

C. J. Guiguet (unpublished field notes) provides

additional details: “Several (7) large roosting colonies

observed - each containing several hundreds of birds -

nesting sites visited on edge of high cliffs north side -

all nests at altitude 525 feet [160 m] - grassy tussocks at

edge of sheer drop - eggs only - fresh. Majority of birds

apparently haven’t laid as yet in areas visited. Total

population using island - several thousands.”

Several trips were made by the RBCM and British

Columbia Ecological Reserves to Tirangle Island in

the 1960s and early 1970s but few details on murres are

available. On 18 and 24 August 1966, small “two-dayold” chicks were collected (RBCM number 11642). On

24 August 1966, a larger chick (RBCM 11645) and an

adult (RBCM number 11677) were collected. On 11

August 1974, “many small young” were noted and one

egg was collected at Triangle Island (R. W. Campbell,

unpublished data; RBCM number E1130). During

seabird studies by the Canadian Wildlife Service,

Vermeer et al. (1976a) conducted a complete count of

5,934 murres attending Triangle Island (i.e., 5,384 on

Puffin Rock and 550 on Castle Rock) on 29 July 1976.

In 1977, lower attendance (about 3,000 birds) was noted

when almost total breeding failure occurred for murres

and tufted puffins Fratercula cirrhata (Vermeer et al.

1979).

Breeding was confirmed at Sartine Island, near

Triangle Island (Figure 2.15), where 236 and 600 murres

were observed on ledges in 1968 and 1975, respectively

(Hancock 1971; Vermeer et al. 1976a). Earlier breeding

had not been reported in 1950 in the Scott Island group,

including Sartine, Beresford, Cox, and Lanz Islands

(Carl et al. 1951). Mink (Mustela vision) and raccoon

(Procyon lotor) were introduced to Cox and Lanz Islands

in 1938–39 and extirpated nesting Cassin’s auklets

(Ptychoramphus aleuticus; Carl et al. 1951; Beebe

1960; Drent and Guiguet 1961; Rodway et al. 1990b).

Mammalian predators are not present at Sartine and

Beresford Islands, which support large populations of

burrow-nesting storm-petrels and alcids, but little

breeding habitat for murres exists (see Appendix I:

Figure I-43; Rodway et al. 1990b).

Early, unsubstantiated records of breeding murres

along the central west coast of Vancouver Island

(Kermode 1904; Brooks and Swarth 1925; Taverner

1928) were not accepted in major historical summaries

(Munro and Cowan 1947; Drent and Guiguet 1961),

but these warrant reconsideration in light of subsequent,

confirmed breeding at Cleland Island, Florencia Islet,

and Starlight Reef. At Cleland Island, breeding was

confirmed between 1969 and 1982 (i.e., 1969–70, 1973–

77, 1979, 1982, and 1983), but not in 1967 (Campbell

and Stirling 1968; Campbell 1976; Campbell et al.

1975, 1990; British Columbia Nest Records Scheme

[BCNRS], see Myers et al. 1957; H. R. Carter and S. G.

Sealy, unpublished data; see Appendix I: Figure I-39).

Between 2 and 150 murres were reported between 1969

and 1982, but only 1 to 8 breeding pairs laid eggs.

When last noted, in 1983, only three murres were seen

that may not have been breeding (G. Kaiser, unpublished

data).

One and two pairs bred on Starlight Reef in 1975

and 1980, respectively (Hatler et al. 1978; BCNRS).

One unsuccessful breeding attempt by a single pair was

recorded at Florencia Islet in 1969 (Campbell et al. 1975;

Hatler et al. 1978), but no murres bred there in 1970,

1974, or 1979 (Campbell et al. 1975; BCNRS; H. R.

Carter and S. G. Sealy, unpublished data). A series of

observations at White Islet (between Florencia Islet and

Cleland Island) between 1968 and 1970 suggested that

1–2 pairs may have attempted to lay eggs but breeding

was not confirmed (R. W. Campbell, unpublished data).

On 30 July 1968, 30 murres were noted near shore and

two adults were seen in potential nesting habitats, but

no eggs or chicks were noted after landing. On 4 August

1969, two adults were again seen in the same location

on the rock but no eggs or chicks were found. No murres

were noted on 28 June 1970, but one adult was again

seen on land in potential breeding habitat on 25 August

1970. Murres were not noted to attend White Islet on

subsequent visits from 1972 to 1979 (R. W. Campbell,

unpublished data).

Solander Island is a large seabird colony on

the northwest coast of Vancouver Island and contains

much suitable breeding habitat (Figure 2.15). However,

breeding murres were not observed in 1954, 1975, 1988,

or 1989 (Guiguet 1955; Beebe 1960; Drent and Guiguet

1961; Campbell 1976; Rodway and Lemon 1990). We
64 USGS/BRD/ITR–2000-0012

have classified Solander Island as a long-inactive colony,

based on available habitat and historic reference as a

breeding colony, but without details (Brooks and Swarth

1925). Although 20 murres were noted flying around

Solander Island on 27 June 1975 (R. W. Campbell,

unpublished data), these birds probably were not

attending potential nesting areas.

A large murre colony on the west coast of Graham

Island in the northern Queen Charlotte Islands was

reported by Haida native people from Masset (Brooks

and Swarth 1925). Three large seabird colonies (i.e.,

Langara, Frederick, and Hippa islands) with some

breeding habitat exist along this coast, but breeding

murres were not reported in 1927, 1946–47, 1952, 1955–

58, 1970–71, 1977, or 1981–88 (Darcus 1930; Beebe

1960; Drent and Guiguet 1961; Campbell and Garrioch

1979; Rodway et al. 1994; C. J. Guiguet, unpublished

field notes; S. G. Sealy, personal communication). Large

numbers of murres were reported off Langara Island and

along the north coast of Graham Island during summer

of 1927, 1946–47, and 1952 (Darcus 1930; C. J. Guiguet,

unpublished field notes). At Langara Island, Darcus

(1930) further noted no murre colonies. On 4 July 1946,

C. J. Guiguet (unpublished field notes) noted “six

California murres sitting on the rocks below the

lighthouse, near sea. This is the first time I’ve observed

these birds on land here”. On 18 May 1947, he noted “.

. . I have no clues on nesting of these birds in this area”.

A female with a fully developed egg was collected near

Langara on 19 July 1930 (Cumming 1931; Munro and

Cowan 1947). We have treated Langara Island as “rocks

attended without confirmed breeding.” We presume that

accounts of large numbers of murres at sea off northern

Graham Island during the summer were related to the

large colony at nearby Forrester Island in southeastern

Alaska (Figure 2.14) that has been documented since

1914 (Willett 1915; Gabrielson and Lincoln 1959;

DeGange et al. 1977; Sowls et al. 1978; Slater 1997). In

fact, Haida natives may have meant this colony in their

original report. Osgood (1901) presumed breeding at

the Skedans Islands off the east coast of Moresby Island

but breeding was never confirmed subsequently.

Breeding was first confirmed on the Kerouard

Islands at the south end of the Queen Charlotte Islands

in 1977 (Campbell and Garrioch 1979). This colony

represents the northern limit of the known breeding

range of the subspecies U. a. californica, and is the

only confirmed common murre colony in northern

British Columbia between Triangle Island and Forrester

Island in Alaska. Although breeding was not confirmed,

10 murres were noted on land on 5 August 1977 at the

northwest rocks at Anthony Island, north of the

Kerouard Islands (R. W. Campbell, unpublished data;

H. R. Carter, personal observation). On 3 and 4 June

1982, three birds were flushed from inaccessible cliffs

(Rodway et al. 1990a; M. S. Rodway, personal

observation). No murres were seen there in 1985 or 1986.

In addition, 40 murres were sighted on an unnamed

rock (“Cone” Islet) on the west coast of Moresby Island

in 1977 (BCNRS; Rodway 1991). Rough weather

prevented a close inspection of the rock to confirm

breeding in 1977 and the site has not yet been revisited.

Current Population Size and Distribution of

Breeding Colonies in British Columbia

In British Columbia, murres now breed almost

entirely at Triangle Island (Table 2.7), and breeding no

longer occurs at four of five other known colonies

(Rodway 1991). Murres have not bred recently at

Cleland Island, Florencia Island, or Starlight Reef in

1982, 1984, and since 1990 (Rodway and Lemon 1990;

BCNRS; A. Dorst, personal communication). At Sartine

Table 2.7. Summary of most-recent surveys of common murres at colonies in British Columbia, 1977–1997.

Colony Colony Number Number Survey

number name counted breeding year

Vancouver Island (Central West Coast)

WV-550 Starlight Reef 0 0 1982

WV-520 Florencia Islet 0 0 1982

WV-020 Cleland Island 0 0 1997

Vancouver Island (North West Coast)

WV-080 Solander Island 0 0 1988

SC-020 Sartine Island 113 0 1989

SC-010 Triangle Island 9,943 8,153 1989

Queen Charlotte Islands (South Moresby Island)

WM-320 Kerouard Islands 200 164 1995

WM-180 “Cone” Islet 40 not confirmed 1977

Total 10,296 8,317
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 65

Island, no murres attended cliffs in 1987 and 1989, but

440 and 113 murres were observed in nearby waters

(Rodway et al. 1990b). At the Kerouard Islands, the

highest numbers (400 murres) were counted on cliffs in

1987 (Rodway et al. 1990a). Annual records kept by

tour-boat operators indicated intermittent attendance

of small numbers of birds from 1989 to 1991, and 1994

to 1996 (200 murres in 1995), but none were observed

in 1992–93 or 1997 (R. W. Campbell, unpublished data).

On occasion, murres also have been noted on land at

other locations wherein no breeding occurred—on 2

July 1974, five murres in breeding plumage were

observed in intertidal habitats at Vivian Island and on 7

July 1974, two murres were noted on a breakwater off

the jetty at the Tsawassen ferry terminal (R. W.

Campbell, unpublished data).

Triangle Island was examined extensively from

1980 to 1985 (Vallee and Cannings 1983; Vallee and

Carter 1987; Rodway 1990; Rodway et al. 1990b).

During this period, murres bred in four main areas: Puffin

Rock, Murre Rock, Castle Rock, and Southeast Point

(Rodway 1990). On 10 July 1982, a partial count of

4,910 murres was obtained at the main colony on Puffin

Rock. In 1984, about 12,000 murres were estimated on

the water in early July, but all breeding attempts failed

(see below) and only small numbers were present on the

breeding slopes. In 1985, murres bred successfully, and

3,956 murres were counted in different breeding areas

between 9 and 19 July.

The most complete estimate of colony size for

Triangle Island was made in 1989 (Rodway 1990). An

average of 5,839 murres (range, 3,335–6,144) was

derived from replicated counts of murres from boat

photographs between 27 July and 17 August 1989.

Numbers from four complete counts (between 1800 and

2000 h [PDT] when daily attendance was highest) ranged

from 5,846 to 6,144 birds. To determine a total number

of birds attending the colony, the 5,839 mean count

was adjusted with a “ground-truthing” or “g” correction

factor of 1.44. This correction factor was determined by

averaging the difference between telescope and photo

counts over the 0700–2100 period. Thus, 8,408 birds

were estimated to attend photographed areas. An average

of 1,535 murres in other areas (i.e., not photographed)

were added to obtain a total of 9,943 birds. To derive an

estimate of the number of breeding adults at the colony,

a k correction factor of 0.82 was applied to derive 8,153

breeding birds or 4,077 breeding pairs. This estimate

was higher than previous estimates due mainly to more

complete coverage of the colony. A repeat of the survey

using similar methodology in 1996 probably

underestimated total numbers because some chicks and

adults had departed from the colony before the count

was completed (Parrish 1997).

By adding recent complete counts of murres at

Triangle Island and the Kerouard Islands, we obtained a

total of 10,296 birds which corresponded to a total

breeding population estimate for British Columbia of

about 8,300 breeding birds (Table 2.7).

Population Trends in British Columbia

Historical records and recent data were inadequate

to determine population trends in British Columbia.

Colonization and abandonment of colonies along the

west coast of Vancouver Island in the late 1960s and

1970s are difficult to interpret and may indicate an

intermittent colonization event, perhaps during a period

of colony growth at Triangle Island and colonies in

Washington.

Replicated counts at three subcolony sites on

Triangle Island in 1982, 1985, and 1989 were highest

in 1982 and lowest in 1985 (Table 2.8; Rodway 1990).

Counts were conducted at different times in the 3 years,

but decrease between 1982 and 1985 and limited

increase between 1985 and 1989 were similar to trends

at certain northern Washington colony complexes (see

Washington section). No murres bred successfully at

Triangle Island in 1984 when complete breeding failure

of murres and most other surface-breeding species

occurred because of severe weather and prey shortage

(Rodway et al. 1990b, 1992). A partial failure also

occurred in 1989. Large numbers of murre eggs had

been eaten by glaucous-winged gulls (Larus

glaucescens), but it was unknown whether predation

contributed to abandonment or occurred afterward

(Rodway 1990). Incubating murres that remained at

breeding sites sat tight on their eggs when approached

by bald eagles or peregrine falcons. Thus, it seemed

unlikely that avian predators were the sole cause of

failure. Large numbers of murres were killed by the 1988

Table 2.8. Comparison of counts of common murres at subcolony sites on Triangle Island in

3 years from 1982 to 1989 (from Rodway 1990).

Location Site number 1982 1985 1989

S side W point 13,14 1,140 540 790

W side W point 15 648 400 523

Murre Rock 22, 25, top 1,843 740 1,466
66 USGS/BRD/ITR–2000-0012

Nestucca oil spill, but a distinct change in the breeding

colony at Triangle Island could not be detected

(Rodway et al. 1989, 1990b; Burger 1992).

Overall Population Assessment

Current Population Size and Distribution of

Breeding Colonies

A complete assessment of the total size and

distribution of the overall breeding population of the

common murre in California, Oregon, Washington, and

British Columbia has been made only once, over a 2-

year period from 1988 to 1989. During this period, the

overall estimated breeding population was

approximately 1.1 million breeding birds (Table 2.9;

see Carter et al. 1995). Several previous population

estimates of common murres for this portion of western

North America were lower and less reliable. Tuck (1961)

roughly estimated not more than 1 million murres for

California and Oregon without details, and it was not

clear if breeding and nonbreeding birds were included

in the estimate. Byrd et al. (1993) used a combination

of 1979–89 data and reported a total of about 826,000

breeding murres: California (363,000 in 1979–80;

Sowls et al. 1980), Oregon (426,000 in 1988; R. W.

Lowe, unpublished data), Washington (31,000 in 1978–

79; Speich and Wahl 1989), and British Columbia (6,000

in 1988–89; Campbell et al. 1990). However, large

population declines occurred in central California and

Washington between 1979 and 1989, which makes this

combination of data less reliable. Tyler et al. (1993)

reported 810,500 breeding murres (minus British

Columbia): California (351,000 in 1989; Carter et al.

1992), Oregon (438,100 in 1989; Briggs et al. 1992),

and Washington (21,400 in 1989; Briggs et al. 1992).

We relied on data largely from the USFWS for murre

numbers in Washington and Oregon to maximize

compatibility among data sets used to generate

population estimates. Rodway (1991) reported 8,640

breeding birds for British Columbia; this estimate was

based on the same information as the 8,300 breeding

birds estimated in this report.

From 13.0 to 20.7 million breeding individuals, or

6.5 to 10.3 million breeding pairs, of common murre

have been estimated in the world, with 54–57% and

43–46% in the Pacific and Atlantic Oceans (including

adjacent areas of the Arctic Ocean), respectively

(Nettleship and Evans 1985; Byrd et al. 1993; Ainley et

al., in preparation). The breeding population in

California, Oregon, Washington, and British Columbia

(about 1.1 million breeding birds) constitutes 5–8%

and 13–28% of the breeding population size of the world

and the Pacific Ocean, respectively.

The common murre is the most abundant breeding

species of seabird in central California, northern

California, and Oregon (Sowls et al. 1980; Varoujean

and Pitman 1980; Carter et al. 1992, 1995; Tyler et al.

1993; R. W. Lowe, unpublished data). Suitable habitat

(small, bare, nearshore rocks) is abundant and widely

distributed along these coasts. Habitat availability and

the ability of murres to exploit various abundant prey

resources in many different marine habitats near shore

and throughout the continental shelf have enabled

murres to exist in high abundance within this

geographic area. In Washington, Cassin’s auklets,

rhinoceros auklets (Cerorhinca monocerata), and

glaucous-winged gulls are more numerous than murres

(Speich and Wahl 1989). In south-central California,

the Brandt’s cormorant becomes the most numerous

species of breeding seabird and murres no longer breed

south of Monterey County (Hunt et al. 1980; Sowls et

al. 1980; Carter et al. 1992). Murres have achieved large

breeding populations at most colonies in northern

California and Oregon in recent decades, probably in

response to the relatively low levels of colony

disturbance and anthropogenic mortality, and excellent

prey conditions within the central part of the California

Current upwelling system (Briggs et al. 1987; Ainley

and Boekelheide 1990; Tyler et al. 1993; Manuwal and

Carter 2001).

About 66% of the overall breeding population of

common murres (U. a. californica) is present in Oregon

(Table 2.9). More than 420,000 murres were estimated

Table 2.9. Total sum of common murres counted and numbers of breeding adults estimated in

California, Oregon, Washington, and British Columbia in 1988–1989.

Year Total Number of Percent

Geographic area counted suma breeding adults of total

Central California 1989 53,985 90,200 8.4

Northern California 1989 156,555 261,400 24.2

Oregon 1988 426,278 711,900 66.0

Washington 1988 4,190 7,000 0.6

British Columbia 1989 10,296 8,300 0.8

Total 651,304 1,078,800

a Sum of whole-colony counts at all colonies in a geographic area.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 67

breeding along the central and north coasts of Oregon

with the largest colonies at Bird Rocks, Three Arch

Rocks, Two Arches Rock complex, and Gull and Colony

Rocks near Newport. The southern Oregon coast

contained approximately 290,000 breeding murres with

the largest colonies at Cat and Kittens, Gull Rock (Cape

Blanco), Orford Reef, Island Rock, Hubbard Mound

Reef, Mack Arch, and outer Whaleshead. Significant

numbers (24%) also bred in northern California, mainly

on several large offshore rocks in Del Norte and

Humboldt Counties (especially Castle Rock, False

Klamath Rock, Green Rock, Flatiron Rock, and False

Cape Rocks). Combined, Oregon and northern

California comprise the current population “core” or

90% of the breeding birds which form the geographic

center of the entire U. a. californica population. This

“core” area is located in the central part of the California

Current upwelling system, characterized by strong and

persistent upwelling during the spring and summer

(Briggs et al. 1987; Tyler et al. 1993). Prey resources

and breeding habitat in the area appear to have been

sufficient to sustain this major part of the population

from 1979 to 1995.

Historically, very large numbers of murres were

present in central California, which also is located within

the central part of the California Current upwelling

system (Briggs et al. 1987; Ainley and Boekelheide

1990; Tyler et al. 1993). In the early nineteenth century,

central California had a much larger proportion of

breeding murres before near extirpation of the immense

colony at the South Farallon Islands. This colony may

have totaled 1–3 million breeding birds at its peak. By

1989, the number of breeding murres in central

California was at the lowest recorded level between 1979

and 1995 and comprised only about 8% of the total

population of breeding murres (Table 2.9). In 1979–82,

more than twice as many murres bred in central

California than in 1989. The largest colonies were

present at the South Farallon Islands, North Farallon

Islands, and Point Reyes. Presently, the southernmost

colony in California is in central California at Hurricane

Point Rocks. In the past, murres bred as far south as

Prince Island in the Channel Islands off southern

California.

The southern limit of the breeding range of the

common murre in the eastern Pacific Ocean is roughly

aligned with the southern edge of the California Current

upwelling system off southern California and western

Baja California, where colder subarctic waters are diluted

by warmer waters from the central ocean gyre (Tyler et

al. 1993). Several other alcids also reach their southern

limit in southern or central California (i.e., pigeon

guillemot [Cepphus columba ], marbled murrelet

[Brachyramphus marmoratus], rhinoceros auklet, and

tufted puffin) or their northern limit (i.e., Xantus’s

murrelet [Synthliboramphus hypoleucus]; Hunt et al.

1980; Sowls et al. 1980; Carter et al. 1992; Gaston and

Jones 1998). A major change in climate, breeding

habitats, prey resources, and natural predators occurs in

this area, which affects breeding by several breeding

seabird species (Hunt et al. 1980; Briggs et al. 1987;

Carter et al. 1992; Tyler et al. 1993). In addition, large

populations of native peoples used mainly marine food

resources and probably prevented breeding in many

parts of the Channel Islands off southern California for

thousands of years (e.g., Glassow 1980) until they were

extirpated from the area in the mid-nineteenth century.

In the nineteenth and twentieth centuries, early European

and American settlers also affected seabird populations

in southern California and northwestern Baja California,

with egg-collecting activities, introduction of predators

to islands (McChesney and Tershy 1998), and other

activities. Thus, the southern limit of breeding murres

U. a. californica may have occurred in the southern

California or possibly northwestern Baja California for

at least tens of thousands of years.

Breeding murres in Washington represented less

than 1% of the total breeding population of U. a.

californica in 1988–89 (Table 2.9) but were several

times more numerous between 1979 and 1982. The few

colonies in British Columbia also comprised less than

1% of total breeding population (Table 2.9). Most birds

in British Columbia bred at one isolated colony at

Triangle Island, at the north tip of Vancouver Island.

Other colonies are small, widely separated, and

irregularly attended. The northernmost colony of U. a.

californica is located at the Kerouard Islands at the

southern end of the Queen Charlotte Islands. There is

no evidence that murres ever bred more widely in British

Columbia.

A major change in breeding habitat occurs on the

west coast of Vancouver Island, British Columbia, where

most of the outer coast islands become forested, and

those that are not tend to be small, low and rounded,

and less suitable for breeding by murres and some other

seabirds (Beebe 1960; Campbell et al. 1990). In

comparison with Washington, Oregon, and California,

the availability of open breeding habitats on islands in

British Columbia are reduced. Washington and southern

British Columbia also are located at the northern end of

the California Current upwelling system where it meets

the Alaska Current during spring and summer (Morgan

et al. 1991; Tyler et al. 1993; Wahl et al. 1993). Different

prey resources are associated with the estuarine

conditions within the extensive fiord system along the

coasts of British Columbia and southeastern Alaska.
68 USGS/BRD/ITR–2000-0012

Also, large populations of native people were present

for at least thousands of years in British Columbia prior

to the mid-nineteenth century (Duff 1997), and probably

visited many seabird nesting islands to obtain eggs and

birds for food. Certain murre colonies may have been

extirpated prior to 1800. However, reduced availability

of breeding habitats and change in prey resources may

be the primary factors contributing to the current

geographic gap between murres breeding in Alaska (U.

a. inornata) and from southern British Columbia to

California (U. a. californica).

During glacial periods in the last 1 million years

(i.e., the last period ended about 10,000 years ago),

continental ice sheets extended to sea level from

northern Washington through much of southern Alaska,

which coincides to a large degree with the current

geographic gap and is related to changes in coastal

topography. Glacial history probably is a major factor

underlying the current gap in distribution, and also may

have strongly influenced the current location of the

major portion of the population of U. a. californica in

Oregon and California. However, the fossil history of

Uria extends back at least 5 million years in southern

California (Barnes et al. 1981; Howard 1949, 1981, 1982;

see Bèdard 1985). Various changes in seabird

communities, marine environments, and coastal

topography have occurred in the North Pacific over

millions of years and influenced the distribution and

abundance of the common murre.

Recent and Historical Population Trends

The numbers and distribution of common murres

in the Oregon and northernCalifornia “core” population

between 1979 and 1995 seem to represent relatively

stable high levels, possibly indicative of near carryingcapacity levels and distribution (Figure 2.16). In this

area, murre numbers have stabilized for several decades,

apparently in relation to available breeding habitat, prey

resources, and relatively low levels of human

disturbance at colonies. Most suitable breeding habitat

is occupied, although some habitat has been removed

historically by either connecting islands to the mainland

with breakwaters or modifying islands for lighthouses

or other structures. The abundance and availability of

prey resources have not been well studied, but evidently

have been adequate to maintain populations at current

high levels. Few natural factors are known that would

disrupt this stability. Lower numbers of breeding birds

attended colonies during severe El Niños in 1983–84

and 1992–93. These events probably caused lower prey

availability or accessibility over the short term (e.g.,

Ainley and Boekelheide 1990). Resultant depressions

in reproductive performance apparently have not had

long-term effects on the size of the “core” populations

in northern California and Oregon. Few anthropogenic

factors have affected murres in Oregon and northern

California in recent decades except in fall and winter

when most Oregon birds move north to Washington

Numbers of murres counted (in thousands)

Year

Central California

0

20

40

60

80

100

120

140

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Northern California

0

20

40

60

80

100

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Oregon

0

20

40

60

80

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Washington

0

10

20

30

40

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996

Figure 2.16. Changes in wholecolony counts of common murres

at breeding colonies in central

California (all colonies), northern

California (excluding the Castle

Rock colony), Oregon (15 sample

colonies), and Washington

(excluding Tatoosh colonies),

1979–95.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 69

and British Columbia. Some Oregon birds undoubtedly

have been killed in gill nets and by oil spills in

Washington and British Columbia (especially the 1988

Nestucca and 1991 Tenyo Maru oil spills) between

1979–95. Yet, despite such deaths, the “core” of the

overall population did not change to a large degree.

The large population size and the wide dispersal of

anthropogenic deaths among many colonies may have

lessened effects on the Oregon population.

To reach current population levels, murres in

northern California and Oregon had to recover over many

decades (mainly from the 1940s to the 1970s) from

extensive human impacts that occurred in the late

nineteenth and early twentieth centuries. As impacts

from native peoples and early settlers declined, the

numbers and range of breeding murres increased to the

current high population levels. During this period,

colony formations (including recolonization events)

occurred widely. Adequate prey resources, available

breeding habitat, and relatively low natural or

anthropogenic deaths must have existed for this recovery

to occur. In northern California, extensive recovery has

occurred in Del Norte and Humboldt Counties but

recovery is still occurring in Mendocino and Sonoma

Counties where recolonization events and population

increase are ongoing.

In central California, historical effects by early

settlers reduced this population to low levels.

Extirpation of colonies in Sonoma and, possibly,

Mendocino counties may have caused the geographic

gap between murres breeding in central and northern

California. Colony extirpation was recorded at San Pedro

Rock and near extirpation at the South Farallon Islands.

By the early 1980s, many colonies had increased

substantially, but were still well below known historical

levels. As in northern California, adequate prey

resources, available breeding habitat, and relatively low

natural and anthropogenic mortality existed for this

limited partial recovery to occur. Breeding habitat at

the South Farallon Islands has been reduced from

historical conditions, thus, it is unlikely this colony

will ever return to levels reached in the early nineteenth

century. Declines between 1982 and 1989 occurred at

all colonies in central California and one colony

(Devil’s Slide Rock) was extirpated. Partial recovery in

central California between 1989 and 1995 has been

slow and limited, possibly reflecting the relative severity

of the original decline, as well as continuing effects.

Breeding success has remained high at the South

Farallon Islands (except during severe El Niños) and is

not a factor impeding recovery at most colonies

(Hastings et al. 1997; Sydeman et al. 1997; McChesney

et al. 1998, 1999; M. W. Parker, unpublished data).

However, mortality from recent oil spills (e.g., 1996

Mohican, 1997–98 Point Reyes Tarball Incidents, and

1998 Command) and the recent resurgence of significant

deaths in gill nets in Monterey Bay have increased

anthropogenic impacts since 1995 (P. R. Kelly, personal

communication).

In Washington, numbers of murres attending

colonies in 1979–82 reflected growth since the early

twentieth century. Decline and little recovery between

1982 and 1995 in Washington appear to have resulted

from severe effects (from natural and anthropogenic

factors) on the murre population over the long term

(Figure 2.16). Murre attendance at the largest colonies

in southern Washington (i.e., Split Rock, Willoughby

Island, Grenville Arch, and Rounded Island) plummeted

to small numbers of irregularly-occurring birds and

evidence of reproductive effort and success has been

largely absent since the initial decline. Small colonies

in northern Washington also declined, but to a lesser

degree and have shown limited growth in recent years,

possibly because of intercolony movements from

southern Washington colonies. Massive decline and a

lack of recovery in southern Washington may be related

to the lower initial population size in Washington before

the decline (compared with populations in Oregon and

California), the high magnitude of natural and

anthropogenic impacts over an extended period of time,

and intercolony movements of birds to northern

Washington colonies. However, small numbers of birds

still attend traditional breeding colony locations in

southern Washington and some recovery may be

possible in the future. The likelihood of rapid natural

recovery in Washington is very low because of continued

anthropogenic and natural effects and the slow rate of

murre recovery documented at severely reduced colonies

elsewhere along the Pacific coast.

Overall, murre numbers in central California and

Washington have declined substantially since the early

1980s and currently exist well below historical

population levels and distribution (Figure 2.16). Major

declines occurred rapidly between 1982–86, and low

numbers have remained over extended periods of time

following these declines. Although limited increase has

occurred in central California in recent years, numbers

remain depressed in Washington. Prey resources have

been little studied but were apparently adequate to

maintain these populations at higher population levels

in 1979–82. Large-scale declines between 1979 and

1989 resulted from long-term impacts from

anthropogenic factors (i.e., gill-net and oil-spill deaths

and human disturbance), coupled with natural factors

(i.e., reduced reproductive effort and success associated

with severe 1982–83 El Niño, and the 1981 warm water
70 USGS/BRD/ITR–2000-0012

event in Washington). At the same time, climate change

has been occurring with a significant warming of coastal

waters which also may be affecting murre prey resources

(Roemmich and McGowan 1995; Ainley et al. 1996).

In central California, climate change has not prevented

recent increase in the murre population, but may have

reduced the rate of increase (Sydeman et al. 1997). The

apparent overall stability of populations in Oregon and

northern California between 1979 and 1989

underscored the fact that natural factors alone were not

responsible for major declines in central California and

Washington (Takekawa et al. 1990; Carter et al. 1995).

Washington populations now persist at extremely low

levels and are affected by continuing anthropogenic

and natural factors, which probably have prevented or

slowed recovery.

The status of common murres in British Columbia

is poorly known. The isolated colony at Triangle Island

has been present since at least the beginning of the

twentieth century. At this colony numbers of breeding

murres were relatively stable between 1982 and 1989.

Small colonies on the west coast of Vancouver Island

disappeared in the 1970s and 1980s. In the past, most

potential breeding islands for murres in British

Columbia probably were visited frequently by native

people hunting seabirds. Murres on Triangle Island

breed largely on inaccessible cliffs far from the coast of

Vancouver Island, enabling this colony to coexist with

native peoples over extended periods of time. Few

Europeans or Canadians settled the outer west coast of

Vancouver Island (except during a brief sardine fishery

in the 1930s), which suggests that human effects were

probably low during the twentieth century. However,

mortality from oil spills or gill nets may have impacted

these colonies, either during the breeding season (e.g.,

Barkley Sound; Carter and Sealy 1984) or in wintering

areas in Juan de Fuca Strait, Puget Sound, or the Straits

of Georgia.

Acknowledgments

This chapter has benefitted greatly from detailed

reviews and editorial comments of various drafts by D.

G. Ainley, D. Bertram, G. V. Byrd, A. J. Gaston, M. P.

Harris, K. Kilbride, G. J. McChesney, D. N. Nettleship,

S. Olson-Edge, M. W. Parker, F. L. Paveglio, J. R. Sauer,

S. G. Sealy, J. L. Trapp, and T. S. Zimmerman.

Administrative support was provided by B. Bortner, D.

L. Orthmeyer, and T. Zimmerman. Assistance with

preparation of figures and tables were provided by M.

Anderson, P. J. Capitolo, J. Daugherty, J. Friday, C.

Gregory, G. J. McChesney, D. L. Orthmeyer, and W. Perry.

In California, funding and support for murre colony

surveys and aerial photograph counting from 1985 to

1995 were provided by USFWS, Humboldt State

University, U.S. Geological Survey (Western Ecological

Research Center), California Department of Fish and

Game (Office of Spill Prevention and Response and Air

Services), Minerals Management Service, U.S. Navy,

U.S. Department of Justice, Point Reyes National

Seashore, Apex Houston Trustee Council, and Point

Reyes Bird Observatory. Administrative assistance was

provided by D. G. Ainley, S. Allen, R. Coleman, D. S.

Gilmer, R. T. Golightly, J. Hamby, L. Heitz, R. Helm, R.

Johnson, T. W. Keeney, P. R. Kelly, V. Lee, D. Lollock,

D. L. Orthmeyer, M. W. Parker, M. O. Pierson, G. Reetz,

W. J. Sydeman, E. Ueber, and D. Welsh. Aerial surveys

were conducted in the Gulf of the Farallones and

Monterey Bay National Marine Sanctuaries in 1993–

95 under permit numbers GFNMS/MBNMS 04-93, 02-

94, and 04-95, with assistance by H. M. Golde, T.

Jackson, S. Kathey, J. Roletto, and E. Ueber. Aerial

surveys were conducted in the Channel Islands National

Marine Sanctuary in 1991–95 under permit numbers

CINMS 02-91, 04-92, 05-93, 02-94, 01-95, with

assistance by M. Crosby, S. Jameson, J. A. Miller, J.

Morris, J. A. Uravitch, and C. Wahle. Significant

assistance with surveys or photograph counting were

provided by L. Accurso-Vicenzio, P. J. Capitolo, T. E.

Harvey, D. L. Jaques-Strong, D. L. Jory-Carter, R. W.

Lowe, G. J. McChesney, W. R. McIver, E. Nelson, L. K.

Ochikubo, M. W. Parker, C. S. Strong, and D. L.

Whitworth. Flights were conducted by Aspen

Helicopters (Camarillo, California), California

Department of Fish and Game (Air Services; Sacramento,

California), and Northern Air Services (Eureka,

California). We also greatly appreciate earlier efforts in

1979–82 to survey murre colonies with aerial

photography in California by K. T. Briggs, A. R.

DeGange, G. S. Lester, D. B. Lewis, J. W. Nelson, A. L.

Sowls, and W. B. Tyler. We lament the tragic death of J.

M. Drust, who piloted many aerial photographic surveys

of murre and other seabird colonies in California in

1991–95.

Funding and support for murre colony surveys and

aerial photograph counting in Oregon from 1988 to

1995 and in Washington from 1979 to 1995 were

provided by the USFWS and Tenyo Maru Trustee

Council. Administrative assistance was provided by B.

Hesselbart, J. E. Houk, J. Kincheloe, P. Sekora, and J.

Welch. Significant assistance with surveys or

photograph counting in Oregon were provided by J.

Anderson, M. Naughton, D. Pitkin, and S. Reimer.

Assistance with historical literature and unpublished

data in Oregon and Washington was provided by R.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 71

Bayer, F. Dobler, M. Graybill, J. Hodder, D. B. Marshall,

R. L. Pitman, S. M. Speich, D. Varoujean, and T. R. Wahl.

Funding and support for murre and other seabird

colony surveys in British Columbia from 1980 to 1989

were provided by Environment Canada (Canadian

Wildlife Service, and Conservation and Protection),

especially with 1989 funding for murre studies at

Triangle Island related to the Nestucca oil spill, and

with administrative assistance by S. Garnham, G. Kaiser,

S. Wetmore, and K. Vermeer. Significant assistance with

surveys and design was provided by D. Bertram, B.

Carter, D. Garnier, A. J. Gaston, D. Grinnell, M. Lemon,

D. Powell, G. E. J. Smith, and K. Summers. Surveys in

the 1970s were funded by Royal British Columbia

Museum; British Columbia Ministry of Environment,

Lands and Parks; and Parks Canada. Assistance with

historical literature, unpublished data, and unpublished

egg records was provided by C. Adkins, R. W. Campbell,

A. Dorst, C. J. Guiguet, G. Kaiser, M. C. E. McNall, and

S. G. Sealy. Also, R. W. Campbell provided certain colony

photographs in Appendix I. We lament the tragic death

of A. Vallée, who studied murres and other seabirds at

Triangle Island in 1980–82.

Valuable historical egg records in California,

Oregon, Washington, and British Columbia were

obtained from collections at Humboldt State University

(Department of Wildlife Museum; Arcata, California),

Museum of Comparitive Zoology (Harvard University,

Cambridge, Massachusetts), National Museum of

Natural History (Washington, D.C.), Royal British

Columbia Museum (Victoria, British Columbia), San

Diego Museum of Natural History (San Diego,

California), Santa Barbara Museum of Natural History

(Santa Barbara, California), University of British

Columbia Zoology Museum (Vancouver, British

Columbia), University of California (Museum of

Vertebrate Zoology; Berkeley, California), and

especially the Western Foundation of Vertebrate

Zoology (Camarillo, California).

Comments on Appendix B were provided by D. G.

Ainley, G. J. McChesney, M. W. Parker, W. D. Shuford,

L. E. Stenzel, W. J. Sydeman, and P. White. Valuable

unpublished field notes containing historical

information on murre colonies in California included

C. I. Clay (Humboldt State University, Special

Collections Library, Arcata, California), H. L. Cogswell

(unpublished data collated and provided by Howard

Cogswell), and L. O. Williams (University of California

Berkeley, Hastings Reservation, Carmel Valley,

California). Invaluable assistance with the collation of

historical egg records from museums was provided by

G. J. McChesney, W. R. McIver, R. T. Golightly, and T.

Danufsky. S. F. Bailey (Pacific Grove Natural History

Museum) provided a copy of the common murre section

of the notebook files for the “Middle Pacific Coast

Region” (Oregon border to Point Conception)

maintained for American Birds and its predecessor

Audubon Field Notes. This notebook file contains the

unpublished observations of many individuals noted

in the text and was checked against observations

published in American Birds. The libraries of the

University of Manitoba (Winnipeg, Manitoba),

University of California (Davis and Berkeley, California),

and Point Reyes Bird Observatory (Stinson Beach,

California) provided much historical literature and

assistance through interlibrary loans. Other unpublished

historical observations were provided by S. Allen, R. A.

Erickson, R. Jurek, and T. Schulenberg. Previous

summaries of historical literature on murres in California

were extremely helpful, especially the works of D. G.

Ainley, R. W. Doughty, J. Grinnell, G. L. Hunt, L. F. Kiff,

T. J. Lewis, A. H. Miller, and T. O. Osborne.

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McChesney, G. J., H. R. Carter, M. W. Parker, J. E.

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progress report. Unpublished report, California

Department of Fish and Game, Wildlife

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rocks of northern California from Cape Mendocino

to the Oregon line. Unpublished report, California

Department Fish and Game, Wildlife Management

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California.

Osborne, T. O., and J. G. Reynolds. 1971. California

seabird breeding ground survey 1969–1970.

Unpublished report, California Department Fish and

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Administrative Report 71-3, Sacramento,

California.

Page, G. W., and H. R. Carter, editors. 1986. Impacts of

the 1986 San Joaquin Valley Crude oil spill on
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 83

marine birds in central California. Unpublished

report, Point Reyes Bird Observatory, Stinson

Beach, California.

Parker, M. W., J. A. Boyce, E. N. Craig, H. Gellerman, D.

A. Nothelfer, R. J. Young, S. W. Kress, H. R. Carter,

and G. A. Moore. 1999. Restoration of common

murre colonies in central California: annual report

1998. Unpublished report, U.S. Fish and Wildlife

Service, San Francisco Bay National Wildlife

Refuge, Newark, California.

Parker, M. W., E. B. McLaren, J. A. Boyce, V. Collins, D.

A. Nothelfer, R. J. Young, S. W. Kress, H. R. Carter,

and A. M. Hutzel. 1998. Restoration of common

murre colonies in central California: annual report

1997. Unpublished report, U.S. Fish and Wildlife

Service, San Francisco Bay National Wildlife

Refuge, Newark, California.

Parker, M. W., E. B. McLaren, S. E. Schubel, J. A. Boyce,

P. J. Capitolo, M. A. Ortwerth, S. W. Kress, H. R.

Carter, and A. Hutzel. 1997. Restoration of common

murre colonies in central California: annual report

1996. Unpublished report, U.S. Fish and Wildlife

Service, San Francisco Bay National Wildlife

Refuge, Newark, California.

Parrish, J. K. 1996. Attendance and reproductive success

of Tatoosh Island common murres. Unpublished

report, University of Washington, Seattle,

Washington.

Parrish, J. K. 1997. The use of decoys to manipulate

behavior: common murres on Triangle Island.

Unpublished report, Simon Fraser University,

Burnaby, British Columbia.

Pierce, J., W. Ritchie and R. Kreuziger. 1994. Preliminary

findings of seabird interactions with the non-treaty

gillnet fishery: Puget Sound and Hood Canal,

Washington. Unpublished report, Washington

Department of Wildlife, Olympia, Washington.

Point Reyes Bird Observatory. 1985. The impacts of the

T/V Puerto Rican oil spill on marine bird and

mammal populations in the Gulf of the Farallones,

6–19 November 1984. Unpublished report, Point

Reyes Bird Observatory, Stinson Beach, California.

Ross, R. E. 1977. Preliminary archaeological

investigations at 35 CU, Port Orford, Oregon.

Unpublished report, Department of Anthropology,

Oregon State University, Corvallis, Oregon.

Sibley, C. G. 1952. The birds of the south San Francisco

Bay region. Unpublished manuscript on file at

library of California State University, Sacramento,

California.

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of the 1986 Apex Houston oil spill on marine birds

in central California. Unpublished report, U. S.

Department of Justice, Washington, D. C.

Slater, L. 1997. Seabird monitoring at Lowrie, Forrester,

and Petrel islands, 1993–1995. Unpublished report,

U.S. Fish and Wildlife Service, Alaska Maritime

National Wildlife Refuge, Homer, Alaska.

Speich, S. M., B. L. Troutman, A. C. Geiger, P. J. MeehanMartin, and S. J. Jeffries. 1987. Evaluation of

military flight operations on wildlife of the Copalis

National Wildlife Refuge, 1984–1985.

Unpublished final report, U.S. Navy, Western

Division, Naval Facilities Engineering Command,

San Bruno, California.

Stenzel, L. E., G. W. Page, H. R. Carter, and D. G. Ainley.

1988. Seabird mortality in California as witnessed

through 14 years of beached bird censuses.

Unpublished report, Point Reyes Bird Observatory,

Stinson Beach, California.

Sullenberger, M. 1980. Dogholes and donkey engines—

a historical resources study of six state park system

units on the Mendocino coast. Unpublished report,

California Department of Parks and Recreation,

Sacramento, California.

Sumner, L. E. 1939. An investigation of Santa Barbara,

Anacapa and San Miguel islands. Unpublished

manuscript, Channel Islands National Park,

Ventura, California.

Swartzman, G., and H. R. Carter. 1991. Long-term injuries

to the central California population of common

murres (Uria aalge) due to mortality from the 1986

Apex Houston oil spill. Unpublished report, U.S.

Department of Justice, Washington, D.C.

Sydeman, W. J., H. R. Carter, J. E. Takekawa, and N. Nur.

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trends at the South Farallon Islands, California,

1985–1995. Unpublished report, Point Reyes Bird

Observatory, Stinson Beach, California, U.S.

Geological Survey, Dixon, California, and U.S. Fish

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Sydeman, W. J., J. A. Thayer, M. M. Hester and N. P.

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Island, California. Unpublished report, Point Reyes

Bird Observatory, Stinson Beach, California.
84 USGS/BRD/ITR–2000-0012

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Farallon Islands, California, Unpublished report,

U.S. Fish and Wildlife Service, Portland, Oregon.

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report, calendar year 1979: Farallons National

Wildlife Refuge. Unpublished report, U.S. Fish and

Wildlife Service, San Francisco Bay National

Wildlife Refuge, Newark, California.

Varoujean, D. H. 1979. Seabird colony catalog:

Washington, Oregon and California. Unpublished

report, U.S. Fish and Wildlife Service, Portland,

Oregon.

Varoujean, D. H., and R. L. Pitman. 1980. Oregon seabird

colony survey, 1979. Unpublished report, U.S. Fish

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demographic impact to common murres (Uria

aalge) killed during the 1991 Tenyo Maru oil spill.

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Unpublished Data and Personal

Communications

Ainley, David G., H. T. Harvey and Associates 3150

Almaden Expressway, Suite 145, San Jose,

California 95118

American Birds Files, Photocopy of unpublished file

for common murre provided to Harry R. Carter by

Steven F. Bailey, Museum of Natural History, 165

Forest Avenue, Pacific Grove, California 93950

Anderson, W. (Deceased), unpublished field notes,

Special Collections Library, Humboldt State

University, Arcata, California 95521

Bleitz, Donald (Deceased), unpublished field notes,

Western Foundation of Vertebrate Zoology, 439

Calle San Pablo, Camarillo, California 93010

Briggs, Kenneth T., Danville Veterinary Hospital, 812

Camino Ramon Road, Danville, California 94526

Campbell, R. Wayne, P. O. Box 6218, Station C,

Victoria, British Columbia V8P 5L5 Canada

Clay, Charles I. (Deceased), unpublished field notes,

Special Collections Library and Wildlife Museum,

Humboldt State University, Arcata, California

95521

Cody, Martin L., Department of Biology, University of

California, Los Angeles, California 90024

Cogswell, Howard L., 1548 East Avenue, Hayward,

California 94541

Dobler, Fred, Washington Department of Fish and

Wildlife, 2108 Grand Boulevard, Vancouver,

Washington 98661

Dorst, Adrian, 820 Campbell Street, Tofino, British

Columbia VOR 2Z0 Canada

Erickson, Richard A., P. O. Box 1706, Laguna Beach,

California 92652

Ford, R. Glenn, R. G. Ford Consulting, 2735 N. E.

Weidler Street, Portland Oregon. 97232

Guiguet, Charles J. (Deceased), unpublished field notes,

Vertebrate Zoology Division, Royal British

Columbia Museum, 675 Belleville Street, Victoria,

British Columbia V8V 1X4 Canada

Jurek, Ronald, California Department of Fish and Game,

Habitat Conservation Planning Branch, 1416 Ninth

Street, Sacramento, California 95814

Kaiser, Gary W., Canadian Wildlife Service, Pacific

Wildlife Research Centre, RR#1, 5421 Robertson

Road, Delta, British Columbia V4K 3N2 Canada

Kelly, Paul R., California Department of Fish and Game,

Office of Spill Prevention and Response, 1700 K

Street, Sacramento, California 94244

Marshall, David B., 4265 S. W. Chesapeake Avenue,

Portland, Oregon 97201, unpublished field notes,

U.S. Fish and Wildlife Service, Oregon Coast

National Wildlife Refuge, 2127 S. E. OSU Drive,

Newport, Oregon 97365

McChesney, Gerard J., U.S. Geological Survey, Western

Ecological Research Center, Dixon Field Station,

6924 Tremont Road, Dixon, California 95620, and

Humboldt State University, Department of Wildlife,

Arcata, California 95521

Miller, Alden H. (Deceased), unpublished field notes,

Museum of Vertebrate Zoology, University of

California, Berkeley, California
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 85

Nettleship, David N., 25 Tidewater Lane, Allen Heights,

Tantallon, Nova Scotia B0J 3J0 Canada

Parker, Michael W., U.S. Fish and Wildlife Service, San

Francisco Bay National Wildlife Refuge, P.O. Box

524, Newark, California 94560

Parrish, Julia K., Zoology Department, University of

Washington, Box 351800, Seattle, Washington

98195

Schulenberg, Thomas S., Environmental Conservation

Programs, Field Museum of Natural History, 1400

South Lake Shore Drive, Chicago, Illinois 60605

Sealy, Spencer G., Department of Zoology, University

of Manitoba, Winnipeg, Manitoba R3T 2N2

Canada

Sowls, Arthur L., U.S. Fish and Wildlife Service, Alaska

Maritime Refuge, 2355 Kachemak Bay Drive,

Homer, Alaska 99603, unpublished survey archive

(California 1979-1980), U.S. Geological Survey,

Western Ecological Research Center, Dixon Field

Station, 6924 Tremont Road, Dixon, California

95620

Spear, Larry B., H. T. Harvey and Associates, 3150

Almaden Expressway, San Jose, California 95118

Speich, Steven M., 4720 North Oeste Place, Tucson,

Arizona 85749

Sydeman, William J., Point Reyes Bird Observatory,

4990 Shoreline Highway, Stinson Beach, California

94970

White, Peter, 761 Condor Drive, Martinez, California

94553

Williams, Laidlaw O. (deceased), unpublished field

notes, University of California, Hastings

Reservation, Carmel Valley, California. Notes are

temporarily stored at: U.S. Geological Survey,

Western Ecological Research Center, Dixon Field

Station, 6924 Tremont Road, Dixon, California

95620
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 87

Appendix A

Techniques for aerial and other photographic surveys of common murre (Uria aalge californica) colonies

in California, Oregon, Washington, and British Columbia

(prepared by H. R. Carter, J. E. Takekawa, R. W. Lowe, and U. W. Wilson)

In this appendix, we summarize various aspects

of techniques for aerial and other photographic surveys

of common murres (Uria aalge californica) conducted

in California, Oregon, Washington, and British

Columbia from 1979 to 1995.

California

Aerial surveys in 1969–70 apparently involved

mainly visual estimates with some photographs taken

for back-up documentation (Osborne and Reynolds

1971; Osborne 1972). In 1979–80, U.S. Fish and Wildlife

Service (USFWS) personnel conducted aerial surveys

of colonies using high-wing Cessna 182 or 210 aircraft,

or U.S. Coast Guard helicopters (Figure A-1; Sowls et

al. 1980). Color photographs were taken at altitudes of

150–250 m, using 35-mm cameras with 70–210- or 300-

mm lenses, mainly near midday. In 1980–82, staff from

the University of California at Santa Cruz conducted

aerial surveys from a high-wing, twin engine Hunting

Pembroke, flying a coastal survey track about 100 m

from shore (Briggs et al. 1983, 1987). Photographs were

taken mostly at altitudes of 100–200 m along most of

the coast (except at the Farallon Islands and other

sensitive areas where altitude was increased to 300–

400 m), using 35-mm cameras with 80–200- or 300-mm

lenses. These techniques were generally comparable,

although few passes were made at each colony, such

that colony coverage and photograph quality often

varied between colonies and surveys. In higher-quality

photographs, counts of individual birds were made and,

in lower-quality photographs, blocks of 10, 50, or 100

birds were counted. Photographs were occasionally

supplemented with visual estimates. Small numbers of

murres were flushed from colonies by low-flying aircraft.

Aerial photographic surveys of murre colonies

were improved and better standardized from 1985 to

1995 by the USFWS, National Biological Service, U.S.

Geological Survey, and Humboldt State University

(Takekawa et al. 1990; Carter et al. 1992, 1995, 1996,

2000; Sydeman et al. 1997; McChesney et al. 1998,

1999; see Tables A-1 and A-2). In general, counts were

considered to be comparable at most colonies from 1979

to 1995. However, notable exceptions were Castle Rock

in 1979–82 and Point Reyes in 1979–81. Since 1985,

all central California colonies have been surveyed using

either a high-wing, twin-engine Partanavia (or a Cessna

337 aircraft). At the South Farallon Islands, colonies

were surveyed from about 183 to 274 m (600 to 900

feet) and others from about 122 to 213 m (400 to 700

feet). Northern California colonies were surveyed at

altitudes of 122 to 213 m (400 to 700 feet) using a

single-engine Cessna 150 or 182 (1985–90) or a highwing, twin-engine Partanavia (1993–95). In most years,

colonies were surveyed once in late May or early June

(i.e., near the end of egg laying and before colony

departure). During this period, murre numbers are high

and least variable (Takekawa et al. 1990). On rare

occasions, small numbers of murres were flushed from

colonies and surveys were continued at higher altitudes.

At the South Farallon Islands, surveys were conducted

Figure A-1. Aerial photography was conducted with hand-held cameras

from helicopters in Oregon and Washington, and from fixed-wing

aircraft in California. In this photo, R. W. Lowe is taking photographs

from a helicopter at Three Arch Rocks, Oregon (Photo by D. S. Pitkin).
88 USGS/BRD/ITR–2000-0012

at higher altitudes and farther from shore to prevent

flushing.

Entire colonies were photographed by two (one

front-seat and one back-seat) photographers between

1000 and 1400 h (PDT), using 35-mm cameras with

300-mm lens. Each part of a colony was passed over

several times to ensure photograph quality and

overlapping coverage of all breeding areas. Close-up

slides of each part of the colony from either

photographer were pieced together using separate

overview photographs taken only by the front-seat

photographer using a 50-mm lens. Slides were then

projected on white paper and each murre was counted

(Figure A-2).

After obtaining direct whole-colony counts of

murres from aerial photographs, a k correction factor

can be used to estimate the total number of breeding

birds using the colony in the survey year. Based on

counts of murres and egg-laying sites in a plot on Upper

Shubrick Point on the South Farallon Islands, California,

Table A-2. Summary of aerial photographic surveys of common murre colonies in northern California, 1979–1995. a

Year Dates Field personnel Sources

1979 15 May; 19 June Sowls, Nelson, Lester, Rodstrom Sowls et al. 1980

12 & 24 July; 2 August

1980 9, 23, & 25 July Sowls, DeGange, Nelson, Lester, Rodstrom Sowls et al. 1980

1980 5–7 May Briggs, Lewis, Tyler Briggs et al. 1983

1–3 July Briggs, Lewis, Tyler Briggs et al. 1983

1981 19–21 May Briggs, Lewis, Tyler Briggs et al. 1983

30 June–2 July Briggs, Lewis, Tyler Briggs et al. 1983

1982 1–3,19 May Briggs, Lewis, Tyler Briggs et al. 1983

28–30 June Briggs, Lewis, Tyler Briggs et al. 1983

1985 5 June Lowe Carter & Takekawab

1986 19 June Takekawa, Nelson Takekawa et al.1990

1987 1 June Takekawa, Nelson Carter & Takekawab

1988 19 May Takekawa, Nelson Carter & Takekawab

1989 30–31 May; 16 June Takekawa, Nelson, Carter Carter et al. 1992

1990 6, 8 June Takekawa, Nelson Carter & Takekawab

1993 8–9 June Takekawa, Carter, Carter Carter et al. 1996

1994 8, 13–14 June Takekawa, Strong, Strong Carter et al. 1996

1995 5–7 June Takekawa, Carter, Parker, Strong Carter et al. 1996

aSee Appendixes C and D

bUnpublished data

Table A-1. Summary of aerial photographic surveys of common murre colonies in central California, 1979–1995. a

Year Dates Field personnel Sources

1979 7, 11 June Sowls, Nelson, Lester, Rodstrom Sowls et al. 1980

1980 24 June Sowls, DeGange, Nelson, Lester, Stewart Sowls et al. 1980

1980 5–7 May Briggs, Lewis, Tyler Briggs et al.1983

13 July Briggs, Lewis, Tyler Briggs et al.1983

1981 19–21 May Briggs, Lewis, Tyler Briggs et al.1983

30 June–2 July Briggs, Lewis, Tyler Briggs et al.1983

1982 1–3, 19 May Briggs, Lewis, Tyler Briggs et al.1983

28–30 June Briggs, Lewis, Tyler Briggs et al.1983

1985 30 May; 12 June Lowe, Boekelheide Takekawa et al.1990

1986 4–5 June Harvey, Penniman Takekawa et al.1990

1987 26–27 May Harvey, Takekawa Carter et al. 2000

1988 23–24 May Takekawa, Accurso, Foerster Carter et al. 2000

1989 23–24 May Takekawa, Accurso, Carter Carter et al. 1992

1990 29–30 May Takekawa, Carter, Albertson, Roster Carter et al. 2000

1993 27–28 May Takekawa, Carter, Gilardi, Rauzon Carter et al. 1996

1994 4, 8 June Takekawa, Carter, Parker Carter et al. 1996

1995 30 May;1–2, 14, Takekawa, Carter, Parker, McChesney, Carter et al. 1996

20 June Carter, McIver, Keeney

aSee Appendixes C and D
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 89

the k1 correction factor is calculated using the formula

k1(tl) = ne(2)/nt (t1) where ne = number of plot sites where

an egg was laid that season, which is then multiplied by

two breeding birds/site, and nt = the number of murres

counted at time t. This calculation differs slightly from

k as described by Birkhead and Nettleship (1980), which

calculates number of breeding pairs. Alternatively, a k2

correction factor also has been used where ne equals the

number of egg-laying sites on the survey day (Takekawa

et al. 1990). Whereas little difference exists between

these versions of k at the South Farallon Islands

(Sydeman et al. 1997), the k1 calculation is preferred

overall because it prevents possible biases relative to

the timing of the survey. Annual k values can be

determined by averaging counts from different days.

Since 1979, various k1 and k2 values have been

used to adjust whole-colony counts to estimate the

number of breeding adults at colonies, which then can

be summed to estimate the breeding population in

California. A general k correction factor of 1.67 was

used to adjust whole-colony counts in 1979–82 (Sowls

et al. 1980; Briggs et al. 1983) based on data from the

South Farallon Islands in the early 1970s (Ainley 1976,

and personal communication). Takekawa et al. (1990)

calculated an average k2 value of 1.68 by averaging

four years of data from 1980 to 1986. This average value

was applied to all colonies since 1980, except at the

South and North Farallon Islands where annual values

were applied. Carter et al. (1992) also used this k2 value

of 1.68 to estimate colony size at all colonies in 1989,

except at the Farallon Islands where an annual 1989

value was used. More details about k correction factors

developed at the South Farallon Islands are available

elsewhere (Boekelheide et al. 1990; Takekawa et al.

1990; Carter et al. 1992). Sydeman et al. (1997)

reevaluated and corrected all data from 1985 to 1995

and calculated k 1 values that averaged 1.67 with

relatively little variation among years. Takekawa et al.

(1990) reported the general accuracy of estimates of

breeding adults at colonies in California to be within

10%. However, further work is required to better

determine error associated with these estimates.

Oregon

Murre colonies in Oregon were censused from

1966 to 1975 by USFWS biologists using fixed-wing

aircraft. These aerial censuses were generally flown in

late June or early July and relied on visual estimation,

rather than aerial photography, to determine the number

of murres present. This method often resulted in

underestimation, especially at larger colonies; 1974–

75 estimates of colony size were probably low. Aerial

photographic surveys were first used in 1979 during

the first coastwide survey of nesting seabirds in Oregon

(Varoujean and Pitman 1980). However, many of the

photographs were taken too late in the season to provide

accurate counts and the population estimate was low.

In late June 1989, Ecological Consulting

Incorporated conducted murre colony counts in Oregon

(Briggs et al. 1992). The focus of their research was to

conduct offshore and coastal strip transects surveys of

marine mammals and seabirds using a fixed-wing

aircraft. On June 27 and 28, they made a nonstandardized

aerial survey of murre colonies and counted murres at

coastal locations using visual estimates from aircraft

Figure A-2. Aerial photographs

were projected onto a wall with

white sheets of paper, best

photographs were selected for

counting, and then each murre

was marked on the paper. In this

photo, the best close-up

photographs of Tillamook Rock,

Oregon, have been pieced

together, and murres on different

parts of the rock are being marked

(Photo by D. S. Pitkin).
90 USGS/BRD/ITR–2000-0012

traveling at 185 km/h parallel to shore (i.e., 0.4 km from

shore at altitudes of 60–300 m). Photographs were taken

of all aggregations of more than 10 birds and later were

inspected to verify visual estimates. Nonstandardized

techniques were used because of permit restrictions near

murre and other seabird colonies and probably resulted

in less accurate whole-colony counts of murres (K. T.

Briggs and R. G. Ford, personal communication). The

uncorrected count was 262,364 birds (Briggs et al. 1992).

Data obtained by Ecological Consulting Incorporated

were considered inaccurate and were not used for trend

analyses in Chapter 2 because (1) nonstandardized

survey techniques were used; (2) the survey did not

include 29 (42%; n = 69) active murre colonies in

Oregon in 1989, especially some large colonies

exceeding 10,000 birds; (3) some counts were reported

for rocks where murre colonies were not present; and (4)

counts for many colonies were lumped together as a

single count. Large discrepancies exist where 1989

standardized counts by the USFWS (7 and 9 June) can

be compared with those of Briggs et al. (1992). At eight

sites compared, the Briggs et al. survey reported greater

numbers at three colonies (range, 5–45%) and

significantly lower numbers at the other five colonies

(range, 49–98%) than the USFWS survey.

Since 1988, single annual surveys of all major

murre colonies in Oregon have been conducted (except

1995; Table A-3) using standardized techniques.

Surveys were flown in early June to coincide with late

incubation and hatching (after Takekawa et al. 1990).

Surveys were conducted using a Hughes 500 (models D

& E) helicopter at altitudes of 260–330 m with both

right-side doors removed. The five-bladed propeller

configuration reduces noise and lessens possible

disturbance. On rare occasions, small numbers of murres

have flushed from rocks. These birds are typically on

the edges of the colony and probably involve

prospecting or roosting birds, but the numbers are

recorded and included in the colony count. Colony

photographs were taken by two photographers using

35-mm cameras with 100–300- or 300-mm lenses for

close-up photographs (front-seat photographers) using

ASA 400 color slide film and shutter speeds of 1/500 or

1/1000 per sec, and 55- or 70–210-mm lenses for colony

overviews (back-seat photographer). Overlapping

colony slides were projected onto large sheets of paper,

simultaneously using 3–4 projectors and individual

birds were counted. A general k correction factor of 1.67

(based on California data) was applied to all count data

to estimate the number of breeding adults at colonies in

Oregon. No study has calculated a k specific to Oregon

colonies.

The first trial of this photographic survey

method was conducted along the southern Oregon coast

in June 1986. The survey was expanded to the entire

Oregon coast in 1987, though not all colonies were

counted. From 1988 to 1995, all major murre colonies

in Oregon were photographed annually.

In 1995, three replicate aerial photographic

surveys were conducted at a subset of Oregon colonies.

These surveys were conducted at 15 north coast study

sites both 2 weeks before and 2 weeks after the standard

June survey (i.e., 23 May, 7 June, and 21 June) to examine

the validity of using a single survey as a general measure

of peak numbers of murres at colonies. The results

showed considerable variation in the number of birds

present at some specific colony sites. However, overall

numbers of birds recorded in each survey were similar.

On 23 May and 21 June, 1.3% more and 2.5% less birds

were recorded, respectively, compared with the standard

survey on 7 June. The mean total of birds recorded for

the three surveys was only 0.4% less than the total for

the standard early June survey. The results indicated

that, at least in 1995, the single standard survey in early

June was sufficient and accurate enough for population

monitoring and trend analyses.

Washington

Murre colonies in Washington were aerially

surveyed each year in late June or early July from 1979

to 1995 (Table A-3). This later timing of surveys

reflected a later timing of breeding (Manuwal and Carter

2001) and greater stability of numbers of murres on

colonies after May (Speich et al. 1987; Parrish 1995).

For the 1979–83 period, a single, annual survey was

flown with a Cessna 172 or 182 at an altitude of 170–

230 m and murres were counted later from aerial

photographic slides. Since 1983, all surveys were

conducted with a Hughes 500 D helicopter at an

elevation of 70–250 m (with the passenger door

removed). Murres were counted with a hand-held tally

counter and binoculars, except in 1987, 1994, and 1995

when birds were photographed and later counted from

slides. Direct counts were considered acceptable because

of the small numbers of birds attending most colonies.

Census data were obtained during single helicopter

flights through 1993. Two flights were conducted in

1994 and four replicate flights in 1995. During fixedwing surveys, it was possible to count only the major

murre colonies, whereas the helicopter allowed surveys

of all sites, except the Tatoosh complex. This complex

has been surveyed by the USFWS only since 1994.

Surveys were flown between 0930 and 1400 h (PDT)

during late June or early July. During multiple survey

years, surveys were conducted between mid-June and
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 91

Table A-3. Summary of aerial photographic surveys of common murre colonies in Oregon and Washington, 1979–1995. a

Year Dates Field personnel Sources

Oregon

1986 25 June; 3 July Lowe, Boone, Brown Loweb

1987 25–26 June Lowe, Anderson Loweb

1988 3–4 June Lowe, Anderson Loweb

1989 7 & 9 June Lowe, Naughton Loweb

1990 11& 14 June Lowe, Naughton Loweb

1991 4 & 5 June Lowe, Naughton Loweb

1992 2 & 4 June Lowe, Reimer Loweb

1993 8 & 24 June Lowe, Pitkin Loweb

1994 8 & 10 June Lowe, Pitkin Loweb

1995 23 May; 7 & 21 June Lowe, Pitkin Loweb

Washington

1979 5 July Wilson Wilson 1991

1980 2 July Wilson Wilson 1991

1981 29 June Wilson Wilson 1991

1982 17 July Wilson Wilson 1991

1983 2 July Wilson Wilson 1991

1984 6 July Wilson Wilson 1991

1985 26 June Wilson Wilson 1991

1986 20 June Wilson Wilson 1991

1987 30 June Wilson Wilson 1991

1988 3 & 5 July Wilson Wilson 1991

1989 22 June Wilson Wilson 1991

1990 23 June Wilson Wilson 1991

1991 8 & 16 July Wilson Wilsonb

1992 6 July Wilson Wilsonb

1993 29 June Wilson Wilsonb

1994 16 June; 5 July Wilson Wilsonb

1995 19 & 25 June; Wilson Wilsonb

13& 27 July

aSee Appendixes E, F, and G

bUnpublished data

late July. The time of day and time of the breeding season

when surveys were conducted roughly matched

methodology in California, but survey dates were later

due to the later breeding phenology in this area. During

1979–94, photographs were taken with a 35-mm camera

and a 135-mm lens. In 1995, the colonies were

photographed with a 70–200-mm lens. Only Kodak

Ektachrome 400 ASA film was used. Counting murres

from slides involved projecting the transparencies onto

a paper flip chart. Small groups of murres (less than 30)

were circled and then counted with a tally counter. This

process was repeated until the entire colony was counted.

When murres were densely packed, or with poor slide

resolution, the number of birds within small groups was

estimated. A general k correction factor of 1.67 (based

on California data) was applied to all count data to

estimate the number of breeding adults at colonies. No

study has calculated a k specific to Washington

colonies.

As in Oregon (see above), Ecological

Consulting Incorporated conducted murre colony

counts in Washington in late June 1989 (Briggs et al.

1992). On June 27 and 28, they made a nonstandardized

aerial survey of murre colonies using visual estimation

and aerial photography. The uncorrected total was

12,810 birds, with 830 at Tatoosh Island (Briggs et al.

1992). On 22 June, USFWS personnel counted 3,925

birds (excluding Tatoosh Island; see Appendix F). Data

obtained by Ecological Consulting Incorporated were

considered inaccurate and were not used for trend

analyses in Chapter 2 because (1) nonstandardized

survey techniques were used, (2) the survey did not

include some active murre colonies in Washington in

1989, (3) some counts were reported for rocks where

murre colonies were not present, and (4) counts for many

colonies were lumped together as a single count. Where

1989 standardized counts by the USFWS can be

compared with those of Briggs et al. (1992), there are
92 USGS/BRD/ITR–2000-0012

large discrepancies. At six sites compared, Ecological

Consulting Incorporated reported much greater numbers

at three sites (range, 280–7630%), much lower numbers

at one site (750%), and hundreds of murres at two sites

(not colonies) where USFWS surveys found none.

Differences between surveys were so large that other

factors also may have been involved (e.g., colony

misidentifications, extensive variation in numbers of

murres attending colonies, or possible colony

disturbances).

British Columbia

The only large murre colony in British

Columbia is at Triangle Island. In 1989, an extensive

study was undertaken to provide the only reliable and

complete estimate to date (Rodway 1990). This study

used ground photographs, telescope counts, and boat

counts to provide complete coverage of the colony and

used breeding phenology, attendance patterns, and k

correction factors from several plots in the colony to

estimate the 1989 colony size (P) using the formula

P = k (Tr + C) where k = ratio of breeding sites to total

birds present on study areas (i.e., equivalent to a k

correction factor), T = total mean count from

photographs of the colony, r = ratio of telescope to

photographic counts on the study plot; and C = count

from the top of Puffin Rock of birds that were obscured

from the water. In 1989, Rodway (1990) calculated a

mean k value of 0.41 (range, 0.39–0.53) using the

formula presented in Birkhead and Nettleship (1980).

This value is comparable to a k1 correction factor value

of 0.82, using the equation presented under California

methods. Rodway (1990) noted that his k value was

much lower than that reported for other Pacific and

Atlantic colonies.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 93

Appendix B

Histories of common murre (Uria aalge californica) colonies in California, 1800–1978

(prepared by H. R. Carter)

As part of the assessment of the status of common

murres (Uria aalge californica) in California, it is

important to appreciate the long history of human

influences on colonies and birds at sea in this area.

Current conservation problems cannot be fully assessed

and conservation actions to best restore colonies or

populations cannot be fully conceived or implemented

without a reasonable concept of the original size and

distribution of the murre population. The known

histories of most murre colonies in California have not

been summarized previously, even though the history

of the South Farallon Island colony has been described

by early naturalists and others in some detail (e.g., Ainley

and Lewis 1974) and the extirpated colony at Prince

Island has been well documented (Hunt et al. 1979). For

other murre colonies, information before 1969–70 (when

murre colonies were first inventoried collectively in

California [Osborne and Reynolds 1971; Osborne

1972]) was poorly recorded and poorly known. In

addition, little information was obtained in the 1970s

before the advent of more frequent monitoring of murre

colonies in 1979 (Sowls et al. 1980). In their major

summary of historical data on the birds of California,

Grinnell and Miller (1944) listed only five colonies in

central and southern California; three active colonies

(South Farallon Islands, Point Reyes, Point Resistance

[i.e., mouth of Bear Valley] and two extirpated colonies

at San Pedro Rock and Prince Island (Santa Barbara

County). They also noted Dawson’s (1923) report of

murres breeding on rocks of Humboldt and Del Norte

Counties but did not provide further details. Many murre

colonies were known much earlier than available sources

would indicate.

In this summary, I collated information from

previous summaries and reported on substantial new

information from more obscure published and

unpublished sources to provide a more detailed summary

of historical information. I also included a more

extensive presentation of historical material for the

South Farallon Islands than found in previous sources.

For colonies other than the South Farallon Islands,

unpublished information and egg records in museum

collections (see Methods) have been especially

enlightening. Although doubtless incomplete, this

summary provides much additional historical

information not found in other summaries to date,

especially for central California colonies. Partial

summaries of conservation problems of murres in

California prior to 1978 are found in several sources

(Osborne 1972; Ainley and Lewis 1974; Hunt et al.

1979; Sowls et al. 1980; Carter 1986; Ainley and

Boekelheide 1990; Takekawa et al. 1990; Sydeman et

al. 1997). Here, I focused on summarizing information

on direct impacts to murre colonies from exploitation,

visitation, or disturbance. Other less direct problems

(e.g., oil and gill-net deaths) will be discussed in greater

detail elsewhere in this assessment (Chapter 3).

My approach to summarizing historical information

on murres involved the following considerations: (1)

revisiting all original sources cited by previous authors,

except where noted; (2) including literature and

unpublished information to allow the reader better

access to all available knowledge; (3) reporting

information as directly as possible from sources with

few judgements about the quality of information, except

where noted and where additional information was

provided with which the reader could make some

judgements; (4) using unpublished field notes of Charles

Clay, Laidlaw Williams, and Howard Cogswell (other

existing field notes were unobtainable, not easily

available, or not known); and (5) summarizing

(historical) human activities that probably affected

murre colonies, especially where the colonies were

poorly documented. Due to the variation between the

type and amount of information available from each

source, I chose not to use a shorter and more convenient

tabular format for presenting information that would

not allow adequate presentation of available

information. Although much new information is made

available here, this summary is incomplete and future

efforts may uncover additional information.

Farallon Islands

Summary

The South Farallon Islands are the type locality for

the “California murre” (U. a. californica) and another

old name is the “Farallone Bird” (Coues 1903; Dawson

1923). Much information on breeding murres at the

South Farallon Islands has been documented (Ainley

and Lewis 1974; Doughty 1974; Carter 1986;

Takekawa et al. 1990; White 1995). This colony

probably once was the largest colony for the common

murre in California, Oregon, Washington, and British
94 USGS/BRD/ITR–2000-0012

Columbia (and perhaps the world) but was all but

destroyed by the 1930s because of human occupation

and commercial egging in the nineteenth century and

oil pollution in the early twentieth century. However,

from 1950 to 1982, the colony grew from a few thousand

to over 100,000 breeding birds. Then, in the 1980s, this

colony and others in the central California population

suffered heavily from gill-net and oil-spill mortalities

and declined significantly (Carter 1986; Ainley and

Boekelheide 1990; Takekawa et al. 1990). The history

of the murre colony at the South Farallon Islands is

relatively well documented, although the North Farallon

Islands are among the least known colonies. Below, I

review the history of Farallon murre colonies in detail

because breeding biology and colony trends at the

South Farallon Islands have been well studied in recent

years and are often cited without reference to the

extensive historical impacts this colony has undergone

or the amount of information available on the size and

status of the colony during certain historical periods. In

particular, estimates of colony size before 1979 are not

directly comparable to more recent estimates.

Russian American Fur Company (1812–1838)

The earliest reported landing on the South Farallon

Islands was by Sir Francis Drake aboard the Golden

Hind in 1579 when the ship stopped on 23–24 July to

collect seal meat and seabirds for food (Hoover 1952;

White 1995). In 1807, the Boston sealing ship O’Cain

visited the Farallon Islands and vast numbers of marine

mammals were noted (Bancroft 1886; Doughty 1974;

White 1995). From 1810 to 1812, several sealing visits

were made by American sealers. From 1812 to 1838, the

Russian American Fur Company, in business with

American sealers, operated a sealing station at the South

Farallon Islands staffed by native people from Alaska

and California who mainly harvested fur seals

(Callorhinus ursinus), elephant seals (Mirounga

augustirostris), and sea lions (Bancroft 1886; White

1995).

In 1817, about 30 people lived on the islands. After

1818, seal numbers were much lower but people

remained to kill sea lions and birds and to collect eggs.

Annually, from 5,000 to 10,000 “gulls and other birds”

or “sea ducks” (probably murres) were killed and the

meat was dried for food (Bancroft 1886; Khlebnikov

1976). In 1828, 50,000 birds were killed and 3,611 lbs

(1,638 kg) of meat were obtained from these birds

(Khlebnikov 1976). Harvest also occurred on the North

Farallon Islands where Russians and “Kadiaks” were

noted in May 1825 (Bancroft 1886). Feathers and meat

were sent to the main Russian establishment in

California at Fort Ross, Sonoma County. In 1827 and

1828, respectively, nine and 11 inflated skins of marine

mammals filled with 1,083 and 1,192 lbs (4,423 and

5,405 kg) of feathers were sent to Fort Ross; “a good

many eggs” also were collected and used for subsistence

on the islands, shipped to Fort Ross, and exported to

Alaska (Khlebnikov 1976; Essig et al. 1991). At this

time, about 30 people still lived on the islands. Egging

probably occurred from the earliest days of the sealing

station. In 1819, Chichinoff (Hoover 1952; Hillinger

1958) noted subsistence harvesting of seabird eggs. In

1825, Morrell (Hoover 1952; Hillinger 1958) noted that

“Aquatic birds in considerable variety resort hither for

purposes of laying and incubation, but the Russians

seldom give them a chance for the latter process,

generally securing eggs as fast as they are deposited.”

The Russians withdrew from the establishment at the

Farallon Islands in 1838 and from Fort Ross in 1841.

However, the extensive hunting of seabirds by the

Russian American Fur Company over at least two

decades must have caused a massive decline in the size

of the murre colony, as well as that of many other seabird

and marine mammal species. In addition, sporadic

hunting continued on the islands during the 1840s

(Bancroft 1886) that probably continued to disrupt the

colony, although at a lower level than previously.

Farallone Egg Company and Murre Egging

(1849–1881)

 Small-scale commercial egging was first conducted

by “Doc” Robinson and O. Dorman in 1849 (White

1995; Brown 1999). Commercial egging began in

earnest in 1850 by several different interests but

eventually came under the sole control of the Pacific or

Farallone Egg Company (Hutchings 1856; Scammon

1875; Greene 1892; Emerson 1904; Doughty 1971;

White 1995). Eggs were supplied to bakeries and

restaurants before the establishment of sufficient

domestic poultry production for the rapidly expanding

human population of the San Francisco area during the

Gold Rush that began in 1848. Between 3 and 4 million

eggs (Hutchings 1856; Taylor 1895) had been brought

to market since 1850 (or an average of 428,571–571,429

eggs per year, based on my calculations).

Heermann (1853) noted that “a trade (in eggs) is

carried on with San Francisco, to the amount of thousands

of dollars per annum,” in 1853. Heermann (1859)

reported that the annual value of eggs reached $100,000–

200,000, based on his 1853 visit. This profit seemed

high to Palmer (1900), evidently because at the highest

reported retail prices of $1.00–1.50 per dozen, profits

should have been between $35,714 and 71,429 per year

using Hutchings’ (1856) reported harvest levels.

However, Taylor (1861) reported that egg prices in 1849
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 95

increased when sold away from the market and were as

high as $6–9 per dozen. Nordhoff (1874) reported that

about 360,000 eggs were shipped in one season in the

early years. Ainley and Lewis (1974) reported an

estimate of about 400,000 breeding birds for 1854 at

the South Farallon Islands, based on an approximate

400,000 eggs removed per year and one egg laid per

breeding pair per year (Ainley and Boekelheide 1990).

This estimate should have been 800,000 breeding birds

by my calculations without accounting for lost or broken

eggs (i.e., 400,000 eggs with two adults per breeding

pair and one egg laid per breeding pair per year).

However, many eggs probably were replaced at least

once. Therefore, 400,000 breeding birds may be

reasonable, assuming an average of one replacement

egg per first egg laid. On the other hand, Ayers reported

over 500,000 eggs were harvested in 1854 on a limited

portion of South Farallon Island and “in the opinion of

the eggers, not more than one egg in six of those

deposited on that island was gathered” (Loomis 1896).

This statement does not suggest careful accounting,

eggers may have been “defending” their practice with

such a statement, and few areas of the islands were

inaccessible to eggers. As many as three million eggs

could have been laid, which could correspond to a much

higher colony size for the early 1850s of at least 6 million

breeding birds. Such an estimate assumes only one egg

laid per breeding pair and includes eggs lost or destroyed

before shipping. If one replacement egg per first egg

was laid, then an estimate of 3 million breeding birds

emerges. In my opinion, the historical colony size prior

to European, Asian, and Alaskan contact in the early

nineteenth century probably was between 1 and 3

million breeding birds. Major factors that I considered

in arriving at this general estimate were (1) the lower

end of the range—1 million—should be much higher

than the previous estimate of 400,000 breeding birds in

the 1850s, given substantial reduction because of

egging, hunting and other disruptions from 1812 to

1838; (2) insufficient information was provided in

historical accounts to determine how many eggs —

probably a substantial number— were not collected of

those laid in the 1850s; and (3) the nature of historical

information prevents determination of a more exact

estimate within this range. It is unclear exactly how

such large numbers of murres, other seabirds, and marine

mammals shared available space at these islands. Earlier

removal of marine mammals also may have benefitted

murres by increasing available breeding space (D. G.

Ainley, personal communication).

After island visits in 1862 and later, Gruber reported

that 240,000–300,000 eggs were harvested for many

years and first sold for $0.50 per dozen and later at

$0.25–0.30 per dozen in the market at San Francisco

(Gruber 1884; Grinnell 1926). However, it is unclear

what years Gruber was referring to because the article

was published in 1884. By 1872 and 1873, respectively,

215,424 and 182,436 eggs were collected (Nordhoff

1874). Nordhoff (1874) determined that over 100,000

murres bred at the South Farallon Islands at this time by

“allowing half a dozen to each murre, this would give

nearly 36,000 [breeding pairs] . . . adding the proper

number for eggs broken, destroyed by gulls, and not

gathered . . .” Murre eggs were collected daily from May

to July and thus were removed shortly after laying.

Whereas murres were known or thought to continue

laying after egg removal, it is unlikely that individual

females laid 6–8 eggs as claimed by the egging

company, and the murre colony probably was much

larger than thought by Nordhoff. Eggs were sold for

$0.26 per dozen in 1873 (Nordhoff 1874). Scammon

(1875) reported that 300,000 eggs were shipped to San

Francisco each year and that eggs were gathered from

the same breeding places only two or three times per

season. Doughty (1971) used Scammon’s 300,000 eggs

each year as the annual harvest level from 1857 to 1871.

Nordhoff was assured by the manager of the egg

company that there had been “no sensible decrease in

the number of birds or eggs for twenty years” but fewer

eggs in fact were being harvested by this time. By

allowing some birds to breed successfully at the end of

the season, eggers had wrongly thought that they had

ensured adequate production of murres to continue the

egging business. From 1874 to 1883, about 180,000

eggs were harvested annually (Emerson 1904).

Commercial egging by the Farallone Egg Company

ended in 1881 when company workers were removed

from the island by a U.S. Marshall and soldiers because

of difficulties with the lighthouse keepers and a longterm dispute over company egging rights with the federal

government. A lighthouse had been erected in 1853

and the islands had been reserved for lighthouse

purposes in 1851, a fact further substantiated by

President Buchanan in 1859 after a legal challenge

(Doughty 1971; White 1995).

Continued Egging and Other Human Impacts

on the Farallon Islands (1882–1904)

Egging by lighthouse keepers and Greek and Italian

fishermen continued beyond 1881 (Bryant 1888;

Blankenship and Keeler 1892; Greene 1892). Greek and

Italian immigrants formed much of the local fishing

community in San Francisco at this time (Daskarolis

1981). The retail price of eggs had fallen to $0.12–0.25

per dozen (Bryant 1888; Greene 1892). In 1884, 300,000

eggs were harvested and between 180,000 and 228,000
96 USGS/BRD/ITR–2000-0012

eggs were harvested in 1885–86 (Bryant 1888, Palmer

1900). In 1887, 300,000 eggs were collected, the largest

harvest in several years (Emerson 1904). Greene (1892)

noted that close to 180,000 eggs were harvested in 1892.

Emerson (1904) reported similar annual harvests from

1888 to 1895. By July 1896, 91,740 eggs were harvested

and the retail price had dropped to $0.125 per dozen.

Extensive egging at the North Farallon Islands also

occurred in 1896 and the “crop was said to be larger

than that of South Farallon” (Loomis 1896). Bryant

(1888) had first reported murres breeding on the North

Farallon Islands although it had been known much

earlier that seabirds bred there in large numbers. In fact,

egging may have occurred there in 1863 (Brown 1999).

In early July 1899, at least 23 eggs were collected by

fishermen at the North Farallon Islands and obtained by

D. A. Cohen for his egg collection; eight of these eggs

are currently housed in the collection at the Western

Foundation of Vertebrate Zoology (WFVZ) , Camarillo,

California (WFVZ Nos. 117,672–117,679). Loomis

encouraged the American Ornithologists’ Union and

the California Academy of Sciences to take actions to

protect the murres and other seabirds (Dutcher 1897;

White 1995). The Lighthouse Board responded to a

letter from the American Ornithologists’ Union and

prohibited egging by lighthouse keepers and all others

at the Farallon Islands in November or December 1896

(Anonymous 1897; Dutcher 1898; Palmer 1900).

Despite protection, Emerson (1904) noted the loss

of several murre breeding areas on the South Farallon

Islands between 1887 and 1903 and considered that “a

great decrease in the laying of the murres had taken

place on South Farallone, and I was prepared to note a

corresponding change in the abundance of murres.”

Illegal egging continued, although at lower levels, until

at least 1904 (Lastreto 1930; Doughty 1971; White

1995). Additional evidence of continued egging is

found in the WFVZ collection. On 22 June 1897, W. E.

Snyder obtained at least one egg (set number 72) that

had been “collected by market eggers” (WFVZ No. 692).

On 8 July 1898, D. De Groot bought at least five eggs

(set numbers 3–7) “in the San Francisco market” (WFVZ

Nos. 45,808–45, 810; 45,812–45,813). On 28 June

1901, J. Mailliard of San Francisco purchased at least

four eggs (set numbers 2–5) “in market” (WFVZ No.

112,939).

In addition to egging, continual human occupation

of the South Farallon Islands since 1853 probably

contributed to a decline in the size of the murre colony

because of breeding habitat changes and disturbance

from island personnel, children, dogs, cats, and livestock.

Island habitats were changed by the construction of

numerous rock walls (e.g., pathways to and foundation

for the lighthouse, the “Farallon Railroad” bed, various

rock walls around buildings and cisterns) and buildings

(e.g., egg storage areas, the original lighthouse keepers’

“Stone House”) using rocks collected from around the

island, especially from breeding slopes on Lighthouse

Hill where rocks are abundant. Such rock-wall building

construction continued until about 1905 when the

current “Carpenter’s Shop” was constructed (P. White,

personal communication). Guano harvesting also

occurred (Barlow 1897). The human population

numbered at least 20 people in 1898 (White 1995), and

the loss of breeding areas above the lighthouse keeper

houses and other areas, noticed between 1887 and 1903

(Emerson 1904) and later, probably resulted in some

degree from human disturbance (Dawson 1923). In fact,

many breeding areas probably were lost well before

1887. Weather stations were built near murre breeding

areas and staffed by additional personnel in 1902 near

Jordan Channel and in 1905 near Shubrick Point (P.

White, personal communication). These stations resulted

in greater human access to West End Island (involving a

walking bridge) and the Shubrick Point area of

Southeast Farallon Island. However, many thousands of

murres were still noted in 1903–04 (Emerson 1904; Ray

1904).

Human Impacts on the Farallon Islands

in the Early Twentieth Century

In addition to the impacts of oil pollution on the

murre colony (Chapter 3), island personnel and facilities

continued to expand at the South Farallon Islands.

During World War I, 26 Marines were stationed on the

island and a naval radio compass station continued to

operate after the war. During World War II, the island

population had grown to 78 people, although only 17

people remained by 1953 (White 1995). One positive

action taken during the early twentieth century was the

creation in 1909 of the Farallon Reservation, which

was to be “a preserve and breeding ground for native

birds” (White 1995). This reservation, however, only

protected colonies on the North Farallon Islands (i.e.,

the South Farallon Islands were not added until 1969,

see later). It is not known why President Roosevelt took

this action but it presumably was related to heavy

impacts to murre colonies at both the South and North

Farallon Islands noted by Loomis (1896), previous

efforts to stop egging at the South Farallon Islands, and

increasing efforts to protect wild birds in the United

States. In particular, earlier efforts by W. L. Finley, W. L.

Dawson, and others to protect seabird colonies in

Oregon and Washington undoubtedly influenced

Roosevelt’s decision to establish national wildlife

refuges.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 97

Murre Colony Sizes (1911–1950)

From 1911 to 1950, murres were not recorded

breeding at the South Farallon Islands in large numbers.

Only a few hundred to a few thousand murres probably

bred there during much of this period. By 1911, fewer

than 20,000 murres were estimated at the South Farallon

Islands (Dawson 1911). Egg collectors frequently

obtained eggs from the South Farallon Islands from 1859

to 1913, based on hundreds of egg specimens collected

during this period in collections at: WFVZ; Santa

Barbara Museum of Natural History (SBNHM), Santa

Barbara, California; University of California Museum

of Vertebrate Zoology (BMVZ), Berkeley, California;

National Museum of Natural History (USNM),

Smithsonian Institution, Washington, D.C.; and Harvard

University Museum of Comparitive Zoology (MCZ),

Cambridge, Massachusetts. I did not present details for

these Farallon-collected eggs in this appendix because

the history of egging and other visits by ornithologists

are well told with other information above. No eggs in

these collections were obtained after this period. On 20

August 1922, murres were considered to be less

numerous than in 1917 although some birds may have

fledged by this date (Allen 1922; Kibbe 1922). However,

murres may have regularly bred that late in the year

because of effects from egging when breeding often

extended into September (Bryant 1888), although

1859–1913 egg specimen dates ranged between 10 May

1890 (USNM B34231) and 28 July 1886 (WFVZ 46016),

with most collected in June. In June 1923, Chaney

(1924) reported only tens of murres breeding in three

small groups in protected crevices. On 24 August 1930,

only five murres were found at the island, which may

have reflected near extermination and earlier breeding

by small numbers since some birds were observed at sea

with chicks (Anonymous 1930; Lastreto 1930). However,

the lighthouse keeper indicated that murres had been

depopulated by about 99% (since Knuder had come to

the Farallones in 1915 [White 1995]); this decline was

related to past egging practices and oil pollution but

remaining smaller numbers of murres were falling prey

to western gulls (Larus occidentalis; Allen 1930; Knuder

1930; Lastreto 1930; Brooks 1937). In August 1933,

Smith (1934) observed only three young in protected

crevices but noted that the main colony probably had

finished breeding earlier. Smith also noted that strict

protection of breeding areas was occurring and no one

was permitted to travel to West End Island from 15 April

to 15 August.

Murre Colony Sizes (1950–1968)

On 22 May 1955, about 2,000 murres were reported

within 3.2 km (2 miles) of the islands but it was unclear

how many were on shore. On 30 April and 22 May 1955,

thousands were reported on the island and on the water

around the island (H. Cogswell, unpublished field notes;

Cogswell 1955; Cogswell and Pray 1955a). On 28 April

1956, Cogswell noted about 1,000 murres at and around

the island, including 600 on the island. On 27 May

1956, he reported 300 murres at the island, and hundreds

also were reported on 3 June 1956 at the island

(Cogswell and Stallcup 1956; H. Cogswell, unpublished

field notes). On 10–17 June 1958, Bowman (1961)

conducted an on-island survey of the South Farallon

Islands and determined about 2,000 birds attending

eggs. He mapped breeding areas and noted small groups

of 5–20 birds breeding in caves and on ledges at several

points. The largest groups were on the westernmost parts

of West End Island (Great Arch, Phil’s Hill, and Indian

Head) and on Sugarloaf and Aulon Islet. Smaller

numbers bred at Southeast Farallon Island (Shubrick

Point, Great Murre Cave, Shubrick Cove, and Fertilizer

Flat), Saddle Rock, the Islets (Arch Rock, Finger Rock,

and Sealion islets), and other parts of West End Island

(Maintop, Pelican Bowl, and West End Cove). Thoreson

(1959) reported a direct count of 6,718 murres and a

range of 6,000–7,000 birds at the South Farallon Islands

in June–August 1959. Most birds were counted at the

Islets (2,000) and West End Island (3,500). Bowman’s

and Thoreson’s estimates seem to be the first well

documented numbers of breeding birds on the South

Farallon Islands but also may reflect lower breeding

effort during El Niño conditions in 1957–59 (Lenarz et

al. 1995). On 3 April 1960, murres and pigeon guillemots

(Cepphus columba) were reported as abundant at the

island (Albertson 1960). D. Bleitz (unpublished field

notes) noted concentrated small colonies on high steepwalled pinnacles on 4 August 1961. On 19 April 1962,

thousands were reported on or near the island (H.

Cogswell, unpublished field notes). On 31 March 1963,

thousands of murres and other species were noted at the

island (Paxton 1963). On 31 May 1964, murres and

other species were “ubiquitous” at the main island

(Paxton 1964). Pinney (1965) mapped locations where

murres bred on Southeast Farallon Island in 1961–64,

including Shubrick Point, Great Murre Cave, Shubrick

Cove, Fertilizer Flat, Tower Point, and Elephant Seal

Blind Point. On 23 April 1966, hundreds of murres flew

from the rocks (Stallcup and Chandik 1966) and H.

Cogswell (unpublished field notes, American Birds

Files; Chase and Chandik 1966) reported several

thousand on the island and noted that the “population

felt to be decidedly larger than 8–10 years previously.”

On 14 June 1967, a rough estimate of 500 murres at

Shubrick Point was made from land (H. Cogswell,

unpublished field notes). During summer 1968, low-
98 USGS/BRD/ITR–2000-0012

flying jet aircraft caused extensive flushing of murre

colonies (Speich et al. 1987).

Lessened Human Impacts and

Murre Colony Sizes (1969–1978)

In 1969, the South Farallon Islands were included,

along with the North Farallon Islands, in the Farallon

National Wildlife Refuge, under the management of the

U.S. Fish and Wildlife Service (USFWS). Osborne (1969)

reported only 200 breeding pairs in July–August 1969,

although surveys probably were conducted too late in

the season. H. Cogswell (unpublished field notes)

estimated 2,000 murres on the island or flying around it

on 29 April 1970; however, numbers “increased from

4,000 to 6,000 during April and May” (Baldridge et al.

1970a,b). Osborne and Reynolds (1971) reported 5,000

breeding pairs at the South Farallon Islands in 1970. In

1971, the Point Reyes Bird Observatory was contracted

by the USFWS to protect and monitor wildlife at the

Farallon Islands. In 1974, all U.S. Coast Guard personnel

left the island. For the first time since the early nineteenth

century, human disturbance by island personnel was

reduced to minimal levels, including newly designated

off-limit areas on Southeast Farallon Island. West End

Island and the North Farallon Islands were designated

as National Wilderness Areas.

Ainley and Lewis (1974) reported 20,500 breeding

birds at the South Farallon Islands in 1972 (based on

detailed on-island ground counts but without a k

correction factor). This 1972 estimate represented a large

increase in the size of the murre colony since 1959 but

the 1972 survey probably constituted a more careful

survey than any conducted previously, as well as

documenting breeding during an El Niño. Piatt et al.

(1991) noted that if the 1972 survey was adjusted with

a k correction factor and adjusted roughly for

comparability with more recent aerial survey estimates

(since 1979) and possible lower breeding effort during

1972–73 El Niño conditions (Lenarz et al. 1995), about

45,000 breeding birds could have laid eggs in 1972. H.

Cogswell (unpublished field notes), from a boat, reported

only 12,000 murres on Southeast Farallon Island (plus

several hundred on Seal Rock) on 30 April, suggesting

differences between counting techniques. On 22 April

1973, H. Cogswell (unpublished field notes) reported

several thousand at the island. No other detailed surveys

of the numbers of breeding murres were conducted at

the South Farallon Islands until 1979 when annual

ground and boat surveys began (Ainley and

Boekelheide 1990; Takekawa et al. 1990; Sydeman et

al. 1997). However, rough estimates of the numbers of

breeding pairs in 1975–79 were reported by Point Reyes

Bird Observatory to the USFWS, respectively, as 14,000,

14,000, 20,000, 25,000, and 30,000 (U.S. Fish and

Wildlife Service 1980). Ainley and Whitt (1974)

reported a 1972 estimate of 14,000 breeding pairs for

San Francisco County. This value included the South

Farallon Islands surveyed in 1972 (Ainley and Lewis

1974) and the North Farallon Islands surveyed in April

1972. By subtracting 10,250 breeding pairs for the South

Farallon Islands (Ainley and Lewis 1974), a total of

between 2,246 and 3,750 breeding pairs can be

calculated for the North Farallon Islands in 1972,

depending on whether a k correction factor was applied.

No other surveys were conducted at the North Farallon

Islands until 1980 (Briggs et al. 1983).

Other Central California Breeding Colonies

Point Reyes Complex

Murres were noted breeding on Point Reyes on 23

June 1897, when three eggs were collected by Italian

fishermen for O. Emerson (WFVZ Nos. 112,841,

114,859–114,860). Emerson noted on the specimen card

that the colony was “regularly visited by eggers until

prohibited by law.” On 20 April 1913, E. B. Coues and

C. E. Ingalls collected at least nine eggs (set numbers

5,369–5,377; USNM Nos. 34,233–34,241). On 12 June

1932, four eggs were collected by J.S. Rowley at Point

Reyes (WFVZ Nos. 26,111–26,114). However, his set

numbers were: 2, 8, 10, 11, suggesting that 11 or more

eggs were collected. On 29 April 1934, 1,500 murres

were noted (L. O. Williams, unpublished field notes)

and “many young in downy plumage” were noted by

McCabe on 5 August 1934 (Allen 1934). One thousand

murres were reported breeding at Point Reyes lighthouse

rocks on 6 June 1938 (Anonymous 1938).

Murres with eggs were noted on 16 May 1939, and

2,200 murres (small downy young present) were counted

on 23 June 1939 on the murre rock at the Point Reyes

lighthouse (L. O. Williams, unpublished field notes).

Williams (1942) noted that murre numbers had “kept

up” at Point Reyes during the years from 1933 to 1940.

Grinnell and Miller (1944) indicated that breeding had

been reported by J. and J. W. Mailliard but did not

present other data. One thousand murres were reported

by Rigby on 13 July 1947 (L. O. Williams, unpublished

field notes). Storer (1952) noted 5,000 murres and H.

Cogswell (unpublished field notes) noted 3,000 murres

on the rock below the lighthouse at Point Reyes on 13

February 1949. It is not clear if Storer counted murres at

other locations (in addition to the rock below the

lighthouse) from other vantage points along the

headlands. However, many murres both below the
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 99

lighthouse and at other points along the headlands

cannot be viewed from the mainland (M. W. Parker,

unpublished data). Thousands were noted on the rocks

at Point Reyes on 11 June 1950 (Scott 1950). H. Cogswell

(unpublished field notes) noted hundreds on the rocks

on 13 November 1954. Tuck (1961) reported 3,000 birds

at Point Reyes.

Murres arrived on their breeding rocks at Point

Reyes on 3 March 1965 (Chase and Paxton 1965). On

27 April 1967, 1,200–1,500 murres were noted breeding

at the Point Reyes lighthouse (Chandik and Paxton

1967; C. J. Ralph, American Birds Files). Osborne (1969)

reported 250 breeding pairs at the rocks north of the

Point Reyes lighthouse in July–August 1969. On 22

August 1970, Osborne and Reynolds (1971) and Osborne

(1972) noted 250 breeding pairs at the rocks north of

the Point Reyes lighthouse. On 3 July 1972, Ainley and

Whitt (1974) reported 7,640 breeding birds at Point

Reyes (based on a ground count adjusted with a k

correction factor) that covered all parts of the Point Reyes

headlands. On 27 February 1971, several thousand

murres were on the rocks under the lighthouse (Mann

1971). Thousands of murres are evident in an aerial

photograph (#194) of the Lighthouse Rock area at Point

Reyes taken on 15 June 1972 (R. Jurek, unpublished

data). On 30 October 1972, murres were noted on the

rocks under the lighthouse (Anonymous 1972). H.

Cogswell (unpublished field notes) observed 3,000

murres on the rocks on the north side of the Point Reyes

lighthouse on 22 April and 6 May 1978.

Points Resistance–Double Complex

(Point Resistance, Double Point Rocks,

and Millers Point Rocks)

Griffies (1894) noted that a “broken reef of sharp,

low rocks . . . extends at intervals from the north end of

Bolinas Bay clear to Point Reyes . . . The patches of

white on the larger of these rocks show them to be

inhabited [by murres and other seabirds].”

Murre breeding was first documented at Point

Resistance on 30 May 1926 (Kibbe 1926). Whereas

Bolander and Bryant (1935) did not note breeding there

in 1929, breeding was again noted at “Bird Rock” by

Mrs. Kibbe on 7 June 1931 (Allen 1931). Stephens and

Pringle (1933) noted that “about a dozen [were] found

on Bird Rock in Drake’s Bay, June 2, 1931, by Herman

de Fremery.” Grinnell and Miller (1944) reported

breeding at a sea-cliff and islet near the mouth of Bear

Valley (i.e., Point Resistance) in 1935–36. One of two

eggs found among Brandt’s cormorants (Phalacrocorax

penicillatus) nesting on a mainland cliff adjacent to the

main breeding rock was collected by A. H. Miller on 15

June 1935 (BMVZ No. 3,797). The egg was described

as “on decomposed rock and dirt on projecting ridge,

moderately steep slope” (A. H. Miller, unpublished field

notes). On 7 and 22 April 1962, H. Cogswell

(unpublished field notes) noted hundreds on “a rocky

islet just off-shore . . . near the end of Bear Valley Road”

(i.e., Point Resistance).

Osborne (1969) reported 200 breeding pairs at Point

Resistance (referred to as “Rock south Bear Valley”) in

July–August 1969. In fact, Point Resistance is north of

the mouth of Bear Valley and this observation possibly

referred to nearby Millers Point Rocks. Osborne and

Reynolds (1971) and Osborne (1972) noted 200

breeding pairs in 1970, based on a ground count.

Hundreds to thousands of murres are evident in an aerial

photograph (#186) at Point Resistance taken on 15 June

1972 (R. Jurek, unpublished data).

Tuck (1961) reported a colony at Double Point

without details. Osborne (1969) reported 700 breeding

pairs at Double Point Rocks (referred to as “Rocks north

Double Point”) in July–August 1969. In fact, Double

Point Rocks occur directly off the north point of Double

Point and this observation possibly referred to Point

Resistance or Millers Point Rocks (see below). Osborne

and Reynolds (1971) and Osborne (1972) noted 700

breeding pairs (or 1,400 murres) from a mainland count

at Double Point Rocks in 1970. On 15 April 1971,

Ainley and Whitt (1974) reported 1,400 breeding birds

at Double Point Rocks (based on a ground count

adjusted with a k correction factor ). Thousands of murres

are evident in six aerial photographs (#3–5, #183–185)

of Double Point Rocks taken on 15 June 1972 (R. Jurek,

unpublished data). In 1978, S. Allen reported about

3,000 birds (Chan 1981).

Varoujean (1979) assigned a 1970 colony of 200

breeding pairs of murres (that had been referred to as

“Rock So. Bear Valley” in Osborne and Reynolds 1971)

to Millers Point Rocks. Sowls et al. (1980) reassigned

this observation to Point Resistance—where they had

found a substantial colony in 1979—instead of Millers

Point Rocks—where they did not report breeding in

1979–80. However, Briggs et al. (1983) did report

breeding murres at Millers Point Rocks in 1980–82, as

did Carter et al. (1992) in 1989. Based on these

subsequent observations, it is not clear which of these

colonies was being referred to although it was most

likely Point Resistance because Millers Point Rocks

are smaller rocks and have had only small numbers

breeding in most recent years.
100 USGS/BRD/ITR–2000-0012

Devil’s Slide Complex (San Pedro Rock and

Devil’s Slide Rock and Mainland)

Bryant (1872) displayed an engraving of San Pedro

Rock with birds (probably murres but not identifiable

to species) on this rock. He further remarked (p. 567)

that “The old promontory, now become an isolated crag,

is covered with sea-birds, and its top is already white

with their guano, ... .”

The murre colony at San Pedro Rock was first

mentioned by Ray (1904). In 1908, the colony was best

documented when it was being extirpated by eggers

who still sold murre eggs in the San Francisco market

(Ray 1909). On 12 July, about 20 birds and eggshell

fragments were left on the rock. However, a fisherman

reported collecting “as many as thirty dozen [or 360

single] murre eggs on a trip” in previous years (Ray

1909). The colony has not been reported as active since,

though H. Cogswell (unpublished field notes) noted 40

or more murres on 29 April 1972 as he passed by in a

small plane.

The Devil’s Slide Rock and Mainland colony is

located about 1.6 km (1 mile) south of San Pedro Rock,

along an inaccessible part of the coast. This colony was

not discovered until after Highway 1 was built across

Devil’s Slide in 1937. Totals of 150–200, 75, and about

100 murres were reported breeding on 5, 8, and 11 June

1938, respectively, by Stephens and the Parmenters

(Anonymous 1938; Linsdale 1938). On 27 July 1939,

Parmenter reported murres “still nesting” at Devil’s Slide

Rock (Anonymous 1939; Sibley 1952). Similarly,

Parmenter noted 100 murres on Devil’s Slide Rock on

9, 24 and 28 July 1941 (L. O. Williams, unpublished

field notes). On 11 April 1954, 13 July 1954, and 12

July 1959, H. Cogswell (unpublished field notes) noted

200, 180, and 200 murres on Devil’s Slide Rock,

respectively. In 1970, Osborne and Reynolds (1971)

and Osborne (1972) reported 350 breeding pairs from a

mainland count. Hundreds to thousands of murres are

evident in a photograph (without additional

information) that was probably taken in 1970–72,

possibly by R. Jurek or J. G. Reynolds (Sowls et al.

1980; unpublished data).

These colonies are located close to the Golden Gate,

so murres there probably were affected heavily by oil

pollution in the early twentieth century (Ainley and

Lewis 1974; Chapter 3), which may have contributed,

with egging, to the loss of the San Pedro Rock colony at

this time. Both colonies also probably were affected by

the construction (1905–08) and operation (1908–20)

of the Ocean Shore Railroad that ran from San Francisco

to Santa Cruz. In 1906, a tunnel was blasted through

San Pedro Point, a railroad bed was blasted along

Devil’s Slide, and a large “saddle cut” was blasted south

of Devil’s Slide (Stanger 1963; VanderWerf 1992).

Railroad construction between San Francisco and

Granada was completed in 1908. In 1908, a fisherman

reported that “the birds had become scarce [at San Pedro

Rock] owing to the continued blasting” during railroad

construction (Ray 1909). The railroad was plagued by

landslides and was often rebuilt along Devil’s Slide until

its demise in 1920. The railroad was built by Greek,

Sikh, and Japanese immigrant workers who lived in the

general area. Greek immigrants were well known for

egging activities at the South Farallon Islands between

1880 and 1900 (see above). The railroad also brought

many people to the San Pedro Point area. In the spring

of 1908, 3,000 excursionists traveled from San Francisco

to Tobin Station near San Pedro Point, prior to the

opening of the railroad to Half Moon Bay (VanderWerf

1992). Thus, the railroad may have provided many

opportunities for people to discover breeding murres

and conduct egging at San Pedro Rock.

Castle–Hurricane Complex (Hurricane Point Rocks

and Castle Rocks and Mainland)

Murres were first noted breeding at Hurricane Point

Rocks in 1940, after Highway 1 was opened through

this previously inaccessible (except by boat) area in

1938. Murres apparently bred only at Hurricane Point

Rocks, especially the larger rock, between 1940 and

1950. On 23 May, about 200 murres were noted on

Hurricane Point Rocks and they were present on 25

May 1940. Williams remarked that “Guy Emerson

discovered colony on May 21 or 22 1940” (L. O.

Williams, unpublished field notes). From 1940 to 1945,

L. O. Williams (unpublished field notes) recorded murres

several times at Hurricane Point Rocks but not at the

nearby Castle Rocks and Mainland colony, where he

did record other bird species. Murre observations were

reported as follows: between 270 and 300 on 19 June

1940, 200 on 15 July 1940, 300 on 11 July 1941, 280

on 25 April 1942, 500 on 29 June 1943, 500 on 29 June

1943, with the remark that the colony had “seemed to

show a slight increase over 1940”, and 600 on 20 May

1945. Several hundreds also were reported by the

Andersons at Hurricane Point Rocks on 23 June 1950

(L. O. Williams, unpublished field notes). On 12 June

1955, Williams reported 530 birds “present in colony”

at Hurricane Point Rocks (American Birds Files;

Cogswell and Pray 1955b). Storer (1952) reported

Hurricane Point as a colony, but without details.

Osborne and Reynolds (1971) and Osborne (1972)

reported 200 and 100 breeding pairs at Hurricane Point

Rocks and Castle Rocks and Mainland, respectively,
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 101

Southern California Colonies

Prince Complex

Hunt et al. (1979) summarized data originally

provided by L. Kiff (personal communication) for the

southernmost known colony of the common murre at

Prince Island, just north of San Miguel Island off

southern California. The colony disappeared in the early

twentieth century, possibly due in part to specimen

collecting for private egg collections. I reviewed egg

records and other information to further investigate the

loss of this colony. Several details on the egg specimens

that I examined differed from those presented in Hunt et

al. (1979), possibly because of more recent accessions

to the WFVZ collection as well as different data

treatment. Between 60 and 227 murre eggs were

collected at Prince Island between 1885 and 1912. Most

on 6 May 1970. However, these estimates were based

on counts of 400 and 300 birds, respectively (Osborne

and Reynolds 1971; Varoujean 1979). Human impacts

to these murre colonies may date back to the early

nineteenth century when Russian hunters worked along

coastal areas (Essig et al. 1991). In the 1850s, a Chinese

abalone fishery operated out of Point Lobos and

fishermen worked the rocks at least as far south as Point

Sur (Armentrout-Ma 1981; Lydon 1985). On 20 April

1875, the steamship Ventura ran aground on either

Castle Rocks and Mainland or Hurricane Point Rocks

(Reinstedt 1975). Several shipwrecks have occurred in

the vicinity of Point Sur.

Possible Historical Colonies in Marin and

San Francisco Counties

 Murres may have previously bred at other locations

with suitable habitat between the Russian River and

San Pedro Rock which probably would have been

extirpated by the activities of early settlers, including

egging, before documentation as murre colonies. Bryant

(1848) noted that, in 1847, “some of the islands in the

harbor, near San Francisco, are white with guano

deposited by these birds [i.e., “waterbirds”] , and boat

loads of eggs were taken from them.” White (1995)

considered this observation to probably refer to murre

egging at the Farallon Islands but several potential

breeding islands for murres and other seabirds exist at

the entrance and inside the mouth of San Francisco Bay.

Bryant (1872) displayed several engravings which

showed birds (possibly murres but not identifiable to

species) on various rocks in this area. Near the town of

“Two Rocks” (i.e., between Estero Americano and Estero

San Antonio in northern Marin County), Bryant

remarked (p. 560) that “The innumerable birds that make

their nests upon the broad, flat summits of these rocks

are not so kindly treated, being robbed at regular

intervals by an egg company formed for that purpose.

Wild and precipitous as these rocks appear, they can be

scaled without difficulty, and the time will inevitably

come when the birds will learn to avoid the place, and

these rocks will lose their chief attraction - their chief

attraction, it must be understood, for the multitude.”

Aldrich (1939) noted murres “congregated” on Seal

Rocks, along with sea lions and other seabird species.

However, no details were provided and other observers

of this frequently-visited area did not note breeding

there.

Possible Historical Colonies in Monterey and

San Luis Obispo Counties

There is no specific documentation of murres

breeding between Hurricane Point Rocks in central

Monterey County and Prince Island in the northern

Channel Islands of southern California. Dawson (1923)

indicated that breeding occurred at the Farallon Islands

and “in lesser numbers south to Prince Islet . . .” but with

no other details. Several other authors also have reported

breeding as far south as Prince Island without details.

Murres may have previously bred at several

undocumented locations with suitable habitat before

extirpation by human activities or natural factors.

European settlement of parts of this coast occurred in

the late eighteenth and early nineteenth centuries when

large and small ranches, towns, and ports were

established. Early settlers likely harvested birds, eggs,

and guano from small islands, close to shore and

accessible to small boats. For example, Piedras Blancas

Island was an early and major landmark for coastal

shipping for the Spanish galleons returning from the

Philippines in the eighteenth century and was located

beside a large ranch and port set up for sending food

and other products to inland missions at San Antonio

de Padua (est. 1771) and San Miguel Arcangel (est. 1797)

(Bancroft 1886; Hamilton 1974). Native people were

sent to the coast daily to obtain sea food that probably

included seabird meat and eggs for the missions. For

three years in the 1880s, guano was harvested from this

rock and sent to San Francisco (Hamilton 1974). Murres

breeding at Piedras Blancas Island probably would have

been extirpated because of early human activities. Many

other human activities also occurred along this coast

(including hunting, mining, logging, shipping, fishing,

etc.), especially since 1850 when human populations

expanded rapidly (Hamilton 1974). Russian hunters

also worked this area in the nineteenth century and may

have egged and eliminated small colonies even earlier

(Essig et al. 1991).
102 USGS/BRD/ITR–2000-0012

were collected between 1905 and 1910 when only about

100 pairs bred at the colony.

On 18 June 1885, W. C. Bradbury collected at least

one egg (set number 2) at Prince Island (WFVZ No.

4,385). On 24 June 1885, Bradbury collected at least

one more egg (set number 1; WFVZ No. 4,377). In late

July 1886, Streator (1888) did not mention murres at

Prince Island but birds might have finished breeding.

On 18 July 1894, Bradbury returned and collected at

least two more eggs (WFVZ Nos. 4,381 and 4,384); one

egg was reported from the “Isle of Santa Barbara” but

another was reported from Prince Island on the same

day. Breeding murres have never been reported from

Santa Barbara Island proper. On 10 July 1895, Bradbury

collected at least one egg (set number 1; WFVZ No.

4,382). In June 1896, Bradbury obtained another egg

(set number 1; WFVZ No. 4,380). Hunt et al. (1979)

reported eight eggs taken by Bradbury on 24 June 1885,

based on specimen numbers (WFVZ Nos. 4,377–4,386)

but examination of the egg specimen cards indicates

that they were collected in different years and dates as

shown above. I could not locate WFVZ No. 4,386,

reported by Hunt et al. (1979).

Eleven eggs (incubation well advanced in each egg)

were collected by H. S. Burt from a ledge on a cliff

running back in large cave about 6–9 m (20–30 feet)

above the water. Burt estimated about 100 birds

breeding on 5 June 1905 (WFVZ Nos. 80,934–80,944;

set numbers 4–13, 18). Probably 18 eggs were collected

although Hunt et al. (1979) reported only 13.

On 2 June 1906, H. Hedrick collected at least one

egg (set number 33) from Prince Island (WFVZ No.

46,466). On 4 June 1906, Hedrick returned and collected

another egg (set number 8) from a damp cave (WFVZ

No. 140,459). On 6 June 1906, J. S. Appleton collected

at least five fresh eggs (WFVZ Nos. 76,219–76,222;

76,224; set numbers 34, 38, 52, 54, 56) and estimated

100 pairs breeding on Prince Island. He noted that eggs

were laid on bare rocks and many eggs had been broken

by waves. At least 10 and as many as 56 or more eggs

probably were collected by Appleton on this visit. On

10 June 1906, Hedrick returned and obtained at least

one egg (WFVZ No. 46,470; set number 30). He listed

nearby San Miguel Island as the collection locality but

this was probably Prince Island. Perhaps 30 or more

eggs were collected by Hedrick on this visit. Two or

three colonies of 5–50 murres each were reported

breeding on the island by Appleton (Hunt et al. 1979).

In 1906, I determined that between 8 and 127 eggs were

collected, based on the information above. Hunt et al.

(1979) reported 20–50 eggs were collected in 1906 by

Hedrick and Appleton.

Several egg collectors collected murre eggs (that

were mostly advanced in incubation), caught adult birds

that did not leave their breeding sites, and estimated

about 100 breeding pairs on Prince Island on 15 June

1910 (Willet 1910; Hunt et al. 1979). Eight eggs

collected by G. Willet were found on the floor of a cave

in rocks (WFVZ nos. 6,174; 45,894–45,895; 80,929–

80,933; set numbers 348, 349, 351, 354–356, 359, 360).

Probably at least 13 eggs were collected by Willet. Four

eggs collected by J. S. Appleton were obtained from the

same cave ledge (WFVZ Nos. 32,113–32,114; 76,217–

76,218; set numbers 31, 35, 36, 37). He probably

collected at least seven and perhaps 37 or more eggs.

Twelve eggs collected by A. Jay also were obtained

from the same cave ledge (WFVZ Nos. 109,801–109,812,

set numbers 1–12). Eight eggs collected by O. W.

Howard apparently were obtained from the same cave

ledge (WFVZ Nos. 46,410–46,417; set numbers 1–3

and 5–9). At least nine eggs probably were collected.

Together, I determined that between 32 and 71 eggs

were collected by these collectors from one small cave

ledge on that one day. Hunt et al. (1979) reported at

least 29 eggs were collected on this trip. They also noted

certain specimen numbers that I could not find (WFVZ

Nos. 6,172–6,173; DM [unknown collection] Nos.

1,226; 1,231).

The last egg record available for Prince Island was

obtained on 12 July 1912. G. K. Synder collected at

least three addled eggs on rocky ledges high above the

water (WFVZ Nos. 47,518–47,520). He indicated that

at least four sets of eggs were collected. Wright and

Synder (1913) reported several small colonies on the

“high overhanging ledges” and many chicks on 12 July

1912. After 1912, the only record of murres on Prince

Island was one bird seen on 18 April 1939 (Sumner

1939, Hunt et al. 1979). It is unlikely that any murres

escaped detection of egg collectors. D. Bleitz

(unpublished field notes) noted that no murres were

breeding on 25 July 1961. Two birds in breeding

(alternate) plumage were observed on Prince Island on

23 July 1976 (McCaskie 1976; Garrett and Dunn 1981),

indicating that nonbreeding attendance may occur

sporadically. Detailed surveys in 1975–77 (Hunt et al.

1979) and 1991, 1994, and 1995 (Carter et al. 1992;

McChesney et al. 1995; H. R. Carter, unpublished data)

failed to find any murres on land at Prince Island and

virtually none at sea nearby during the breeding season.

In 1999, murres were noted on land at Prince Island

during the early breeding season (see Chapter 2 text).

In summary, the extensive egging evident in these

records as well as the close temporal proximity of the

collecting and extirpation support the assertion by Hunt

et al. (1979) that specimen collecting contributed to
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 103

and may have been the main factor leading to final

extirpation of this colony. The colony also may have

been affected in the nineteenth and early twentieth

centuries by undocumented human disturbance, egging,

hunting, deaths from oiling, climate change, or factors

at the southern edge of the breeding range (Hunt et al.

1980). Other murre colonies also could have existed in

the northern Channel Islands (especially at nearby

Castle Rock off San Miguel Island where suitable habitat

exists) but were extirpated before the 1880s when egg

collecting became focused at Prince Island.

Northern California Colonies

Castle Rock (Castle Complex)

Castle Rock probably was egged heavily by early

residents of Crescent City (e.g., about 800 residents by

1854 [Smith 1989]) because of easy access by small

boat. The first record of murre breeding on Castle Rock

was an egg collected on 6 July 1894, without other

data, in the egg collection of C. I. Clay which is housed

at the museum within the Department of Wildlife at

Humboldt State University (HSUWM No. 605).

Numerous eggs were collected from Castle Rock

between 1917 and 1935, after the South Farallon Islands

and Prince Island no longer provided specimens for

collectors (see above). On 20–22 July 1917, C. I. Clay

collected at least 4 eggs and murres were noted only as

“seen” (HSUWM Nos. 345–347, 1387; C. I. Clay,

unpublished field notes in the HSU Special Collections

Library [HSU-SCL]; see Osborne 1972). On 23 June

1923, at least two eggs were collected, without other

data (HSUWM Nos. 1615, 1618). On 18 May 1925, at

least one egg was collected (HSUWM No. 1088). On 2

June 1924, F. J. Smith (probably with C. I. Clay) collected

at least five eggs; two eggs were marked as sets numbers

3 and 10 (WFVZ Nos. 32,111; 32,115) from a “small

nesting colony,” whereas three other eggs had the same

date, without other data (HSUWM Nos. 309, 1614,

1616). On 23–25 June 1925, F. J. Smith and C. I. Clay

collected at least seven eggs and one small chick that

was found dead (MCZ 328596). Two eggs were marked

as set numbers 2 and 40 (WFVZ Nos. 73,885; 140,513)

and three eggs were marked as set numbers 1, 2, and 3

(MCZ 9421–9423), whereas two other eggs had the same

dates without other data (HSUWM Nos. 1386, 1613).

One other egg bore only the date 1925 (HSUWM No.

1623). Clay (unpublished notes in the HSUWM egg

collection) made a list of eggs of several seabirds

collected at Castle Rock on 24 July 1925, noting 50

murre eggs collected. In June 1926, at least one egg was

collected (HSUWM No. 1621), whereas one other egg

bore only the date 1926 (HSUWM No. 1617). On 22–

24 June 1928, F. J. Smith and C. I. Clay collected at

least 10 eggs (WFVZ No. 73,886; BMVZ Nos. 13,284–

13,291; HSUWM No. 296). Clay (unpublished notes in

the HSUWM egg collection) made a list of eggs of

several seabirds collected at Castle Rock on 24 June

1928, noting 100 murre eggs collected. On 17–18 May

1929, F. J. Smith (probably with C. I. Clay) collected at

least 15 eggs: three eggs were marked with set numbers

9, 10, and 16 (WFVZ Nos. 37,036; 73,887; 73,888),

whereas 12 eggs had no other data (HSUWM Nos. 293,

294, 302, 310, 340–344, 684 [note: HSUWM Nos. 340,

342, and 344 include two eggs per specimen number]).

On 25 May 1929, J. T. Fraser collected at least one egg,

marked as set number 3/29 (WFVZ No. 88,133). On 9

July 1929, G. D. Atwell collected at least three eggs,

marked as set numbers 117–119 (HSUWM Nos. 1738–

1740). On 18 May 1930, L. Zerlang and J. T. Fraser

collected at least four eggs: three eggs were marked

with Zerlang’s set numbers 1, 2, and E5, and one egg

was marked with Fraser’s set number 2 (WFVZ Nos.

37,036; 73,887; 73,888). On 28 June 1930, at least six

eggs were collected, probably by C. I. Clay (HSUWM

Nos. 295, 299, 669, 671, 675, 676). On 20 May 1931, L.

Zerlang collected at least one egg, marked as set number

4 (WFVZ No. 47,408). On 27 June 1931, at least four

eggs were collected, probably by C. I. Clay (HSUWM

Nos. 297, 298, 300, 301). On 12 June 1932, L. Zerlang

and J. T. Fraser collected at least four eggs: two were

marked with Zerlang’s set numbers 17 and 57, and two

with Fraser’s set numbers 332 and 532 (WFVZ Nos.

46,406; 47,409; 88,111; and 88,113).

On 20 May 1934, C. I. Clay collected at least ten

eggs, of which nine eggs are in the HSUWM collection

(HSUWM Nos. 1,089; 1,090; 1,095; 1,096; 1,098;

1,100; 1,105; 1,107; and 1,680). Clay (HSU-SCL

unpublished field notes) provided additional

information for each egg collected (field nos. 2305–

2310, 2313–2317), including the following notes of

interest: No. 2305 (HSUWM No. 1,100) - “Colony

murres on north side and about 100 feet above sea level;

large colony with eggs close together”; No. 2,306

(HSUWM No. 1095) - “All the eggs in 3 major colonies

were laid on bare rock; in some cases extremely rough”;

No. 2,310 (HSUWM No. 1090) - “... taken on extreme

top of the highest peak on rock. Estimated 167' above

sea level”; No. 2,313 (HSUWM No. 1089) - “... in large

colony on extreme seaward side of island”; No. 2,315

(HSUWM No. 1,089) - “This egg placed in center of

large colony of murres on the east side of the island.

Birds in this colony touched each other, while on the

nest, they were so thick. This colony laid eggs right out

to the edge of a more than 100 foot cliff...”; and No.

2,316 - “Same nesting side as the last runt egg [i.e., No.

2,315]... The colony was the most compact nesting of
104 USGS/BRD/ITR–2000-0012

any of the murre colonies... .” In addition, Clay (HSUSCL unpublished field notes) made the following

general notes: “The California Murre were in full

nesting. Eggs fresh to slight incubation”; and “The

greedy Western Gull was seen to make off with a murre’s

egg at every opportunity, holding it firmly between his

beaks, with the large end towards his mouth.” In June

1934, Fraser (Osborne 1972) also noted breeding murres

at Castle Rock.

On 18–20 May 1935, C. I. Clay collected at least

13 eggs, of which 12 are specimens in the HSUWM

collection (HSUWM Nos. 1,091–1,094; 1,097; 1,099;

1,101–1,103; 1,106; 1,108; and 1,109). Clay (HSU-SCL

unpublished field notes) noted each of the 13 eggs

collected (field nos. 2,337–2,350) on the “north high

point of island” with the following notes of interest:

“Three separate rookeries are on the island....The murres

were all sitting on their eggs”; and field no. 2,338

(HSUWM No. 1,094) - “This was 11 P.M. Bright

moonlight overhead. The colony next our position

crowded close against each other as we approached their

position.” Talmadge also noted breeding murres in two

large colonies in the mid-1930s (Osborne 1972). In

addition to the above egg specimens, another 24 eggs

without any data are housed in the HSUWM collection

that were probably collected by C. I. Clay at Castle

Rock between 1917 and 1935.

On 27 May 1956, L. T. Stevens noted “10,000 pair

nesting” and collected at least 18 eggs with set numbers

ranging between 2402 and 2504. Ten eggs are in the

WFVZ collection (WFVZ Nos. 34,224; 78,967–78,969;

124,155–124,157; 132,452; 145,266; and 145,267), six

eggs are in the SBNHM collection (SBNHM Nos. 2,403;

2,412–2,413; and three without catalogue numbers),

and two eggs are in the USNM collection (USNM Nos.

46,569; 46,574). On 28 May 1961, L. T. Stevens and J.

D. Daynes noted 5,000 breeding pairs or 5,000 birds at

Castle Rock and collected at least 28 eggs with Stevens’

set numbers ranging between 3172 and 3209 and

Dayne’s set numbers ranging between 9 and 27. Twentyfour eggs are in the WFVZ collection (WFVZ Nos.

30,161–30,162; 34,205–34,215; 34,217–34,222;

34,225–34,228; 145,268) and four eggs are in the USNM

collection (USNM Nos. 46,570–46,573).

In July–August 1969, breeding pairs were estimated

at 5,400 (Osborne 1969) although surveys were

conducted late in the season. On 7 February 1970, 250

birds were present with irregular attendance until

breeding started. In 1970, about 20,000 pairs were

reported breeding, although between 16,600 and 32,000

birds were counted on various dates in April–June

(Osborne 1971). Osborne (1972) reported 40,000

breeding pairs in June 1970 and noted that the murre

population of northern California had increased since

1900 when egg predation by native people and

European immigrants began to decline. If a k correction

factor of 1.67 was applied to 1970 counts, a range of

27,700–53,400 breeding birds or 14,000–27,000 pairs

can be calculated. Because low counts may have

occurred prior to egg laying, rough counting techniques

were used, and aerial photograph counts are often greater

than visual estimates, the upper end of this range is

compared to 1979 (see Chapter 2 text). On 18 July 1976,

1,000 were reported (T. Schulenberg, American Birds

Files and personal communication). H. Cogswell

(unpublished field notes) roughly estimated at least

50,000 from a small aircraft on 2 July 1977, as well as

300,000 murres from a telescope count from the adjacent

mainland, hundreds of meters away.

Whaler Island (Castle Complex)

On 23 June 1928, F. J. Smith collected one murre

egg (set number 8) on “Whale [sic] Island, Crescent

City, California . . . about 80 feet [24 m] above the sea”

(BMVZ No. 13,292). He also collected eggs from nearby

Castle Rock at this time (see earlier). Whaler Island was

a well-known location at Crescent City harbor, so there

does not seem to have been confusion between Whaler

Island and Castle Rock. This is the only available

documentation of murres breeding at Whaler Island.

Murres were not reported there by egg collectors and

early naturalists in May 1916, July 1919, 22 March

1925, 20 May 1934, or June 1939 when thousands of

nesting Leach’s and fork-tailed storm-petrels

(Oceanodroma leucorhoa and O. furcata) and other

species were noted (Howell 1920; Osborne 1972; Clay,

HSU-SCL unpublished field notes). A small breakwater

was completed by 1939 connecting the island to the

mainland. In the early 1950s, the island was partly

quarried and the breakwater strengthened. In 1969,

Osborne (1972) visited the island and noted rats (Rattus

sp.) and no breeding seabirds.

False Klamath Complex

Dawson (1923) noted breeding by murres on rocks

of Humboldt and Del Norte Counties but provided no

exact breeding localities. A large congregation of murres

was noted by Kelly on the large rock offshore near

Requa (probably False Klamath Rock) on 1–6 June 1941

and the “whole side of rock was covered with birds” (L.

O. Williams, unpublished field notes). Clay (HSU-SCL

unpublished field notes) did not provide any earlier

observations of seabirds at False Klamath Rock. In 1969,

5,000 breeding pairs were reported (Osborne 1971;

Osborne and Reynolds 1971), apparently from an aerial
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 105

count (Osborne 1972). However, 2,500 breeding pairs

were reported in 1969 by Osborne (1969). Osborne

(1972) reported 10,000 breeding pairs in 1970. On 18

July 1976, 1,200 murres were reported at False Klamath

Rock (T. Schulenberg, American Birds Files and personal

communication).

Redding Complex

Osborne (1972) reported that Clay told him that

murres bred on Redding Rock in the 1930s. No reference

to this observation or any visit to Redding Rock was

reported on paper by Clay (HSU-SCL unpublished field

notes). Osborne (1971) and Osborne and Reynolds

(1971) noted 200 breeding pairs at Redding Rock in

1969. Osborne (1972) noted 300 breeding pairs in 1970

based on an aerial survey on 12 May. A navigational

aid light was placed on Redding Rock prior to the

1950s. Annual maintenance activities by the U.S. Coast

Guard have affected the colony (see Chapter 2 text).

Trinidad Complex (Green Rock, Flatiron Rock,

Pilot Rock, Blank Rock, White Rock,

and Sea Lion Rock)

Trinidad Bay was discovered on 9 June 1775 by

Juan Francisco de la Bodega y Cuadra aboard the

Spanish ship Sonora (Coy 1929). The pilot A. Mourelle

noted: “At the entrance of the port is a small island of

considerable height, without a single plant upon it [Pilot

Rock]; and on the sides of the coast are high rocks,

which are very convenient for disembarking [e.g.,

Flatiron Rock]; ...” Thus, some harvesting of seabirds

or their eggs may have occurred. In late June and early

July 1817, the British ship Columbia visited and the

chief officer noted: “This bay is full of high rocks, which

are always covered with birds, and round it are scattered

many Indian villages.” Trinidad was one of the first

settlements along the northern California coast,

established in 1850. These rocks probably were egged

heavily by early residents but egging by native people

also probably took place because of the accessibility of

these colonies by canoe from the Yurok village of Tsurai

(Heizer and Mills 1991). On 2 July 1897, murre eggs

were collected from unidentified “rocks off the coast of

Humboldt Co.” (probably off Trinidad) for A. M. Shields.

A total of 72 eggs were found in the WFVZ collection

(set numbers between 3 and 198). On 18 July 1900,

murre eggs were collected from unidentified “rocky

islands of the coast of Humboldt Co. . . . for L. Kessing.”

A total of 343 eggs were found in the WFVZ collection

(sets of 20 eggs each, set numbers between 1 and 133);

thus, as many as 2,660 eggs may have been collected.

On 28 June 1901, at least four murre eggs were collected

from unidentified “islands off Humboldt County . . .

collected by a sailor for W. L. Chambers” (WFVZ

47,401–47,402; 47,664; 80,928). This group of colonies

near Trinidad in Humboldt County probably were the

breeding rocks in Humboldt County referred to by

Dawson (1923).

Green Rock was first reported as a breeding colony

in 1930s by Talmadge (Osborne 1972). On 11 August

1938, Clay (HSU-SCL unpublished field notes) reported

finding a dead murre “in the surf at mouth of Luffenholtz

Creek, 2 miles south of Trinidad ... California Murre

nest on fishermen’s rock [i.e., Green Rock] 1 1⁄2 miles

north of Trinidad.” On 10 May 1941, Clay (HSU-SCL

unpublished field notes) noted a substantial colony at

“Fishermen’s Rock” (i.e., Green Rock) and described it

as follows: “A considerable colony of California Murres

nest on this bold, rather round dome 125 feet above the

waterline. I have worked other rocks along this locality

many times in past years; but never this particular one;

it being the only accessible one with a murre rookery in

these parts... I doubled back and up an sought ridge of

easy going soon to hear the incessant grumbling roar of

the approximately 2000 California Murres which were

packed tight on the very top of the rocky dome. I was on

a rather, grassy flat 10 feet wide running in a circle at the

bottom of a 6 foot wall, just out of sight of the murre

colony.” These notes and the lack of observations at

other nearby islands suggest that murres only bred on

Green Rock in the Trinidad area from at least 1910 to

the early 1940s. W. Anderson (HSU-SCL unpublished

field notes) reported murres as “numerous on sea cliffs,

Trinidad” on 15–16 May 1943 and “A few left on rocks

off Trinidad” on 15 August 1943. These observations

appear to refer to Green Rock alone, but also may refer

to Flatiron Rock (see below). Murres were not reported

on the cliffs of Trinidad Head in 1910–40 by Clay (HSUSCL unpublished field notes) who conducted extensive

collections in this area. Anderson (HSU-SCL

unpublished field notes) also noted murres breeding,

probably at Green Rock and Flatiron Rock, in 1947

(see below). On 10 June 1948, two eggs (set number

236) were collected from a “large colony on island near

Trinidad” (probably Green Rock but possibly Flatiron

Rock; see below) by A. Andresen (WFVZ No. 68,333).

Osborne (1969) reported 1,200 breeding pairs in July–

August 1969. Osborne (1971) and Osborne and

Reynolds (1971) noted 10,000 breeding pairs of murres

in 1970. In fact, counts ranged between 6,000 and 20,000

birds on various dates in April–June 1970 and colony

attendance began in February 1970. Osborne (1972)

reported 20,000–24,000 breeding pairs in 1969–70. If

a k correction factor was applied to 1970 counts, a range

of 10,000–33,000 breeding birds or 5,000–17,000 pairs
106 USGS/BRD/ITR–2000-0012

can be calculated. Since low counts may have occurred

prior to egg laying, rough counting techniques were

used, and visual counts were made, the actual number

was probably between 10,000 and 15,000 pairs.

Clay (HSU-SCL unpublished field notes) did not

note murres on several egg collecting trips to “Off

Trinidad Rock” (i.e., Flatiron Rock) on 22 May 1910,

16 July 1911, and 21 July 1912. Osborne (1972) reported

Clay’s lack of murre observations in these years and in

1934. Greater accessibility of this rock by canoe (native

people) or boat (eggers) may have resulted in earlier

colony extirpation. However, on 31 May 1947, W.

Anderson (HSU-SCL unpublished field notes) noted that

murres were “apparently nesting in considerable

numbers on two islands in Trinidad region.” On 13 July

1947, Anderson (HSU-SCL unpublished field notes)

further noted: “Great numbers of half-grown downy

young seen from skiff on the larger of the 2 Murre rocks.

Adults bringing single fish on each trip.” Murres likely

expanded from Green Rock onto Flatiron Rock, which

has extensive breeding habitat and is located near Green

Rock. Osborne (1969) reported 1,000 breeding pairs in

July–August 1969. Osborne (1971, 1972) and Osborne

and Reynolds (1971) noted 2,500 breeding pairs in

1970, based on the highest mainland count of 5,000

birds on 5 April 1970. In fact, counts ranged from 1,100

to 5,000 in April–June 1970 and murres began

attendance of the colony in early February 1970

(Osborne 1971). Osborne (1971) also noted an estimate

of 2,000 breeding pairs that seems to be an error. Osborne

(1972) reported 5,200. Varoujean (1979) and Sowls et

al. (1980) cited this value as 5,000 breeding pairs in

1969–70. If a k correction factor was applied to 1970

counts, 2,000–8,000 breeding birds or 1,000–4,000

pairs can be calculated. Because low counts may have

occurred prior to egg laying, rough counting techniques

were used, and aerial photograph counts are often greater

than visual estimates, the upper end of this range is

compared to 1979 (see Chapter 2 text). On 6 February

1971, 5,000 birds (95% in breeding plumage) were

reported at Flatiron Rock (DeSante and Wang 1971; R.

A. Rowlett and R. LeValley, American Birds Files).

Several observations of murres at Green and Flatiron

rocks were recorded by R. A. Erickson, T. S. Schulenberg,

and others between 1973 and 1976 (R. A. Erickson and

T. S. Schulenberg, unpublished data; American Birds

Files), including many hundreds on 16 April 1973;

6,000 on 17 March 1974 (Greenburg and Stallcup 1974);

5,000 on 6 April 1974; 5,500 on 19 April 1974; 4,500

on 4 May 1974; 4,500 on 8 June 1974; 2,000 on 4 May

1975; 12 on 17 August 1975; and 2,500 on 12 June

1976.

Osborne (1972) reported murres at Pilot Rock in

1969 although breeding was not noted there by Osborne

and Reynolds (1971). Murres also were noted in 1966–

69 by S. W. Harris (Osborne 1972).

Murres were not reported breeding at Blank Rock

in 1969–70 (Osborne 1969, 1971, 1972; Osborne and

Reynolds 1971). However, 1,000 and 5,000 murres were

reported at Blank Rock on 13 and 21 March 1965,

respectively, by F. Zeillemaker (R. A. Erickson,

unpublished data, American Birds Files).

Osborne (1971, 1972) and Osborne and Reynolds

(1971) noted 600 breeding pairs at White Rock in 1969,

based on mainland counts. Osborne (1969) reported 250

breeding pairs in July–August 1969.

Clay and Hallmark (Osborne 1972) noted that

murres bred on Sea Lion Rock before the 1950s when

the entire south half of the rock fell into the water.

Previously, murres had bred on the flat top of the rock.

Breeding has not been reported since then (Osborne

1972; Sowls et al. 1980; Carter et al. 1992).

Cape Mendocino Complex

(False Cape Rocks and Steamboat Rock)

Osborne (1969) first reported 350 breeding pairs at

False Cape Rocks in July–August 1969. In 1969–70,

Osborne (1971) and Osborne and Reynolds (1971) noted

600 breeding pairs at False Cape Rocks (based on a

July 1969 aerial count). Osborne (1972) reported 800

breeding pairs at False Cape Rocks in 1969, based on

an aerial count (reported as 1970 in Varoujean 1979

and Sowls et al. 1980). Clay (HSU-SCL unpublished

field notes) did not report any earlier visits to False

Cape Rocks.

On 7 July 1917, Clay (HSU-SCL unpublished field

notes) did not note murres at Steamboat Rock but did

note that “... a great many Brandt cormorants were seen

and they appeared to be nesting in great numbers.” It is

possible that no murres bred within this complex at this

time, given this observation and Clay’s comment on 10

May 1941 that murres bred only at Green Rock “in

these parts” (see above). However, this observation was

made from the adjacent mainland and most of the murre

breeding areas on this rock are not visible from shore.

Osborne (1969) reported 150 breeding pairs at

Steamboat Rock in July–August 1969. Osborne (1972)

indicated that 300 birds were observed on 16 July 1969.

In 1970, 300 pairs bred, based on ground and aerial

counts in 1969–70 (Osborne 1971; 1972; Osborne and

Reynolds 1971).
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 107

Although Sugarloaf Rock (near False Cape and

Steamboat Rocks) has suitable breeding habitat, murres

have been noted there only once and have not been

recorded breeding there. Briggs et al. (1983) reported

334 birds at the rock in July 1981, but none during

other May and July surveys in 1980–82. I did not,

therefore, consider these birds to be breeding, but birds

at this colony may have abandoned without any

documentation of earlier breeding.

Mendocino County Colonies

Murres had not been reported breeding in

Mendocino and Sonoma Counties before 1979 when

breeding was first reported at Cape Vizcaino (Sowls et

al. 1980). Osborne and Reynolds (1971) did not note

any murres there in 1969–70 although other nesting

species were recorded at many rocks and islands.

Osborne’s surveys may have been conducted too late in

the season to detect the Cape Vizcaino colony.

Murres may have bred at sites throughout

Mendocino and Sonoma Counties in the past but been

extirpated by early settlers since 1850 (Lorentzen 1995).

This area was colonized rapidly during and after the

Gold Rush when many small coastal logging

communities sprung up along the coast. Most of the

islands along this coast are small, close to shore, and

easily accessible by small boat. Accessible colonies

probably would have been egged heavily during the

early years of colonization by U. S. settlers when food

was scarce. In addition, native peoples in canoes also

may have adversely affected murre colonies before and

during U. S. settlement. There is little documentation of

egging in this area. In the first week of June 1900,

however, 24 murre eggs obtained by fishermen from

somewhere along the “Mendocino coast” were bought

in the San Francisco market by L. Kessing for D. A.

Cohen. The labels of seven specimens in the WFVZ

give this information (WFVZ Nos. 117,680–117,685).

However, murre eggs also were obtained for L. Kessing

on unidentified rocks in Humboldt County in July 1900

(see Trinidad Complex above). Thus, it is possible that

an incorrect general location was applied to these 24

eggs.

If murres did breed along the Mendocino coast,

their colonies probably were adversely affected by the

construction of log chutes, piers, and wharves. This area

has no large natural harbors and chutes were built for

loading logs onto ships from coastal bluffs. Often, the

ocean end of a chute or pier was built on small offshore

rocks located close to shore at several points along the

coast (Sullenberger 1980; Hendrickson 1994). One of

the largest wharfs was at Cottaneva (or Rockport) where

the first suspension bridge on the West Coast was

constructed in 1877. The bridge extended over 92 m

(275 feet) of ocean onto several offshore rocks, the largest

of which was called “Sea Lion Rock” (Mendocino

Historical Research, Inc. 1978; Lorentzen 1995; Cook

and Hawk 1999). These rocks were cut down to form a

flat surface for bridge construction and for storing

lumber. In 1888, the wharf was rebuilt and fortified in

the same location. The mill closed for 10 years during

the Great Depression (about 1928–38), during which

time the bridge fell down. The mill reopened in 1938

and a skyline was built between the mainland and the

rock. The skyline was used for a short period to load

boats before the switch to hauling lumber by truck. The

mill burned in 1942 (Lorentzen 1995; Cook and Hawk

1999). Since 1989, these rocks (now called Rockport

Rocks) have been used for breeding by murres (Carter

et al. 1992), despite the cement supports that are still

visible on the rocks. It is likely that murres were forced

off these rocks when the wharf was built. Other colonies

probably were similarly affected by wharfs and chutes.

Murres breeding near Fort Ross or other areas farther

north also would have been heavily egged by the

resident Russians in the early nineteenth century, based

on their activities at the Farallon Islands (see above).

Unfortunately, the coasts of Sonoma and Mendocino

Counties were visited little by early ornithologists and

breeding seabirds were poorly recorded and poorly

known. In 1997, murres were confirmed breeding at three

other colonies along the Mendocino coast (see Chapter

2 text).
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 109

Appendix C

Population data for common murre (Uria aalge californica) colonies in California, 1979–1986

(prepared by H. R. Carter and J. E. Takekawa)

Table. Summary of whole-colony counts of murres (Uria aalge californica) from aerial photographic and other surveys conducted in California

in 1979–1986 by the U.S. Fish and Wildlife Service, University of California, and other groups. See extended table legend at end of this appendix

for format.

Colony Year

number Colony name 1979a,b 1980a,b,c 1981c1982c1985d1986d

Castle Complex

325-006 Castle Rock 76,000a,b 78,925c(July) 41,400(July) 85,250(July) PNC 59,863

18,690c(May) 42,515(May) 39,996(May)

325-045 Whaler Island ND {0}

a(June) ND ND ND ND

False Klamath Complex

325-048 Rock R {0

a,b(May)} 0a(June) ND ND ND ND

[3

b(June)]

325-009 Sister Rocks {0

a,b(May)} {50b(May)} 25(July) 94(May) ND ND

{30a,b(June)} 30(May)

325-010 False Klamath Rock 16,000a,b 22,510c(July) 10,000(July) 31,801(July) ND 28,762

5,200c(May) 14,000(May) 15,300(May)

Redding Complex

325-013 Redding Rock 500b(May) 1,275a,b 650(July) 700(July) ND 780

1,031c(July) 800(May) 880(May)

1,050c(May)

Trinidad Complex

325-018 Sea Lion Rock {0

a,b(August)} {0a,b(June)} ND ND ND ND

325-019 White Rock 1,600a,b 1,980c(July) 3,277(July) 3,055(July) ND ND

3,028c(May) 2,000(May) 3,780(May)

325-020 Green Rock 25,000b 32,934a(July) 25,155(July) 23,084(July) ND 20,726

{35,000b(June)} 14,000(May) 19,998(May)

16,960c(July)

21,500c(May)

325-023 Flatiron Rock 14,650a,b 10,600c(July) 14,330(July) 10,757(July) ND 16,238

14,500c(May) 3,500(May) 18,600(May)

325-024 Blank Rock 0

a,b(July) 600a,b(July) 325(July) 3,200(July) ND ND

259c(July) 400(May) 325(May)

325-026 Pilot Rock ND 1,538a,b(July) 1,100(July) 1,443(July) ND ND

800b(June) 900(May) 1,450(May)

874c(July)

Cape Mendocino Complex

325-040 False Cape Rocks 4,661a,b(August) 6,580c(July) 9,100(July) 8,619(July) ND ND

{2,800b(July)} 8,450c(May) 9,340(May) 11,800(May)

325-041 Sugarloaf Rock {0

a,b(July)} ND 0 ND ND ND

[200(July)]

325-042 Steamboat Rock 2,800a,b(July) 3,072c(July) 4,400(July) 4,720(July) ND ND

4,000c(May) 3,500(May)

Vizcaino Complex

379-001 Rockport Rocks {0

a,b(June)} ND ND ND ND ND

379-002 Cape Vizcaino 1,261b(August) 3,500c(July) 501(May) 4,364(July) ND ND

3,473a,c(May) 2,720(May)

Newport–Kibesillah Complex

379-021 Newport Rocks {0

(June)} ND ND 0 ND ND

379-004 Kibesillah Rock {0

a,b} 0a,b ND ND ND ND

[4b(August)] [3b(June)]

Goat Complex

379-006 Goat Island Area {0

b(June)} 0a,b(July) ND ND ND ND
110 USGS/BRD/ITR–2000-0012

Noncomplex locations

379-010 White Rock {0

a(June)} 0a(July) ND ND ND ND

[4b(June)]

404-004 Gualala Point Island {0

a} {0a} ND ND ND ND

[4a(June)]

Point Reyes Complexe,f

429-001 Point Reyes {11,095b(July)} 13,423c(July) 16,474(July) 26,337(July) 9,242 9,360

{9,880a(July)} 18,644c(May) 34,865(May) 15,906(May)

Points Resistance–Double Complex

429-024 Point Resistance 2,970b(July) 4,440a,b(June) 3,600(July) 4,100(July) 2,255 1,805

4,379c(July) 10,628(May) 2,875(May)

1,550c(May)

429-002 Millers Point Rocks ND 63c(July) 66(July) 497(May) 0 ND

18(May)

429-003 Double Point Rocks 3,990b(July) 8,850c(July) 5,875(July) 7,100(July) 3,378 1,950

7,750a,b(June) 13,859(May) 8,650(May)

1,533c(May)

North Farallon Complex

429-051 North Farallon Islands ND 31,428c(July) 29,100(July) 30,914c(July) 18,597 12,780

13,442c(May) 21,550(May) 30,050c(May)

{29,940e(June)}

South Farallon Complexg

429-052 South Farallon Islands ND 52,527c(July) 49,975(July) 61,510(July) {31,738} {31,101}i

{35,928a(May)} 12,657c(May) 23,500(May) 44,250(May) {33,780}d {31,045}d

{31,750h(May)} {30,035h(June)} {45,100h(June)} {50,700h(June)} {30,841}i

{30,485i} {45,600i} {53,550i} {30,716}i

Devil’s Slide Complex

429-013 San Pedro Rock 0

a,b (June) ND ND ND ND ND

429-014 Devil’s Slide Rock and {1,400a,b} 1,750c(July) 800(July) 1,530(July) ND 0

 Mainland 1,000b(July) 1,531c(May) 1,418(May) 2,300(May) [93]

Noncomplex location

429-033 Martin’s Beach {0

a,b(July)} {0a,b(June)} ND 0 ND ND

[18]

Castle–Hurricane Complexf

454-010 Castle Rocks and {1,524b(July)} {2,275a,b} 6,683(July) 1,105(July) ND 642k

 Mainlandj 795c(July) 1,198(May) 1,000(May)

1,098c(May)

454-011 Hurricane Point Rocksj {492b(July)} {1,400a,b(June)} 1,500(July) 1,016(July) ND 93k

1,144c(July) 2,000(May) 3,030(May)

1,427c(May)

Prince Complex

501-004 Prince Island ND ND ND ND {0

l} {0l}

a Source is Sowls et al. (1980).

b Source is Sowls et al. (unpublished survey data).

c Source is Briggs et al. (1983).

d Source is Takekawa et al. (1990).

e McChesney et al. (1998) indicated that 1979–81 data are not directly comparable to 1985–95 data.

f McChesney et al. (1998, 1999) reexamined survey data from 1979 to 1982 and derived revised whole-colony counts at these

colonies. We have not included these revised numbers in this appendix but did use this information to verify surveys selected for

analyses in this report.

g For 1985, Sydeman et al. (1997:123) used a new combined total of 30,841 birds (based on a reexamination of raw data) as a

“standardized” total for calculating an estimate of colony size for 1985. In fact, the correct value for this new total is 30,716 birds,

based on data in their Appendix 6. However, they also omitted the g correction factor (0.841) used by Takekawa et al. (1990) to

make aerial survey counts in 1985 more comparable with 1986 and later surveys. In this appendix, we used the new combined

totals in Sydeman et al. (1997). However, since West End Island (WEI) was surveyed with aerial photographs, we applied the g

correction factor to the WEI total (14,030) to derive a WEI total of 16,683, before adding other subcolonies without a correction

Table. (continued)

Colony Year

number Colony name 1979a,b 1980a,b,c 1981c1982c1985d1986d
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 111

factor (15,055) to derive a colony or colony complex total of 31,738. For 1986, Takekawa et al. (1990) did not apply a g correction

factor. We have used the new combined count reported in Sydeman et al. (1997).

h Source is Ainley and Boekelheide (1990).

i Source is Sydeman et al. (1997).

j For 1986, Takekawa et al. (1990) could not determine separate counts for these two colonies but provided a combined count of

1,881 murres. McChesney et al. (1999) reexamined these aerial photographs, excluded some counted photographs from another

colony that had been misidentified, and determined incomplete total counts for each colony as noted.

k Source is McChesney et al. (1999).

l Source is Lewis et al. (1988).

Extended legend: Colonies are ordered from north to south. Colony names, not italicized, indicate colonies attended regularly and

where breeding is confirmed. Underlined and italicized colony names indicate long-inactive colonies and rocks attended without

confirmed breeding, respectively. Numbers without brackets refer to total murre counts from aerial photographs. Underlined

counts were incomplete. Numbers with brackets ([ ]) indicate murres attending colonies but breeding not suspected. Braces ({ })

indicate either combined counts from aerial and ground–boat surveys, ground surveys, or boat surveys. Data considered to be best

for trend analyses in this study are indicated in bold font, based on several criteria: (1) Aerial photograph counts usually provided

higher and better colony numbers than boat and ground counts, except for small areas not photographed. (2) Surveys during the

main part of the breeding season (late May to mid-July) were prioritized over earlier or later surveys. (3) Archived raw counts were

preferred over back-calculated raw counts. (4) Otherwise less reliable surveys were not used. Italicized counts were used to obtain

population sums and colony complex totals but were not considered to be comparable to other data for the colony. Codes: ND, no

data obtained; PNC, photographs taken but not counted.

Table. (continued)
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 113

Appendix D

Population data for common murre (Uria aalge californica) colonies in California, 1987–1995

(prepared by H. R. Carter and J. E. Takekawa)

Table. Summary of whole-colony counts of murres (Uria aalge californica) from aerial photographic and other surveys conducted in California

by the U.S. Fish and Wildlife Service, Humboldt State University, National Biological Service, and other groups. See extented table legend at

end of this appendix for format.

Colony Year

number Colony name 1987a1988a,b 1989a,b,c,d 1990a,b 1993a,b,d 1994d1995d

Castle Complex

325-006 Castle Rock PNC PNC 64,475 PNC PNC PNC PNC

{10,883}

325-045 Whaler Island ND ND {0} ND ND ND ND

False Klamath Complex

325-048 Rock R ND ND 0 ND 0 0 0

[194] [142]

{116}

325-009 Sister Rocks ND ND 0 ND 0 0 0

[216] [62]

{70}

325-010 False Klamath Rock PNC PNC 26,130 PNC PNC PNC 28,698

{10,200}

Redding Complex

325-013 Redding Rock PNC PNC 1,632 PNC PNC PNC PNC

{1,150}

Trinidad Complex

325-018 Sea Lion Rock ND ND {0} ND ND PNC PNC

325-019 White Rock PNC PNC 3,157 PNC PNC PNC PNC

{1,100}

325-020 Green Rock PNC PNC 19,060 PNC PNC PNC PNC

{8,620}

325-023 Flatiron Rock PNC PNC 19,914 PNC 4,846 22,408 25,494

{3,930}

325-024 Blank Rock PNC PNC 331 PNC PNC PNC PNC

{190}

325-026 Pilot Rock PNC PNC 1,358 PNC PNC PNC PNC

{450}

Cape Mendocino Complex

325-040 False Cape Rockse PNC PNC 9,594 PNC 1,156 10,946 12,426

6,578

{1,133}

325-041 Sugarloaf Rock PNC ND 0 PNC PNC PNC PNC

325-042 Steamboat Rock PNC PNC 5,454 PNC PNC PNC PNC

{390}

Vizcaino Complex

379-001 Rockport Rocks ND ND 915 PNC PNC PNC PNC

{237}

379-002 Cape Vizcaino ND ND 4,125 PNC 3,670 4,557 4,950

{550}

Newport–Kibesillah Complex

379-021 Newport Rocks ND ND 0 PNC 0 0 0

[7] [163] [379]

379-004 Kibesillah Rock ND ND {0} PNC 0 0 0

[163]

Goat Complex

379-006 Goat Island Area ND ND 0 PNC 0 0 0

[34] [49] [104]
114 USGS/BRD/ITR–2000-0012

Noncomplex locations

379-010 White Rock ND ND 0 PNC PNC PNC PNC

404-004 Gualala Point Island ND ND 0 PNC 0 0 0

Point Reyes Complex f

429-001 Point Reyesg 12,046a,f 10,955a,f {9,501a,f} 11,807a,f 15,380a,f 15,381a,f 17,811a,f

{17,719f} {9,021} 17,719f

9,141f

Point Resistance–Double Point Complex

429-024 Point Resistance 1,864 2,635 2,094 3,474 3,454 3,775 3,132

3,913

429-002 Millers Point Rocks 23 67 146 380 365 485 713

{213} 1,060

429-003 Double Point Rocks 2,826 3,197 2,657 2,979 3,250 3,694 3,759

3,814

North Farallon Complex

429-051 North Farallon Islands 16,505 13,398 15,428 14,621 19,428 23,332 23,069

South Farallon Complexh

429-052 South Farallon Islands 24,679a,i 25,325a,b,i 23,066a,d,i 40,926a,b 34,724a,b,d,i 40,268a,d 40,385

{19,655i} 23,085b,c 40,919i {26,226i} 39,773i {41,599i}

{20,417i} 23,006i

Devil’s Slide Complex

429-013 San Pedro Rock ND 0 0 0 0 0 0

429-014 Devil’s Slide Rock

 and Mainland 0 0 0 0 0 0 0

[128] [1] [5]

Noncomplex location

429-033 Martin’s Beach ND ND {0} ND ND ND ND

Castle–Hurricane Complex j

454-010 Castle Rocks

 and Mainlandk 954 567 728 841 972 1,439 1,376

{625c} 1,240

{753j} {1,445j}

454-011 Hurricane Point Rocks 310 480 365 420 489 496 440

423

Prince Complex

501-004 Prince Island {0l} {0l} {0l} {0l} 0 0 0

a

 Source is Carter et al. (2000).

b

 Source is Carter et al. (1995).

c

 Source is Carter et al. (1992).

d

 Source is Carter et al. (1996).

e For 1989, Carter et al. (1992) accidentally omitted 5,011 birds counted at subcolony 02.

f

 Source is McChesney et al. (1998).

g For 1989, Carter et al. (1992) misidentified certain subcolonies in aerial survey data that were combined with boat survey data to

derive a total number of murres attending the colony. McChesney et al. (1998) corrected this error and provided a separate aerial

survey count of 9,141 birds. However, we used the corrected combined colony total instead of the aerial count alone due to

incomplete coverage during the 1989 aerial survey.

h For 1989, Sydeman et al. (1997:110) reported an incorrect colony total of 23,006 due to a typographical error. In Carter et al.

(1996) and elsewhere in Sydeman et al. (1997:121), the correct total (23,066) is given, which corrects an error found in Carter et

al. (1992). For 1990, Sydeman et al. (1997:110) reported a “standardized” colony total of 40,919 birds and a Southeast Farallon

Island (SEFI) total of 13,752 birds, by excluding 7 birds at Great Murre Cave. Carter et al. (1996) reported the correct 1990

colony total of 40,926 birds. In 1994, Sydeman et al. (1997:110) also reported a “standardized” colony total of 39,773 and a SEFI

total of 13,797, by excluding 77 birds at North Landing. In addition, they used incorrect subtotals for West End Island (WEI)

(16,551), West End Cove (2,309) and Pelican Bowl (5,001). The correct subtotals are WEI (16,969), West End Cove (2,752) and

Pelican Bowl (4,976). Carter et al. (1996) reported the correct 1994 colony total of 40,268.

i

 Source is Sydeman et al. (1997).

j

 Source is McChesney et al. (1999).

Table. (continued)

Colony Year

number Colony name 1987a1988a,b 1989a,b,c,d 1990a,b 1993a,b,d 1994d1995d
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 115

k

 For 1989, Carter et al. (1992) reported an incomplete total of 625 murres, by combining highest aerial and ground counts.

McChesney et al. (1999) reexamined aerial photographs, omitted ground counts and substituted aerial counts, found and counted

a photograph which covered a missing section of the colony, and determined a complete total count of 728 murres. For 1994,

Carter et al. (1996) reported a total of 1,435 murres. McChesney et al. (1999) reexamined aerial photographs, found and counted

an omitted photograph with four additional birds, and determined a total count of 1,439 murres.

l

 Sources are Ingram (1992); Ingram and Carter (1997).

Extended table legend: Colonies are ordered from north to south. Nonitalicized colonies were attended regularly and breeding is

confirmed. Underlined and italicized colony names indicate long-inactive colonies and rocks attended without confirmed breeding,

respectively. Numbers without brackets refer to total murre counts from aerial photographs. Underlined counts were incomplete.

Numbers with brackets ([]) indicate murres attending colonies but breeding not suspected. Braces ({}) indicate either combined

counts from aerial and ground–boat surveys, ground surveys, or boat surveys. Data considered to be best for trend analyses in this

study are indicated in bold font, based on several criteria: (1) Aerial photograph counts usually provided higher and better colony

numbers than boat and ground counts, except for small areas not photographed. (2) Surveys during the main part of the breeding

season (late May to mid-July) were prioritized over earlier or later surveys. (3) Archived raw counts were preferred over backcalculated raw counts. (4) Otherwise less reliable surveys were not used. Italicized counts were used to obtain population sums and

colony complex totals but were not considered to be comparable to other data for the colony. Codes: ND, no data obtained; PNC,

photographs taken but not counted.

Table. (continued)
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 117

Appendix E

Population data for common murre (Uria aalge californica) colonies in Oregon, 1987–1995

(prepared by R. W. Lowe)

Table. Summary of the total numbers of murres (Uria aalge californica) counted from aerial photographic surveys in Oregon in 1987–1995 by the

U.S. Fish and Wildlife Service. See extended table legend at end of this appendix for format.

Colony Year

number Colony name 1987 1988 1989 1990 1991 1992 1993 1994 1995

219-001 Unnamed rock ND 8 ND ND ND ND ND ND 0

219-002 Unnamed rock ND 40 ND ND ND ND 7 107 67

219-003 Unnamed rock ND 173 ND ND ND ND ND 7 118

219-005 Tillamook Rock 3,745 5,628 3,654 6,414 6,419 5,732 608 5,484 7,199

219-007 Unnamed rock 0 0 0 0 0 0 0 0 0

219-010 Unnamed rock ND 21 56 112 186 113 0 160 129

219-013 Sea Lion Rock ND 1,602 1,912 1,761 ND 2,188 546 2,144 2,694

219-014 Unnamed rock ND 18 27 29 ND 56 7 43 130

219-017 Bird Rocks N ND 2,798 2,462 2,902 2,480 2,697 151 2,335 3,145

219-018 Bird Rocks W ND 19,250 ND ND ND ND ND ND ND

219-019 Bird Rocks SC ND 5,610 6,034 ND ND ND ND ND 7,143

219-026 Castle Rock ND 6,893 ND ND ND ND ND ND 6,132

219-027 Gull Rock ND 3,960 ND ND ND ND ND ND 5,342

219-029 Cape Falcon NF ND ND ND ND ND ND ND ND ND

219-030 Cape Falcon Rock ND 6 0 0 ND ND ND ND ND

219-036 Unnamed rock ND 0 0 0 0 0 0 Pr 43

219-044 Pyramid Rock ND 5,940 ND ND ND ND ND ND 4,926

219-045 Pillar Rock ND 6,645 ND 6,229 6,895 6,196 0 5,302 7,079

219-047 Cape Meares NPNF ND 20 ND ND ND ND ND ND ND

219-048 Cape Meares NP ND 20 ND ND ND ND ND ND ND

219-049 Cape Meares NPSF ND 5 ND ND ND ND ND ND ND

219-050 Cape Meares NC ND 70 ND ND ND ND ND ND ND

219-051 Cape Meares NF ND 13 ND ND ND ND ND ND ND

219-054 Finley Rock ND 28,224 ND ND ND ND 0 ND ND

219-055 Middle Rock ND 23,842 ND ND ND ND 0 ND ND

219-056 Shag Rock ND 79,415 ND ND ND ND 0 ND ND

219-057 Seal Rock ND 0 157 68 99 0 0 0 0

219-060 Brown Rock 1,013 1,473 2,506 1,494 2,117 2,315 0 2,278 1,922

219-061 Cape Lookout NF ND 163 ND ND ND ND ND ND ND

219-062 Cape Lookout WF ND 90 ND ND ND ND ND ND 132

219-063 Cape Lookout SF ND 8,031 ND ND ND ND ND ND ND

219-068 Cascade Head (Mnld) ND 110 97 ND ND ND 0 ND ND

219-069 Unnamed rock ND 2,158 2,069 ND 2,170 2,008 753 2,207 2,772

219-070 Unnamed rock ND 972 622 649 741 870 306 900 773

219-071 Unnamed rock ND 970 632 801 567 443 134 571 777

219-072 Two Arches Rock ND 12,176 15,982 ND ND 14,265 ND ND ND

219-073 Unnamed rock ND 8,400 ND ND ND ND ND ND ND

243-010 Gull Rock ND 13,730 14,219 14,377 12,243 11,704 8,651 11,278 13,013

243-015 Colony Rock 12,473 14,134 19,147 18,668 14,423 14,787 8,795 13,752 15,440

243-015A Subcolony Rock 0 0 0 75 56 33 0 6 73

243-016 Yaquina Head (Mnld) 0 0 0 0 0 0 168 119 265

243-017 Flat Top Rock 0 0 0 8 192 603 783 1,201 1,692

270-015 N. Coquille Pt. Rock ND 6,194 ND 6,647 ND 6,440 ND ND ND

270-016 M. Coquille Pt. Rock ND 0 0 0 5 17 0 107 90

270-017 Unnamed rock ND 0 0 46 324 795 204 1,180 1,079

270-019 Cat and Kittens ND 20,403 23,220 ND ND 22,917 ND ND ND

270-020 Face Rock ND 3,198 ND ND ND ND ND ND ND

270-023 Tower Rock ND 1,011 ND ND ND ND ND ND ND

270-025 Unnamed rock ND 300 ND ND ND ND ND ND ND
118 USGS/BRD/ITR–2000-0012

270-027 Gull Rock ND 24,057 ND ND ND ND ND ND ND

270-029 Best Rock ND 15,405 ND ND ND 13,988 ND ND ND

270-032 Square White Rock ND 4,016 ND ND ND 4,110 ND 4,961 ND

270-034 Conical White Rock ND 2,051 1,775 1,883 2,149 1,310 793 2,317 1,737

270-035 West Conical Rock ND 1,161 ND ND ND 625 ND 922 ND

270-036 Arch Rock ND 69 ND ND ND 89 ND ND ND

270-043 Redfish Rocks N 1,564 1,399 1,398 1,888 1,521 1,841 197 1,514 1,244

270-044 Redfish Rocks NC ND 816 738 859 666 710 32 1,074 733

270-045 Redfish Rocks EC ND 5,017 ND ND ND ND ND ND ND

270-046 Redfish Rocks SC ND 1,771 ND ND ND ND ND ND ND

270-047 Redfish Rocks S ND 4,268 ND ND ND ND ND ND ND

270-048 Unnamed rock ND 2,091 ND ND ND ND ND ND ND

270-049 Island Rock ND 12,865 ND ND ND ND ND ND ND

270-063 Hubbard Mound Rock 14,731 13,091 ND ND ND ND ND ND ND

270-064 Dog Rock 2,043 2,026 2,207 2,087 2,389 1,579 1,729 2,004 1,732

270-067 Double Rock ND 519 ND ND ND ND ND ND ND

270-068 Needle Rock ND 1,884 2,070 ND 2,102 1,202 0 2,138 2,336

270-085 Unnamed rock ND 44 59 72 75 64 54 88 142

270-086 Unnamed rock ND 327 87 90 85 65 50 164 61

270-087 Mack Arch ND 13,839 ND ND ND ND ND ND ND

270-110 Unnamed rock ND 24,316 ND ND ND ND ND ND ND

270-115 Twin Rocks E 1,225 1,006 ND ND ND ND ND ND ND

270-116 Twin Rocks W 7,422 5,023 6,959 6,400 7,588 4,147 2,199 6,292 6,017

270-117 Unnamed rock ND 1,810 1,918 1,657 1,340 748 528 1,497 1,521

270-122 Unnamed rock ND 820 676 768 576 474 223 701 618

270-123 Goat Island 2,616 2,873 2,896 2,968 2,584 2,219 918 2,835 2,910

Extended table legend: Colonies are ordered from north to south. Nonitalicized colonies were attended regularly and breeding

is confirmed. Bold colony numbers and names indicate sample colonies used for trend analyses from 1988 to 1995. Italicized

colony numbers and names indicate rocks attended without confirmed breeding. Codes: ND, photographs taken but not counted

or no photos were taken; Pr, murres present.

Table. (continued)

Colony Year

number Colony name 1987 1988 1989 1990 1991 1992 1993 1994 1995
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 119

Appendix F

Population data for common murre (Uria aalge californica) colonies in Washington, 1979–1989

(prepared by U. W. Wilson)

Table. Summary of the total numbers of murres (Uria aalge californica) counted from aerial photographic surveys conducted in Washington in

1979–1989 by the U.S. Fish and Wildlife Service. See extended table legend at end of this appendix for format.

Colony Year

number Colony name 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989

Point Grenville Complex

586 Erin 1,575 1,175 250 1,735 320 150 50 800 0 80 150

585 Erin’s Bride 675 730 200 790 590 250 250 800 250 75 0

584 Unnamed rock 0 0 0 0 0 0 0 0 0 0 175

575 Grenville Arch a 8,985 5,825 3,250 5,015 0 0 50 15 5,050 250 75

570 Radio Stack 1,550 1,690 1,200 1,115 0 650 0 0 200 300 650

Split–Willoughby Complex

531 Split Rock a 9,150 3,075 8,350 10,450 0 0 100 0 450 50 75

529 Willoughby Rock a 5,300 3,115 3,800 5,270 850 0 0 40 0 35 200

Other Locations

480 Destruction Island b 0 0 0 0 0 0 0 0 0 300 250

458 Middle Rock 0 0 0 0 0 0 1,800 450 0 0 0

457 North Rock NS NS NS NS NS 0 0 15 0 0 0

426 Unnamed rock NS NS NS NS NS 0 0 10 0 0 0

419 Unnamed rock NS NS NS NS NS 0 0 0 20 0 0

409 Rounded Island 2,130 3,435 850 2,180 200 800 300 0 0 0 0

Quillayute Needles Complex

367 Unnamed rock NS NS NS NS NS 0 10 0 0 0 0

363 Table Rock 210 275 250 320 30 0 175 50 0 450 150

361 Huntington Island a 895 630 0 0 0 0 0 250 2,000 1,600 1,400

361A Cakesosta a 450 685 50 580 0 0 0 150 370 600 250

355-359 Unnamed rocks b NS NS NS NS NS 0 0 0 0 0 100

333 Gunsight Rock NS NS NS NS NS 0 0 50 50 0 0

332 Petrel Island 480 1,600 0 855 1,200 620 0 350 1,480 0 0

317 Cake Rock NS NS NS NS NS 0 0 0 0 0 0

Carroll–Jagged Complex

294 Unnamed rock NS NS NS NS NS 0 2 0 0 0 0

269 Carroll Pillar NS NS NS NS NS 0 0 0 0 0 0

262 Carroll Island a 0 0 0 0 0 0 0 0 0 0 0

258 Jagged Pillar 0 0 0 0 0 0 0 0 0 0 0

256 Jagged Island a 0 0 155 0 0 0 655 0 800 450 450

Other Locations

192 White Rock 120 0 0 630 0 0 0 0 55 0 0

140 Unnamed rock NS NS NS NS NS 0 0 125 0 0 0

Tatoosh Complex

35 Tatoosh Rock NS NS NS NS NS NS NS NS NS NS NS

23 Tatoosh Rock NS NS NS NS NS NS NS NS NS NS NS

22 Tatoosh Rock NS NS NS NS NS NS NS NS NS NS NS

21 Tatoosh Island a NS NS NS NS NS NS NS NS NS NS NS

a

 Breeding has been confirmed with observations of eggs or chicks.

b

 These locations lacked suitable breeding habitat.

Extended table legend: Colonies are ordered from south to north. Nonitalicized colonies were attended regularly and breeding

is expected. Italicized colonies indicate rocks with murre attendance in less than 4 years or no suitable breeding habitat. Codes: NS,

site not aerially surveyed by the U.S. Fish and Wildlife Service.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 121

Appendix G

Population data for common murre (Uria aalge californica) colonies in Washington, 1990–1995

(prepared by U. W. Wilson)

Table. Summary of the total numbers of murres counted from aerial photographic surveys conducted in Washington in 1990–1995 by the

U.S. Fish and Wildlife Service. See extended table legend at end of this appendix for format.

Year

Colony 1994 a 1995 b

number Colony name 1990 1991 1992 1993 6/16 7/5 6/19 6/25 7/13 7/27

Point Grenville Complex

586 Erin 125 25 75 45 230 175 110 0 110 55

585 Erin’s Bride 0 50 75 70 190 130 395 35 105 80

584 Unnamed rock 0 0 0 0 0 0 0 0 0 0

575 Grenville Arch c 850 25 50 15 25 85 0 0 0 0

570 Radio Stack 0 350 350 250 75 220 0 0 605 5

Split–Willoughby Complex

531 Split Rock c 0 150 0 0 15 0 0 0 170 70

529 Willoughby Rock c 15 75 0 0 0 0 0 0 35 0

Other Locations

480 Destruction Island d 250 650 350 0 0 0 0 0 0 215

458 Middle Rock 0 0 0 0 0 0 0 0 0 0

457 North Rock 0 0 0 0 0 0 0 0 0 0

426 Unnamed rock 0 0 0 0 0 0 0 0 0 0

419 Unnamed rock 0 0 0 0 0 0 0 0 0 0

409 Rounded Island 0 0 0 0 0 0 0 0 0 0

Quillayute Needles Complex

367 Unnamed rock 0 0 0 0 0 0 0 0 0 0

363 Table Rock 350 350 175 0 550 375 0 0 0 0

361 Huntington Island c 1,050 550 1,500 0 1,660 1,265 2,480 2,460 2,590 1,755

361A Cakesosta c 450 300 295 0 370 10 590 815 950 605

355-359 Unnamed rock d 360 250 150 0 150 15 280 225 205 140

333 Gunsight Rock 35 0 15 25 0 55 50 45 100 70

332 Petrel Island 0 0 0 5 40 15 0 50 80 75

317 Cake Rock 175 0 25 0 0 0 0 0 0 0

Carroll–Jagged Complex

294 Unnamed rock 0 0 0 0 0 0 0 0 0 0

269 Carroll Pillar 0 0 0 45 0 120 375 345 430 455

262 Carroll Island c 0 0 0 75 0 95 815 1,275 1,260 1,025

258 Jagged Pillar 0 25 0 0 0 0 0 0 0 0

256 Jagged Island c 250 500 250 0 0 125 0 0 0 0

Other Locations

192 White Rock 450 175 175 0 350 110 110 5 0 85

140 Unnamed rock 0 0 0 0 0 0 0 0 0 0

Tatoosh Complex

35 Tatoosh Rock NS NS NS NS NS 0 165 190 190 200

23 Tatoosh Rock NS NS NS NS 490 360 660 0 355 925

22 Tatoosh Rock NS NS NS NS 0 130 110 70 60 60

21 Tatoosh Island c NS NS NS NS 585 260 550 220 285 520

a

 In 1994, two surveys were conducted on 16 June and 5 July.

b

 In 1995, four surveys were conducted on 19 and 25 June and 13 and 27 July.

c

 Breeding has been confirmed with observations of eggs or chicks.

d

 These locations lacked suitable breeding habitat.

Extended table legend: Colonies are ordered from south to north. Nonitalicized colonies were attended regularly and breeding

is expected. Italicized colonies indicate rocks with murre attendance in fewer than 4 years or no suitable breeding habitat. Codes:

NS, site not aerially surveyed by the U.S. Fish and Wildlife Service.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 123

Appendix H

Summary of regression analyses

(prepared by J. L. Yee and H. R. Carter)

We conducted the following three types of

regression analysis: (1) Simple linear regression to

demonstrate major trends in the log-transformed annual

sums of whole-colony counts for populations of

common murres in central California, northern

California, Oregon, southern Washington, northern

Washington, and Washington (referred to as “Sum

Regressions”); (2) Poisson Regression to demonstrate

major trends in annual sums of whole-colony counts for

colony complexes in central California and

Washington; and (3) Averaged Poisson Regressions for

colony complexes over a certain period within central

California to derive “Route Regressions” for comparison

with Sum Regressions over the same period (Geissler

and Sauer 1990; Link and Sauer 1994). For either

regression method (Sum Regression or Route

Regression), trends can be fit with Poisson Regression

directly on counts or simple linear regression on logtransformed counts. Both approaches fit a linear relation

between time and population size on a log-scale,

allowing percent per annum change to be derived from

the exponent of the slope of log(N). Further, the logtransformation helps the data to better meet the constant

variance assumption of simple linear regression

(Rawlings 1988; Neter et al. 1990). Both approaches

provide consistent results when counts are large.

However, they differ in assumptions regarding the

distribution of errors in the model and there are problems

in the simple regression approach when counts are too

close to zero. We chose to use simple linear regression

on the log-scale for the Sum Regression method since it

is a more accessible approach and the data sums involved

were large enough to make the two approaches

comparable. The Poisson Regression was selected for

the Route Regression method because some individual

colony complex counts reached zero. To examine

possible violation of independence in using a series of

years of available data for regression analyses, we

performed Durbin–Watson tests (Durbin and Watson

1950, 1951) but did not find evidence of autocorrelation.

All regressions were performed using SAS 7 (SAS 1997),

and graphs were prepared using Microsoft Excel 97.

With regard to the practical application of linear

regression techniques, we have not assumed that true

linearity exists in the data examined since different

results can be obtained by merely considering slightly

different samples of years. A wider class of models able

to reflect nonlinear relations between population size

and time would produce better fitting models but, for

our objective, this exercise probably would produce

needlessly complex models. We instead used the

approach that reasonable line approximations to

nonlinear functions can be taken over subset ranges of

data. To standardize the use of regression analyses in

this chapter, we conducted regressions over three time

periods (1) data throughout the 1979–95 period that

used all years of standardized whole-colony count data

when all colonies were surveyed; (2) a subset of

population data confined roughly to the first half of

this period (i.e., between 1979 and 1989) with a

consistent trend of decrease, increase, or no change

during this period; and (3) a subset of population data

confined roughly to the second half of this period (i.e.,

between 1984 and 1995) with a consistent trend of

decrease, increase, or no change. Subsets were based on

trends evident from inspection of sums of whole-colony

counts. For Poisson and Route Regressions of colony

complexes, the same range of years of data was applied

(as for Sum Regressions of the larger population), but

additional years of data for colony complexes were

included if available. All regressions were presented in

tables.

To perform Sum Regressions, we collated

population sums for each geographic area from available

data in Appendixes C, D, E, F, and G. Population sums

are summarized in Table H-1, including sums for (1) all

colonies in central California between 1980 and 1995;

(2) all colonies, except Castle Rock, in northern

California between 1979 and 1989; (3) 15 sample

colonies in Oregon between 1988 and 1995; (4) all

colonies in southern Washington between 1979 and

1995; (5) all colonies, except Tatoosh Island and

associated rocks, in northern Washington in 1979–95;

and (6) all colonies, except Tatoosh Island and

associated rocks, in Washington between 1979 and 1995.

The regressions were conducted by examining the

relation of N on year where N is the sum of wholecolony counts for all colonies (or all sample colonies)

in a geographic area. To describe Sum Regressions for

three time periods, we presented in Table H-2 (1) the

slope of ln(N) with standard error and 95% confidence

limits; (2) the percent per annum change, with 95%
124 USGS/BRD/ITR–2000-0012

confidence limits; (3) the r

2

 value; and (4) the p-value

for testing whether the slope was statistically different

from zero. In Figures 2.4, 2.10, and 2.12, Sum Regression

lines are indicated for trends that were statistically

different from zero at the 0.05 significance level.

To perform Poisson Regressions, we summed

available data from individual colonies within colony

complexes in central California and Washington from

Appendixes C, D, F, and G (Tables H-3 and H-4). The

regressions were conducted by examining the relation

of N on year where N is the sum of whole-colony counts

for all colonies in a colony complex, and using the

deviance to adjust the standard errors for overdispersion

(McCullagh and Nelder 1989; SAS 1997). We described

Poisson Regressions for three time periods by presenting

in Tables H-5 and H-6: (1) the slope of ln(N) for each

colony complex with standard error and 95% Bonferroni

simultaneous confidence limits; (2) the percent per

annum change for each colony complex, with 95%

Bonferroni simultaneous confidence limits; (3) the

Bonferroni-adjusted p-values for testing whether the

slopes were significantly different from zero (Westfall

and Young 1993); and (4) results of testing for

differences between trends for different colony

complexes. In Figures 2.3 and 2.11, Poisson Regression

lines are indicated at colony complexes with trends that

were statistically different from zero at the 0.05

significance level under Bonferroni adjustments for

simultaneous inference across colony complexes in

central California and Washington.

We performed Route Regressions by taking the

averages of percent per annum changes from Poisson

Regressions for colony complexes within geographic

areas (weighted by population size and survey effort).

Standard errors were obtained by bootstrap (Efron and

Tibshirani 1993). Both Sum Regression and Route

Regression methods aim to estimate trends for

geographic areas. However, Route Regression better

accounts for between-site variation in trends when study

sites are randomly sampled, thus often producing a more

reliable test and confidence interval for trend, but does

not produce an estimate of intercept. In Table H-7, we

compared trends depicted with Sum Regressions and

Route Regressions in central California, which helped

to assess the general consistency of the Sum Regression

methods used to derive population trends for central

California.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 125 Table H-2. Trends in sums of whole-colony counts of common murres (Uria aalge californica) for California, Oregon and Washington, 1979–1995, using Sum Regressions (see Table H-1).

b = Slope of ln (N) Percent per annum = e

b - 100%

Time 95% CI

Ho: b = 0 95% CI

Geographic area period r

2 Estimate SE Lower Upper p-value Estimate Lower Upper

Central California 1979–95 0.154 -0.024 0.019 -0.066 0.018 0.232 -2.4 -6.4 1.9

1979–89 0.883 -0.104 0.017 -0.147 -0.060 0.002 -9.9 -13.7 -5.81985–95 0.829 0.057 0.011 0.031 0.083 0.002 5.9 3.2 8.7

Northern California 1979–89 0.472 0.022 0.017 -0.050 0.095 0.313 2.3 -4.9 9.9Oregon 1988–95 0.099 -0.038 0.046 -0.151 0.076 0.447 -3.7 -14.0 7.9Southern Washington 1979–95 0.710 -0.295 0.049 -0.399 -0.191 <0.001 -25.5 -32.9 -17.4

1979–86 0.743 -0.575 0.138 -0.913 -0.238 0.006 -43.7 -59.9 -21.11984–95 0.371 -0.202 0.083 -0.386 -0.017 0.035 -18.3 -32.0 -1.7

Northern Washington 1979–95 0.050 -0.038 0.043 -0.130 0.054 0.390 -3.7 -12.2 5.5

1979–86 0.295 -0.143 0.090 -0.363 0.078 0.165 -13.3 -30.4 8.11984–95 0.011 -0.026 0.081 -0.207 0.154 0.751 -2.6 -18.7 16.7

Washington 1979–95 0.468 -0.142 0.039 -0.226 -0.059 0.002 -13.3 -20.2 -5.7

1979–86 0.745 -0.400 0.095 -0.633 -0.166 0.006 -32.9 -46.9 -15.31984–95 0.049 -0.043 0.059 -0.174 0.089 0.487 -4.2 -16.0 9.3

Table H-1. Summary of population sums of whole-colony counts of common murres (Uria aalge californica) in California, Oregon, and Washington, 1979–1995, used for Sum Regressions (see AppendixesC, D, E, F, and G).

a

Year

Geographic area 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995Central California b ID 116,156 109,206 134,109 ND ND ID 57,824 59,335 56,624 53,985 75,449 ND ND 78,062 88,875 90,685Northern California c 66,472 84,642 ID 88,962 ND ND ND ID ND ND 92,080 ND ND ND ID ID IDOregon 

d ND ND ND ND ND ND ND ND ND 55,108 60,585 62,317 56,730 50,552 25,202 53,439 57,474

Southern Washington

e 27,235 15,610 17,050 24,375 1,760 1,050 450 1,655 5,950 790 1,325 990 675 550 380 610 35

Northern Washington

f 4,285 6,625 1,305 4,565 1,430 1,420 2,942 1,575 4,775 3,400 2,600 3,370 2,800 2,935 150 2,185 5,220

Washington 

f 31,520 22,235 18,355 28,940 3,190 2,470 3,392 3,230 10,725 4,190 3,925 4,360 3,475 3,485 530 2,795 5,255

a Codes: ND, no data available; ID, incomplete data.b Sums for central California included all colonies, plus small numbers of nonbreeding birds at Devil’s Slide Rock in 1986–94 (see Appendixes C and D).c Sums for northern California included all colonies, except Castle Rock (see Appendixes C and D).d Sums for Oregon included 15 sample colonies (see Appendix E).e Sums for southern Washington included all colonies and other locations (see Appendixes F and G).f Sums for northern Washington and Washington include all colonies and other locations, except Tatoosh Island and associated rocks (see Appendixes F and G).
126 USGS/BRD/IT

R–2000-0012

Table H-4. Summary of whole-colony count sums for colonies and colony complexes of common murres (Uria aalge californica) in Washington, 1979–1995, used in all regressions. Codes: ND, nodata collected.

Year

Colony or Complex a 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995Northern Washington

Tatoosh b ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 750 480Carroll–Jagged 0 0 155 0 0 0 657 125 800 450 450 250 525 250 120 340 1,620Quillayute Needles 2,035 3,190 300 1,755 1,230 620 185 850 3,900 2,650 1,900 2,420 1,450 2,160 30 1,735 3,595Other c 2,250 3,435 850 2,810 200 800 2,100 600 75 300 250 700 825 525 0 110 5Sum Regression Total d 4,285 6,625 1,305 4,565 1,430 1,420 2,942 1,575 4,775 3,400 2,600 3,370 2,800 2,935 150 2,185 5,220

Southern Washington

Willoughby–Split 14,450 6,190 12,150 15,720 850 0 100 40 450 85 275 15 225 0 0 0 0Point Grenville 12,785 9,420 4,900 8,655 910 1,050 350 1,615 5,500 705 1,050 975 450 550 380 610 35Sum Regression Total 27,235 15,610 17,050 24,375 1,760 1,050 450 1,655 5,950 790 1,325 990 675 550 380 610 35

Washington

(Sum Regression total d) 31,520 22,235 18,355 28,940 3,190 2,470 3,392 3,230 10,725 4,190 3,925 4,360 3,475 3,485 530 2,795 5,255

a Colonies and complexes are defined in Appendixes F and G.b For the Tatoosh complex, standardized U.S. Fish and Wildlife Service aerial survey data were not available prior to 1994 (Appendixes F and G). This colony complex was not analyzedby regression.c Includes murres attending Destruction Island, Middle Rock, North Rock, Colony No. 426, Colony No. 419, Rounded Island, White Rock, and Colony No. 140.d Northern Washington and Washington totals excluded the Tatoosh complex.

Table H-3. Summary of whole-colony count sums for colony complexes of common murres (Uria aalge californica) in central California, 1979–1995, used for all regressions. Codes:ND, no data available; NC, all or a portion of available data are not comparable; ID, incomplete data.

Year

Colony Complex a 1979 1980 1981 1982 1985 1986 1987 1988 1989 1990 1993 1994 1995Point Reyes 11,095 13,423 16,474 26,337 9,242b 9,360 12,046 10,955 9,501 11,807 15,380 15,381 17,811Points Resistance– Double 6,960b 13,353 9,541 11,697b 5,633b 3,755b 4,713 5,899 4,897 6,833 7,069 7,954 7,604North Farallon ND 31,428 29,100 30,914 18,597 12,780 16,505 13,398 15,428 14,621 19,428 23,332 23,069South Farallon ND 52,527 49,975 61,510 31,738 31,101 24,679 25,325 23,066 40,926 34,724 40,268 40,385Devil’s Slide 1,400 1,750 1,418b 1,530 ND 93 128 0 0 1 0 5 0Castle–Hurricane c NC 3,675 2,698b 2,121 ND ID(735) 1,264 1,047 1,093 1,261 1,461 1,935 1,816Sum Regression Total d NC/ID 116,156 109,206 134,109 ID 57,824 59,335 56,624 53,985 75,449 78,062 88,875 90,685a Complexes are defined in Appendixes C and D. The Devil’s Slide complex includes one active colony at Devil’s Slide Rock and Mainland and one extirpated colony

at San Pedro Rock.

b Although data were incomplete (Appendix C), the whole-complex counts are accepted as reasonably complete.c ID count in 1986 was excluded from Poisson regressions for this complex.d In 1986, the Castle–Hurricane ID count was included in the sum regression total which was treated as reasonably complete.
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 127

Table H-5. Trends in sums of whole-colony counts of common murres (Uria aalge californica) for six colony complexes in central California, 1979–1995, using Poisson Regressions (seeTable H-3). Slope estimates were used in Route Regressions (see Table H-7).

b = Slope of ln(N) Percent per annum = e

b - 100%

95% CI b Ho = 0 95% CI 

b

 Time period Colony complex 

a Estimate SE Lower Upper p-value 

b Estimate (%) Lower (%) Upper (%)

1979–95 Point Reyes 

c -0.001 0.018 -0.050 0.047 1.000 -0.1 -4.8 4.8

South Farallon Islands 

c -0.028 0.018 -0.075 0.019 0.704 -2.7 -7.2 1.9

Points Resistance–Double c -0.028 0.019 -0.078 0.022 0.840 -2.8 -7.5 2.2North Farallon Islands 

c -0.030 0.018 -0.078 0.018 0.595 -3.0 -7.5 1.8

Castle–Hurricane 

c -0.051 0.021 -0.107 0.005 0.097 -5.0 -10.2 0.5

Devil’s Slide 

d -0.358 0.064 -0.527 -0.190 <0.001 -30.1 -40.9 -17.3

1979–89 Point Reyes c -0.048 0.035 -0.140 0.044 1.000 -4.7 -13.1 4.5

Points Resistance–Double c -0.091 0.031 -0.172 -0.009 0.020 -8.7 -15.8 -0.9North Farallon Islands, c -0.105 0.017 -0.149 -0.061 <0.001 -9.9 -13.8 -5.9South Farallon Islands 

c -0.108 0.017 -0.153 -0.062 <0.001 -10.2 -14.2 -6.0

Castle–Hurricane c -0.136 0.016 -0.179 -0.093 <0.001 -12.7 -16.4 -8.9Devil’s Slide c -0.333 0.085 -0.557 -0.109 <0.001 -28.3 -42.7 -10.3

1985–95 Castle–Hurricane 

c 0.069 0.015 0.028 0.110 <0.001 7.2 2.9 11.6

Point Reyes 

c 0.063 0.009 0.038 0.088 <0.001 6.5 3.9 9.2

Points Resistance–Double c 0.055 0.014 0.019 0.091 <0.001 5.7 1.9 9.5North Farallon Islands 

c 0.045 0.015 0.005 0.086 0.020 4.6 0.5 9.0

South Farallon Islands 

c 0.039 0.017 -0.007 0.085 0.148 4.0 -0.7 8.9

Devil’s Slide 

c -0.790 0.331 -1.664 0.084 0.103 -54.6 -81.1 8.8

a Within each time period, complexes are ordered from most positive trend to most negative trend.b Bonferroni 95% confidence intervals and Bonferroni-adjusted 

p-values for simultaneous inference on six colony complexes within the same time period.

c, d Complexes with the same superscript letter within a time period do not have statistically different trends from each other (Bonferroni multiple comparison test, 

α = 0.05).
128 USGS/BRD/IT

R–2000-0012

Table H-6. Trends in sums of whole-colony counts of common murres (Uria aalge californica) for four colony complexes in Washington, 1979–1995, using Poisson Regressions (see Table H-4).

b = Slope of ln(N) Percent per annum = eb - 100%

95% CI b H

o

: b = 0 95% CI b

Time period Colony complex a Estimate SE Lower Upper p-value b Estimate (%) Lower (%) Upper (%)1979–95 Carroll / Jagged c 0.154 0.054 0.018 0.290 0.019 16.7 1.8 33.7

Quillayute Needles c 0.020 0.036 -0.070 0.110 1.000 2.0 -6.8 11.6Point Grenville d -0.245 0.045 -0.358 -0.132 <0.001 -21.7 -30.1 -12.3Willoughby / Split d -0.436 0.092 -0.666 -0.207 <0.001 -35.4 -48.6 -18.7

1979–86 Carroll / Jagged c 0.452 0.309 -0.321 1.225 0.576 57.2 -27.4 240.4

Quillayute Needles c -0.226 0.108 -0.495 0.043 0.144 -20.2 -39.1 4.4Point Grenville c -0.398 0.098 -0.643 -0.153 <0.001 -32.8 -47.4 -14.2Willoughby / Split c -0.412 0.179 -0.859 0.036 0.086 -33.7 -57.6 3.6

1984–95 Carroll / Jagged c 0.094 0.073 -0.090 0.277 0.809 9.8 -8.6 31.9

Quillayute Needles c 0.057 0.065 -0.104 0.219 1.000 5.9 -9.9 24.4Willoughby / Split c -0.119 0.123 -0.427 0.188 1.000 -11.2 -34.7 20.7Point Grenville c -0.143 0.088 -0.362 0.077 0.418 -13.3 -30.4 8.0

a Within each time period, complexes are ordered from most positive trend to most negative trend.b Bonferroni 95% confidence intervals and Bonferroni-adjusted p-values for simultaneous inference on four colony complexes within the same time period.c, d Complexes with the same superscript letter in the same time period do not have statistically different trends from each other (Bonferroni multiple comparison test, “ = 0.05).Table H-7. Comparison of trends in whole-colony counts of common murres (Uria aalge californica) in central California from 1979 to 1995, using Sum and Route Regressions.

b = Slope of ln(N) Percent per annum = eb - 100%

Regression Time 95% CI 95% CImethod period Estimate SE z-stat p-value Lower Upper Estimate (%) SE (%) z-stat p-value Lower (%) Upper (%)

Sum 1979–95 -0.024 0.019 -1.3 0.232 -0.066 0.018 -2.4 -6.4 1.9Route 1979–95 -0.026 -0.042 -0.009 -2.5 0.8 -3.1 0.002 -4.1 -0.9Sum 1979–89 -0.104 0.017 -6.1 0.002 -0.147 -0.060 -9.9 -13.7 -5.8Route 1979–89 -0.096 -0.123 -0.069 -9.1 1.2 -7.3 <0.001 -11.6 -6.7Sum 1985–95 0.057 0.011 5.4 0.002 0.031 0.083 5.9 3.2 8.7Route 1985–95 0.047 0.036 0.057 4.8 0.6 8.2 <0.001 3.6 5.9
BIOLOGY AND CONSERVATION OF THE COMMON MURRE 129

Figure I-1. Prince Island (north cliffs), southern

California, 15 June 1991, photo number 91-

GJM-4-8 (photo by H. R. Carter).

Figure I-2. Hurricane Point Rocks, central

California, 2 June 1995, photo number 95-MP-8-

24 (photo by J. E. Takekawa).

Figure I-3. Castle Rocks & Mainland, central

California, 8 June 1994, photo number 94-MP6-14 (photo by J. E. Takekawa).

Figure I-4. Devil’s Slide Rock & Mainland, central

California, 30 June 1979, photo number 29 (photo

by J. W. Nelson).

Figure I-5. South Farallon Islands (east side),

central California, 27 May 1993, photo number 93-

JDG-2-30 (photo by J. E. Takekawa).

Figure I-6. South Farallon Islands (Southeast

Farallon Island and Islets), central California, 2 June

1995, photo number 95-MP-4-22 (photo by J. E.

Takekawa).

Figure I-7. South Farallon Islands (West End

Island), central California, 2 June 1995, photo

number 95-MP-5-28 (photo by J. E. Takekawa).

Figure I-8. South Farallon Islands (Shubrick Point),

central California, 27 May 1993, photo number 93-

JDG-2-25 (photo by J. E. Takekawa).

Figure I-9. North Farallon Islands, central

California, 2 June 1995, photo number 95-MP-6B11 (photo by J. E. Takekawa).

Figure I-10. Point Resistance, central California,

23 May 1989, photo number 89-LA-18-12 (photo

by L. Accurso).

Figure I-11. Point Reyes (Lighthouse Rock), central

California, 20 June 1995, photo number 95-CRT01 (photo by H. R. Carter).

Figure I-12. Cape Vizcaino, northern California, 5

June 1995, photo number 95-RAM-2-4 (photo by

H. R. Carter).

Appendix I

Overview aerial photographs of selected breeding colonies of common murres (Uria aalge californica) in

California, Oregon, Washington, and British Columbia

(prepared by H. R. Carter, J. E. Takekawa, R. W. Lowe, U. W. Wilson, and M. S. Rodney
Figure I-13. Steamboat Rock, northern California,

7 June 1995, photo number 95-RAM-9-33 (photo

by J. E. Takekawa).

Figure I-14. False Cape Rocks, northern California,

7 June 1995, photo number 95-RAM-9-20 (photo

by J. E. Takekawa).

Figure I-15. Flatiron Rock, northern California, 14

June 1994, photo number 94-T-7-12 (photo by J. E.

Takekawa).

Figure I-16. Green Rock, northern California, 14

June 1994, photo number 94-T-7-28 (photo by J. E.

Takekawa).

Figure I-17. White Rock, northern California, 30

May 1989, photo number 89-EN-7-2 (photo by E.

Nelson).

Figure I-18. Redding Rock, northern California, 6

June 1995, photo number 95-RAM-5-5 (photo by

J. E. Takekawa).

Figure I-19. False Klamath Rock, northern

California, 6 June 1995, photo number 95-RAM-5-

29 (photo by J. E. Takekawa).

Figure I-20. Castle Rock, northern California, 30

May 1989, photo number 89-HRC-2-19 (photo by

H. R. Carter).

Figure I-21. Unnamed Rock (Colony number 270-

110), southern Oregon, 8 June 1995 (photo by R. W.

Lowe).

Figure I-22. Mack Arch (Colony number 270-087),

southern Oregon, 29 June 1979 (photo by R. L.

Pitman).

Figure I-23. Mack Arch (Colony number 270-087),

southern Oregon, June 1996 (photo by D. S. Pitkin).

Figure I-24. Hubbard Mound Rock (Colony number

270-063), southern Oregon, June 1996 (photo by D.

S. Pitkin).

130 USGS/BRD/ITR–2000-0012
Figure I-25. Gull Rock (Colony number 270-027),

southern Oregon, June 1997 (photo by D. S. Pitkin).

Figure I-26. Flat Top Rock (Colony number 243-

017), northern Oregon, 9 June 1997 (photo by R. W.

Lowe).

Figure I-27. Yaquina Head area (Colony Rock,

Colony number 243-015, in background; Colony

number 243-017, in foreground), northern Oregon,

10 June 1994 (photo by D. S. Pitkin).

Figure I-28. Three Arch Rocks (Colony Nos. 219-

055 to 219-057), northern Oregon, 19 June 1997

(photo by R. W. Lowe).

Figure I-29. Shag Rock at Three Arch Rocks

(Colony number 219-056), northern Oregon, 22

June 1979 (photo by R. L. Pitman).

Figure I-30. Bird Rocks (Colony Nos. 219-017 to

219-019), northern Oregon, 22 June 1979 (photo

by R. L. Pitman).

Figure I-31. Tillamook Rock (Colony number 219-

005), northern Oregon, 7 June 1995 (photo by D. S.

Pitkin).

Figure I-32. Sea Lion Rock (Colony 219-013),

northern Oregon, June 1996 (photo by D. S. Pitkin).

Figure I-33. Point Grenville, southern Washington,

13 July 1999 (photo by U. W. Wilson).

Figure I-34. Willoughby and Split rocks, southern

Washington, 13 July 1999 (photo by U. W. Wilson).

Figure I-35. Quillayute Needles, northern

Washington, 13 July 1999 (photo by U. W. Wilson).

BIOLOGY AND CONSERVATION OF THE COMMON MURRE 131
Figure I-36. Petrel Island and Gunsight Rock,

northern Washington, 13 July 1999 (photo by U. W.

Wilson).

Figure I-37. Jagged and Carroll islands, northern

Washington, 13 July 1999 (photo by U. W. Wilson).

Figure I-38. Tatoosh Island, northern Washington,

27 July 1999 (photo by U. W. Wilson).

Figure I-39. Cleland Island (adult murre with chick),

British Columbia, 20 August 1969 (photo by R. W.

Campbell).

Figure I-40. Triangle Island (view from Puffin Rock),

British Columbia, 16 July 1985 (photo by M. S.

Rodway).

Figure I-41. Triangle Island (Puffin Rock), British

Columbia, 16 July 1985 (photo by M. S. Rodway).

Figure I-42. Triangle Island, British Columbia, June

1949 (photo by G. C. Carl and C. J. Guiguet).

Figure I-43. Sartine Island, British Columbia,

August 1987 (photo by M. S. Rodway).

Figure I-44. Kerouard Islands, British Columbia,

10 June 1986 (photo by M. S. Rodway).
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Leslie E. Holland-Bartels

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Jerry D. Cox and Deborah K. Harris

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