Suggested Citation: Capitolo, P. J., G. J. McChesney, H. R. Carter, M. W. Parker, J. N. Hall, R. J. Young, and R. T. Golightly. 2006. Whole-colony counts of Common Murres, Brandt’s Cormorants and Double- crested Cormorants at sample colonies in northern and central California, 1996-2004. Unpublished report, Department of Wildlife, Humboldt State University, Arcata, California; and U.S. Fish and Wildlife Service, San Francisco Bay National Wildlife Refuge Complex, Newark, California. 40 pp.

Data May Not be Cited Without Written Permission from G. J. McChesney.

ii TABLE OF CONTENTS

LIST OF FIGURES ...... iv LIST OF TABLES...... iv EXECUTIVE SUMMARY ...... 1 INTRODUCTION ...... 3 METHODS ...... 4 Regions and Murre Colony Complexes...... 4 Colonies and Years Counted...... 5 Aerial Surveys...... 8 Photograph Counting ...... 8 Incomplete Coverage/Estimating Numbers from Overviews...... 8 RESULTS ...... 9 Northern California...... 9 Castle Complex ...... 9 False Klamath Complex...... 14 Redding Complex...... 15 Trinidad Complex ...... 15 Cape Mendocino Complex...... 16 Vizcaino Complex ...... 16 Newport-Kibesillah Complex...... 17 Goat Complex ...... 17 Casket-White Complex...... 18 Irregular Attendance of Other Colonies...... 19 Central California...... 19 Point Reyes Complex ...... 19 Points Resistance-Double Complex (Drake’s Bay) ...... 19 North Farallon Complex...... 20 South Farallon Complex...... 20 Devil’s Slide Complex...... 20 Castle-Hurricane Complex ...... 20 Brandt’s Cormorant Sample Colonies...... 21 DISCUSSION...... 22 Common Murre...... 22 Brandt’s Cormorant ...... 25 Double-crested Cormorant...... 26 ACKNOWLEDGMENTS ...... 27 LITERATURE CITED ...... 27 Appendix 1...... 33 Appendix 2...... 40

iii LIST OF FIGURES

Figure 1. Seabird colonies in northern California Common Murre colony complexes counted for 1996-2004...... 6

Figure 2. Common Murre colony complexes and sample Brandt’s Cormorant colonies in central California, 1996-2004...... 7

Figure 3. Common Murre count subareas used at Castle Rock National Wildlife Refuge, 1989-2004 ...... 13

Figure 4. Total numbers of Common Murres counted at all colonies in Mendocino County, California, 1989-2004. Data for 1993-1995 do not include Rockport Rocks. ND = no data...... 24

Figure 5. Total numbers of Brandt’s Cormorant nests counted at sample colonies in northern California, 1989-2004 (see Table 2 for list of colonies). ND = no data; ID = incomplete data ...... 26

LIST OF TABLES

Table 1. Raw whole-colony counts of Common Murres in northern California, 1996-2004 (updated from Capitolo et al. 2004a). Counts are also provided for 1989 (Carter et al. 1992) for comparison. Colony names in bold are sample colonies. Colony names in italics refer to locations without confirmed murre breeding in 1979-2004. NC = photographs not yet counted...... 10

Table 2. Whole-colony counts of Brandt’s Cormorant nests at sample and non-sample colonies in northern California, 1996-2004. Counts are also provided for 1989 (Carter et al. 1992) for comparison. Colony names in bold are sample colonies. NC = photographs not yet counted...... 11

Table 3. Subarea and whole-colony counts of Common Murres at Castle Rock National Wildlife Refuge, California, 1989-2004 (see Figure 3)...... 14

Table 4. Whole-colony counts of Common Murres in central California, 2002-2004. Colony names in italics refer to locations without confirmed murre breeding in 1979-2004 ...... 21

Table 5. Total numbers of Brandt’s Cormorant nests at sample colonies in central California, 2002-2004...... 22

Table 6. Numbers of Common Murre chicks noted from aerial photographs of colonies in northern California in 2001...... 25

iv EXECUTIVE SUMMARY

From 1996 to 2004, annual aerial photographic surveys of all northern and central California breeding colonies of Common Murres (Uria aalge), Brandt’s Cormorants (Phalacrocorax penicillatus), and Double-crested Cormorants (P. auritus) were conducted by the Common Murre Restoration Project (CMRP), in cooperation with the California Department of Fish and Game. These surveys have continued a long-term dataset (initiated in 1979) of whole- colony counts derived from aerial photographs; these counts have been used as indices of population size for estimation of breeding population size and for assessing long-term population trends.

In this report, we present a summary of whole-colony counts in northern California for 1996 to 2004 and in central California for 2002 to 2004, and briefly discuss population status and general trends evident for murres and cormorants during these periods. For northern California, we counted all murre breeding colonies for 1997, 1999, 2001, 2003 and 2004, and certain sample murre colonies for other years. For central California, we counted all murre breeding colonies and other sample Brandt’s Cormorant colonies for 2002 to 2004. Numbers of California Brown Pelicans (Pelecanus occidentalis californicus) roosting within murre and cormorant colonies also were counted to provide information on use of coastal rocks by this endangered species during the late May and early June survey period.

For Common Murres in northern California (defined as north of Point Reyes to the Oregon border; 38-42°N), a total of 211,421 birds were counted at 16 active colonies and one irregularly attended colony in 2004, corresponding to a rough estimate of 353,100 breeding individuals or 176,550 breeding pairs. The 2004 total count was 28% higher than the 2003 count, and total counts were similar in 1999, 2001, and 2003. Lower numbers in 1997 seemed to partly reflect reduced photograph quality. Less than 10% of the northern California murre population occurs in Mendocino County, but numbers there increased steadily since 1996 and two new colonies formed. No murre colonies occur in Sonoma and northern Marin counties. Overall, the murre population in northern California from 1996 to 2004 appeared to be slowly increasing and expanding farther south, continuing the trend noted in 1979-1995.

For Common Murres in central California (defined as Point Conception to Point Reyes; 34.5-38°N), a total of 161,572 birds were counted at 10 active colonies in 2004, corresponding to a rough estimate of 269,800 breeding individuals or 134,900 breeding pairs. The total count for nearshore colonies in 2004 was 14% higher than in 2002, following lower numbers in 2003. Total counts for offshore colonies at the North and South Farallon Islands were very similar from 2002 to 2004. Overall, the murre population in central California from 2002 to 2004 appeared stable, but had increased earlier.

For Brandt’s Cormorants in northern California, a total of 4,728 nests were counted at 13 active sample colonies in 2004. Sample colonies accounted for about 70% of the total number of nests in northern California in 1989 and 2003. The 2004 nest total for sample colonies was similar to the 1989 total despite reduced breeding populations in the late 1990s due to impacts from El Niño conditions in 1992-1993 and 1998. Sample colonies of Double-crested

1 Cormorants accounted for only 10% of the northern California nest total in 2003 and trends were not determined.

For Brandt’s Cormorants in central California, a total of 12,784 nests were counted at 13 active sample colonies in 2004. Sample colonies accounted for about 50% and 63% of central California nest totals in 1989 and 2003, respectively. The single sample Double-crested Cormorant colony accounted for only 13% of the central California nest total in 2003 and trends were not determined.

Additional statistical analyses and consideration of factors affecting different colonies are needed to better describe murre and cormorant population trends in northern and central California since 1996 with available count data. For complete assessment of Common Murre population trends in California, aerial photographs of certain northern California colonies from 1996, 1998, 2000, and 2002 would need to be counted. For complete assessment of population trends of Brandt’s and Double-crested Cormorants in northern and central California, aerial photographs of certain colonies from 1996 to 2002 and 2004 still need to be counted and analyzed.

2 INTRODUCTION

The Common Murre (Uria aalge) is the most abundant breeding seabird in northern and central California (Sowls et al. 1980, Carter et al. 1992, 2001) and one of the most abundant species found at sea (Briggs et al. 1987, Ford et al. 2004). In 1989-1991, the Brandt’s Cormorant (Phalacrocorax penicillatus) and the Double-crested Cormorant (P. auritus) were the second and ninth most abundant breeding seabird species in coastal California, respectively (Carter et al. 1992). Murres and Brandt’s Cormorants nest abundantly in the Gulf of the Farallones and Monterey Bay National Marine Sanctuaries and are important components of the at-sea fauna in this region, including the Cordell Bank National Marine Sanctuary. Double-crested Cormorants are less abundant and forage mainly in estuarine and nearshore waters in this region. Murres and Brandt’s Cormorants, and to a lesser degree Double-crested Cormorants, are good indicators of annual and long-term oceanographic changes (e.g., Ainley and Boekelheide 1990, Carter et al. 1995b, 2001, Nur and Sydeman 1999, Capitolo et al. 2004b, Nevins et al. 2005). Murres, and to a lesser degree Brandt’s and Double-crested Cormorants, are also susceptible to anthropogenic impacts such as oil spills and commercial fisheries interactions (e.g., Takekawa et al. 1990, Page et al. 1990, Carter et al. 2001, 2003a,b, Hampton et al. 2003, Roletto et al. 2003). As indicators of oceanographic variation and anthropogenic impacts, murres and cormorants have been focal species in several population and ecological studies, as well as restoration projects in California (e.g., Ainley and Boekelheide 1990, Parker et al. 1997, Carter et al. 2003a).

Since 1996, the Common Murre Restoration Project (CMRP), in collaboration with the California Department of Fish and Game (CDFG), has continued annual aerial photographic surveys throughout coastal northern (38-42°N) and central (34.5-38°N) California to obtain whole-colony counts of Common Murres, Brandt’s Cormorants, and Double-crested Cormorants (e.g., Parker et al. 1997, McChesney et al. 2005). From 1979 to 1995, these surveys were conducted by U.S. Fish and Wildlife Service (USFWS), Humboldt State University, and University of California (summarized in Carter et al. 2001). These earlier surveys demonstrated dramatic declines of Common Murres at all central California colonies during the 1980s, including the extirpation of the Devil’s Slide Rock colony, due largely to mortality from gill net fishing and oil spills (Takekawa et al. 1990, Carter et al. 2001, 2003a). Most colonies had partially recovered by 1995, although the Devil’s Slide Rock colony remained without breeding murres and little recovery had occurred at the Castle Rocks and Mainland and Hurricane Point Rocks colonies (Carter et al. 2001). At northern California colonies, murre numbers were relatively stable during the 1980s but with some increases from 1979 to 1995 (Takekawa et al. 1990, Carter et al. 2001). New colonies discovered in Mendocino County in the 1989-1995 period indicated an expanding population in that area (Carter et al. 2001).

Counts of seabirds from annual aerial photographic surveys in northern and central California since 1996 had been limited almost entirely to central California murre colonies. These counts have provided critical information related to assessing: a) the efficacy of social attraction projects for murres at Devil's Slide Rock and San Pedro Rock; b) the status and recovery of central California murre colonies; c) continued impacts of mortality in gill nets and oil spills (e.g., Drake’s Bay colonies; Carter et al. 2003b); and d) large-scale population changes over time. However, comparisons to trends of the northern California population were important in previous assessments of large-scale murre population trends at central California colonies.

3 Both regions are subject to similar oceanographic conditions, but less oil pollution and no gill net fishing has occurred in northern California. Such comparisons were critical in demonstrating that mortality from anthropogenic sources, rather than effects from the severe 1983 El Niño or other cyclic environmental changes, was the primary reason for population decline of murres in central California in the 1980s (Takekawa et al. 1990, Carter et al. 2001).

Thus, to help interpret recent population trends of the central California murre population, the CMRP recently counted aerial photographs of sample northern California murre colonies for 1996 to 2002 and of all northern California murre colonies (i.e., sample and non- sample) for 2003 (Capitolo et al. 2004a). Sample colonies had been previously selected as part of the development of an annual monitoring program for California during the 1993-1995 period because available funding did not allow counting of all colonies for each year (Carter et al. 1996). Additional sample murre colonies (i.e., Castle Rock, Redding Rock, Rock R, Sister Rocks, Rockport Rocks, Casket Rock, and White Rock) were selected for the 1996-2003 period to better ensure that the sample was representative of the northern California murre population (Capitolo et al. 2004a). Other sample cormorant colonies defined by Carter et al. (1996) were not included in our recent counting efforts.

In this report, we summarize the latest counting effort of aerial photographs of murre colonies in northern California, which included non-sample colonies for 1997, 1999, 2001, and all colonies (i.e., sample and non-sample) for 2004. Combined with the previous counting effort described above, the CMRP aimed to estimate a complete northern California breeding population size for Common Murres in 1997, 1999, 2001, 2003, and 2004. This amount and spacing of count data were considered sufficient for determining murre population trends in northern California for comparison to central California trends from 1996 to 2004. Whole- colony counts of Common Murres, Brandt’s Cormorants, and Double-crested Cormorants at these colonies in 1996-2004 are provided, and we make brief comparisons with earlier data. Counts of roosting Brown Pelicans (Pelecanus occidentalis) are also provided for northern California, though pelicans also roost at additional locations other than murre or cormorant colonies. We also provide data from 2002 to 2004 for all central California murre colonies and sample cormorant colonies and describe recent trends at these colonies.

METHODS

Regions and Murre Colony Complexes

We defined northern California as the region from the Oregon border to (but not including) Point Reyes (42-38°N), encompassing Del Norte, Humboldt, Mendocino, Sonoma and northern Marin Counties (after Carter et al. 1992, 2001). Eight murre colony complexes (i.e., single colonies > 5 km from nearest colonies or groups of colonies within 5 km of each other) have been previously described in this region. No murre colony complexes have been previously documented in Sonoma or northern Marin counties (Carter et al. 2001; Figure 1).

We defined central California as the region from Point Reyes to (and including) Point Conception (38-34.5°N), encompassing southern Marin, San Francisco, San Mateo, Santa Cruz,

4 Monterey, San Luis Obispo, and northern Santa Barbara Counties, as well as other counties in the San Francisco Bay area (after Carter et al. 1992, 2001). Six murre colony complexes have been previously described in this region (Carter et al. 2001; Figure 2). Murres currently do not breed south of Monterey County, but a colony previously documented until 1912 at Prince Island off San Miguel Island in Santa Barbara County has been recently attended by small numbers of non-breeding murres (Carter et al. 2001).

Colonies and Years Counted

For this report, we counted aerial photographs from 1997, 1999, and 2001 for “non- sample” northern California murre colonies (i.e., False Klamath, White [Humboldt County], Green, Blank, Pilot, and Steamboat Rocks). For 2004, aerial photographs of all “sample” and non-sample murre colonies were counted (Figure 1, Table 1). Also for 2004, aerial photographs of other seabird colonies where irregular murre attendance had been noted were inspected but not counted, including Prince Island, Unnamed Small Rocks, White Rock, and High Bluff South in Del Norte County, Sea Lion Rock in Humboldt County, and Gualala Point Island in Sonoma County. Sugarloaf Island was previously counted in all years from 1996 to 2004 as part of a separate study (Capitolo et al., in prep.). Previously counted and archived aerial photographs of northern California colonies from 1989 and 1993-1995 were also inspected by PJC for comparisons to 1996-2004 data.

Counting effort was focused on murre colonies; Brandt’s Cormorants, Double-crested Cormorants and roosting Brown Pelicans also were counted where they co-occurred with murres. A substantial portion of Brandt’s Cormorant colonies in northern California co-occur with murre colonies. However, only a small portion of Double-crested Cormorant colonies co-occur with murre colonies.

For central California, aerial photographs of all Common Murre colonies and sample Brandt's Cormorant colonies in the Gulf of the Farallones region (Figure 2) were counted separately for 1996 to 2004. Data are provided here for 2002 to 2004. Most Brandt’s Cormorant colonies in the Gulf of the Farallones between Point Reyes and Año Nuevo Island were counted. Small numbers of Brandt’s Cormorants are known to nest among Pelagic Cormorants (P. pelagicus) at cliff colonies on the San Mateo County coast (Carter et al. 1992) that are not annually photographed. Many other Brandt’s Cormorant colonies that occur south of Año Nuevo Island in central California were not counted. Only one Double-crested Cormorant colony co-occurs with a murre colony (South Farallon Islands) and represents a small percentage of Double-crested Cormorants nesting in central California; most colonies occur in San Francisco and San Pablo Bays (Carter et al. 1995a).

5 125° 124° 123° 42° 42° DEL NORTE

Castle Complex Castle Rock Y# Rock R/Sister Roc ks Y# False Klamath Complex False Klamath Rock Y#

Redding Complex Redding Rock Y#

White Rock Green Rock Trinidad Complex Flatiron Rock Y# Y# HU MBOLDT 41° Blank Rock 41° Pilot Rock âArcata

False Cape Rocks Y# Cape Mendocino Complex Cape Mendocino Steamboat Rock Y#

â Shelter Cove 40° 40°

Rockport Rocks Vizcaino Complex Cape Vizca ino Y# MEND OCI NO Newport Rocks Y# Newport-Kibesillah Complex Kibesillah Rock â Fort Bragg Goat Complex Goat Island Area Y# Casket Rock Y# Casket-White Complex White Rock Y# 39° 39° Point Arena

N SONOMA

50 0 50 100 Kilometers MA RIN 38° 38°

125° 124° 123°

Figure 1. Seabird colonies in northern California Common Murre colony complexes counted for 1996-2004.

6 124° 123° 122°

Point Reyes Complex MA RIN # Y# 38° Point Reyes Y ist. Y# 38° es t. Alcatraz t. R P Y# Island P ers t. Drake's Bay ill e P M ubl Complex Do Y# North Farallon Lobos RockY#Y# Complex Y# Seal Rocks SF South Farallon Y# Complex San Pedro Rock Y# Devil's Slide Complex Devil's Slide Rock Y#

SAN MA TEO

Y# Año Nuevo Isl and SANTA CRUZ 37° 37°

Monterey Bay

Point Lobos

N Bench Mark-227X Y# Castle-Hurricane Complex Castle Rocks & Mainland Y# Hurricane Point Rocks MONTEREY Point Sur

25 0 25 50 75 Kilometers

36° 36°

124° 123° 122°

Figure 2. Common Murre colony complexes and sample Brandt’s Cormorant colonies in central California, 1996-2004.

7 Aerial Surveys

Nearly all aerial photographic surveys in the 1996-2004 period were conducted from a CDFG Partenavia, a twin engine fixed-wing aircraft. Certain surveys in 1996 and 1997 were conducted in a Cessna 182 or 185 aircraft. In 1996, photographs were taken through a side window photo port (lead photographer) or side window (back-up photographer). Beginning in 1997, photographs were taken vertically through the belly port of the plane. Colonies were photographed with 35mm cameras and color slide film by two observers. The lead photographer usually obtained complete coverage of colonies with close-up photographs using a 300mm telephoto lens, while the second photographer took overview photographs and back-up close-ups with 50mm, 70-200mm, and 300mm lenses.

Photograph Counting

For northern California, most small murre colonies were counted by PJC alone, and all large colonies were counted by PJC and JNH together. Colonies where past counts of murres totaled less than 5,000 birds were considered to be small. Small colonies of similar size in Drake’s Bay in central California have also been counted previously by one experienced “dotter” (Carter et al. 2003b). Counting of murres, cormorants, and pelicans followed standard protocols described elsewhere (Takekawa et al. 1990, Carter et al. 1992, 1996, 1998, 2000, 2001, McChesney et al. 1998a,b, 1999, 2001, Capitolo et al. 2003, 2004b). In addition to whole- colony counts, counts were also determined for subcolonies (following Carter et al. 1992, 1996) at colonies where birds nested on more than one rock.

For murres, only counts of birds were determined since murres do not build a nest structure. Murre chicks were also counted when they were visible (see Carter et al. 2003b, Capitolo et al. 2004a). For cormorants, nests, territorial sites, and birds were counted. Nest totals reported for cormorants include: well-built nests (X), poorly-built nests (P), nests with chicks (C), abandoned nests (A), and empty nests (E). Total numbers of sites include territorial sites (Z) and undetermined sites (S). Undetermined sites (S) were rarely recorded. Total numbers of birds included any roosting cormorants within and adjacent to breeding areas, but may not have included all roosting cormorants on other nearby areas or nearby rocks. Nests that could not be identified to cormorant species in aerial photographs occurred rarely at Castle Rock and Cape Vizcaino. Brown Pelicans were aged as adults or immatures and total numbers of roosting birds are reported in Appendix 1.

Central California colonies in 2002-2004 were counted separately by other CMRP staff (Knechtel et al. 2003, McChesney et al. 2004, 2005).

Incomplete Coverage/Estimating Numbers from Overviews

Coverage of all nesting areas at all colonies with close-up photographs was usually complete. Exceptions occurred in 1997 when camera malfunctions resulted in underexposed photographs from the lead photographer’s camera. Colonies in 1997 were therefore counted using only photographs from the back-up photographer’s camera. However, large portions of nesting areas were missed by the back-up camera in 1997 at Castle, False Klamath, Green,

8 Flatiron, and Steamboat Rocks. Similar problems occurred at False Klamath Rock in 1999. Smaller areas (< 200 murres estimated) were also missed by close-up photographs in 1997 at False Cape Rocks, in 2001 at Castle Rock and Flatiron Rock, and in 2003 at Green Rock and Flatiron Rock (see Capitolo et al. 2004a).

We determined which areas were missed by close-up photographs by projecting an overview photograph and outlining on a sheet of paper the approximate boundaries of counted areas. Areas counted with close-up photographs were then tallied. Estimates of numbers of murres missed were determined by visually comparing in the overview the density and distribution of murres in missed and counted areas. This method is not as accurate as direct counts and may have led to relatively large underestimates for these areas in 1997. However, we felt that such adjustments were useful to ensure relative comparability of count data between years (see McChesney et al. 1998b).

For pelicans, all possible roosting areas may not have been photographed at each colony on each survey, but pelicans often roosted near breeding cormorants and murres and were regularly captured in photographs of breeding areas and areas immediately adjacent to breeding areas.

RESULTS

Northern California

A brief description of each murre colony complex in northern California is provided below, along with general comments on apparent trends for whole-colony murre and cormorant counts in the 1996-2004 period, including those made in earlier assessments (Carter et al. 2001, Capitolo et al. 2004a). Comparisons are also made to data from 1989, the last year prior to 1997 for which all murre colonies in California have been counted (Carter et al. 1992, 2001).

Castle Complex

Castle Rock is currently the sole colony within this complex. Historical murre breeding occurred at Whaler Island (Carter et al. 2001). From 1996 to 2004, Castle Rock remained the largest murre colony in northern California, and in 2004 had the highest whole colony count in all of California (Tables 1,4). Compared to 1989, the whole colony count in 1997 was 30% lower. Part of this difference is likely due to incomplete coverage of the colony with close-up photographs and the difficulties in estimating numbers of murres from overviews; Jaques and Strong (2001) estimated 9,715 birds (22%) from overviews for 1997. Following reduced attendance during 1998 El Niño conditions, numbers increased in 1999 and 2001, and were lower in 2003. Whole-colony counts in 2001 and 2003 were similar to the 1989 count. The 2004 whole-colony count was 32% higher than the 2003 count (Tables 1,3).

9 Table 1. Raw whole-colony counts of Common Murres in northern California, 1996-2004 (updated from Capitolo et al. 2004a). Counts are also provided for 1989 (Carter et al. 1992) for comparison. Colony names in bold are sample colonies. Colony names in italics refer to locations without confirmed murre breeding in 1979-2004. NC = photographs not yet counted. Colony CCN 1989 1996 1997 1998 1999 2000 2001 2002 2003 2004 Prince Island DN-414-03 0 01 01 01 01 11 01 01 001 Castle Rock DN-414-06 64,475 NC 45,0572 30,6222 58,6802 NC 67,177 NC 62,504 82,697 Unnamed Small Rocks DN-414-10 0 0 01 0 51 0 0 0 0 01 Rock R DN-412-01 194 73 0 0 0 5 0 0 0 0 Sister Rocks DN-412-02 216 3 7 0 6 0 0 0 0 0 False Klamath Rock DN-412-07 26,130 NC 22,9503 NC 27,4974 NC 26,402 NC 23,599 27,304 White Rock DN-412-11 0 01 01 01 11 21 41 61 0 21 High Bluff South DN-412-12 0 01 01 161 01 01 01 01 15 01 Redding Rock HU-412-01 1,632 229 162 33 290 248 147 83 76 88 Sea Lion Rock HU-410-07 0 0 0 1 0 0 0 0 0 0 White Rock HU-410-08 3,157 NC 2,067 NC 2,409 NC 2,419 2,735 2,272 2,836 Green Rock HU-410-09 19,060 NC 15,5036 NC 18,4497 NC 19,850 NC 18,775 24,026 Flatiron Rock HU-410-13 19,914 NC 18,6378 NC 22,830 NC 23,788 NC 23,477 30,464 Blank Rock HU-410-14 331 NC 408 NC 561 NC 561 NC 636 540 Pilot Rock HU-410-16 1,358 NC 738 NC 1,097 NC 987 NC 1,036 1,336 False Cape Rocks HU-402-01 9,594 NC 8,668 NC 12,448 NC 12,850 NC 13,908 16,734 Sugarloaf Island HU-402-02 0 0 0 0 0 0 0 0 0 0 Steamboat Rock HU-402-03 5,454 NC 4,5529 NC 6,006 NC 5,924 NC 7,011 9,360 Rockport Rocks ME-394-07 915 1,115 1,208 969 1,219 1,468 1,279 1,324 1,242 2,226 Cape Vizcaino ME-394-08 4,125 4,082 4,452 3,829 5,016 6,798 6,357 6,545 7,444 9,764 Kibesillah Rock ME-392-04 0 175 349 101 296 372 385 370 516 516 Newport Rocks ME-392-05 0 278 303 174 244 270 200 215 240 284 Goat Island Area ME-390-01 34 213 291 120 800 1,223 1,556 1,874 2,420 2,972 Casket Rock ME-390-11 0 0 0 0 0 0 36 123 120 0 White Rock ME-390-13 0 0 0 0 20 84 85 010 222 272 Gualala Point Island SO-384-01 0 01 01 01 01 01 01 01 0 01 Total 156,589 - 125,352 - 157,874 - 170,007 - 165,498 211,421 1Photographs inspected but not counted, and data not included in database; 2Source: Jaques and Strong (2001); 3Includes 7,400 murres estimated from overviews; 4Includes 3,900 murres estimated from overviews; 5Ground count from mainland on 1 August 2003; 6Includes 5,450 murres estimated from overviews; 7Includes 150 murres estimated from overviews; 8Includes 4,350 murres estimated from overviews; 9Includes 1,665 murres estimated from overviews; 10No photos (see text).

10 Table 2. Whole-colony counts of Brandt’s Cormorant nests at sample and non-sample colonies in northern California, 1996-2004. Counts are also provided for 1989 (Carter et al. 1992) for comparison. Colony names in bold are sample colonies. NC = photographs not yet counted. Colony CCN USFWSCN 1989 1996 1997 1998 1999 2000 2001 2002 20032 2004 Castle Rock DN-414-06 325-006 1,132 NC 8191 6901 6041 NC 1,008 NC 1,034 1,561 Rock R DN-412-01 325-048 98 54 0 18 0 21 0 0 24 28 Sister Rocks DN-412-02 325-009 51 0 0 0 0 0 0 0 0 0 False Klamath Rock DN-412-07 325-010 324 NC 196 NC 97 NC 143 NC 218 311 Redding Rock HU-412-01 325-013 112 3 0 0 17 0 0 0 30 0 White Rock HU-410-08 325-019 - NC - NC - NC - - - - Green Rock HU-410-09 325-020 28 NC 1 NC 22 NC 16 NC 36 0 Flatiron Rock HU-410-13 325-023 469 NC 3843 NC 196 NC 277 NC 254 446 Blank Rock HU-410-14 325-024 46 NC 65 NC 16 NC 0 NC 0 0 Pilot Rock HU-410-16 325-026 0 NC 0 NC 0 NC 1 NC 7 18 False Cape Rocks HU-402-01 325-040 360 NC 139 NC 118 NC 143 NC 178 138 Steamboat Rock HU-402-03 325-042 211 NC 120 NC 97 NC 113 NC 165 321 Rockport Rocks ME-394-07 379-001 385 77 73 31 50 39 42 53 77 250 Cape Vizcaino ME-394-08 379-002 772 482 437 315 216 478 600 845 889 931 Kibesillah Rock ME-392-04 379-004 30 92 100 24 28 33 50 57 15 19 Newport Rocks ME-392-05 379-005 87 0 0 0 13 0 0 0 47 5 Goat Island Area ME-390-01 379-006 494 252 253 134 191 239 325 486 476 601 Casket Rock ME-390-11 379-009 32 135 57 45 8 48 161 221 39 99 White Rock ME-390-13 379-010 226 0 67 0 94 80 16 0 239 0 Total4 4,8574 - 2,7114 - 1,7674 - 2,8954 - 3,7284 4,7284 1Source: Jaques and Strong (2001); 2Source: Capitolo et al. (2004b); 3Incomplete data – no estimate was determined for areas missed by both close-ups and overviews (see Capitolo et al. 2004a); 4Note that totals are for colonies that co-occur with murre colonies only and several other Brandt’s Cormorant colonies occur in northern California (see text).

11 To detect possible patterns of population growth or decline on certain parts of the island, subtotals for the west portion of the island and for six distinct subareas on the east portion of the island were determined and compared to subtotals from other years (Table 3; Figure 3; Capitolo et al. 2004a,b). Compared to 2003, higher murre numbers in 2004 occurred at all subareas; the West Island subtotal was 35% higher and the East Island subtotal was 26% higher. Growth of certain areas of East Island since 1989 was associated with a progressive loss of vegetation in these areas. Numbers increased from 1989 to 2004 in North Central and Southwest Veg. Group areas, and increased 74% since 1989 on the Southeast Corner of East Island. Reductions in the amount of vegetated area on these portions of the East Island are evident when comparing overview photographs from 1989 and 2004, and also when comparing photographs from 2003 and 2004. Nesting by murres and Brandt’s Cormorants has expanded in these areas as they have become progressively denuded. Nesting Brandt’s Cormorants are likely contributing to denuding of areas (also see Goat Complex below). Osborne (1972) noted a decline in Calamagrostis nutkaensis on Castle Rock by 1970, and described Brandt’s Cormorants as using this bunchgrass almost exclusively in their nest structures where it was available and killing vegetation with their guano. Aleutian Cackling Geese (Branta hutchinsii leucopareia) use Castle Rock as a staging area in spring and also are likely contributing to loss of vegetation. In 1999, as many as 27,000 geese used Castle Rock for night-roosting and foraging (Jaques and Strong 2001). In 2004, small numbers of geese remained at Castle Rock through at least 15 July (Jaques 2004) and 11 were counted in our aerial photographs. Nesting Double-crested Cormorants may also contribute to loss of vegetation.

Compared to 1989, numbers of Brandt’s Cormorant nests at Castle Rock were lower in 1997. Coverage of Brandt’s Cormorant nesting areas with close-up photographs was apparently complete in 1997, despite incomplete coverage of murre areas. Numbers decreased further in 1998 and 1999 as much nest abandonment was noted in 1998 during severe El Niño conditions (Jaques and Strong 2001). Numbers increased by 2001 and were similar in 2003. In 2004, the total number of nests was 51% higher than in 2003 (Table 2).

Double-crested Cormorants were first noted nesting at Castle Rock in 1997. In 1997- 1999, Jaques and Strong (2001) counted 22, 29 and 40 nests, respectively. Similar counts occurred in 2001 (37 nests) and 2004 (58 nests; Appendix 1). In 2003, 136 nests were counted, but some may have been Brandt’s Cormorant nests that were misidentified (see Capitolo et al. 2004a). Additional ground and boat observations at Castle Rock are needed to confirm the recent distribution of Double-crested Cormorant nests and plant materials used for nest structures.

12 A F E D

C B

Figure 3. Common Murre count subareas used at Castle Rock National Wildlife Refuge, 1989-2004. Lettered subareas: A = Southeast Corner; B = Northeast Cliffs; C = North Central; D = Southwest Veg. Group; E = South Central Ridge; F = West Island (see Table 3). Areas A-E comprise East Island. Photograph taken by PJC, 2 June 2004, with a 4.0 megapixel digital camera.

13 Table 3. Subarea and whole-colony counts of Common Murres at Castle Rock National Wildlife Refuge, California, 1989-2004 (see Figure 3). 2003-04 Area 19891,2 20012 20032 2004 % Change3 East Island Southeast Corner 9,921 14,627 13,614 17,304 27.1 Northeast Cliffs 249 19 04 97 NA North Central 1,074 2,148 2,564 2,883 12.4 Southwest Veg. Group 38 51 103 162 57.3 South Central Ridge 417 433 398 504 26.6

East Island Subtotal 11,699 17,278 16,679 20,950 25.6

West Island Subtotal 52,776 49,899 45,825 61,747 34.7

Castle Rock Total 64,475 67,177 62,504 82,697 32.3 1Source: Carter et al. (1992, unpubl. survey archives); 2Source: Capitolo et al. (2004a); 3Actual percent change = (2004 total-2003 total)/2003 total; 4Correction to Capitolo et al. (2004a), which reported 10 birds for Northeast Cliffs and 13,604 birds for Southeast Corner.

False Klamath Complex

This murre colony complex is comprised of the large False Klamath Rock colony and three irregularly-attended rocks (i.e., Rock R, Sister Rocks and Unnamed Small Rocks). At False Klamath Rock, the whole-colony count of murres in 1999 (27,497 birds) was the highest for the 1997-2004 period, but only 1% higher than the 2004 count. The 1999 count was also just 5% higher than the 1989 count, indicating little change (Table 1). No obvious change in the distribution of murres was evident in photographs. Numbers of Brandt's Cormorant nests declined from 1997 (196 nests) to 1999 (97 nests) following the 1997-1998 El Niño event, and increased after 1999 to 311 nests in 2004. The 2004 nest total was similar to the 1989 nest total (324 nests; Table 2). Numbers of Double-crested Cormorant nests oscillated slightly in the 1997-2004 period, ranging from 56 in 1999 to 103 in 2004 (Appendix 1).

At Rock R, where breeding by murres has not been confirmed, 194 murres were counted in 1989 amid nesting Brandt’s Cormorants (Carter et al. 1992, 2001; Table 1). In the 1996-2004 period, murres were noted in 1996 and 2000, also amid nesting Brandt's Cormorants. In 1996, many of the 73 murres counted were in incubation posture in apparently suitable breeding habitat against small rock walls, and breeding may have taken place. In 2000, only five isolated murres were present, four of which were standing and apparently not incubating. Brandt's Cormorants nested at Rock R in 5 of 9 years in the 1996-2004 period (Table 2).

At adjacent Sister Rocks, small numbers of murres reportedly bred in 1980-82 but breeding has not been confirmed since (Sowls et al. 1980, Carter et al. 2001, Capitolo et al. 2005). In the 1996-2004 period, less than 10 murres were noted in 1996, 1997 and 1999 (Table 1). Brandt's Cormorants did not nest at Sister Rocks in 1996-2004 (Table 2). Unnamed Small Rocks was added to this complex based on murre attendance noted in 1999 (Table 1; Capitolo et al. 2005).

14 Redding Complex

Redding Rock is considered to be its own colony complex because of its considerable distance (>5 km) to nearest colonies (Carter et al. 2001). Numbers of murres at Redding Rock in 1996-2004 were much lower than in 1989 (Table 1). Decline in numbers of murres was evident on the top of the rock in areas surrounding the lighthouse, where the majority of the 1,632 birds counted in 1989 were located. In 1996-2004, numbers of murres on top of the rock declined from 120 birds in 1996 to 20 birds in 2001. In 2002-2003, murres were restricted to three cliff ledges on the west and south sides of the rock, and just two ledges in 2004. During 1998 El Niño conditions, murres were present on only one ledge. Brandt’s Cormorants nested at Redding Rock in 1996, 1999, and 2003 (Table 2).

Disturbance from U.S. Coast Guard activities (including use of helicopters) to maintain the lighthouse and disturbance by hauled-out sea lions have likely contributed to the decline in murre numbers (Carter et al. 2001, Capitolo et al. 2005). California Sea Lions (Zalophus californianus) were hauled out on Redding Rock in all years in 1996-2004. Smaller numbers of the threatened Steller Sea Lion (Eumetopias jubatus) were noted in photographs from 2002 and may have been present in other years. Disturbance from lighthouse maintenance activities is also of concern for sea lions. Haul-out areas were primarily low on the east side of the rock. When much larger numbers were present in 1998, 2002 and 2003, sea lions hauled out over the east slope of the rock and portions of the top of the rock. Though numbers were lower in 1997, 1999, and 2004, some sea lions were still hauled out around the base of the lighthouse. In 2000, when no sea lions were hauled out near the lighthouse, small numbers of murres were present immediately adjacent to the base of the lighthouse. Disturbance to murres caused by sea lions also has been noted at colonies in central California (Parker et al. 1999, Carter et al. 2003b), and sea lion predation of murre chicks on the ocean surface has been observed (Long and Gilbert 1997). A restoration concept to reduce disturbance to seabirds and marine mammals at Redding Rock has been proposed with settlement funds from the 1999 Stuyvesant oil spill (Stuyvesant Trustee Council 2004).

Trinidad Complex

This murre colony complex off Trinidad Head is comprised of White, Green, Flatiron, Blank, and Pilot Rocks, as well as the historic Sea Lion Rock colony (Carter et al. 2001). Flatiron Rock had the second highest whole-colony murre count in northern California in 2004, after Castle Rock. At all five rocks, numbers of murres were lowest in 1997, similar in 1999, 2001, and 2003, and highest in 2004 (Table 1). Lower numbers in 1997 at Flatiron and Green Rocks may have been partly due to estimating numbers of murres in overview photographs for certain areas missed by close-up photographs. Photographic coverage at White, Blank, and Pilot Rocks in 1997 was complete. The distribution of murres at these colonies was similar in 2004 and 1989. At Blank Rock in 1997-2004, small numbers of murres (< 100) attended an area low on the north side that was not attended by murres in 1989, but where Brandt's Cormorants nested in 1989.

Brandt’s Cormorants nest primarily at Flatiron Rock in this colony complex. Numbers of nests at Flatiron Rock declined from 1997 (384 nests) to 1999 (196 nests), following 1998 El

15 Niño conditions, then increased after 1999 to 446 nests in 2004. The 2004 nest total was similar to the 1989 nest total (469 nests; Table 2). Double-crested Cormorants nested only at Pilot Rock in 1997 (Appendix 1), as they did in 1989 (Carter et al. 1992).

Cape Mendocino Complex

This murre colony complex is comprised of False Cape Rocks and Steamboat Rock. Murres also were noted at Sugarloaf Island once in July 1981, but without confirmed breeding (Carter et al. 2001). False Cape Rocks consists of three subcolonies: the small east rock (Subcolony 01), the low-lying, flat-topped middle rock (Subcolony 02), and the larger, steep west rock (Subcolony 03). Numbers of murres at False Cape Rocks increased from 1997 (8,668 birds) to 2004 (16,734 birds; Table 1), surpassing highest earlier numbers found in 1995 (12,426 birds; Carter et al. 2001). Lower numbers in 1997 reflected reduced attendance at all three subcolonies (Appendix 1; Carter et al. 1996). At Steamboat Rock, numbers of murres increased from 1997 to 1999, were similar in 1999 and 2001, and continued to increase from 2001 to 2004 (Table 1).

Numbers of Brandt's Cormorant nests at both colonies were lowest in 1999, following 1998 El Niño conditions. Compared to 1989, nest totals in 2004 were lower for False Cape Rocks but higher for Steamboat Rock (Table 2). Double-crested Cormorants nest amid murres along the highest ridge of Subcolony 03 at False Cape Rocks, and formerly on Subcolony 02. Double-crested Cormorants have not nested on Subcolony 02 since 1990, perhaps due to competition for nesting space with increasing numbers of murres (Capitolo et al., in prep.). Numbers of murres counted on Subcolony 02 have increased from 5,011 in 1989 (Carter et al. 2001) to nearly 8,000 in 2004 (Appendix 1).

Vizcaino Complex

The Vizcaino Complex is comprised of Rockport Rocks and Cape Vizcaino. Cape Vizcaino is the oldest known murre colony in Mendocino County with breeding first noted in 1979 (Sowls et al. 1980, Carter et al. 2001). Seabirds primarily nest on the large islet (Subcolony 06) but breeding cormorants and murres have also been recorded on some of the smaller islets (i.e., Subcolonies 10-12) since the mid 1990s (Carter et al. 1992, 1996). Total numbers of murres at Cape Vizcaino in 1996-97 were similar to 1989 numbers, but reduced attendance occurred during El Niño conditions in 1998. Numbers of murres increased during the 1999-2004 period, reaching a high count of 9,764 birds in 2004 (Table 1).

Murres were first noted at Rockport Rocks in 1989, when 915 murres were counted (Carter et al. 1992). Numbers increased slightly by 1996 and were similar through 2003, before increasing 79% from 2003 (1,242 birds) to 2004 (2,226 birds) (Table 1).

Numbers of Brandt’s Cormorant nests at both colonies were similar in 1996-1997, but lower than 1989 numbers. Following reduced numbers in 1998-1999, numbers of nests increased at both colonies from 2000 to 2004. At both colonies combined, similar numbers of nests were counted in 1989 (1,157 nests) and 2004 (1,181 nests; Table 2).

16 Increased numbers of murres on Subcolony 04 at Rockport Rocks since 1989 may have contributed to lower numbers of nesting cormorants on this flat-topped rock (Capitolo et al. 2004a). By attending colonies earlier in the season, murres may out-compete cormorants for nesting space at some California colonies (Ainley and Boekelheide 1990). In 1989, 172 cormorant nests were counted on Subcolony 04, whereas the high count of nests in 1996-2003 was only 77. However, the number of cormorant nests increased to 250 in 2004 along with a 79% increase in murres. Thus, earlier reduction of cormorant numbers may have been due primarily to other factors or cormorants adjusted to increases in murre numbers and distribution.

Newport-Kibesillah Complex

This complex is comprised of colonies at Newport Rocks and Kibesillah Rock, which occur within 500 m of each other. Murre attendance was noted at both colonies prior to 1996 (Carter et al. 1996), but breeding was not confirmed until 1997 when chicks were observed from the adjacent mainland (Carter et al. 2001; GJM, pers. obs.). At Kibesillah Rock, less than 10 murres were present in 1979 and 1980 (Sowls et al. 1980, Carter et al. 2001), but murres were not noted again until 1995 (Carter et al. 1996, 2001). In 1996-2004, numbers of murres were lowest during 1998 El Niño conditions, were similar in 2000-2002, then increased to a high count of 516 birds in both 2003 and 2004 (Table 1).

Newport Rocks consists of two rocks (Subcolonies 01, 02) less than 100 m apart (Carter et al. 1996). Murres were first noted at a location believed to be Newport Rocks in 1982 (Briggs et al. 1983, Carter et al. 1996, 2001). Murres were not present in 1989 (Carter et al. 1992), but were present annually in 1993-1995 (Carter et al. 1996, 2001, Capitolo et al. 2004a). In 1996- 2004, murres primarily occurred on Subcolony 02, where numbers were similar in all years (range = 174-303; Table 1). Murres attended Subcolony 01 only in 2003, the only year Brandt’s Cormorants nested there (Appendix 1).

Brandt’s Cormorants nested at Kibesillah Rock each year in 1996-2004 (range = 15-100 nests). Some colony-shifting between Kibesillah Rock and Newport Rocks likely occurs, as Brandt’s Cormorants nest irregularly at Newport Rocks and usually with a proportionate decrease in numbers of nests at Kibesillah Rock (Table 2). At Kibesillah Rock, one Double- crested Cormorant nest with two large chicks was observed from the mainland on 13 July 1997 (GJM, pers. obs.). To our knowledge, this was the first recorded nesting of this species in coastal Mendocino County (Capitolo et al. 2004a,b).

Goat Complex

Goat Island Area is currently the sole colony in this complex. Murre attendance was noted prior to 1996 in several years, beginning in 1989 when 34 birds were counted on Subcolony 02 (Carter et al. 1992, 1996, 2001). Breeding by murres was confirmed in 1997 with ground-based observations (Carter et al. 2001; GJM, pers. obs.). In 1996-2004, the total numbers of murres at Goat Island Area increased from 213 birds in 1996 to 2,972 in 2004 (Table 1). Following a 175% increase from 1997 to 1999, numbers continued to increase by an average of 30% per year through 2004. Attendance of Subcolony 01 by murres was first recorded on aerial surveys in 1999 (Appendix 1). However, small numbers of non-breeding murres (high

17 count of 6 birds) were observed flying into and out of the cormorant colony on Subcolony 01 on 12 July 1997 (GJM, pers. obs.).

Numbers of Brandt’s Cormorant nests were similar in 1996-1997, lowest in 1998 during El Niño conditions, and increased from 1999 to 2004 (Table 2). Most nests occurred on Subcolony 02 (Appendix 1). Compared to 1989, the amount of vegetation on Subcolony 02 was reduced by 1993. The amount of vegetation declined gradually each year and the rock was nearly devoid of vegetation by 2003, with murres and Brandt’s Cormorants occupying denuded areas.

Casket-White Complex

Both murre colonies within this complex were newly established in the 1996-2004 period, but both locations have hosted Brandt's Cormorant colonies for many years (Sowls et al. 1980, Carter et al. 1992). Although slightly more than 5 km apart and with breeding by murres likely but yet to be confirmed, we have lumped them within the same new colony complex because of their isolation from other colonies.

Murres were first noted at Casket Rock in 2001 near the middle of the rock amid nesting Brandt’s Cormorants. Brandt’s Cormorants also nested at Casket Rock in 1996-2000, but murres were not in attendance during surveys in these years. In both 2001 and 2002, murres were distributed in small clumps of up to about 10 birds near the middle of the rock, spread through the cormorant nesting area, usually against a small rock wall. In 2003, when cormorants nested only at the southeast end of the rock, murres remained in the central area but appeared more densely grouped. At least some murres were in incubating posture in all years in the 2001-2003 period; breeding may have occurred but was not confirmed. However, no murres were present during surveys in 2004 (Table 1) and 2005 (USFWS, unpubl. data).

Four murres were first noted at White Rock in 1979, but none were seen in 1980 or 1989 and Carter et al. (2001) previously considered the rock to be attended without confirmed breeding. We first recorded murres in 1999 (20 birds), and each year thereafter except 2002. Numbers increased to 272 birds in 2004 (Table 1). The presence of murres in incubation posture in these years indicated that murre breeding may have occurred, though it was not confirmed. In 2002, no photographs were taken of White Rock and no visual observations of the rock were recorded on the flight log datasheet. Although the rock was likely checked and nesting Brandt’s Cormorants are not likely to have been overlooked, small numbers of murres could have been overlooked. White Rock was photographed in 1996-1998 and murres clearly were not in attendance during surveys in these years.

Brandt’s Cormorants nested at Casket Rock each year in the 1996-2004 period, but nested irregularly at White Rock. The whole-complex count of cormorant nests varied somewhat between years, but similar totals suggested that cormorants shifted nesting between these rocks to some extent (Table 2).

18 Irregular Attendance of Other Colonies

Irregular attendance by murres amid cormorant colonies has been noted at four other locations in Del Norte County: Prince Island, Unnamed Small Rocks, White Rock, and High Bluff South. One murre was also noted at Sea Lion Rock in Humboldt County, where historical breeding has been reported (Carter et al. 2001). Such prospecting behavior may lead to future colony formations. These observations have been described in Capitolo et al. (2005).

Four murres were noted at Gualala Point Island in Sonoma County in 1980, but none were observed there in 1979, 1989, 1993-1995, and 2003 and the rock has been considered to be attended without confirmed breeding (Carter et al. 2001).

Central California

A brief description of each murre colony complex in central California is provided below, along with general comments on apparent trends for whole-colony murre counts in 2002-2004. Additional detail can be found in Knechtel et al. (2003) and McChesney et al. (2004, 2005). Among these colony complexes, Double-crested Cormorants nest only at the South Farallon Complex. Because data are also provided for sample Brandt’s Cormorant colonies outside murre colony complexes, Brandt’s Cormorants are treated separately below.

Point Reyes Complex

Point Reyes is the sole colony of this complex but is comprised of many subcolonies on rocks and mainland cliffs, mainly along the western half of the Point Reyes Headlands. The largest murre subcolony occurs at Lighthouse Rock, a fairly large offshore rock adjacent to the west end of the headlands. Numbers of murres decreased from 2002 to 2003 and increased from 2003 to 2004. The 2004 whole-colony count (24,437) was 4.9% higher than the 2002 count (Table 4).

Points Resistance-Double Complex (Drake’s Bay)

At this colony complex, murres currently nest on four rocks within three colonies, including the fairly large, low-lying offshore rock at Point Resistance, the north and south rocks at Millers Point Rocks, and the large, low-lying rock at Double Point Rocks known as Stormy Stack. Murre attendance has been recently noted at a mainland point at Point Resistance and on the south rock at Double Point Rocks (Carter et al. 2000, 2003b, Capitolo et al. 2005).

Numbers of murres increased at Point Resistance from 2002 to 2004. At Millers Point Rocks and Double Point Rocks, numbers decreased from 2002 to 2003, then increased from 2003 to 2004. Whole-complex counts of murres were 32% higher in 2004 than in 2002 (Table 4).

19 North Farallon Complex

The North Farallon Islands is the sole colony of this offshore complex, but is comprised of four large islets with breeding murres. Whole-colony counts in 2002-2004 were remarkably similar, varying by less than 1% between years (Table 4). With whole-colony counts greater than 40,000 birds, this is the third largest murre colony in California and second largest in central California.

South Farallon Complex

The South Farallon Islands is the sole colony of this complex, but is comprised of four main subareas. Murres nest on Southeast Farallon and West End islands, and on Saddle Rock and The Islets. As at the North Farallon Complex, numbers of murres in 2002-2004 were very similar between years (Table 4). Whole-colony counts for the South Farallon Islands were the highest in California in 2002-2003 but were exceeded in 2004 by Castle Rock (Tables 1,4).

The South Farallon Islands is the only murre colony complex in central California where Double-crested Cormorants also nest. Numbers of nests declined from 520 in 2002 to 439 in 2003, then increased to 561 in 2004 (Knechtel et al. 2003, McChesney et al. 2004, 2005). Nests occur only on the upper slopes and peak of “Maintop” on West End Island. In 2003, this colony accounted for 13% of the Double-crested Cormorant population in coastal central California (Capitolo et al. 2004b).

Devil’s Slide Complex

This murre colony complex consists of Devil’s Slide Rock and Mainland, and the long extirpated San Pedro Rock colony. Ongoing restoration efforts at these colonies resulted in recolonization of Devil’s Slide Rock by murres in 1996, but recolonization did not occur at San Pedro Rock (Parker et al. 1997, Carter et al. 2001, McChesney et al. 2005). Monitoring efforts by the CMRP have noted a steady increase in the number of breeding pairs of murres at Devil’s Slide Rock since 1996. Numbers of pairs decreased slightly from 2002 to 2003, but increased from 2003 to 2004. Whole-colony counts from aerial surveys in the 2002-2004 period showed a similar pattern (Table 4).

Castle-Hurricane Complex

The Castle-Hurricane colony complex is comprised of three colonies: Bench Mark-227X, Castle Rocks and Mainland, and Hurricane Point Rocks. Hurricane Point Rocks is currently the southernmost murre breeding colony in California. Whole-complex counts of murres increased by 9% from 2002 to 2003 and 4% from 2003 to 2004 (Table 4).

20 Table 4. Whole-colony counts of Common Murres in central California, 2002-2004. Colony names in italics refer to locations without confirmed murre breeding in 1979-2004. Colony CCN USFWSCN 2002 2003 2004 Point Reyes MA-374-01 429-001 23,294 21,518 24,437 Point Resistance MA-374-03 429-024 3,505 3,800 4,246 Millers Point Rocks MA-374-04 429-002 1,135 615 904 Double Point Rocks MA-374-05 429-003 6,483 6,012 9,472 North Farallon Islands SF-FAI-01 429-051 43,135 43,364 43,071 South Farallon Islands SF-FAI-02 429-052 75,904 76,827 76,287 San Pedro Rock SM-372-02 429-013 0 0 0 Devil’s Slide Rock & Mainland SM-372-03 429-014 193 144 291 Bench Mark-227X MO-362-18 454-029 96 01 323 Castle Rocks & Mainland MO-362-19 454-010 1,733 2,187 1,737 Hurricane Point Rocks MO-362-20 454-011 688 555 804 Total 156,166 155,022 161,572 1Small numbers of murres (< 10) nested that were not photographed during aerial surveys.

Brandt’s Cormorant Sample Colonies

Fourteen sample Brandt’s Cormorant colonies were counted in the Gulf of the Farallones region (Point Reyes to Año Nuevo Island, including North and South Farallon Islands) in 2002- 2004. Total numbers of Brandt’s Cormorant nests decreased from 2002 to 2003 by 5% and were highest in 2004, increasing 31% compared to 2003. The Brandt’s Cormorant colony at the South Farallon Islands is the largest in the world and accounted for about 70% of the nests in this region in 2002-2004 (Table 5).

Nearshore colonies from Point Reyes to Año Nuevo Island (excluding North and South Farallon Islands) decreased by 3% from 2002 to 2003, then increased 50% from 2003 to 2004 (Table 5). Point Reyes, Points Resistance-Double, and Devil’s Slide Colony Complexes followed this general pattern. The Alcatraz Island colony in San Francisco Bay, however, increased in both 2003 (20%) and 2004 (34%). This colony was first noted in 1993 and has increased steadily since then (Thayer et al. 1999, Carter et al. 1996, 2000, Capitolo et al. 2004b). Lobos Rock & Land’s End and Seal Rocks act as a Brandt’s Cormorant colony complex, with birds shifting nesting between different rocks in most years. Combined nest totals varied little from 2002 to 2004. Nest totals at Año Nuevo Island were similar in 2002 and 2003, but increased 69% from 2003 to 2004. This colony was first noted in 1989 and has increased dramatically since the mid 1990s (Carter et al. 1992, 1996, 2000, Capitolo et al. 2004b; USFWS, unpubl. data).

At the Castle-Hurricane murre colony complex, numbers of Brandt’s Cormorant nests decreased 48% from 2002 to 2003, then increased 28% from 2003 to 2004 (Table 5). Between Año Nuevo Island and the Castle-Hurricane Colony Complex, large numbers of Brandt’s Cormorants nest at several colonies near Monterey and Point Lobos that have been counted recently only for 2003. Shifting of nesting between colonies apparently occurred in the 2002- 2004 period within the Castle-Hurricane Colony Complex as well as at colonies in surrounding

21 areas (Table 5; Capitolo et al. 2004b). Thus, Brandt’s Cormorant populations within this region of central California cannot be fully assessed without counting photographs of other central California colonies in these years.

Table 5. Total numbers of Brandt’s Cormorant nests at sample colonies in central California, 2002-2004. Colony CCN USFWSCN 2002 2003 2004 Point Reyes MA-374-01 429-001 534 439 580 Point Resistance MA-374-03 429-024 0 26 14 Millers Point Rocks MA-374-04 429-002 118 29 148 Double Point Rocks MA-374-05 429-003 103 125 164 North Farallon Islands SF-FAI-01 429-051 98 98 51 South Farallon Islands SF-FAI-02 429-052 7,259 6,801 8,507 Alcatraz Island SFB-SF-11 429-036 490 589 789 Lobos Rock & Land’s End SF-374-02 429-029 0 99 119 Seal Rocks SF-374-03 429-009 92 0 0 Devil’s Slide Rock & Mainland SM-372-03 429-014 292 263 346 Año Nuevo Island SM-370-04 429-023 990 969 1,639 Bench Mark-227X MO-362-18 454-029 355 0 222 Castle Rocks & Mainland MO-362-19 454-010 273 333 171 Hurricane Point Rocks MO-362-20 454-011 16 0 34 Total 10,620 9,771 12,784

DISCUSSION

Common Murre

In 2004, a total of 211,421 murres were counted in northern California at 16 active colonies and one irregularly attended colony. Seven other locations (Prince Island, Unnamed Small Rocks, Rock R, Sister Rocks, High Bluff South, Sea Lion Rock, and Casket Rock) had no murres in 2004, but were attended by small numbers of birds in certain years in the 1996-2004 period (Table 1; Capitolo et al. 2005). In central California, a total of 161,572 murres were counted at 10 active colonies. Using an average k correction factor of 1.67 (based on data from the South Farallon Islands in the 1985-1995 period; Sydeman et al. 1997), we determined a rough estimate of 622,900 breeding individuals or 311,450 breeding pairs of Common Murres for California in 2004. Carter et al. (2001; Appendix A) provides additional discussion of k correction factors.

Higher numbers in 2004 compared to 2003 were noted in both northern (28%) and central California (4%). At nearshore colonies in central California, numbers of murres were 21% higher in 2004 than in 2003. At the large, offshore colony complexes (North and South Farallon Islands) numbers were similar in 2002-2004, following substantial increases between 2001 and 2002 (USFWS, unpubl. data). Three main factors may account for the relatively large increase

22 from 2003 to 2004 seen in northern California and at central California nearshore colonies: 1) high recruitment in 2004 due to increased juvenile and subadult survival rates; 2) slightly reduced attendance in 2003 during mild El Niño conditions; and 3) possible immigration of murres from colonies in Oregon and Washington where much recent disturbance by Bald Eagles (Haliaeetus leucocephalus) has occurred. The number of breeding pairs at Devil’s Slide Rock and Mainland increased 54% from 2002 to 2004 (after lower numbers in 2003), indicating recruitment was relatively high in 2004 (McChesney et al. 2005); however, this colony is in active stage of growth after recolonization with social attractants and does not directly represent other colonies. Increased survival rates may be due to relatively high food availability in certain years (especially during La Niña conditions in 1999-2000), reduced mortality from oil spills and gill net fishing, or reduced disturbance at some colonies. The average 30% increase in murre numbers at Goat Island Area each year in 1999-2004 also suggests possible immigration.

Overall, the northern California murre population appears to be increasing and expanding southward. Prior to the higher numbers noted in 2004, numbers of murres at most colonies in Del Norte and Humboldt Counties remained mostly stable between 1989 and 2003, though some small or ephemeral colonies declined. In 2003, the total number of murres counted in these counties combined was 1% higher than in 1989, though attendance in 2003 may have been slightly reduced due to mild El Niño conditions. Redding Rock declined from counts of over 1,600 murres in 1989 to less than 100 murres in 2002-2004. About 200 murres were counted at both Rock R and Sister Rocks in 1989, but few murres attended these colonies in 1996-2004. Disturbance from boats may be one factor preventing murres from recolonizing these small, low- lying rocks. Reduced murre attendance also was noted in northern California during severe El Niño conditions in 1993 and 1998 (Carter et al. 1996; Table 1).

Less than 10% of the northern California murre population occurs in Mendocino County, but six new colonies have formed since 1989, though murre breeding has not been confirmed at Casket and White rocks (Carter et al. 1992, 1996, 2001, Capitolo et al. 2004a, this study). In 1996-2004, the total number of murres counted at colonies in Mendocino County more than doubled (Figure 4), largely due to increases at Cape Vizcaino and Goat Island Area after 1998 (Table 1).

Common Murre chicks, rarely seen in aerial photographs in most years, were conspicuous at northern California colonies in 2001 (Table 6; also see Brandt’s Cormorant below). Early initiation of egg laying was likely associated with an extended period of high upwelling and enhanced marine productivity in the California Current System (Venrick et al. 2003). Confirmation of early breeding with chick observations should be searched for in future counting of aerial photographs.

Central California accounted for 48% and 43% of total numbers of murres in the state in 2003 and 2004, respectively, compared to just 26% in 1989 (Carter et al. 2001). Following extensive decline in 1982-1989 due to mortality in gill nets and oil spills, and effects of intense El Niño conditions in 1982-1983, most central California murre colonies have increased since 1989. Increases at the large offshore colony complexes account for much of the central California increase since 1989, but these complexes were stable in the 2002-2004 period. Small increases occurred at all central California nearshore colony complexes in 2002-2004; only the

23 Millers Point Rocks colony was lower in 2004 than in 2002. Carter et al. (2003b) detected impacts to the murre population in the Points Resistance-Double Colony Complex in 1998-2000 from mortality due to the 1997-1998 Point Reyes Tarball Incidents and severe El Niño conditions in 1998, but this complex now appears to be growing again. Concern also exists over potential impacts to murre breeding success at all nearshore colony complexes from various other forms of natural and anthropogenic disturbances (McChesney et al. 2005; USFWS, unpubl. data).

18,000

16,000

14,000

12,000

s e r r u 10,000 M f

o r e b

m 8,000 u N

6,000

4,000

2,000

ND ND ND 0 1989 1991 1993 1995 1997 1999 2001 2003

Year

Figure 4. Total numbers of Common Murres counted at all colonies in Mendocino County, California, 1989-2004. Data for 1993-1995 do not include Rockport Rocks. ND = no data.

24 Table 6. Numbers of Common Murre chicks noted from aerial photographs of colonies in northern California in 2001. Colony CCN USFWSCN Survey Date Murre Chicks Castle Rock DN-414-06 325-006 6 June “many”1 False Klamath Rock DN-412-07 325-010 6 June 7 White Rock HU-410-08 325-019 4 June 12 Green Rock HU-410-09 325-020 4 June 106 Flatiron Rock HU-410-13 325-023 4 June 371 Blank Rock HU-410-14 325-024 4 June 1 Pilot Rock HU-410-16 325-026 4 June 1 Steamboat Rock HU-402-03 325-042 4 June 1 1Source: Capitolo et al. (2004a).

Brandt’s Cormorant

Annual variation in breeding population size of Brandt’s Cormorants at the South Farallon Islands due to differences in the proportion of adults that breed, recruitment of first-time breeders, and adult and subadult mortality has been well documented (Ainley et al. 1988, Boekelheide and Ainley 1989, Ainley and Boekelheide 1990, Nur and Sydeman 1999). Effects of oceanographic conditions and prey availability on these parameters typically result in substantially lower breeding populations during years of severe El Niño conditions, followed by several years of growth before the next severe El Niño (Carter et al. 1996, McChesney et al. 1998b, 1999, Capitolo et al. 2004b). Total numbers of Brandt’s Cormorant nests at murre colonies in northern California exhibited this pattern in the 1997-2004 period (Figure 5).

Compared to 1989, the total number of Brandt's Cormorant nests at murre colonies in northern California in 1997 was 44% lower. However, the northern California population in 1997 was likely still recovering from impacts from severe El Niño conditions in 1992-1993. Following the severe 1997-1998 El Niño, nest totals in 1999-2003 also reflected a recovering population. By 2004, nest totals were just 3% lower than in 1989 (Table 2). Thus, Figure 5 depicts an apparently stable population overall, with periodic large decreases in breeding population size due to severe El Niños.

Though shifting of nesting between nearby colonies can occur between years, a similar pattern to Figure 5 would likely have been seen if all northern California Brandt’s Cormorant colonies had been counted also. All other cormorant colonies in northern California that do not co-occur with murre colonies have been counted recently only for 1989 (Carter et al. 1992) and 2003 (Capitolo et al. 2004b). In both years, Brandt’s Cormorants nesting at murre colonies (see Table 2) comprised 69% of the total population for northern California.

Egg laying by Brandt's Cormorants in northern California apparently began earlier in the year in 2000-2002 than in other years. In 2000-2002, most colonies had cormorant nests where chicks were visible in our aerial photographs. Fewer nests with chicks were noted in 2003 and none were noted in 1996-99 and 2004.

25 6,000

5,000

s 4,000 t

s e N t

n a

or m r 3,000 o

C s ' ndt

a r

B 2,000

1,000

ND ND ND ID ID ID ID ID ID ID

0 1989 1991 1993 1995 1997 1999 2001 2003

Year Figure 5. Total numbers of Brandt’s Cormorant nests counted at sample colonies in northern California, 1989-2004 (see Table 2 for list of colonies). ND = no data; ID = incomplete data.

Double-crested Cormorant

Double-crested Cormorants regularly nest among Common Murres at three colonies in northern California (i.e., Castle Rock, False Klamath Rock, and False Cape Rocks) and one colony in central California (i.e., South Farallon Islands). No large-scale changes in cormorant numbers or distribution at sample colonies were apparent for the 1996-2004 period. Regional changes in population sizes and distribution of colonies of Brandt's and Double-crested Cormorants in California between state-wide surveys in 1975-1980, 1989-1991 and 2001-2003 have been recently examined elsewhere (Carter et al. 1992, 1995a, Capitolo et al. 2004b).

26 ACKNOWLEDGMENTS

Funding for counting aerial photographs of northern California colonies (non-sample colonies for 1997, 1999, 2001, and both sample and non-sample colonies for 2004) and report preparation was provided to the U.S. Fish and Wildlife Service, San Francisco Bay National Wildlife Refuge Complex (USFWS-SFBNWRC), by the National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), under NOS Agreement # MOA-2004- 183/1274 (DOI/FWS Agreement Code CRA-2004-1971-1102), through the efforts of T. Gill and J. Roletto. Funds were provided to Humboldt State University Foundation by USFWS- SFBNWRC under Cooperative Agreement #14-48-0001-96502. Funding for aerial photographic surveys and other counting efforts in northern and central California in 1996-2004 was provided by the Apex Houston Trustee Council (USFWS, NOAA, and California Department of Fish and Game [CDFG]) through the efforts of D. Welsh, P. Kelly, D. Lollock, E. Ueber, M. Brown, J. Boyce, and J. Buffa. Flight support was provided by CDFG (Office of Spill Prevention and Response) with assistance from P. Kelly. Aerial surveys were conducted safely and efficiently thanks to expert piloting by W. Burnett, L. Heitz, R. Morgan, and R. VanBenthuysen (CDFG, Air Services, Sacramento). Aerial surveys in the Gulf of the Farallones and Monterey Bay National Marine Sanctuaries in 2002-2004 were conducted under NOAA permit number GFNMS/MBNMS-2000-003-G. Assistance conducting aerial surveys was provided by J. Boyce, J. Buffa, N. Jones, B. McDermott, E. McLaren, K. Mills, E. Nelson, D. Orthmeyer, M. Steinkamp, and C. Strong. Counting of central California aerial photographs was conducted by N. Jones, A. Robinson, T. Poitras, K. Vickers, H. Knechtel, M. Murphy, J. Koepke, and K. Bixler. Numerous other CMRP staff members have assisted with slide labeling, data proofing, and other related tasks. Administrative assistance was provided by J. Buffa, M. Kolar, S. Baham, and E. Tong (USFWS-SFBNWRC), and J. Bonino, B. Clueit, E. Craig, J. Davy R. Okey, and T. Penland (Humboldt State University).

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32 Appendix 1. Subcolony counts of Common Murres, Brandt’s Cormorants, Double-crested Cormorant and Brown Pelicans at sample colonies in northern California, 1996-2004 (updated from Capitolo et al. 2004a). Dashes indicate nesting by that species has not been documented at that location. COMU Brandt’s Cormorant Double-crested Cormorant BRPE Colony USFWSCN SC # Date Birds Nests Sites Birds Nests Sites Birds Birds Castle Rock1 325-006 01 30 May 1997 45,057 819 ND ND 22 ND ND ND Castle Rock1 325-006 01 2 June 1998 30,622 690 ND ND 29 ND ND ND Castle Rock1 325-006 01 8 June 1999 58,680 604 ND ND 40 ND ND ND Castle Rock 325-006 01 6 June 2001 67,177 1,008 166 1,581 37 0 46 216 Castle Rock 325-006 01 11 June 2003 62,504 1,034 43 1,158 136 0 138 0 Castle Rock 325-006 01 2 June 2004 82,697 1,561 42 1,808 58 0 64 0 Rock R 325-048 01 4 June 1996 73 54 0 79 - - - 0 Rock R 325-048 01 30 May 1997 0 0 0 12 - - - 34 Rock R 325-048 01 2 June 1998 0 18 8 50 - - - 11 Rock R 325-048 01 8 June 1999 0 0 0 0 - - - 0 Rock R 325-048 01 15 June 2000 5 21 6 34 - - - 0 Rock R 325-048 01 6 June 2001 0 0 0 12 - - - 27 Rock R 325-048 01 4 June 2002 0 0 0 11 - - - 10 Rock R 325-048 01 11 June 2003 0 24 2 68 - - - 23 Rock R 325-048 01 1 June 2004 0 28 0 50 - - - 5 Sister Rocks2 325-009 01 4 June 1996 3 0 0 0 - - - 0 Sister Rocks 325-009 01 30 May 1997 7 0 0 0 - - - 0 Sister Rocks 325-009 01 2 June 1998 0 0 0 0 - - - 0 Sister Rocks 325-009 01 8 June 1999 6 0 0 0 - - - 0 Sister Rocks 325-009 01 15 June 2000 0 0 0 0 - - - 0 Sister Rocks 325-009 01 6 June 2001 0 0 0 0 - - - 0 Sister Rocks 325-009 01 4 June 2002 0 0 0 0 - - - 0 Sister Rocks 325-009 01 11 June 2003 0 0 0 0 - - - 0 Sister Rocks 325-009 01 1 June 2004 0 0 0 0 - - - 0

33 Appendix 1 (continued). COMU Brandt’s Cormorant Double-crested Cormorant BRPE Colony USFWSCN SC # Date Birds Nests Sites Birds Nests Sites Birds Birds False Klamath Rock 325-010 01 30 May 1997 22,950 196 2 215 97 0 98 0 False Klamath Rock 325-010 01 8 June 1999 27,497 97 0 111 56 0 57 0 False Klamath Rock 325-010 01 6 June 2001 26,402 143 16 223 96 0 100 178 False Klamath Rock 325-010 01 11 June 2003 23,599 218 8 271 68 0 67 0 False Klamath Rock 325-010 01 1 June 2004 27,304 311 4 363 103 0 110 0 Redding Rock 325-013 01 4 June 1996 229 3 0 6 - - - 0 Redding Rock 325-013 01 30 May 1997 162 0 0 0 - - - 8 Redding Rock 325-013 01 2 June 1998 33 0 0 10 - - - 3 Redding Rock 325-013 01 7 June 1999 290 17 4 40 - - - 3 Redding Rock 325-013 01 15 June 2000 248 0 0 17 - - - 0 Redding Rock 325-013 01 5 June 2001 147 0 0 1 - - - 2 Redding Rock 325-013 01 6 June 2002 83 0 0 3 - - - 0 Redding Rock 325-013 01 3 June 2003 76 30 9 79 - - - 5 Redding Rock 325-013 01 1 June 2004 88 0 0 14 - - - 0 White Rock 325-019 01 30 May 1997 2,067 - - - 0 0 0 0 White Rock 325-019 01 7 June 1999 2,409 - - - 0 0 0 0 White Rock 325-019 01 4 June 2001 2,419 - - - 0 0 0 0 White Rock 325-019 01 4 June 2002 2,735 - - 1 0 0 0 0 White Rock 325-019 01 3 June 2003 2,272 - - - 0 0 0 0 White Rock 325-019 01 1 June 2004 2,836 - - - 0 0 0 0 Green Rock 325-020 01 30 May 1997 15,503 1 0 1 - - - 0 Green Rock 325-020 01 7 June 1999 18,449 22 23 46 - - - 0 Green Rock 325-020 01 4 June 2001 19,850 16 0 19 - - - 0 Green Rock 325-020 01 3 June 2003 18,775 36 21 78 - - - 55 Green Rock 325-020 01 1 June 2004 24,026 0 0 11 - - - 0 Flatiron Rock 325-023 01 30 May 1997 18,637 384 25 433 - - - 0

34 Appendix 1 (continued). COMU Brandt’s Cormorant Double-crested Cormorant BRPE Colony USFWSCN SC # Date Birds Nests Sites Birds Nests Sites Birds Birds Flatiron Rock 325-023 01 7 June 1999 22,830 196 7 215 - - - 0 Flatiron Rock 325-023 01 4 June 2001 23,788 277 52 388 - - - 66 Flatiron Rock 325-023 01 3 June 2003 23,477 254 16 312 - - - 61 Flatiron Rock 325-023 01 1 June 2004 30,464 446 4 521 - - - 33 Blank Rock 325-024 01 30 May 1997 408 65 1 73 - - - 0 Blank Rock 325-024 01 7 June 1999 561 16 0 16 - - - 0 Blank Rock 325-024 01 4 June 2001 561 0 0 0 - - - 0 Blank Rock 325-024 01 3 June 2003 636 0 0 0 - - - 0 Blank Rock 325-024 01 1 June 2004 540 0 0 0 - - - 0 Pilot Rock 325-026 01 30 May 1997 738 0 0 0 27 6 37 21 Pilot Rock 325-026 01 7 June 1999 1,097 0 0 0 0 0 0 0 Pilot Rock 325-026 01 4 June 2001 987 1 0 1 0 0 0 0 Pilot Rock 325-026 01 3 June 2003 1,036 7 7 27 0 0 0 4 Pilot Rock 325-026 01 1 June 2004 1,336 18 0 20 0 0 0 0 False Cape Rocks 325-040 01 30 May 1997 73 0 0 0 - - - 0 False Cape Rocks 325-040 01 7 June 1999 368 0 0 1 - - - 0 False Cape Rocks 325-040 01 4 June 2001 166 0 0 15 - - - 1 False Cape Rocks 325-040 01 3 June 2003 642 3 5 12 - - - 0 False Cape Rocks 325-040 01 1 June 2004 866 17 3 43 - - - 3 False Cape Rocks 325-040 02 30 May 1997 4,665 1 0 3 0 0 0 0 False Cape Rocks 325-040 02 7 June 1999 6,123 0 0 1 0 0 0 3 False Cape Rocks 325-040 02 4 June 2001 6,433 0 0 17 0 0 0 20 False Cape Rocks 325-040 02 3 June 2003 6,021 0 0 0 0 0 0 0 False Cape Rocks 325-040 02 1 June 2004 7,923 0 0 0 0 0 0 0 False Cape Rocks 325-040 03 30 May 1997 3,930 138 19 202 77 0 89 0 False Cape Rocks 325-040 03 7 June 1999 5,957 118 24 170 64 2 87 0

35 Appendix 1 (continued). COMU Brandt’s Cormorant Double-crested Cormorant BRPE Colony USFWSCN SC # Date Birds Nests Sites Birds Nests Sites Birds Birds False Cape Rocks 325-040 03 4 June 2001 6,251 143 37 240 77 0 102 0 False Cape Rocks 325-040 03 3 June 2003 7,245 175 21 239 52 0 58 2 False Cape Rocks 325-040 03 1 June 2004 7,945 121 2 150 38 0 46 0 Steamboat Rock 325-042 01 30 May 1997 4,552 120 26 170 - - - 1 Steamboat Rock 325-042 01 7 June 1999 6,006 97 7 120 - - - 0 Steamboat Rock 325-042 01 4 June 2001 5,924 113 28 204 - - - 0 Steamboat Rock 325-042 01 3 June 2003 7,011 165 3 225 - - - 16 Steamboat Rock 325-042 01 2 June 2004 9,360 321 9 457 - - - 0 Rockport Rocks 379-001 023 3 June 2003 0 0 0 0 - - - 155 Rockport Rocks 379-001 033 7 June1999 2 ------0 Rockport Rocks 379-001 04 3 June 1996 1,115 77 0 76 - - - 6 Rockport Rocks 379-001 04 28 May 1997 1,208 73 2 84 - - - 0 Rockport Rocks 379-001 04 1 June 1998 969 31 18 75 - - - 85 Rockport Rocks 379-001 04 7 June 1999 1,217 50 1 61 - - - 0 Rockport Rocks 379-001 04 15 June 2000 1,468 39 0 52 - - - 94 Rockport Rocks 379-001 04 4 June 2001 1,279 42 0 65 - - - 33 Rockport Rocks 379-001 04 3 June 2002 1,324 53 0 106 - - - 0 Rockport Rocks 379-001 04 3 June 2003 1,242 77 1 130 - - - 60 Rockport Rocks 379-001 04 1 June 2004 2,226 250 28 400 - - - 67 Cape Vizcaino 379-002 06 3 June 1996 4,068 438 42 495 - - - 0 Cape Vizcaino 379-002 06 28 May 1997 4,452 437 162 666 - - - 0 Cape Vizcaino 379-002 06 1 June 1998 3,829 315 83 461 - - - 84 Cape Vizcaino 379-002 06 7 June 1999 5,006 178 15 180 - - - 0 Cape Vizcaino 379-002 06 15 June 2000 6,644 422 152 762 - - - 0 Cape Vizcaino 379-002 06 4 June 2001 6,165 594 62 838 - - - 0 Cape Vizcaino 379-002 06 3 June 2002 6,545 777 121 1,271 - - - 0

36 Appendix 1 (continued). COMU Brandt’s Cormorant Double-crested Cormorant BRPE Colony USFWSCN SC # Date Birds Nests Sites Birds Nests Sites Birds Birds Cape Vizcaino 379-002 06 3 June 2003 7,444 847 41 1,234 - - - 0 Cape Vizcaino 379-002 06 1 June 2004 9,593 821 139 1,366 - - - 0 Cape Vizcaino 379-002 104 4 June 2001 0 0 0 2 - - - 0 Cape Vizcaino 379-002 104 3 June 2003 0 8 0 9 - - - 0 Cape Vizcaino 379-002 114 7 June 1999 0 3 0 3 - - - 0 Cape Vizcaino 379-002 114 15 June 2000 154 48 0 66 - - - 0 Cape Vizcaino 379-002 114 4 June 2001 192 0 0 0 - - - 0 Cape Vizcaino 379-002 114 1 June 2004 171 110 0 135 - - - 0 Cape Vizcaino 379-002 124 3 June 1996 14 44 0 46 - - - 0 Cape Vizcaino 379-002 124 7 June 1999 10 35 38 76 - - - 0 Cape Vizcaino 379-002 124 15 June 2000 0 8 0 14 - - - 0 Cape Vizcaino 379-002 124 4 June 2001 0 6 0 7 - - - 0 Cape Vizcaino 379-002 124 3 June 2002 0 68 3 111 - - - 0 Cape Vizcaino 379-002 124,5 3 June 2003 0 34 0 69 - - - 0 Kibesillah Rock 379-004 01 3 June 1996 175 92 4 108 0 0 0 0 Kibesillah Rock 379-004 01 28 May 1997 349 100 5 119 16 0 1 0 Kibesillah Rock 379-004 01 1 June 1998 101 24 2 26 0 0 0 22 Kibesillah Rock 379-004 01 7 June 1999 296 28 0 32 0 0 0 0 Kibesillah Rock 379-004 01 15 June 2000 372 33 0 39 0 0 0 0 Kibesillah Rock 379-004 01 4 June 2001 385 50 13 111 0 0 0 5 Kibesillah Rock 379-004 01 3 June 2002 370 57 10 89 0 0 0 1 Kibesillah Rock 379-004 01 3 June 2003 516 15 1 23 0 0 0 0 Kibesillah Rock 379-004 01 1 June 2004 516 19 0 28 0 0 0 0 Newport Rocks 379-005 01 3 June 1996 0 0 0 15 - - - 0 Newport Rocks 379-005 01 28 May 1997 0 0 0 13 - - - 1 Newport Rocks 379-005 01 1 June 1998 0 0 0 11 - - - 16

37 Appendix 1 (continued). COMU Brandt’s Cormorant Double-crested Cormorant BRPE Colony USFWSCN SC # Date Birds Nests Sites Birds Nests Sites Birds Birds Newport Rocks 379-005 01 7 June 1999 0 0 0 23 - - - 0 Newport Rocks 379-005 01 15 June 2000 0 0 0 21 - - - 71 Newport Rocks 379-005 01 4 June 2001 0 0 0 59 - - - 0 Newport Rocks 379-005 01 3 June 2002 0 0 0 42 - - - 5 Newport Rocks 379-005 01 3 June 2003 16 31 3 131 - - - 125 Newport Rocks 379-005 01 1 June 2004 0 0 0 0 - - - 0 Newport Rocks 379-005 02 3 June 1996 278 0 0 0 - - - 0 Newport Rocks 379-005 02 28 May 1997 303 0 0 0 - - - 0 Newport Rocks 379-005 02 1 June 1998 174 0 0 0 - - - 0 Newport Rocks 379-005 02 7 June 1999 244 13 8 26 - - - 1 Newport Rocks 379-005 02 15 June 2000 270 0 0 0 - - - 0 Newport Rocks 379-005 02 4 June 2001 200 0 0 8 - - - 7 Newport Rocks 379-005 02 3 June 2002 215 0 0 0 - - - 0 Newport Rocks 379-005 02 3 June 2003 224 16 9 87 - - - 6 Newport Rocks 379-005 02 1 June 2004 284 5 8 46 - - - 0 Goat Island Area 379-006 01 3 June 1996 0 40 4 46 - - - 0 Goat Island Area 379-006 01 28 May 1997 0 35 0 35 - - - 0 Goat Island Area 379-006 01 1 June 1998 0 14 0 9 - - - 0 Goat Island Area 379-006 01 7 June 1999 72 95 51 153 - - - 0 Goat Island Area 379-006 01 15 June 2000 15 12 0 15 - - - 0 Goat Island Area 379-006 01 4 June 2001 47 33 0 57 - - - 0 Goat Island Area 379-006 01 6 June 2002 67 63 17 128 - - - 0 Goat Island Area 379-006 01 3 June 2003 205 79 18 158 - - - 0 Goat Island Area 379-006 01 1 June 2004 393 154 26 348 - - - 0 Goat Island Area 379-006 02 3 June 1996 213 212 3 234 - - - 0 Goat Island Area 379-006 02 28 May 1997 291 218 14 247 - - - 0

38 Appendix 1 (continued). COMU Brandt’s Cormorant Double-crested Cormorant BRPE Colony USFWSCN SC # Date Birds Nests Sites Birds Nests Sites Birds Birds Goat Island Area 379-006 02 1 June 1998 120 120 7 110 - - - 0 Goat Island Area 379-006 02 7 June 1999 728 96 3 116 - - - 0 Goat Island Area 379-006 02 15 June 2000 1,208 227 41 329 - - - 5 Goat Island Area 379-006 02 4 June 2001 1,509 292 36 427 - - - 0 Goat Island Area 379-006 02 6 June 2002 1,807 423 31 593 - - - 0 Goat Island Area 379-006 02 3 June 2003 2,215 397 56 594 - - - 0 Goat Island Area 379-006 02 1 June 2004 2,579 447 51 751 - - - 0 Casket Rock 379-009 01 3 June 1996 0 135 13 173 - - - 0 Casket Rock 379-009 01 28 May 1997 0 57 2 61 - - - 0 Casket Rock 379-009 01 1 June 1998 0 45 0 46 - - - 0 Casket Rock 379-009 01 7 June 1999 0 8 0 9 - - - 0 Casket Rock 379-009 01 15 June 2000 0 48 17 99 - - - 22 Casket Rock 379-009 01 4 June 2001 36 161 5 248 - - - 0 Casket Rock 379-009 01 3 June 2002 123 221 1 305 - - - 9 Casket Rock 379-009 01 3 June 2003 120 39 2 67 - - - 1 Casket Rock 379-009 01 1 June 2004 0 99 2 176 - - - 0 White Rock 379-010 01 3 June 1996 0 0 0 0 - - - 0 White Rock 379-010 01 28 May 1997 0 67 14 91 - - - 0 White Rock 379-010 01 1 June 1998 0 0 0 6 - - - 35 White Rock 379-010 01 7 June 1999 20 94 39 178 - - - 0 White Rock 379-010 01 15 June 2000 84 80 1 104 - - - 0 White Rock 379-010 01 4 June 2001 85 16 0 59 - - - 3 White Rock7 379-010 01 3 June 2002 0 0 0 0 - - - 0 White Rock 379-010 01 3 June 2003 222 239 0 406 - - - 82 White Rock 379-010 01 1 June 2004 272 0 0 0 - - - 0 1Source: Jaques and Strong (2001); 2Subcolonies 2 and 3 had zero birds in all years; 3Subcolonies 2 and 3 had zero birds in other years; 4Subcolonies 10-12 had zero birds in other years; 5Correction to Capitolo et al. (2004a) which stated Subcolony 11; 6Ground count from mainland on 13 July 1997; 7No photos (see text).

39 Appendix 2. Summary of aerial photographic surveys conducted in northern California in 1996-2004. Year Date Photographers Data Recorder Pilot Locations Surveyed 1996 28 May H. Carter, M. Parker E. McLaren R. Morgan South of Point Arena 3 June H. Carter, M. Parker E. McLaren L. Heitz Point Arena to Little River Rock 4 June H. Carter, M. Parker E. McLaren L. Heitz Humboldt Bay; Pilot Rock to Oregon border 1997 28 May H. Carter, M. Parker E. McLaren R. Morgan Gualala Point Island to Soldier Frank Point 29 May H. Carter, M. Parker E. McLaren L. Heitz Bird Rock (MA) to Russian Gulch 30 May H. Carter, M. Parker E. McLaren L. Heitz Anderson Cliffs to Oregon border; Humboldt Bay 1998 1 June H. Carter, M. Parker J. Boyce R. VanBenthuysen South of Point Arena to Cape Mendocino; Humboldt Bay 2 June C. Strong, M. Parker J. Boyce R. VanBenthuysen Little River Rock to Oregon Border 1999 2 June M. Parker, J. Boyce E. McLaren W. Burnett Bird Rock (MA) to Russian Gulch 7 June H. Carter, M. Parker M. Steinkamp W. Burnett Gualala Point Island to White Rock (DN) 8 June H. Carter, M. Parker M. Steinkamp W. Burnett Humboldt Bay; False Klamath Rock to Oregon border 2000 9 June H. Carter, M. Parker P. Capitolo W. Burnett South of Point Arena 15 June M. Parker, P. Capitolo K. Mills R. VanBenthuysen Point Arena to Oregon border 16 June M. Parker, P. Capitolo K. Mills R. VanBenthuysen Cape Mendocino; Humboldt Bay; Little River and False Klamath 2001 4 June H. Carter, P. Capitolo M. Parker W. Burnett South of Point Arena to White Rock (HU); Humboldt Bay 5 June H. Carter, M. Parker P. Capitolo W. Burnett Redding Rock to Radar Station Rocks 6 June H. Carter, M. Parker P. Capitolo W. Burnett False Klamath Rock to Oregon border 2002 30 May H. Carter, M. Parker P. Capitolo L. Heitz South of Point Arena 3 June H. Carter, M. Parker N. Jones R. Morgan Point Arena to Steamboat; Little River to White (HU); Arcata Wharf 4 June H. Carter, M. Parker N. Jones R. Morgan Green Rock to Rock R; Teal Island 6 June H. Carter, G. McChesney D. Orthmeyer R. Morgan Goat Island Area; Cape Mendocino; Redding Rock 14 June H. Carter, M. Parker B. McDermott R. Morgan Castle Rock to Oregon border 2003 28 May P. Capitolo, G. McChesney J. Irwin L. Heitz South of Point Arena 3 June H. Carter, G. McChesney J. Buffa W. Burnett Point Arena to Redding Rock; Humboldt Bay 11 June P. Capitolo, G. McChesney E. Nelson L. Heitz High Bluff South to Oregon border 2004 25 May P. Capitolo, G. McChesney J. Buffa W. Burnett South of Point Arena 1 June P. Capitolo, G. McChesney N. Jones R. Morgan Point Arena to Rock R 2 June P. Capitolo, G. McChesney N. Jones R. Morgan Cape Mendocino; Humboldt Bay; Castle Rock to Oregon border

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