Black Oystercatcher (Haematopus bachmani) Statewide Reproductive Performance in
California in 2012-2014
A. Laurie Harvey1, Anna Weinstein2, Katherine Krieger2 and Liling Lee2 1Sutil Conservation Ecology, 30 Buena Vista Avenue, Fairfax, CA 94930 USA 2Audubon California, 220 Montgomery Street, Suite 1000, San Francisco, CA 94104 USA
FINAL REPORT Prepared for Audubon California 12 October 2017
Suggested citation: Harvey, A.L., A. Weinstein, K. Krieger, and L. Lee. 2017. Black Oystercatcher (Haematopus bachmani) statewide reproductive performance in California in 2012-2014. . Unpublished report submitted to Audubon California by Sutil Conservation Ecology. 66 pp. Cover photo courtesy of H. Ceja. Table of Contents INTRODUCTION ...... 6 METHODS ...... 7 RESULTS ...... 8 Overview of the 2012-2014 monitoring effort ...... 8 Table 1. Total linear kilometers of coastline surveyed in the six Black Oystercatcher monitoring regions in 2012-2014...... 8 Figure 1. Overview map of Black Oystercatcher regional monitoring areas in California, 2012-2014...... 9 Table 2. Survey effort as number of observers and survey hours in the six Black Oystercatcher monitoring regions, 2012-2014...... 10 Black Oystercatcher reproductive performance, 2012-2014...... 10 Table 3. Sample sizes for Black Oystercatcher nest success calculations in 2012-2014 (total number of nest attempts, including replacement clutches)...... 10 Table 4. Black Oystercatcher nest success, 2012-2014, expressed as the percentage of nest attempts that fledged at least one chick...... 11 Figure 2. Black Oystercatcher nest success (percentage of attempts that fledged at least one chick) in the six regional monitoring areas, 2012-2014...... 12 Table 5. Sample sizes used for Black Oystercatcher fledging success calculations (number of pairs with known outcomes) in 2012-2014...... 12 Table 6. Fledging Success expressed as total number of Black Oystercatcher chicks fledged per pair in 2012-2014...... 13 Figure 3. Black Oystercatcher fledging success at the six monitoring areas in 2012-2014. . 13 Figure 4. Within-year comparisons of regional Black Oystercatcher average fledging success in 2012-2013...... 14 REGIONAL RESULTS...... 14 Mendocino County...... 14 Table 7. Total linear kilometers of coastline surveyed in the Mendocino County ...... 16 Black Oystercatcher monitoring region in 2012-2014...... 16 Table 8. Sample sizes (individual pairs with known fates) for Black Oystercatcher fledging success calculations in the Mendocino monitoring area, 2012-2014...... 16 Table 9. Black Oystercatcher fledging success (young fledged/pair) in the Mendocino monitoring area, 2012-2014...... 17 Figure 5. Black Oystercatcher fledging success from thirteen areas in Mendocino County, 2012-2014...... 17 Figure 6. Black Oystercatcher mean fledging success in Mendocino County in 2012-2014.18
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San Luis Obispo County (SLO) ...... 18 Table 11. Sample sizes (individual pairs with known fates) for fledging success calculations in San Luis Obispo County Monitoring Area...... 19 Table 12. Black Oystercatcher productivity (young fledged/pair) in San Luis Obispo County Monitoring Area, 2012-2014...... 20 Figure 7. Black Oystercatcher fledging success from seven areas in San Luis Obispo County, 2012-2014...... 20 Sonoma County...... 20 Figure 8. Black Oystercatcher mean fledging success in the Sonoma County monitoring area in 2012-2014...... 21 Monterey County...... 22 Table 13. Total linear kilometers surveyed in the Monterey County monitoring locations in 2012-2014...... 22 San Mateo County...... 22 San Francisco Bay Area ...... 23 Table 14. Total linear kilometers surveyed in the San Francisco Bay area Black Oystercatcher monitoring locations in 2012-2014...... 23 Table 15. Sample sizes (individual pairs with known fates) for fledging success calculations in San Francisco Bay Area Black Oystercatcher monitoring area in 2012-2014...... 24 Table 16. Black Oystercatcher productivity (young fledged/pair) in San Francisco Bay Area monitoring areas, 2012-2014...... 24 DISCUSSION ...... 25 ACKNOWLEDGEMENTS ...... 26 LITERATURE CITED ...... 27 APPENDIX I. Overview map of California counties in which monitoring for Black Oystercatcher reproductive success occurred in 2012-2014...... 28 APPENDIX II. Black Oystercatcher monitoring areas and individual nest sites located in 2012- 2014 in Mendocino County ...... 29 Figure 1. Overview map of Mendocino County monitoring areas in 2012...... 29 Figure 2. Locations of individual nests in the Laguna Point (LP) and Glass Beach (GB) monitoring areas in Mendocino County, 2012...... Error! Bookmark not defined. Figure 3. Locations of individual nests in the GP Mill (GP) and Noyo Harbor (NO) monitoring areas in Mendocino County, 2012...... Error! Bookmark not defined. Figure 4. Locations of individual nests in the Point Cabrillo (PC) monitoring area in Mendocino County, 2012...... Error! Bookmark not defined.
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Figure 5. Locations of individual nests in the Russian Gulch (RG) monitoring area in Mendocino County, 2012...... Error! Bookmark not defined. Figure 6. Locations of individual nests in the Mendocino Headlands (MH) monitoring area in Mendocino County, 2012...... Error! Bookmark not defined. Figure 7. Locations of individual nests in the Spring Ranch (SR), and Little River (LR) monitoring areas in Mendocino County, 2012...... Error! Bookmark not defined. Figure 8. Locations of individual nests in the Navarro Point (NP) monitoring areas in Mendocino County, 2012...... Error! Bookmark not defined. Figure 9. Overview map of Mendocino County monitoring areas in 2013. ... Error! Bookmark not defined. Figure 10. Locations of individual nests in the Hardy Rock monitoring area in Mendocino County, 2013...... Error! Bookmark not defined. Figure 11. Locations of individual nests in the Laguna Point (LP) and Glass Beach (GB) monitoring areas in Mendocino County, 2013...... Error! Bookmark not defined. Figure 12. Locations of individual nests in the Point Cabrillo (PC) monitoring area in Mendocino County, 2013...... Error! Bookmark not defined. Figure 13. Locations of individual nests in the Russian Gulch (RG) monitoring area in Mendocino County, 2013...... Error! Bookmark not defined. Figure 14. Locations of individual nests in Mendocino Headlands (MH) and Mendocino Bay (MBO) monitoring areas in Mendocino County, 2013...... Error! Bookmark not defined. Figure 15. Locations of individual nests in Spring Ranch (SR), and Little River Headlands (LRH) monitoring areas in Mendocino County, 2013...... Error! Bookmark not defined. Figure 16. Locations of individual nests in the Navarro Point (NP) monitoring area in Mendocino County, 2013...... Error! Bookmark not defined. Figure 17. Overview map of Mendocino County monitoring areas in 2014. . Error! Bookmark not defined. Figure 18. Locations of individual nests in the Ten Mile (TM) monitoring area in Mendocino County, 2014...... Error! Bookmark not defined. Figure 19. Locations of individual nests in the Laguna Point (NP) and Glass Beach (GB) monitoring areas in Mendocino County, 2014...... Error! Bookmark not defined. Figure 20. Locations of individual nests in the Point Cabrillo (PC) monitoring area in Mendocino County, 2014...... Error! Bookmark not defined. Figure 21. Locations of individual nests in the Russian Gulch (RG) monitoring area in Mendocino County, 2014...... Error! Bookmark not defined. Figure 22. Locations of individual nests in the Mendocino Headlands (MH) and Mendocino Bay Overlook (MO) monitoring areas in Mendocino County, 2014...... Error! Bookmark not defined.
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Figure 23. Locations of individual nests in the Spring Ranch (SR) and Little River Headlands (LH) monitoring areas in Mendocino County, 2014...... Error! Bookmark not defined. Figure 24. Locations of individual nests in the Navarro Point (NP) monitoring area in Mendocino County, 2014...... Error! Bookmark not defined. APPENDIX III. Black Oystercatcher monitoring area and individual nest sites located in 2012- 2014 in Sonoma County...... Error! Bookmark not defined. Figure 1. Locations of individual nests in the Sea Ranch monitoring area in Sonoma County, 2012...... Error! Bookmark not defined. Figure 2. Locations of individual nests in the Sea Ranch monitoring area in Sonoma County, 2013...... Error! Bookmark not defined. Figure 3. Locations of individual nests in the Sea Ranch monitoring area in Sonoma County, 2014...... Error! Bookmark not defined. APPENDIX IV. Black Oystercatcher monitoring locations and individual nest sites located in 2012-2014 in the San Francisco Bay Area...... Error! Bookmark not defined. Figure 1. Overview map of San Francisco Bay Area monitoring locales in 2012-2014. Note that not all locations were surveyed in each year (see below). .. Error! Bookmark not defined. Figure 2. Location of single nest at the Alameda monitoring location, San Francisco Bay Area, in 2012 and 2014. No nesting occurred in 2013...... Error! Bookmark not defined. Figure 3. Location of single nest at Alcatraz Island monitoring location, San Francisco Bay Area, in 2012...... Error! Bookmark not defined. Figure 4. Location of single nest at Alcatraz Island, San Francisco Bay Area, in 2013. ... Error! Bookmark not defined. Figure 5. Location of individual nests monitored at Alcatraz Island, San Francisco Bay Area, in 2014...... Error! Bookmark not defined. Figure 6. Location of single nest at Marin Headlands, Point Bonita, San Francisco Bay Area in 2012, 2013, and 2014 (same location each year)...... Error! Bookmark not defined. Figure 7. Location of individual nests at East and West Marin Islands (EMI and WMI, respectively), San Francisco Bay Area in 2012...... Error! Bookmark not defined. Figure 8. Location of individual nests at East and West Marin Islands (EMI and WMI, respectively); San Francisco Bay Area, in 2013. No monitoring occurred at this locale in 2014...... Error! Bookmark not defined. Figure 9. Location of the single active nest at the Richardson Bay (Aramburu Island) monitoring area in 2013 and 2014. No nesting occurred at this locale in 2012...... Error! Bookmark not defined. APPENDIX V. Black Oystercatcher monitoring areas and individual nest sites located in 2012- 2014 in San Mateo County...... Error! Bookmark not defined.
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Figure 1. Location of the active nests at the Pescadero Rock monitoring area in San Mateo County in 2014 (Ceja and Hanks 2014). No monitoring occurred at this locale in 2012 or 2013...... Error! Bookmark not defined. Figure 2. Location of the active monitored nests at the Año Nuevo Island monitoring (Carle et al. 2014)...... Error! Bookmark not defined.
INTRODUCTION
The Black Oystercatcher (Haematopus bachmani, BLOY) nests from the Aleutian Islands south to Baja California, Mexico (Andres and Falxa 1995). A long-lived, monogamous shorebird, BLOY are territorial during the nesting season. Breeding habitat is located on marine shorelines in close proximity to foraging areas in the intertidal zone. The most recent population estimate for BLOY indicated a global population of 10,000 individuals; however, a large degree of uncertainty exists due to the lack of systematic surveys for the species (Morrison et al. 2006, Andres et al. 2012, Tessler et al. 2014). The majority (ca. 80%) of the breeding population was believed to occur in the northern portion of the range (Alaska and British Columbia; Tessler et al. 2014).
The first dedicated statewide survey to estimate the BLOY breeding population in California was conducted in 2011 (Weinstein et al. 2014). Results of that study indicated the statewide population at 4,749-6,067 individuals, a much greater number than previously estimated during the course of other seabird studies (888 individuals reported in Carter et al. 1992). Though the 2011 study sampled only a portion (approximately 19%) of California marine coastlines, the survey methodology allows for repeated sampling in future. Importantly, the results of the 2011 survey indicate that California hosts a much higher abundance, and therefore proportion of the breeding population, than previously suspected.
Following the California population estimate completed in 2011, a citizen science nest monitoring program was initiated in 2012 by Audubon California. Major goals of this statewide program are to (1) better understand the demographics of BLOY in California by collecting reproductive data using standardized methodology for a minimum of five contiguous years; (2) conduct a population viability analysis; (3) increase public awareness of BLOY and their habitats by incorporating outreach and education into the monitoring efforts; (4) utilize the five year data set to advance conservation of BLOY and their habitats, and (5) examine the utility of BLOY
Page 6 of 30 reproductive parameters in modeling exercises addressing effects of climate change on rocky intertidal communities in California. In this report we compiled data, calculated summary statistics, and provided details of monitoring areas from the 2012-2014 Black Oystercatcher breeding seasons for use in future analysis and modeling projects.
METHODS
Monitoring methodology. The citizen science nest monitoring effort was led by regional coordinators who organized surveys, provided training, and compiled data sheets. Nesting surveys were conducted using binoculars or spotting scopes from land or boat observation points. Surveys were conducted at least every seven days; in some locations, more frequent (up to daily) observations of selected nests were made. Nesting stage was recorded by identifying the presence or absence of adults, eggs, and chicks. Annual data were submitted to Audubon California via annual reports and/or raw data sheets.
Geographic data. Nest locations were recorded by observers using either handheld GPS units or hard copies of area maps and subsequently incorporated into database. Point counts of single nests were assigned a total linear survey distance of 100 meters. To determine contiguous linear survey distances of monitoring areas which were surveyed as transects, we traced coastline imagery using ArcGIS 10.1 (California Department of Fish and Wildlife).
Parameter definitions. We reported reproductive parameters as follows:
Active nest: nest site with egg laying documented or inferred by incubation posture on more than one nest visit (i.e., at least two weeks). Potential nests are not reported herein.
Nest attempt: Single clutch as evidenced by direct observation of eggs or chicks or by confirmation of incubation at the nest site; note that multiple nest attempts may be made by individual pairs.
Nest success: at least one chick did or did not fledge per nest attempt. We do not distinguish between re-nests herein; the sample size for total nest attempts is therefore higher than that for total nesting pairs.
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Fledging success: Total number of chicks fledged per pair. Fledging was determined either by direct observation or inferred at 38 days post-hatch (Andres and Falxa 1995).
Since most pairs monitored in the study area were not banded, there is an unknown degree of variability when documenting whether sequential nest attempts which occurred in (or in close proximity to) nest attempts that previously failed were made by the same or by different pairs. Generally, in the absence of documented territorial disputes, new clutches that are initiated at or very near to a previous failed attempt were assigned as “relay attempts” by the same pair (i.e. replacement clutches).
Phenology: Because phenology information was not available in standardized format from all areas in 2012-2014, we do not report estimated clutch initiation, hatch, and fledging dates. These data will be available from the 2015 season, and selected information may be incorporated from 2012-2104 in future reports for comparative purposes.
RESULTS
Overview of the 2012-2014 monitoring effort. Nest monitoring was conducted in six main regions in 2012-2014: Mendocino County, Sonoma County, SF Bay area, San Mateo County, Monterey County, and San Luis Obispo County (Figure 1). Total linear survey distances varied among years and locations; an estimated 48 km were surveyed in both 2012 and 2013; survey effort increased to include 80 km of coastline in 2014 (Table 1). Survey effort varied considerably among the six monitoring regions. The total number of surveyors per region ranged from 51 to 66 per year; total survey hours (h) increased annually from 704 h in 2012 to 2,566 h in 2014 (Table 2).
Table 1. Total linear kilometers of coastline surveyed in the six Black Oystercatcher monitoring regions in 2012-2014.
Survey Region 2012 2013 2014
Mendocino County 21.29 19.68 30.67
Sonoma County 17.13 17.13 17.13
San Francisco Bay Area 3.19 5.21 3.84
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San Mateo County 1.39 1.39 1.60
Monterey County nd 0.95 20.49
San Luis Obispo County 4.91 4.13 6.61
Totals 47.91 48.49 80.34
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Figure 1. Overview map of Black Oystercatcher regional monitoring areas in California, 2012-2014.
Table 2. Survey effort as number of observers and survey hours in the six Black Oystercatcher monitoring regions, 2012-2014.
Total Observers Total Survey Hours Area1 2012 2013 2014 2012 2013 2014 Mendocino County 16 18 19 273 500 630 Sonoma County 12 17 12 135 145 155 San Francisco Bay Area 5 5 7 90 144 90 San Luis Obispo County 6 8 10 200 290 450 Monterey County 18 3 18 nd 250 1,255 Totals 57 51 66 704 1,315 2,566 1 Año Nuevo monitoring effort is not included herein.
Black Oystercatcher reproductive performance, 2012-2014. In total, 299 nest attempts (including replacement clutches) with known outcomes from 280 pairs were monitored from 2012-2014 (Table 3). Sample sizes were similar in 2012 and 2013 (88 and 87 nest attempts, respectively) but increased in 2014 by more than 40% to 124 nest attempts. This increase was primarily due to changes in monitoring effort; see individual area results, below, for details.
Nest success in the general regions (the percentage of nest attempts, including replacement clutches, which fledged at least one chick) ranged from 0% to 86% from 2012 to 2014 (Table 4, Figure 2). Overall nest success was similar among years, ranging from 25% to 33%.
Table 3. Sample sizes for Black Oystercatcher nest success calculations in 2012-2014 (total number of nest attempts, including replacement clutches). Area 2012 2013 2014 Total
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Mendocino 33 48 56 137 Monterey 24 5 20 49 San Luis Obispo 1 8 21 41 San Mateo 1 4 7 12 Sonoma 9 15 15 39 SF Bay Area 9 7 5 21 Total (n) 88 87 124 299
Table 4. Black Oystercatcher nest success, 2012-2014, expressed as the percentage of nest attempts that fledged at least one chick.
Area 2012 2013 2014 Total
Mendocino 36% 25% 27% 29% Monterey 21% 40% 25% 24% San Luis Obispo 8% 13% 19% 15% San Mateo 0% 50% 86% 50% Sonoma 56% 27% 53% 44% SF Bay Area 22% 29% 60% 33%
Total Succeeded 28% 25% 33% 29%
Fledging success (FS) during the three year monitoring effort from all areas combined ranged from zero to 1.14 chicks per pair (Tables 5, 6; Figure 3). Fledging success in 2012 was 0.47 chicks fledged per pair (range: zero to 0.89). In 2013, overall FS decreased slightly to 0.41 (range: 0.13 to 0.60). Interestingly, FS was reduced at all areas in 2013 in comparison to 2012 with the exception of Monterey and San Mateo areas. However, monitoring in Monterey was reduced from 24 pairs in 2012 to 5 pairs in 2013 (see individual monitoring area results, below). In 2014, overall FS was 0.48 (range: 0.26 to 1.14). The comparatively high success (1.14) observed in San Mateo County was influenced by the addition of a new monitoring site (FS=1.40 at Pescadero Rock), although the sample size was small at 5 pairs. In total, the three years of monitoring documented 128 fledged chicks from the six monitoring regions.
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Preliminary comparisons among areas indicated no significant differences in mean fledging rates within monitoring years in 2012 or 2013, although fledging rates in Sonoma County in 2012 were higher than in other areas (p>0.01, Figure 4). However, we observed a greater degree of variability in 2014: Mendocino, Monterey, and San Luis Obispo monitoring areas showed similar reproductive success levels, which were significantly lower than those observed in the SF Bay area, San Mateo, and Sonoma County monitoring areas (p<0.01). More work is needed to determine appropriate levels of comparisons among years using a longer time series with standardized sample sizes. Interannual comparisons of fledging success rates within each area are discussed below.
Figure 2. Black Oystercatcher nest success (percentage of attempts that fledged at least one chick) in the six regional monitoring areas, 2012-2014.
Table 5. Sample sizes used for Black Oystercatcher fledging success calculations (number of pairs with known outcomes) in 2012-2014.
Area 2012 2013 2014 Grand Total
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Mendocino 32 44 53 129
Monterey 24 5 15 44
San Luis Obispo 11 8 19 38
San Mateo 1 4 7 12
Sonoma 9 13 15 37
SF Bay Area 8 7 5 20
Total 85 81 114 280
Table 6. Fledging Success expressed as total number of Black Oystercatcher chicks fledged per pair in 2012-2014.
Area 2012 2013 2014 Total
Mendocino 0.59 0.39 0.36 0.43
Monterey 0.25 0.60 0.53 0.39
San Luis Obispo 0.27 0.13 0.26 0.24
San Mateo 0.00 0.50 1.14 0.83
Sonoma 0.89 0.54 0.67 0.68
SF Bay Area 0.50 0.43 1.00 0.60
Total 0.47 0.41 0.48 0.46
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Figure 3. Black Oystercatcher fledging success at the six monitoring areas in 2012-2014.
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Figure 4. Within-year comparisons of regional Black Oystercatcher average fledging success in 2012-2013.
REGIONAL RESULTS.
Mendocino County. Thirteen areas in Mendocino County were monitored in 2012-2014, seven of which were monitored each year (Osello 2012, 2013, 2014). Seven of the monitoring areas in Mendocino County are located in California State Parks land: Laguna Point (LP) and Glass Beach (GB) fall within the MacKerricher State Park boundary, Little River Headlands (LR) and Spring Ranch (SR) are located in the Van Damme State Park, and monitoring occurs in the Russian Gulch (RG), Point Cabrillo (PC), and Mendocino Headlands State Park (MH). Five of these areas also have State Marine Conservation Area (SMCA) designations (MacKerricher, Van Damme, and Russian Gulch State Parks). Point Cabrillo State Park and Ten Mile State Reserve (TM) are further designated as State Marine Reserves (SMR). The Noyo Headlands ([NO], formerly “GP Mill monitoring location is managed by the City of Fort Bragg; the Mendocino Bay Overlook (MO) site is managed by Mendocino County, and the Navarro Point Preserve (NP) is managed by the Mendocino Land Trust. While the State Park, State Marine Reserve, and State Marine Conservation Area designations each confer a specific suite of protections, all areas with the exception of the Ten Mile State Marine Reserve are open to the public for, at a minimum, recreation activities. See http://www.parks.ca.gov/?page_id=27788 for information about levels of protection at each area in the Mendocino monitoring complex.
The monitoring effort in Mendocino County represents the largest geographic area and nest density of the six regions discussed in this report. The total length of coastline surveyed in Mendocino ranged from low of 19.7 km in 2013 to high of 30.7 km in 2014 (Table 7). A total of 162 nest attempts (including replacement clutches) from 154 pairs were documented in Mendocino County from 2012-2014 (Table 8). Just 38 of the 162 nest attempts (28%) ultimately succeeded with at least one chick fledged. Excluding nests with unknown fledging outcomes, the total sample size for the three year period was 139 attempts, including 8 second attempts among 131 pairs.
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Annual fledging success in the region was 0.59 in 2012 (n=32 pairs), 0.39 in 2013 (n=44 pairs), and 0.36 in 2013 (n=55 pairs; Table 9, Figure 5). A total of 55 fledged BLOY were observed in 2012-2014, resulting in a mean three year productivity of 0.44 young fledged per pair (n=131 pairs, SD=0.13).
In 2012, ten areas in Mendocino County were monitored: GB, GP, NO, LP, LR, MH, NP, PC, RG, and SR. There were 43 nest attempts identified from all areas, including 1 replacement clutch. Sample size for fledging calculations was 32 pairs; 19 chicks fledged (FS = 0.59; n=32). The total length of coastline surveyed in 2012 was 21.3 km.
In 2013, ten areas in Mendocino County were monitored: GB, HR, LP, LR, MH, MO, NP, PC, RG, and SR A total of 53 nest attempts were identified, including 3 replacement clutches. Sample size for fledging calculations was 44 pairs; 17 chicks fledged (one from a replacement clutch) with ultimate FS = 0.39 (n=44 pairs). A total of 19.7 km of coastline was surveyed in 2013.
In 2014, ten areas Mendocino County were monitored: GB, LP, LR, MH, MO, NP, PC, RG, SR, and TM. A total of 66 nest attempts were identified, including 3 replacement clutches. Sample size for fledging calculations was 55 pairs. A total of 19 chicks fledged (1 from a replacement clutch) for an overall fledging rate 0.35 FS (n=55 pairs). While fledging success decreased in each of the three monitoring years, there was no significant difference in fledging rates in this small time series (p>0.01, Figure 6). A total of 30.7 km of coastline was surveyed in 2014.
Table 7. Total linear kilometers of coastline surveyed in the Mendocino County Black Oystercatcher monitoring region in 2012-2014.
Monitoring Locale 2012 2013 2014 Glass Beach (GB) 2.63 2.34 2.63 GP Mill/Noyo Harbor (GP/ NO) 4.47 0.00 0.00 Hardy Rock (HR) 0.00 0.10 0.00 Laguna Point (LP) 2.22 2.21 2.22 Little River Headlands (LR) 0.95 1.00 1.00 Mendocino Bay Overlook (MO) 0.00 0.47 0.47 Mendocino Headlands (MH) 2.54 1.88 2.21 Navarro Point (NP) 0.54 0.69 0.54
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Point Cabrillo (PC) 1.47 3.40 4.07 Russian Gulch (RG 5.00 5.69 6.35 Spring Ranch (SR) 1.48 1.91 2.04 Ten Mile (TM) 0.00 0.00 9.15 Total km surveyed 21.29 19.68 30.67
Table 8. Sample sizes (individual pairs with known fates) for Black Oystercatcher fledging success calculations in the Mendocino monitoring area, 2012-2014. Area 2012 2013 2014 Total Glass Beach 6 3 4 13 GP Mill 1 0 0 1 Hardy Rock 0 1 0 1 Laguna Point 3 3 0 6 Little River Headlands 5 6 5 16 Mendocino Bay Overlook 0 1 1 2 Mendocino Headlands 4 2 6 12 Navarro Point 2 3 2 7 Noyo Harbor 0 0 0 0 Point Cabrillo 2 7 7 16 Russian Gulch 4 10 12 26 Spring Ranch 5 8 9 22 Ten Mile 0 0 9 9 Total Pairs 32 44 55 131
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Table 9. Black Oystercatcher fledging success (young fledged/pair) in the Mendocino monitoring area, 2012-2014. Area 2012 2013 2014 Total Glass Beach 0.67 0.00 0.00 0.31 GP Mill 0.00 nd nd 0.00 Hardy Rock nd 0.00 nd 0.00 Laguna Point 0.67 0.00 nd 0.33 Little River Headlands 1.00 0.33 0.00 0.44 Mendocino Bay Overlook nd 0.00 0.00 0.00 Mendocino Headlands 0.75 2.00 0.50 0.83 Navarro Point 0.00 0.00 0.00 0.00 Noyo Harbor nd nd nd nd Point Cabrillo 0.50 0.29 0.57 0.44 Russian Gulch 0.25 0.90 0.83 0.77 Spring Ranch 0.60 0.00 0.22 0.23 Ten Mile nd nd 0.00 0.00 Total 0.59 0.39 0.35 0.42
3.00 2012 2.50 2013 2.00 2014 1.50 1.00 0.50
Young Fledged per Pair per Fledged Young 0.00
Monitoring Area
Figure 5. Black Oystercatcher fledging success from thirteen areas in Mendocino County, 2012-2014.
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Least Squares Means
1.0
0.5
0.0
-0.5
MeanFledgingSuccess
-1.0 2012 2013 2014 Year Figure 6. Black Oystercatcher mean fledging success in Mendocino County in 2012-2014.
San Luis Obispo County (SLO). A total of seven areas were monitored in San Luis Obispo County in 2012-2014 (J. Isaacs unpubl. data). Three areas were monitored annually (Avila Beach, Cayucos, and Estero Bluffs). Offshore rocks in all three areas are managed by BLM, with additional management by City of Avila Beach and County of San Luis Obispo (Avila Beach), City of Cayucos, and California State Parks (Estero Bluffs). The four additional survey areas were managed by City of Morro Bay (Morro Bay), California State Parks (Montana de Oro), City of Pismo Beach (Pismo), and PG&E (Buchon Trail). Total survey lengths were 4.9, 4.3, and 6.6 km in 2012, 2013, and 2014, respectively (Table 10).
Table 10. Total linear kilometers surveyed in the San Luis Obispo County Black Oystercatcher monitoring region, 2012-2014. Locale 2012 2013 2014 Avila Beach 0.10 0.10 0.10 Buchon Trail 0.00 0.00 0.10 Cayucos 1.17 1.17 0.10 Estero Bluffs 3.65 2.77 5.49 Montana de Oro 0.00 0.10 0.63 Morro Bay 0.00 0.00 0.10 Shell Beach 0.00 0.00 0.10 Total km surveyed 4.91 4.13 6.61
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Sample sizes in each area ranged from one to 12 pairs; the Estero Bluffs area had the largest sample size in each year (3-12 pairs; Table 11). Annual nest success increased in each monitoring year: 8%, 13%, and 19% in 2012, 2013, and 2014, respectively (Table 4). The three- year mean fledging rate from all combined areas was 0.22 young fledged per pair (n=42 pairs; SD=0.83; Table 12). Annual reports were not produced for SLO in 2012-2014; data for this report were extracted from field data sheets (J. Isaacs unpubl. data).
Three areas were monitored in SLO in 2012: Avila Beach, Estero Bluffs, and Cayucos. Eleven pairs made 12 nest attempts, just one of which succeeded with 3 fledged chicks. Overall fledging rate was 0.27 (n=12 pairs; Figure 7). Four areas were monitored in 2013 (Avila Beach, Estero Bluffs, Cayucos, and Montana de Oro); 9 active nests; zero re-lay attempts; one chick fledged for FS = 0.11 (n=9 pairs). In 2014, seven areas were monitored in SLO (Avila Beach, Buchon Trail, Estero Bluffs, Cayucos, Morro Bay (North Jetty), Montana de Oro, and Shell Beach); 19 pairs made 21 nest attempts (2 pairs with a second attempt each). Five chicks fledged, all from first attempts, for FS=0.26 (n=19 pairs).
Table 11. Sample sizes (individual pairs with known fates) for fledging success calculations in San Luis Obispo County Monitoring Area.
Area 2012 2013 2014 Total
Avila Beach 1 1 1 3
Buchon Trail 0 0 1 1
Cayucos 4 3 1 8
Estero Bluffs 6 3 12 21
Montana de Oro 0 1 2 3
Morro Bay 0 0 1 1
Shell Beach 0 0 1 1
Grand Total 11 8 19 38
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Table 12. Black Oystercatcher productivity (young fledged/pair) in San Luis Obispo County Monitoring Area, 2012-2014. Area 2012 2013 2014 Total Avila Beach 3.00 0.00 1.00 1.33 Buchon Trail nd nd 2.00 2.00 Cayucos 0.00 0.33 0.00 0.13 Estero Bluffs 0.00 0.00 0.08 0.05 Montana de Oro nd 0.00 0.00 0.00 Morro Bay nd nd 1.00 1.00 Shell Beach nd nd 0.00 0.00 Total 0.27 0.13 0.26 0.24
Figure 7. Black Oystercatcher fledging success from seven areas in San Luis Obispo County, 2012-2014.
Sonoma County. The Sonoma County monitoring area is comprised of a single 17.13 km continuous transect along the Sea Ranch residential community; this transect has been replicated in each monitoring year (D. Hichwa unpubl. data). All BLOY nests in the survey area are on offshore rocks (excepting a historic record of one nest on shore which was not active in 2012-
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2014; D. Hichwa pers. comm.). The Sea Ranch is a privately owned homeowner’s association. Private access is possible and public access is also allowed at several locations along the beaches, four of which have at least one nest on offshore rocks. Only one location (Shell Beach) with two nests seemed to have possible disturbance impacts due to people out on the rocks recreationally due to easy access from shore. At other locations, offshore rocks are inaccessible from the shore. Recreational use by kayakers at Shell Beach also has potential for disturbance, but most nests on offshore rocks appear to be in inaccessible cliff locations.
Overall nest success in the Sea Ranch monitoring area was 44% (range 27% to 56%) in 2012- 2014 (Table 4). Nest success in 2013 was about 50% lower than that observed in both 2012 and 2014. Similarly, fledging success in 2013 was much reduced in comparison to 2012, and improved in 2014, although this variability was not statistically significant (p>0.01, Figure 8). In 2012, 14 nest attempts from 13 pairs were observed in the Sea Ranch monitoring area of Sonoma County. A total of 8 chicks fledged from known fate nests for FS = 0.89 (n=9) in 2012. In the following year (2013), a total of 17 nest attempts from 15 pairs (2 second attempts) were observed. Seven (7) chicks fledged, all from 1st attempts, for a fledging success of 0.47 (n=15).
In 2014, a total of 15 nest attempts (zero relaysLeast) were Squares documented Means; 10 chicks fledged for total FS 0.67 (n=15 pairs). 2
1
0
MeanFledgingSuccess (Sonoma) -1 2012 2013 2014 Year Figure 8. Black Oystercatcher mean fledging success in the Sonoma County monitoring area in 2012-2014.
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Monterey County. Survey areas in Monterey County varied considerably among years. For 2012, we reported results from individual nests monitored, but were unable to reliably determine survey areas. The annual reports prepared for the 2013 and 2014 breeding seasons contain substantial information for these monitoring areas, including notes on disturbance reduction efforts and area characterizations are not further summarized herein (see Ceja et al. 2013, Ceja and Hanks 2013).
In 2012, a total of 24 nest attempts by 22 pairs (2 relays) were monitored. A total of 6 chicks fledged, resulting in fledging success of 0.27. Since monitoring areas changed substantially in subsequent years, we did not report linear survey distance for 2012.
In 2013, only the Pacific Grove area was monitored (Ceja et al. 2013). A total of five active nests produced 3 chicks for FS=0.60. Total linear survey distance was 0.9 km (Table 13).
In 2014, two areas were monitored in Monterey County: Monterey Peninsula and Point Lobos (20.5 km; Table 13; Ceja and Hanks 2014). A total of 20 nest attempts from 15 pairs (including 4 second attempts and one third attempt) produced 8 fledged young (7 from 1st attempts and 1 from a 2nd attempt). Fledging success in 2014 was 0.53 young per pair.
Table 13. Total linear kilometers surveyed in the Monterey County monitoring locations in 2012-2014. Locale 2012 2013 2014 Point Lobos No data 0.0 12.1 Monterey Peninsula No data 0.9 8.4
San Mateo County. Two locations were surveyed in San Mateo County in 2012-2014: Pescadero Rock and Año Nuevo Island (Appendix x). Año Nuevo Island is protected as part of the Año Nuevo State Reserve; extensive restoration has occurred at this location, and annual reproductive information for Black Oystercatchers was collected as part of the associated seabird studies there (Oikonos unpubl. data, Carle et al. 2014). Shoreline lengths for Año Nuevo and Pescadero Rock were estimated at 1.4 and 0.2 km, respectively.
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Fledging success at Año Nuevo was zero in both 2012 and 2013 (n=1 and 4 nests, respectively; Carle et al. 2014); in 2014, 1 chick fledged from 2 pairs (FS=0.5). Pescadero Rock was monitored for the first time in 2014; a total of 7 chicks fledged from 5 pairs there (FS=1.40; Ceja and Hanks 2014).
San Francisco Bay Area. A maximum of six monitoring locations were monitored in 2012- 2014 in the SF Bay area. Alcatraz Island is a popular tourist destination managed by the National Park Service (V. Seher pers. comm.). Aramburu Island is an artificial island in Richardson Bay constructed in the early 1960s; ongoing habitat restoration commenced there in 2010 (http://richardsonbay.audubon.org/aramburu-island). Aramburu Island is protected and managed by Marin County Parks Department (K. Wilcox pers. comm). The Alameda monitoring location is a section of dock adjacent to the Ballena Bay Yacht Club; no formal protection is known to exist currently (V. Nelson, pers. comm.). The Point Bonita monitoring location is a small offshore rock in the small cove of the Marin Headlands and falls under the jurisdiction of the CCNM. East and West Marin Islands are located in the San Pablo Bay and are part of the Marin Islands National Wildlife Refuge managed by the USFWS. At all locations, the entire shoreline is surveyed either from land or boat observation points; annual shoreline lengths ranged from 3.1 to 5.2 in 2012-2014 (Table 14.).
Table 14. Total linear kilometers surveyed in the San Francisco Bay area Black Oystercatcher monitoring locations in 2012-2014. Locale 2012 2013 2014 Alameda 0.0 0.1 0.1 Alcatraz Island 1.4 1.3 1.3 East Marin Island 1.0 0.9 0.0 Point Bonita 0.4 0.4 0.4 Richardson Bay 0.0 2.1 2.1 West Marin Island 0.4 0.4 0.0 Total 3.1 5.2 3.8
A total of 22 nest attempts were documented on 6 islands or offshore rocks from 2012-2014 in the SF Bay area. Three-year average fledging success from all areas combined was 0.64 young fledged per pair (SD=0.31, n=20 pairs; Tables 15,16).
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Table 15. Sample sizes (individual pairs with known fates) for fledging success calculations in San Francisco Bay Area Black Oystercatcher monitoring area in 2012-2014. Area 2012 2013 2014 Total Alameda 1 nd 1 2 Alcatraz Island 1 1 2 4 East Marin Island 4 4 nd 8 Point Bonita 1 1 1 3 Richardson Bay nd 1 1 2 West Marin Island 1 nd nd 1 Grand Total 8 7 5 20
Table 16. Black Oystercatcher productivity (young fledged/pair) in San Francisco Bay Area monitoring areas, 2012-2014. Area 2012 2013 2014 Total Alameda 1.00 nd 0.00 0.50 Alcatraz Island 0.00 0.00 0.50 0.25 East Marin Island 0.00 0.25 nd 0.13 Point Bonita 3.00 2.00 3.00 2.67 Richardson Bay nd 0.00 1.00 0.50 West Marin Island 0.00 nd nd 0.00 Total 0.50 0.43 1.00 0.60
In 2012, five islands or offshore rocks were monitored in the SF Bay area in 2012: Alameda, Point Bonita Cove, Alcatraz Island, East Marin Island, and West Marin Island. Aramburu Island was not monitored in 2012. Four chicks fledged from 9 nest attempts (8 pairs), for an overall reproductive success of 0.50 chicks fledged per pair (n=8). At the Alameda location, One nest attempt was documented at the Alameda monitoring location in 2012 and produced one chick (FS = 1.00). One nest was monitored in Point Bonita Cove in 2012; the nest produced 3 chicks from one nesting attempt. One nest was monitored on Alcatraz Island in 2012, producing a total of zero chicks. A total of 4 nest attempts from 4 pairs were monitored on East Marin Island in 2012; all nests failed. A total of 2 nest attempts from one pair were monitored on East Marin Island in 2012, both of which failed.
Five general areas were monitored in the SF Bay area in 2013; Combined fledging success was 0.43 from the 8 nests (n=7 nests with known fates; zero replacement clutches were documented).
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There were no nest attempts at the Alameda monitoring location in 2013. One nest was monitored in Point Bonita Cove in 2013; the nest produced 2 chicks from one nesting attempt. One nest occurred on both Alcatraz and Aramburu Island in 2013; no young survived to fledge from either location. Five nests were monitored on the Marin Islands in 2013, with 1 chick ultimately fledged (FS=0.25, n=4 nests with known fates).
Four areas were monitored in the SF Bay area in 2014; five nests, each with a single attempt, were documented producing a total of 5 chicks. No monitoring occurred on the Marin Islands in 2014. One nest was monitored in Alameda in 2014, producing zero chicks and no renesting attempts. One nest was monitored in Point Bonita Cove in 2014; the nest produced 3 chicks from one nesting attempt. Two nests with single attempts each were monitored on Alcatraz Island in 2014, producing a total of 1 chick. One chick fledged from a single nest attempt on Aramburu Island in 2014.
DISCUSSION
The Black Oystercatcher statewide reproductive monitoring program was initiated by Audubon California in 2011 and has been a successful example of citizen science advancing ecological knowledge. Information regarding BLOY reproduction in California was scarce prior to this program, and the monitoring effort in 2012-2014 represented a new and rapidly evolving approach to determining basic reproductive parameters for BLOY in California. The statewide BLOY monitoring program was designed to provide a minimum of five contiguous years of standardized data collection. The current report provides summary survey results from the 2012- 2014 breeding seasons.
Annual sample sizes ranged from 87 to 124 nest attempts along 48 to 80 linear kilometers of coastline surveyed between Mendocino County and San Luis Obispo County. Survey results were garnered using a dedicated corps of citizen scientists led by area biologists; annual effort increased from about 700 survey hours in 2012 to over 2,500 hours in 2014. Annual nest success for all areas combined was 28% in 2012, 26% in 2013, and 33% in 2014. Fledging success ranged from a low of 0.41 chicks per pair in 2013 to a high of 0.48 chicks per pair in 2014.
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Sample sizes, survey areas, and reproductive success varied considerably among monitoring areas. We did not attempt to define trends with the limited data herein; future analyses of the full time series will incorporate post-hoc standardization strategies prior to statistical analyses.
Beginning in 2015, we modified the data collection protocol to better standardize metrics including nest failure causalities, disturbance events, geographic descriptors, predator observations, and several other variables. This expanded data collection platform will allow us to create a more explicit picture of BLOY reproduction in California.
The ultimate applications of a contiguous five year (at minimum) data set describing BLOY reproduction are numerous. At the local scale, reliably collected data will help inform managers of areas where intervention may improve reproduction, for example by reducing disturbance through signage, outreach, or other measures. Regionally, a robust estimate of BLOY reproductive parameters collected from a diverse areas along the California coast will inform statewide and rangewide abundance and population viability modeling exercises. Large-scale analyses and modeling of impacts to the California coast, including climate change mediated alterations, will be greatly enhanced by the addition of an upper trophic level organism of the rocky intertidal environment. Finally, the large citizen science component of the program provides a great benefit to conservation efforts by providing education and outreach both to monitoring participants and to those with whom they interact.
ACKNOWLEDGEMENTS
This project would not be possible without the excellent leadership of area coordinators and their cadre of dedicated volunteers. We thank coordinators J. Osello, R. LeValley, T. Fuller for Mendocino data; D. Hichwa for Sonoma County data; V. Seher and W. Legge for San Francisco data; Oikonos Ecosystem Knowledge (R. Carle) for Año Nuevo data and Año Nuevo State Park for supporting the research there; R. Hanks and H. Ceja for Monterey County data, and J. Isaacs for San Luis Obispo data.
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LITERATURE CITED
Andres, B. and G. Falxa. 1995. Black Oystercatcher, Haematopus bachmani. In” Poole, A. & Gill, F. (Eds.). The birds of North America, No. 155. Philadelphia: The Academy of Natural Sciences, and Washington, D.C.: American Ornithologists’ Union. Andres, B.A., P.A. Smith, R.I.G. Morrison, C.L. Gratto-Trevor, S.C. Brown, &C.A. Friis. 2012. Populaiton estimates of North American shorebirds, 2012. Wader Study Group Bull. 119(3): 178-194. Carle, R., J. Beck, D. Calleri and M. Hester. 2014. Seabird conservation and habitat restoration: 2014. Unpublished report to Calif. Dept. of Parks and Recreation, Año Nuevo State Park. Carter, H.R., G.J. McChesney, D.L. Jaques, C.S. Strong, M.W. Parker, J.E. Takekawa, D.L. Jory, and D.L. Whitworth. 1992. Breeding populations of seabirds in California, 1989–1991. Volume I – Population Estimates. Unpublished draft final report, U.S. Fish and Wildlife Service, Northern Prairie Wildlife Research Center, Dixon, California. Ceja, H.J., S. Aroche, and H.E. Hanks. 2013. Black Oystercatcher (Haematopus bachmani) reproductive success: 2013 monitoring report, Point Pinos to Asilomar, Monterey Peninsula, Pacific Grove, California. Unpublished report to Environment for the Americas and California Coastal National Monument. Ceja, H.J. and H.E. Hanks. 2014. Black Oystercatcher (Haematopus bachmani) 2014 reproductive success monitoring, Monterey Peninsula and Point Lobos California Central Coast. Unpublished report to Audubon California and California Coastal National Monument. Morrison, R.I.G., B.J. McCaffery, R.E. Gill, S.K. Skagen, S.L. Jones, G.W. Page, C.L. Gratto- Trevor &B.A. Andres. 2006. Population estimates of North American shorebirds, 2006. Wader Study Group Bull. 111:b67-85. Osello, J. Black Oystercatcher conservation, Mendocino County, CA final report on nesting success in 2012. 2012. Final report to Mendocino Coast Audubon Society. Osello, J. Black Oystercatcher conservation, Mendocino County, CA final report on nesting success in 2013. 2013. Final report to Mendocino Coast Audubon Society. Osello, J. Black Oystercatcher conservation, Mendocino County, CA: final report on nesting success in 2014. 2014. Final report to Mendocino Coast Audubon Society. Tessler, D.F., J.A. Johnson, B.A. Andres, S. Thomas, & R.B. Lanctot. 2014. A global assessment of the conservation status of the Black Oystercatcher Haematopus bachmani. International Wader Studies 20:83-96. Weinstein, A., L. Trocki, R. Leballey, R.H. Doster, T. Distler, & K. Krieger. 2014. A first population assessment of Black Oystercatcher Haematopus bachmani in California. Marine Ornithology 42: 49-56.
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APPENDIX I. Overview map of California counties in which monitoring for Black Oystercatcher reproductive success occurred in 2012-2014.
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APPENDIX II. Black Oystercatcher monitoring areas and individual nest sites located in 2012-2014 in Mendocino County (Note: Redacted for public facing website. Data available through query.)
Figure 1. Overview map of Mendocino County monitoring areas in 2012.
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