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Neotropical Migratory Bird Monitoring Study at Marine Corps Base Camp Pendleton, California—2021 Annual Data Summary

Shannon M. Mendia, Barbara E. Kus, D.T. Bolger, M.A. Patten, D.C. Bostock, K.P. Burnham · U.S. Geological Survey

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Ecosystems Mission Area—Species Management Research Program Prepared in cooperation with Assistant Chief of Staff, Environmental Security, U.S. Marine Corps Base Camp Pendleton

Neotropical Migratory Bird Monitoring Study at Marine Corps Base Camp Pendleton, California—2021 Annual Data Summary

Open-File Report 2024–1024

U.S. Department of the Interior U.S. Geological Survey

Cover. Orange-crowned Warbler (Leiothlypis celata), Yellow-breasted Chat (Icteria virens), and Yellow Warbler (Setophaga petechia) in hand at Marine Corps Base Camp Pendleton. Photographs by Shannon Mendia, U.S. Geological Survey, 2021.

Neotropical Migratory Bird Monitoring Study at Marine Corps Base Camp Pendleton, California—2021 Annual Data Summary By Shannon M. Mendia and Barbara E. Kus

Ecosystems Mission Area—Species Management Research Program Prepared in cooperation with Assistant Chief of Staff, Environmental Security, U.S. Marine Corps Base Camp Pendleton

Open-File Report 2024–1024

U.S. Department of the Interior U.S. Geological Survey

U.S. Geological Survey, Reston, Virginia: 2024

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–392–8545. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov/ or contact the store at 1–888–275–8747. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Mendia, S.M., and Kus, B.E., 2024, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2021 annual data summary: U.S. Geological Survey Open-File Report 2024–1024, 69 p., https://doi.org/10.3133/ofr20241024. ISSN 2331-1258 (online)

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Acknowledgments This work was funded by Environmental Security Department, Resources Management Division, Marine Corps Base Camp Pendleton, California. Data either are not available or have limited availability owing to restrictions of the funding entity (U.S. Marine Corps). Contact Ryan Besser; [email protected], for more information. The authors thank the biologists who assisted in data collection for this project: Lisa Allen, Lesley Handa, Alexandra Houston, Suellen Lynn, Rachelle McLaughlin, Jessica Medina, Elin Pierce, Benjamin Stubbs, Devin Taylor, and Michelle Treadwell.

Contents Acknowledgments��iii Executive Summary��1 Introduction��2 Methods��2 Bird Banding��2 Analyses��5 Population Trends��5 Productivity, Survival, and Population Size��6 Effect of Precipitation on Productivity and Survival��6 Results��7 De Luz Creek��7 Overview of 2021 Captures��7 Population Trends��8 Productivity��8 Santa Margarita River��16 Overview of 2021 Captures��16 Population Trends��17 Productivity��20 Survival��20 Predictors of Population Size��20 Discussion��34 Conclusions��36 References Cited��36 Appendix 1. Alpha Codes, Common Names, and Scientific Names for Species Captured at De Luz Creek and Santa Margarita River, Camp Pendleton, California��39 Appendix 2. Tables for De Luz Creek, Camp Pendleton, California��42 Appendix 3. Tables for Santa Margarita River, Camp Pendleton, California��58

Figures 1. Map showing net locations at De Luz Creek, Marine Corps Base Camp Pendleton, California��3 2. Map showing net locations at Santa Margarita River, Marine Corps Base Camp Pendleton, California��4 3. Graph showing the number of individuals captured per species at De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021��8 4. Graphs showing local adult populations of resident species and migrant species, adjusted for effort: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021��9 5. Graphs showing adult population trends of resident species and migrant species, adjusted for effort: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021��10 6. Graphs showing linear trendlines for local adult populations of resident species and migrant species, adjusted for effort at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021��12 7. Graphs showing annual productivity of focal species and winter precipitation for the associated bio-year: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021��13 8. Graph showing number of individuals captured per species: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2021��17 9. Graphs showing local adult populations of resident species and migrant species, adjusted for effort at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��18 10. Graphs showing adult population trends of resident species and migrant species, adjusted for effort at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��19 11. Graphs showing linear trendlines for local adult populations of resident species and migrant species, adjusted for effort at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��22 12. Graphs showing annual productivity of focal species and winter precipitation for the associated bio-year at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��23 13. Graphs showing model averaged annual adult survival of focal species by sex and winter precipitation for the associated bio-year at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��30

Tables 1. Results of linear regression analyses to model population trends over time for 12 bird species captured at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021��11 2. Logistic regression models for the effect of precipitation on productivity for four bird species captured at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021��15 3. Results of multiple regression analyses to predict productivity for four bird species captured at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021��16

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4. Results of linear regression analyses to model population trends over time for 13 bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��21 5. Logistic regression models for the effect of precipitation on productivity for six bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��26 6. Results of multiple regression analyses to predict productivity for six bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��27 7. Logistic regression models for the effect of year on survival for two resident and four migrant bird species captured at Santa Margarita, Marine Corps Base Camp Pendleton, California, 1998–2021��28 8. Results of multiple regression analyses to predict population size for six bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021��33

Conversion Factors International System of Units to U.S. customary units

Multiply

To obtain

centimeter (cm)

0.3937

inch (in.)

millimeter (mm)

0.039

inch (in.)

meter (m)

3.281

foot (ft)

Length

Datum Horizontal coordinate information is referenced to the World Geodetic System of 1984 (WGS 84).

Abbreviations AICc

Akaike’s Information Criterion for small sample size

KSHB

Kuroshio Shot Hole Borer

MAPS

Monitoring Avian Productivity and Survivorship

MCBCP

Marine Corps Base Camp Pendleton

standard deviation

Neotropical Migratory Bird Monitoring Study at Marine Corps Base Camp Pendleton, California—2021 Annual Data Summary By Shannon M. Mendia and Barbara E. Kus

Executive Summary Two Monitoring Avian Productivity and Survivorship (MAPS) stations were operated at Marine Corps Base Camp Pendleton (MCBCP), California, in 2021: one at De Luz Creek and one at the Santa Margarita River. The stations were established to provide data on Neotropical migratory birds at MCBCP to support the dual missions of environmental stewardship and military readiness. A total of 1,227 individual birds were captured in 2021 between the two stations: 395 at De Luz and 832 at Santa Margarita (both 15 banding days). Of these 1,227 individuals captured, 955 were newly banded (273 at De Luz and 682 at Santa Margarita), 150 were recaptures banded before 2021 (28 at De Luz and 122 at Santa Margarita, excluding recaptures released before reading band number [1 at De Luz and 3 at Santa Margarita]), and 118 were unbanded (93 at De Luz and 25 at Santa Margarita). Return rate in 2021 was much lower than the annual mean at De Luz (1995–2019) and similar to the annual mean at the Santa Margarita station (1998–2020). The sex ratio of known-sex adult birds was skewed toward males at both stations in 2021. Species richness was similar at De Luz from 2019 to 2021, increased at Santa Margarita from 2020 to 2021 and was above annual means at both sites (1995–2019 and 1998–2020, respectively). The most abundant species at De Luz were Wrentit (Chamaea fasciata) and Allen’s Hummingbird (Selasphorus sasin). Song Sparrow (Melospiza melodia) and Common Yellowthroat (Geothlypis trichas) were most abundant at Santa Margarita. Since 2002, we have examined the population trends of 12 species at De Luz and 13 species at Santa Margarita for which numbers of known-age individuals were adequate for statistical analysis. We estimated population size and calculated indices of productivity and survival for a subset of these species with sufficient captures and recaptures for valid parameter estimation—four at De Luz and six at Santa Margarita. We determined that in 2021, abundance of 42 percent (5 of 12) of focal species at De Luz and 38 percent (5 of 13) of focal species at Santa Margarita was below the annual mean abundance. Of the focal species below mean abundance, 40 percent (2 of 5) at De Luz and 60 percent (3 of 5) at Santa Margarita were migrant populations. Of the focal species, 25 (3 of 12) percent at De Luz and 31 percent

(4 of 13) at Santa Margarita had declining population trends during the span of station operation. With few exceptions, these declines appeared to be associated with conditions on the breeding grounds. Annual productivity (calculated as the ratio of juveniles to adults among individual captures) was zero for all focal species at De Luz in 2021. At Santa Margarita, productivity increased from year 2020 to 2021 for Common Yellowthroat, Song Sparrow, and Yellow Warbler (Setophaga petechia) and declined from year 2020 to 2021 for Least Bell’s Vireo (Vireo bellii pusillus), but productivity was above the 1998–2020 mean for all four species, whereas productivity was maintained for Orange-crowned Warbler (Leiothlypis celata) and Yellow-breasted Chat (Icteria virens). Winter precipitation affected productivity of Black-headed Grosbeak (Pheucticus melanocephalus), Common Yellowthroat, and Song Sparrow at De Luz and affected productivity of Common Yellowthroat, Orange-crowned Warbler, Song Sparrow, Yellow-breasted Chat, and Yellow Warbler at Santa Margarita. We calculated the mean annual adult survival for 1998–2020 at Santa Margarita, excluding years when the station was not operated. Survival could not be calculated for De Luz in 2021 because the station was not operated in 2020. Model-averaged annual adult survival ranged from 42 to 66 percent for residents and from 30 to 66 percent for migrants at Santa Margarita. Survival of Common Yellowthroat, Song Sparrow, and possibly Yellow Warbler was found to be affected by winter precipitation. Sex was a significant predictor of survival for Common Yellowthroat, Least Bell’s Vireo, Orange-crowned Warbler, and Yellow-breasted Chat at Santa Margarita, where females were found to have lower survival than males. At Santa Margarita, multiple regression analyses examining adult survival and productivity as predictors of future population size indicated that resident Song Sparrow and migrant Yellow Warbler populations were affected by population size from the previous year, migrant Yellow-breasted Chat populations were affected by productivity from the previous year, and migrant Orange-Crowned Warbler populations were affected by survival from the previous year. Updated previous-year population size predictions could not be calculated for De Luz because the station was not operated in 2020.

2 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Introduction This report is the 22nd annual progress update summarizing the activities of two Monitoring Avian Productivity and Survivorship (MAPS) stations at Marine Corps Base Camp Pendleton (MCBCP or Base). MAPS is an international monitoring program that uses capture and banding data to compile basic demographic parameters of migratory bird species, many of which are imperiled regionally and even globally (DeSante and others, 2005). Age- and sex-specific data on annual survival, reproduction, and recruitment can be gathered and compared across stations to identify population trends for species of interest and can be used to identify proximate factors responsible for trends, in particular, negative trends. In turn, information obtained from long-term monitoring of bird populations can be used to guide management activities intended to maintain or reestablish viable populations throughout the species’ ranges. Two MAPS stations were established at Camp Pendleton in 1995 and operated annually thereafter: one in riparian habitat along De Luz Creek and the other in oak woodland near Case Springs in a mountainous region of the Base. A third station was established in 1998 in riparian habitat along the Santa Margarita River, west of Ysidora Basin, at the site of the former water treatment settling ponds. These stations were established as part of a long-term study of the status of Neotropical migratory birds at Camp Pendleton and are being operated in a manner consistent with other banding stations participating in an effort to monitor birds worldwide. Operation of the Case Springs station ceased after the 1999 season because of low annual capture rates (Kus and Beck, 2001). The following progress report deals exclusively with results from the De Luz Creek and Santa Margarita River stations that have been operated annually since 1995 and 1998, respectively. Neither of these stations were operated in 2003, 2005, 2011, or 2012, and the De Luz station was not operated in 2020 when funding was unavailable. Partway through the 2004 season, a wildfire known as the India fire burned part of De Luz Canyon, including the De Luz station. The fire, which started on May 2, burned for several days, and drastically changed the habitat at the De Luz station. It left little to no herbaceous or shrub vegetation and scorched most trees through the canopy layer. By August 2004, an altered herbaceous layer had returned, and trees and shrubs showed new growth. We continued to operate the De Luz station in 2004 after the fire on a modified basis; nets were operated fewer hours per day in order to minimize sun exposure of birds in nets resulting from the change in vegetation structure. Individual captures, total captures, and capture rates were extremely low because of loss of habitat and reduced net-hours (Kus and Falcone, 2006). In 2006, standard banding operations resumed at the De Luz station.

There were subsequent fires in and around De Luz Canyon, but they did not burn the De Luz station. The Santa Margarita station has never burned. In 2017, heavy winter rains resulted in flooding at the De Luz station, which thinned or removed the understory and deposited sand throughout part of the station. The flooding in 2017 restricted access to the station until mid-May and delayed operations until late in the season. Consequently, adults expected to be captured during that time were missed, skewing adult population size estimates and inflating estimates of productivity.

Methods Bird Banding Following standardized MAPS protocol (DeSante and others, 2021), the Santa Margarita station was operated 1 day during every 10-day netting period (hereafter referred to as period) between April 6 and August 24, 2021, for a total of 15 days (periods). The De Luz station was operated 1 day during every 10-day netting period between April 7 and August 25, 2021, for a total of 15 periods. The first three periods in April were designated as −3, −2, and −1, whereas those between May 1 and August 31 were designated as 1, 2, and so forth to conform to the standard MAPS nomenclature, where station operation begins on May 1. A total of 10 mist nets, placed 60–100 meters (m) apart, were erected at each site in fixed locations, chosen in the first year of the study for their potential to capture birds moving through the vegetation (figs. 1, 2). Net 9 at De Luz was moved in 2017 after winter flooding scoured away the vegetation around it; it was renamed net 19 in accordance with MAPS protocol (fig. 1). After further winter flooding (winter 2018–19), the center of the site was scoured, eliminating nets 5, 6, 7, and 10. With nets 8 and 19 as the southernmost nets, the station was extended north, adding eight new net locations labeled 20–27 (fig. 1). Mist nets were made of 30-millimeter (mm) mesh black nylon and were 12 m long by 2.6 m high with four trammels (pockets) running the length of the net. Nets were suspended from vertical aluminum poles anchored by permanent rebar stakes and covered a vertical area ranging from approximately 0.25 to 2.5 m above the ground. Nets were opened within 30 minutes after dawn and were run for 5 hours, typically until between 1100 and 1200 Pacific Daylight Time (PDT). Nets were not operated during inclement weather, such as rain, heavy wind, or extreme heat or cold. Any deficiency in netting time totaling more than 2.5 hours, because of weather or other events, was corrected by netting for that amount of time on the next available day.

Methods 3 117°19'30"

117°19'15"

117°19'

EXPLANATION 33° 23' 15"

Redding

2019–2021 net locations and identifier

8 1995–2018 net locations and identifier

Sacramento San Francisco

Banding station

CALIFORNIA

27 24

25 26

Banding station

Los Angeles

Study area San Diego

22 21

33° 23'

19 9

7 6

8 10 5

4 3 33° 22' 45"

0.1

0.2 MILES

0.1

0.2 KILOMETERS

Net

Latitude

Longitude

Net

Latitude

Longitude

Net

Latitude

Longitude

33.37737

–117.32429

33.38154

–117.32256

33.38432

–117.31973

33.37866

–117.32378

33.38186

–117.32144

33.38494

–117.32029

33.37945

–117.32311

33.38066

–117.3225

33.38514

–117.32054

33.38001

–117.32328

33.38243

–117.32216

33.38429

–117.3206

33.3803

–117.32259

33.38222

–117.32089

33.384

–117.32048

33.3807

–117.32302

33.38368

–117.32009

33.3855

–117.32032

Figure 1. Net locations at De Luz Creek, Marine Corps Base Camp Pendleton, California. Net coordinates in decimal degrees.

4 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary 117°22'30"

117°22'15"

117°22'

EXPLANATION 9

1998–2021 net locations and identifier Banding station

33° 16' 15"

7 6

2 33° 16'

3 4

Banding station

33° 15' 45"

0 0

Net

Latitude

0.1

0.2 MILES

0.1

0.2 KILOMETERS

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Net

Latitude

Longitude

33.26641

–117.37221

33.26834

–117.3715

33.26701

–117.37269

33.2688

–117.37165

33.26763

–117.37252

33.26787

–117.37036

33.26687

–117.37174

33.26741

–117.37034

33.26764

–117.37135

33.26649

–117.37039

Figure 2. Net locations at Santa Margarita River, Marine Corps Base Camp Pendleton, California. Net coordinates in decimal degrees.

Methods 5 Nets were checked every 30–40 minutes by observers working circuits. Hummingbirds, game birds, and raptors were not banded but were identified to species, age, and sex when possible and released at the capture site. All other birds were removed from nets, held in cloth bags labeled with the net number, and taken to a central processing location within 250 m of the most distant net, where they were banded with federal numbered aluminum bands. Data recorded for each individual caught included age, sex, breeding condition, weight, wing chord, fat deposition, feather wear, and molt status (Pyle, 1997). Birds were held for 5–30 minutes, depending on the number of birds captured during one net run. After processing, juveniles, brooding females, and all Wrentits (Chamaea fasciata) were released in the vicinity of the net in which they had been captured, while all other birds were released at the processing station. Typically, three field personnel operated the De Luz station (hereafter, De Luz) and four operated the Santa Margarita station (hereafter, Santa Margarita). Fieldwork was authorized under Federal Recovery Permit ESPER0004080-0 and Federal Bird Banding Permit 22372 by Lisa Allen, Lesley Handa, Alexandra Houston, Suellen Lynn, Rachelle McLaughlin, Jessica Medina, Shannon Mendia, Elin Pierce, Benjamin Stubbs, Devin Taylor, and Michelle Treadwell.

Analyses All banding data were entered into MAPSPROG, the Institute for Bird Populations (IBP) data entry program, for verification and error checking, which included cross-checking against previous years’ data (Froehlich and others, 2006). Finalized MAPSPROG data were submitted to IBP and analyzed as described in the following section. Bird captures were quantified by species, age, sex, and number of captures for each year. We used the total number of captures (newly banded birds, birds that were captured but not banded [unbanded; including hummingbirds, game birds, raptors, and birds that escaped prior to banding], and previously banded birds [recaptures]) to create a list of captured species and a total count of captures per species for the sites. We intentionally did not band hummingbirds because they are difficult to band and recapture and would require a concentrated effort beyond the scope of a MAPS station. We included hummingbirds in the total count of captures and the captured species list, but we did not include them in further analyses because we could not determine individual identity, and therefore, could not accurately calculate abundance, productivity, or survival. The total number of individuals captured each year included only newly banded birds, unbanded birds, and first-time recaptures of

birds banded at the sites in previous years and represents the number of unique individuals caught, even though some may have been captured more than once during the season. We calculated annual capture rates for each species by dividing the total number of captures by the total number of hours nets were open at the banding station (net-hours) and multiplying this number by 100. Captures per 100 net-hours is a standard unit of measurement used for bird banding analyses. Calculating capture rates in this manner allowed us to account for variability in the number of banding hours each day and make between-year comparisons. We calculated species richness (the number of species captured at the site), relative species abundance (the proportion of all individuals represented by a particular species), sex and age ratios (to determine the demographic composition of the population), productivity (a reproductive index represented by the number of juveniles captured divided by the number of adults captured), adult survival (based on encounter histories and recapture probabilities using Program MARK; White and Burnham, 1999; see “Productivity, Survival, and Population Size” for details), and population trends. Subsets of species were examined for population trends, population composition, productivity, survival, and population size analyses. The species examined differed among the various analyses and were based on the requirements of particular analyses and the methods of past reports. All comparisons with previous years’ data refer to the following reports: Kus, 1995, 1996; Kus and Beck, 1997, 1999, 2000; Kus and Sharp, 2002; Kus and Kisner, 2003; Kus and Falcone, 2006; Howell and others, 2007, 2008; Rogne and others, 2008; Rogne and Kus, 2009, 2010; Madden-Smith and others, 2012; Allen and Kus, 2014, 2015; Madden and others, 2015; Hall and Kus, 2016, 2017; Mendia and others, 2018; Mendia and Kus, 2019.

Population Trends As in past reports, we examined the population trends of 12 breeding species at De Luz and 13 breeding species at Santa Margarita with historically adequate numbers of known-age individuals (Kus and Kisner, 2003; Kus and Falcone, 2006). At the time the species were chosen, the requirements were that the species averaged greater than six captures per year, bred at the stations, and had easily distinguishable age classes (Kus and Kisner, 2003). We used the number of adult captures per 100 net-hours to compare population trends, while accounting for minor differences in annual effort. We considered residents and migrants separately because these two groups experience different conditions affecting their populations. Resident species spend their entire annual cycle at Camp Pendleton, whereas migratory species split the year between Camp Pendleton breeding grounds, migration routes, and distant wintering grounds.

6 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Seven resident species (Bewick’s Wren [Thryomanes bewickii], California Towhee [Melozone crissalis], CommonYellowthroat [Geothlypis trichas], House Wren [Troglodytes aedon], Song Sparrow [Melospiza melodia], Spotted Towhee [Pipilo maculatus], and Wrentit) and five migrant species (Ash-throated Flycatcher [Myiarchus cinerascens], Black-headed Grosbeak [Pheucticus melanocephalus], Least Bell’s Vireo [Vireo bellii pusillus], Pacific-slope Flycatcher [Empidonax difficilis], and Yellow-breasted Chat [Icteria virens]) were selected for consideration of population trends at De Luz. Seven resident species (American Goldfinch [Spinus tristis], Bewick’s Wren, Common Yellowthroat, House Wren, Song Sparrow, Spotted Towhee, and Wrentit) and six migrant species (Black-headed Grosbeak, Least Bell’s Vireo, Orange-crowned Warbler [Leiothlypis celata], Willow Flycatcher [Empidonax traillii], Yellow Warbler [Setophaga petechia], and Yellow-breasted Chat) were selected at Santa Margarita. We used linear regression to analyze long-term population trends of the focal species, with year as the independent variable and individuals captured per 100 net-hours as the dependent variable. Analyses were considered significant if P was less than or equal to (≤) 0.10. For each species with significant trends, we calculated the percent annual change by dividing the slope of the regression line by the mean annual captures per 100 net-hours and multiplying by 100 (Nott and Michel, 2005).

Productivity, Survival, and Population Size To determine the contributions of breeding productivity and annual adult survival to annual population size, we estimated population size and calculated indices of productivity and survival for each year for a subset of bird species with sufficient captures and recaptures for valid parameter estimation. At De Luz, we analyzed productivity for two migrant species (Black-headed Grosbeak and Least Bell’s Vireo) and two resident species (Common Yellowthroat and Song Sparrow). At Santa Margarita, we analyzed productivity and survival for four migrant species (Least Bell’s Vireo, Orange-crowned Warbler, Yellow-breasted Chat, and Yellow Warbler) and two resident species (Common Yellowthroat and Song Sparrow). Productivity was calculated as the number of juvenile captures (hatch-year [HY]) divided by the number of adult captures (after-hatch-year [AHY]) to control for fluctuations in adult population size. We used the number of individual adults captured per 100 net-hours for each species as the relative population estimate for each year. For Santa Margarita, we calculated annual survival of focal species in Program MARK (White and Burnham, 1999), using the ‘RMark’ package (Laake, 2013) in R (R Core Team, 2021). We estimated only adult survival because first-year survival was small and therefore difficult to differentiate from recapture probability. Birds were grouped by sex (female

versus male), and birds of unknown sex were excluded from analyses. For MARK analyses, we created encounter histories for each of the selected species based on if an individual was captured at the station within a particular year. Multiple captures of individuals within a year were counted as a single encounter. We assumed constant recapture probability because we expended a nearly constant effort each year. Because we did not operate the MAPS stations during 2003, 2005, 2011 (operated only during fall migration and therefore not comparable to other years), and 2012, we were unable to calculate annual survival for several years. De Luz was not operated in 2020, so annual survival was not calculated for 2021. We analyzed these data using multiple regression, where the independent variables were the previous year’s population estimate (yearx−1), the previous year’s productivity (yearx−1), and model-averaged survival from the previous year (yearx−1) to the survey year (yearx), and the dependent variable was the survey year’s (yearx) population estimate. To account for effort, we used population estimate per 100 net-hours in these analyses. Analyses were considered significant if P≤0.10.

Effect of Precipitation on Productivity and Survival We examined the effect of winter precipitation on productivity and survival of the focal species at each station because several studies have found it to be an important predictor (Nott and others, 2002; Sillett and Holmes, 2002; Bolger and others, 2005; DeSante and others, 2005; LaManna and others, 2012; Rockwell and others, 2017; Zarzycki, 2017). Monthly precipitation data were gathered from Camp Pendleton’s Lake O’Neill station for years that the Camp Pendleton MAPS stations were operated (Office of Water Resources, 2021). We grouped total precipitation values over two periods of the local rainy season of each bio year (from July to June): from October to December (hereafter, early winter) and from January to March (hereafter, late winter), since timing of precipitation likely affects the timing of increased availability of food resources (seeds, fruits, and insects). We created a set of models using total winter precipitation (early and late winter precipitation combined), early winter precipitation, and late winter precipitation as independent variables, and a model with early and late winter precipitation together as two predictors in the same model, to estimate the regression equation coefficients for each variable while controlling for the other. We used multiple regression to build models and an information-theoretic approach (Akaike’s Information Criterion for small sample size [AICc]) to evaluate support for models that tested the effect of winter precipitation on productivity of focal species (Burnham and Anderson, 2002). We used the productivity values (calculated as stated earlier) for each focal species as dependent variables. Productivity models for De Luz did not include 2004 or 2017 because the effort in those years was inconsistent with other survey years.

Results 7 We also used AICc to evaluate support for models that tested the effect of sex, year (annual variability related to habitat condition, such as wildfire, flooding, hurricanes, and disturbances by other causes), and winter precipitation as predictors of survival of focal species at Santa Margarita. We used logistic regression in a mark-recapture modeling framework to build models. First, we generated a constant survival model to serve as a reference. We then modeled sex, year, and winter precipitation and evaluated support for the models relative to the constant survival. The best-fitting model was selected from a set of models using AICc. Models were considered well supported if they were within 2 AICc of the highest-ranked (top) model (ΔAICc was less than 2), AIC weight that was greater than 0.05, and parsimony (favoring simpler models over more complex models with similar support). We estimated productivity and survival from the top model, unless more than one model in the model set had a ΔAICc value of less than 2, in which case we averaged the parameters of all the models in the model set using the ‘MuMIn’ package (version 1.43.17; Barton, 2020) in R (R Core Team, 2021) for productivity and the ‘RMark’ package (Laake, 2013) in R (R Core Team, 2021) for annual survival estimates (Burnham and Anderson, 2002).

Results De Luz Creek Overview of 2021 Captures From April 7 to August 25, 2021, 395 individuals of 42 species were captured during 710.6 net-hours (operation of one net for 1 hour; unidentified species not included in individual or species total; see appendix 1, table 1.1 for common and taxonomic species names of alpha codes used in tables and figures; appendix 2, tables 2.1, 2.2). The number of individuals captured in 2021 decreased by 25 percent from 2019 but was higher than the annual mean (±standard deviation [SD]) of 372±93 individuals (appendix 2, table 2.1) during years of standard banding operations (1995–2002, 2006–10, 2013–16, 2018, and 2019). Species richness stayed at 42 species in 2019 and 2021 and was higher than the annual mean (±SD) of 40±3 species (1995–2002, 2006–10, 2013–17, 2018, and 2019). One new species, Black-throated Gray Warbler (Setophaga nigrescens), was captured at De Luz in 2021, increasing the station total to 81 species. Overall captures, including recaptures of some individuals, totaled 443; 24 percent less than in 2019. Of those 443 captures, 395 were individual captures, with 273 new individuals captured, 29 individuals recaptured from previous years (including 1 recapture that escaped

before reading its band number), and 93 unbanded individuals (appendix 2, tables 2.1, 2.3). Mean capture rate over all dates was 0.6 captures per net-hour (range 0.3–1.0 captures per net-hour), 25 percent lower than in 2019 (appendix 2, table 2.2). Of the species making up at least 5 percent of the total number of individuals captured, Wrentit and Allen’s Hummingbird (Selasphorus sasin) were the most abundant species captured (49 and 36 individuals, respectively). California Towhee was the third most abundant species (29 individuals), Spotted Towhee was the fourth most abundant species captured (27 individuals), Anna’s Hummingbird (Calypte anna) and Black-headed Grosbeak were tied for the fifth most abundant species (both with 23 individuals), and Bushtit (Psaltriparus minimus) and Song Sparrow were tied for the sixth most abundant species (both with 20 individuals; fig. 3; appendix 2, table 2.1). These eight species together accounted for 57 percent of all individuals captured at De Luz in 2021. The sex ratio of adults of known sex (N=217) was skewed toward males (58:42, M:F; appendix 2, table 2.4). The proportion of juveniles among birds captured in 2021 was 20 percent, 21 percent lower than the 1995–2019 mean (±SD) of 25±16 percent (not including 2017, when juvenile numbers were inflated because of delayed entry to the station). A total of 67 juveniles of 15 species were captured. The species making up at least 5 percent of the total number of juveniles captured were Allen’s Hummingbird, Anna’s Hummingbird, Costa’s Hummingbird (Calypte costae), Bushtit, and Bewick’s Wren; these five species made up 82 percent of all juveniles captured at De Luz in 2021. Of the individual birds captured at the station, 76 percent (300/395) were banded, either in 2021 or in previous years (excludes 1 recapture that escaped before reading its band number; appendix 2, tables 2.1, 2.3). A total of 93 birds were not banded, 83 of which were hummingbirds and 5 of which were game birds. The remaining five birds escaped before banding. Capture rates were highest at 100 captures per 100 net-hours in early May during MAPS period 1, coinciding with migration at this time of year, and in mid-July during MAPS period 8 (appendix 2, table 2.2). Peak species richness of 22 species was seen in early May during MAPS period 1 (appendix 2, table 2.5). A total of 29 individual birds, 7 percent of all individuals captured (banded and unbanded; 29/395), were banded in previous years at De Luz (appendix 2, tables 2.1, 2.3), which was 48 percent lower than the mean annual return rate (±SD) from 1996 to 2019 of 12±5 percent. All recaptures were originally banded from 2016 to 2019. Of the recapture total, 52 percent consisted of Song Sparrows and Spotted Towhees (with seven individuals each). The two oldest individuals recaptured in 2021, both at least 6 years old and banded as adults in 2016, were a Wrentit of unknown sex and a male Bullock’s Oriole (Icterus bullockii; appendix 2, table 2.3).

8 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Species left of this line each account for 5 percent or more of the individuals captured

27 23 23 20 20

13 9 9 9

7 7 7

5 5 5

4 4 4 4 4 4 4

3 3 3

2 2 2 2 2

1 1 1 1 1 1 1

WREN ALHU CALT SPTO ANHU BHGR BUSH SOSP COHU BEWR HOOR ACWO ATFL BUOR AUWA CATH PSFL RUHU COYE LEGO SWTH CAQU HOFI HOWR PHAI RCSP WIWA YEWA LBVI LISP NUWO HETH OATI OCWA WETA YBCH BTYW CAKI CASJ MGWA MODO NOMO UNHU

All unique individuals captured, including adults and young

Species

Figure 3. Number of individuals (banded and unbanded) captured per species at De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes.

Population Trends Of the focal species, 33 percent (4/12) had population sizes above their 1995–2019 annual means in 2021, as measured by the number of adult individuals captured per 100 net-hours (annual means calculated without 2004 or 2017; figs. 4, 5). Among residents, three species (43 percent) were above their annual means, whereas only one migrant species (20 percent) was above the annual mean. Of the five focal species with populations below their annual means (42 percent), three were residents and two were migrants. Three species (25 percent) had population sizes in 2021 that were comparable to their 1995–2019 annual means. Results from linear regression showed significantly decreasing trends for three of the 12 focal species (25 percent). Common Yellowthroat declined by 4.7 percent per year, Song Sparrow declined by 3.5 percent per year, and Yellow-breasted Chat declined by 8.1 percent per year. No significant trend was detected for nine species (75 percent; Bewick’s Wren, California Towhee, House Wren, Spotted Towhee, Wrentit,

Ash-throated Flycatcher, Black-headed Grosbeak, Least Bell’s Vireo, and Pacific-slope Flycatcher; models were considered significant if P≤0.10; table 1; figs. 4–6). Of the species in decline, 33 percent were migrants and 67 percent were resident populations (table 1; figs. 4–6).

Productivity The observed productivity in 2021 was zero young per adult for residents Song Sparrow and Common Yellowthroat and migrants Black-headed Grosbeak and Least Bell’s Vireo, because no juveniles of these species were captured in 2021 (fig. 7). Winter precipitation had a positive effect on productivity of all focal species at De Luz except Least Bell’s Vireo (tables 2, 3). Total winter precipitation predicted Black-headed Grosbeak and Song Sparrow productivity, and total winter precipitation and late winter precipitation predicted Common Yellowthroat productivity (P<0.10).

Results 9 A

12.0

Individuals captured (adults), per 100 net-hours

Mean 1995–2019 2021 10.0

8.0

6.0

4.0

2.0

0.0

Individuals captured (adults), per 100 net-hours

4.0 3.5

BEWR

CALT

COYE

HOWR

SOSP

SPTO

WREN

Mean 1995–2019 2021

3.0 2.5 2.0 1.5 1.0 0.5 0.0

ATFL

BHGR

LBVI

PSFL

YBCH

Figure 4. Local adult populations of A, resident species and B, migrant species, adjusted for effort: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021 (banded birds only; excludes 2017). Error bars represent standard deviations. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes.

10 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary A

Individuals captured (adults), per 100 net-hours

BEWR

CALT

COYE-

HOWR

SOSP-

SPTO

WREN

16 14 12 10 8 6 4 2 0 Year

B Individuals captured (adults), per 100 net-hours

6 ATFL

BHGR

LBVI

PSFL

YBCH-

0 Year

Figure 5. Adult population trends of A, resident species and B, migrant species, adjusted for effort: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021 (banded birds only). Significant (P≤0.10) negative trends are denoted by “−” in the species label. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviation: ≤, less than or equal to.

Results 11 Table 1. Results of linear regression analyses to model population trends over time for 12 bird species captured at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021. [Population estimates accounted for effort. Abbreviations: β, Parameter estimates; SE, standard error; P, p-values; R2, model explaining population trends over time; —, no data; <, less than; ≤, less than or equal to]

Focal species

Parameter

45.78

0.34

0.21

Residents Bewick's Wren

Intercept Year

−0.022

0.02

0.36

—

California Towhee

Intercept

−52.730

54.75

0.35

0.22

Year

0.027

0.03

0.33

—

Common Yellowthroat

Intercept

569.053

178.15

1<0.01

0.59

Year

−0.281

0.09

10.01

—

Intercept

−35.907

46.46

0.45

0.18

Year

0.019

0.02

0.43

— 0.53

House Wren Song Sparrow Spotted Towhee Wrentit

44.916

Intercept

365.635

134.04

10.01

Year

−0.180

0.07

10.01

—

Intercept

30.862

63.77

0.63

0.10

Year

−0.014

0.03

0.66

—

Intercept

−5.842

103.04

0.96

0.02

Year

0.005

0.05

0.93

—

Migrants Ash-throated Flycatcher

Intercept

30.937

21.94

0.17

0.30

Year

−0.015

0.01

0.19

—

Intercept

73.412

68.86

0.30

0.23

Year

−0.036

0.03

0.31

—

Intercept

−4.933

33.37

0.88

0.04

Year

0.003

0.02

0.86

—

Pacific-slope Flycatcher

Intercept

32.581

40.44

0.43

0.18

Year

−0.016

0.02

0.44

—

Yellow-breasted Chat

Intercept

326.122

50.20

1<0.001

0.83

Year

−0.161

0.03

1<0.001

—

Black-headed Grosbeak Least Bell's Vireo

1Significant parameter (P≤0.10).

12 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary A Individuals captured (adults), per 100 net-hours

18 16

BEWR

CALT

COYE-

HOWR

SOSP-

SPTO

WREN

14 12 10 8 6 4 2 0

Year B Individuals captured (adults), per 100 net-hours

6 ATFL

BHGR

LBVI

PSFL

YBCH-

5 4 3 2 1 0

Year Figure 6. Linear trendlines for local adult populations of A, resident species and B, migrant species, adjusted for effort at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021 (banded birds only; excludes 2017). Significant (P≤0.10) negative trends are denoted by “−” in the species label. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviation: ≤, less than or equal to.

Results 13

Common Yellowthroat

12.0

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar)

Productivity 50 8.0 40 6.0 30 4.0 20 2.0

Precipitation, in centimeters

Productivity, in number young per adult

10.0

** *

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Song Sparrow

12.0

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar)

Productivity 50 8.0 40 6.0 30 4.0 20 2.0

** *

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Precipitation, in centimeters

Productivity, in number young per adult

10.0

Year

Figure 7. Annual productivity of focal species and winter precipitation for the associated bio-year (total winter is October–March, early winter is October–December, and late winter is January–March): De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021. Intervals affected by lack of banding denoted by * and intervals with only migration banding denoted by ** (banded birds only).

14 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Least Bell's Vireo

12.0

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar)

Productivity 50 8.0 40 6.0 30 4.0 20 2.0

** *

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Precipitation, in centimeters

Productivity, in number young per adult

10.0

Year

Black-headed Grosbeak

12.0

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar)

Productivity 50 8.0 40 6.0 30 4.0 20 2.0

** *

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Figure 7.—Continued

Precipitation, in centimeters

Productivity, in number young per adult

10.0

Results 15 Table 2. Logistic regression models for the effect of precipitation on productivity for four bird species captured at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021 (excluding 2004 and 2017 because of inconsistency in survey effort). [Models are ranked from best to worst based on Akaike’s Information Criterion for small samples (AICc), difference between AICc of model and AICc of the highest-ranked (top) model (ΔAICc), and Akaike weights (w). AICc is based on −2×loge likelihood (logLik) and the number of parameters (K) in the model. Abbreviation: +, plus]

Model

logLik

AICc

ΔAICc

Common Yellowthroat Total winter precipitation

−19.2

0.56

Late winter precipitation

−20.1

47.7

1.68

0.24

Early winter precipitation+late winter precipitation

−19.1

48.8

2.87

0.13

Early winter precipitation

−21.3

50.2

4.22

0.07

Early winter precipitation

−20.7

48.9

0.37

Total winter precipitation

−20.9

49.3

0.39

0.31

Early winter precipitation+late winter precipitation

−19.8

50.2

1.28

0.2

Late winter precipitation

−21.8

51.1

2.19

0.12

Song Sparrow

Black-headed Grosbeak Early winter precipitation

−18.1

43.6

0.58

Total winter precipitation

−19.3

2.32

0.18

Early winter precipitation+late winter precipitation

−18

46.4

2.76

0.15

Late winter precipitation

−19.9

47.3

3.63

0.09

Least Bell’s Vireo Total winter precipitation

−16.3

40.3

0.36

Early winter precipitation

−16.5

40.7

0.39

0.29

Late winter precipitation

−16.6

40.9

0.61

0.26

Early winter precipitation+late winter precipitation

−16.2

43.2

2.89

0.08

16 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 3. Results of multiple regression analyses to predict productivity for four bird species captured at De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021 (excluding 2004 and 2017 because of inconsistency in survey effort). [Model-averaged parameter estimates (β), standard error (SE), 95-percent (%) confidence intervals (CI), Z-values (Z), and P-values (P) averaged over all models with ΔAICc<2. Abbreviation: <, less than; ≤, less than or equal to]

Parameter

95% CI

−0.589–0.585

0.01

Common Yellowthroat Intercept

−0.002

0.3

Late winter precipitation

0.024

0.011

0.003–0.046

2.18

10.03

Total winter precipitation

0.024

0.006

2.56

10.01

Intercept

0.03

−0.57–0.634

0.1

0.92 10.06

Song Sparrow 0.31

Early winter precipitation

0.06

0.03

−0.002–0.113

1.91

Late winter precipitation

0.01

−0.007–0.035

1.31

0.19

Total winter precipitation

0.02

0.01

0.001–0.039

2.08

10.04

Black-headed Grosbeak Intercept

−0.002

Early winter precipitation

0.049

0.231 0.024

−0.455–0.452 −0.01

0.99

0.003–0.096

2.07

10.05

Least Bell's Vireo Intercept

0.12

0.26

−0.38–0.63

0.48

0.63

Early winter precipitation

0.03

−0.03–0.08

0.32

Late winter precipitation

0.01

−0.01–0.03

0.91

0.36

Total winter precipitation

0.01

−0.01–0.03

1.15

0.25

1Significant parameter (P≤0.10).

Santa Margarita River Overview of 2021 Captures From April 6 to August 24, 2021, 832 individuals of 38 species were captured during 798 net-hours (appendix 3, tables 3.1, 3.2; unidentified species not included in species total). The number of individuals captured in 2021 increased by 38 percent from 2020 and was 36 percent higher than the annual mean (±SD) of 610±153 individuals (appendix 3, table 3.1) during years of standard banding operations (1998–2002, 2006–10, 2013–16, 2018, and 2019). Species richness increased to 38 species between 2020 and 2021 and was higher than the annual mean (±SD) of 32±5 species. The station total for all years was at 67 species in 2021. Overall captures, including recaptures of some individuals, totaled 1,032, which is 42 percent more than in 2020. Of those 1,032 captures, 682 were new individuals banded, 125 were individuals recaptured from previous years (including 3 recaptures that escaped before reading their band numbers and 1 recapture that was originally recorded as a lost band in 2019), and 25 were unbanded individuals (appendix 3, table 3.3). Overall capture rates by date ranged from 0.7 to

2.4 captures per net-hour for an average (±SD) capture rate of 1.4±0.6 per net-hour, 17 percent higher than in 2020 (appendix 3, table 3.2). Of the species consisting of at least 5 percent of the total number of individuals at Santa Margarita in 2021, Song Sparrow was the most abundant species, with 236 individual captures representing 28 percent of all individuals captured. Common Yellowthroat was the second most abundant species, with 222 individuals representing 27 percent of all individuals. The third most abundant species was Orange-crowned Warbler (77 individuals), and Least Bell’s Vireo (39 individuals) was the fourth most abundant species. Together, these four species consisted of 69 percent of individual captures at Santa Margarita in 2021 (fig. 8; appendix 3, tables 3.1, 3.4). The sex ratio of adults of known sex (N=387) was slightly skewed toward males (55:45, M:F; appendix 3, table 3.4). The proportion of juveniles in the known-age population in 2021 was 40 percent, 18 percent above the annual mean (±SD) of 34±14 percent from 1998 to 2020. The juvenile population consisted of 335 individuals of 20 species. Song Sparrow and Common Yellowthroat were by far the most abundant species among juveniles, with 124 and 114 juveniles captured, respectively. These 2 species consisted of 37 percent and 34 percent, respectively, of juveniles captured at the Santa Margarita station.

Results 17

236 222

Species left of this line each account for 5 percent or more of the individuals captured

200

150

100 77

26 24

22 19 19

15 13

SOSP COYE OCWA LBVI WREN YEWA SPTO WIWA BUSH YBCH HOWR SWTH PSFL LEGO BEWR WAVI ALHU DOWO HUVI NUWO CATH HOFI ATFL AMGO HETH HOOR MODO TOWA UNHU WEWP ANHU BHGR CLSW COHU LAZB LISP MGWA TRES WIFL

All unique individuals captured, including adults and young

250

Species

Figure 8. Number of individuals (banded and unbanded) captured per species at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2021. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes.

Of the individual birds captured at the station, 96 percent (802/833) were banded in 2021 or recaptured from previous years. This excludes three recaptures that escaped before reading their band numbers: one Common Yellowthroat originally recorded as a lost band in 2019 from a data loss, and two recaptured juvenile Least Bell’s Vireos that were banded at a nearby nest monitoring survey area at MCBCP as nestlings in 2021 (appendix 3, tables 3.1, 3.3). A total of 25 birds were not banded: 9 were hummingbirds and 2 were game birds. The remaining 14 birds escaped before banding. Capture rates peaked at 2.4 captures per net-hour in mid-May during MAPS period 2, coinciding with migration at this time of year (appendix 3, table 3.2). Species richness among captures peaked in mid-May, with 23 species (MAPS period 2), also attributable to species migrating through the area at this time of year (appendix 3, table 3.5). There were 120 birds, 14 percent of all individuals captured (banded and unbanded; 120/832; excludes 3 recaptures that escaped before reading their band numbers and 1 recapture that was originally recorded as a lost band; appendix 3, table 3.3), that were banded in previous years at the Santa Margarita station, slightly below the mean (±SD)

annual return rate from 1999 to 2020 of 16±5 percent. Song Sparrow, Common Yellowthroat, and Orange-crowned Warbler together consisted of 78 percent of all recaptures from previous years. The oldest individual recaptured at the Santa Margarita station in 2021 was a Wrentit that was at least 9 years old, originally banded in 2013.

Population Trends Of the focal species, 38 percent (5/13) had population sizes below their 1998–2020 annual means in 2021, as measured by the number of individuals captured per 100 net-hours (figs. 9, 10). Among residents, two species (29 percent of focal resident species) were below their annual means, and three migrant species (50 percent of focal migrant species) were below their annual means. Of the six species with populations above their annual means (46 percent of all focal species), three were residents and three were migrants. Two species, residents House Wren and Spotted Towhee, had population sizes in 2021 that were comparable to their 1998–2020 annual means.

18 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Individuals captured (adults), per 100 net-hours

35.0

30.0

25.0

20.0

15.0

10.0

5.0

0.0

Mean 1998–2020 2021

AMGO

BEWR

COYE

HOWR

SOSP

SPTO

WREN

12.0 Mean 1998–2020

Individuals captured (adults), per 100 net-hours

2021 10.0

8.0

6.0

4.0

2.0

0.0

BHGR

LBVI

OCWA

WIFL

YBCH

YEWA

Figure 9. Local adult populations of A, resident species and B, migrant species, adjusted for effort at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021 (banded birds only). Error bars represent standard deviations. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes.

Results 19 A

60 Individuals captured (adults), per 100 net-hours

AMGO-

BEWR

COYE

HOWR+

SOSP

SPTO+

YBCH

YEWA-

WREN+

Year B

14 Individuals captured (adults), per 100 net-hours

BHGR-

LBVI

OCWA

WIFL-

12 10 8 6 4 2 0

Year Figure 10. Adult population trends of A, resident species and B, migrant species, adjusted for effort at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021 (banded birds only). Significant (P≤0.10) positive trends are denoted by + and negative trends are denoted by “−” in the species label. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviation: ≤, less than or equal to.

20 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Results from linear regression showed significantly decreasing long-term trends for four focal species (31 percent). American Goldfinch declined by 12.7 percent per year, Black-headed Grosbeak declined by 8.9 percent per year, Willow Flycatcher declined by 13.7 percent per year, and Yellow Warbler declined by 5.4 percent per year. Significantly increasing trends were detected for three species (23 percent). House Wren increased by 3.9 percent per year, Spotted Towhee increased by 2.4 percent per year, and Wrentit increased by 4.8 percent per year. No significant trend was detected for six species (46 percent; Bewick’s Wren, Common Yellowthroat, Song Sparrow, Least Bell’s Vireo, Orange-crowned Warbler, and Yellow-breasted Chat; models were considered significant if P≤0.10; table 4; figs. 9–11). Of the species in decline, 75 percent (3/4) were migrants and 25 percent (1/4) were resident species.

Productivity The observed productivity in 2021 increased relative to 2020 for all resident and one migrant focal species but decreased for the other three migrant focal species (fig. 12). Resident Common Yellowthroat productivity increased to 1.1 young per adult, 11 percent higher than the annual mean (±SD) of 1.0±0.9; resident Song Sparrow productivity increased to 1.1 young per adult, 2 percent higher than the annual mean of 1.1±1.1. Productivity of migrant Orange-crowned Warbler remained at 0.4 young per adult equal to the annual mean of 0.4±0.3. Migrant Yellow-breasted Chat productivity remained at 0.1 young per adult, 81 percent lower than the annual mean of 0.3±0.5. Productivity increased to 0.2 young per adult for migrant Yellow Warbler, 100 percent higher than the annual mean of 0.1±0.1. Migrant Least Bell’s Vireo productivity decreased to 0.6 young per adult but was 40 percent higher than the annual mean of 0.4±0.3. Winter precipitation had a positive effect on the productivity of all focal species at the Santa Margarita station except Least Bell’s Vireo (tables 5, 6). Song Sparrow, Orange-crowned Warbler, Yellow-breasted Chat, and Yellow Warbler productivity was predicted by total winter precipitation (Song Sparrow, Orange-crowned Warbler, and Yellow-breasted Chat: P<0.10; Yellow Warbler: P=0.10). Common Yellowthroat productivity was predicted by total, early, and late winter precipitation (P<0.01).

Survival Top models of adult survival were different among focal species (table 7). The top models for resident Common Yellowthroat included sex and a weak effect of total winter

precipitation. Survival estimates were higher for males than females and increased with increasing total winter precipitation. Although the top models for resident Song Sparrow included early winter precipitation and early winter plus late winter precipitation, examination of 95-percent confidence intervals of the beta estimates indicated that early winter precipitation was the stronger driver of Song Sparrow survival, which increased with increased early winter precipitation. The top predictor for migrants Least Bell’s Vireo, Orange-crowned Warbler, and Yellow-breasted Chat survival was sex, where survival estimates were higher for males than for females. Yellow Warbler survival was best modelled as constant. Models with winter precipitation and sex were within 2 units of AICc but were not parsimonious, and these variables were not found to be significant contributors to the models based on an examination of the 95 percent confidence intervals of the beta estimates. Model averaged annual adult survival ranged from 42 to 66 percent for residents and from 30 to 66 percent for migrants at Santa Margarita (fig. 13). Mean model averaged annual survival from 1998 to 2021 was higher for males than females in all focal species except Yellow Warbler, where survival (±SD) did not differ between the sexes (Common Yellowthroat: female 43±2 percent, male 47±2 percent; Song Sparrow: female 55±6 percent, male 56±6 percent; Yellow-breasted Chat: female 31±0.4 percent, male 48±0.4 percent; Least Bell’s Vireo: female 41±0.05 percent, male 66±0.05 percent; Orange-crowned Warbler: female 42±1 percent, male 57±1 percent; and Yellow Warbler: female 34±1 percent, male 34±1 percent).

Predictors of Population Size Adult population size in the previous year was a significant predictor for Yellow Warbler population size (R2=0.61, P<0.10; table 8). Adult survival from the previous year was a significant predictor of population size for Song Sparrow and Orange-crowned Warbler (Song Sparrow: R2 = 0.66; P<0.10; Orange-crowned Warbler: R2=0.58, P<0.10). Productivity from the previous year was a significant predictor of Yellow-breasted Chat population size (R2=0.67; P<0.10). However, neither adult survival, productivity, nor adult population size from the previous year were significant predictors of Common Yellowthroat or Least Bell’s Vireo population size (Common Yellowthroat: R2=0.38; P>0.10; Least Bell’s Vireo: R2=0.15, P>0.10).

Results 21 Table 4. Results of linear regression analyses to model population trends over time for 13 bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. [Population estimates accounted for effort. Abbreviations: β, Parameter estimates; SE, standard error; P, p-values; R2, model explaining population trends over time; —, no data; <, less than; ≤, less than or equal to]

Focal species

Parameter

38.23

1<0.001

0.88 —

Residents American Goldfinch Bewick's Wren Common Yellowthroat House Wren

Intercept Year

−0.149

0.02

1<0.001

Intercept

0.192

45.53

1.00

0.01

Year

0.001

0.02

0.97

—

Intercept

239.944

485.12

0.63

0.11

Year

−0.109

0.24

0.66

—

−146.371

78.43

10.08

0.41

0.074

0.04

10.07

—

Intercept Year

Song Sparrow Spotted Towhee

Intercept

71.4

695.74

0.92

0.02

Year

−0.026

0.35

0.94

—

33.05

1<0.001

0.67 —

Intercept Year

Wrentit

299.866

Intercept Year

−123.074 0.063

0.02

1<0.001

−358.950

77.37

1<0.001

0.74

0.180

0.04

1<0.001

—

Migrants Intercept

48.499

16.80

10.01

0.56

Year

−0.024

0.01

10.01

—

Least Bell's Vireo

Intercept

−5.599

58.29

0.92

0.04

Year

0.004

0.03

0.88

—

Orange-crowned Warbler

Intercept

−22.345

121.59

0.86

0.06

Year

0.015

0.06

0.80

—

Willow Flycatcher

Intercept

84.070

17.16

1<0.001

0.75

Year

−0.042

0.01

1<0.001

—

Yellow-breasted Chat

Intercept

−23.962

47.59

0.62

0.13

Year

0.013

0.02

0.58

—

Yellow Warbler

Intercept

246.707

64.97

1<0.01

0.66

Year

−0.122

0.03

1<0.01

—

Black-headed Grosbeak

1Significant parameter (P≤0.10).

22 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary A

60 Individuals captured (adults), per 100 net-hours

AMGO-

BEWR

COYE

HOWR+

SOSP

SPTO+

WREN+

Year B

14 Individuals captured (adults), per 100 net-hours

BHGR-

LBVI

OCWA

WIFL-

YBCH

YEWA-

12 10 8 6 4 2 0

Year Figure 11. Linear trendlines for local adult populations of A, resident species and B, migrant species, adjusted for effort at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021 (banded birds only). Significant (P≤0.10) positive trends are denoted by + and negative trends are denoted by “−” in the species label. See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviation: ≤, less than or equal to.

Results 23 Common Yellowthroat

5.0

Productivity, in number young per adult

4.0 3.5

Total winter precipitation (Oct–Mar)

Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Productivity

3.0

2.5 30

2.0 1.5

Precipitation, in centimeters

4.5

1.0 10 0.5

** *

19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Song Sparrow

5.0

Productivity, in number young per adult

4.0 3.5

Total winter precipitation (Oct–Mar)

Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Productivity

3.0

2.5 30

2.0 1.5

Precipitation, in centimeters

4.5

1.0 10 0.5

** *

19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Figure 12. Annual productivity of focal species and winter precipitation for the associated bio-year (total winter is October–March, early winter is October–December, and late winter is January–March) at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. Intervals affected by lack of banding denoted by * and intervals with only migration banding denoted by ** (banded birds only).

24 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Least Bell's Vireo

5.0

Productivity, in number young per adult

4.0 3.5

Total winter precipitation (Oct–Mar)

Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Productivity

3.0

2.5 30

2.0 1.5

Precipitation, in centimeters

4.5

1.0 10 0.5

** *

19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Orange-crowned Warbler

5.0

Productivity, in number young per adult

4.0 3.5

Total winter precipitation (Oct–Mar)

Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Productivity

3.0

2.5 30

2.0 1.5

1.0 10 0.5

** *

19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Figure 12.—Continued

Precipitation, in centimeters

4.5

Results 25 Yellow-breasted Chat

5.0

Productivity, in number young per adult

4.0 3.5

Total winter precipitation (Oct–Mar)

Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Productivity

3.0

2.5 30

2.0 1.5

Precipitation, in centimeters

4.5

1.0 10 0.5

** *

19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Yellow Warbler

5.0

Productivity, in number young per adult

4.0

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec)

Late winter precipitation (Jan–Mar) Productivity

3.5 3.0

2.5 30

2.0 1.5

1.0 10 0.5

** *

19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21

0.0

Year

Figure 12.—Continued

Precipitation, in centimeters

4.5

26 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 5. Logistic regression models for the effect of precipitation on productivity for six bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. [Models are ranked from best to worst based on Akaike’s Information Criterion for small samples (AICc), difference between AICc of model and AICc of the highest-ranked (top) model (ΔAICc), and Akaike weights (w). AICc is based on −2×loge likelihood (logLik) and the number of parameters (K) in the model. Abbreviations: +, plus; ≤, less than or equal to]

Model

logLik

AICc

ΔAICc

Common Yellowthroat Total winter precipitation

−11.9

31.3

0.55

Early winter precipitation+late winter precipitation

−11

32.8

1.46

0.26

Late winter precipitation

−12.9

33.5

2.16

0.19

Early winter precipitation

−21.8

51.2

19.93

Total winter precipitation

−16.6

40.9

0.72

Early winter precipitation+late winter precipitation

−16.4

43.7

2.81

0.18

Late winter precipitation

−18.5

44.6

3.77

0.11

Early winter precipitation

−24.4

56.4

15.55

Total winter precipitation

0.6

6.4

0.41

Late winter precipitation

0.3

6.9

0.53

0.31

Early winter precipitation

−0.1

7.9

1.46

0.2

Early winter precipitation+late winter precipitation

0.6

9.7

3.26

0.08

Song Sparrow

Least Bell's Vireo

Orange-crowned Warbler Total winter precipitation

3.8

−0.1

0.73

Early winter precipitation+late winter precipitation

3.8

3.2

3.24

0.15

Late winter precipitation

3.6

3.69

0.12

Early winter precipitation

−1.1

9.9

9.91

0.01

−8.5

24.5

0.68

Yellow-breasted Chat Total winter precipitation

Early winter precipitation+late winter precipitation

−8.3

27.5

2.94

0.16

Late winter precipitation

−10.4

28.5

3.96

0.09

−10.8

29.2

4.71

0.06

Total winter precipitation

13.2

−18.6

0.41

Late winter precipitation

13.1

−18.6

0.04

0.4

Early winter precipitation

11.9

−16

2.59

0.11

Early winter precipitation+late winter precipitation

13.3

−15.5

3.13

0.08

Early winter precipitation Yellow Warbler

1Significant parameter (P≤0.10).

Results 27 Table 6. Results of multiple regression analyses to predict productivity for six bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. [Model-averaged parameter estimates (β), standard error (SE), 95-percent (%) confidence intervals (CI), Z-values (Z), and P-values (P) averaged over all models with ΔAICc<2. Abbreviations: <, less than; ≤, less than or equal to]

Parameter

95% CI

−1.112–−0.021

2.03

0.04

Common Yellowthroat Intercept

−0.57

0.28

Early winter precipitation

0.04

0.02

−0.004–0.085

1.78

10.08

Late winter precipitation

0.07

0.01

0.047–0.101

5.41

1<0.01

Total winter precipitation

0.06

0.01

0.043–0.084

6.1

1<0.01

−1.33–−0.03

−2.05

0.06

0.05–0.1

5.69

1<0.01

Song Sparrow Intercept

−0.68

Total winter precipitation

0.33

0.07

0.01

Least Bell's Vireo Intercept

0.25

0.14

−0.021–0.523

1.81

0.07

Early winter precipitation

0.01

−0.013–0.034

0.9

0.37

Late winter precipitation

0.01

−0.005–0.023

1.26

0.21

Total winter precipitation

0.01

−0.003–0.018

1.43

0.15

Orange-crowned Warbler Intercept

−0.05

0.113

−0.27–0.18

−0.4

Total winter precipitation

0.02

0.004

0.01–0.03

4.44

Intercept

−0.39

0.69 1<0.01

Yellow-breasted Chat 0.22

−0.82–0.03

0.01

−1.82

0.09

0.01–0.04

3.47

1<0.01

0.97

Total winter precipitation

0.03

Intercept

0.003

0.071

−0.137–0.143

0.04

Late winter precipitation

0.016

0.004

−0.001–0.014

1.62

0.11

Total winter precipitation

0.005

0.003

−0.001–0.011

1.63

10.1

Yellow Warbler

1Significant parameter (P≤0.10).

28 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 7. Logistic regression models for the effect of year on survival for two resident and four migrant bird species captured at Santa Margarita, Marine Corps Base Camp Pendleton, California, 1998–2021. [Models are ranked from best to worst based on Akaike’s Information Criterion for small samples (AICc), difference between AICc of model and AICc of the highest-ranked (top) model (ΔAICc), and Akaike weights (w). AICc is based on −2×loge likelihood and the number of parameters (K) in the model. Abbreviation: +, plus]

AICc

ΔAICc

Sex

476,642.3

0.0

0.48

Total winter precipitation

476,643.8

1.6

0.22

Early winter precipitation+late winter precipitation

476,645.6

3.3

0.09

Late winter precipitation

476,645.7

3.4

0.09

Early winter precipitation

476,646.1

3.8

0.07

Constant survival

476,647.2

4.9

0.04

Sex+year

476,649.3

7.1

0.01

Year

476,653.2

11.0

0.00

Early winter precipitation

58,312.0

0.0

0.59

Early winter precipitation+late winter precipitation

58,313.5

1.4

0.29

Total winter precipitation

58,316.7

4.7

0.06

Sex

58,316.9

4.9

0.05

Late winter precipitation

58,321.9

9.9

0.00

Constant survival

58,322.1

10.1

0.00

Sex+year

58,332.5

20.4

0.00

Year

58,336.3

24.3

0.00

Sex

1,724.4

0.0

0.98

Constant survival

1,733.7

9.3

0.01

Early winter precipitation

1,734.6

10.3

0.01

Total winter precipitation

1,735.2

10.8

0.00

Late winter precipitation

1,735.7

11.3

0.00

Early winter precipitation+late winter precipitation

1,736.7

12.3

0.00

Sex+year

1,753.3

28.9

0.00

Year

1,762.2

37.8

0.00

Focal species

Model Residents

Common Yellowthroat

Song Sparrow

Migrants Least Bell's Vireo

Results 29 Table 7. Logistic regression models for the effect of year on survival for two resident and four migrant bird species captured at Santa Margarita, Marine Corps Base Camp Pendleton, California, 1998–2021.—Continued [Models are ranked from best to worst based on Akaike’s Information Criterion for small samples (AICc), difference between AICc of model and AICc of the highest-ranked (top) model (ΔAICc), and Akaike weights (w). AICc is based on −2×loge likelihood and the number of parameters (K) in the model. Abbreviation: +, plus]

AICc

ΔAICc

36,550.0

0.0

0.89

Total winter precipitation

36,555.5

5.5

0.06

Early winter precipitation+late winter precipitation

36,556.2

6.1

0.04

Early winter precipitation

36,558.2

8.2

0.01

Late winter precipitation

36,563.8

13.7

0.00

Constant survival

36,566.2

16.1

0.00

Sex+year

36,568.4

18.3

0.00

Year

36,584.0

34.0

0.00

Sex

3,178.8

0.0

0.87

Constant survival

3,185.1

6.3

0.04

Late winter precipitation

3,185.1

6.3

0.04

Total winter precipitation

3,186.1

7.3

0.02

Early winter precipitation+late winter precipitation

3,186.9

8.0

0.02

Early winter precipitation

3,187.0

8.2

0.01

Sex+year

3,200.9

22.1

0.00

Year

3,209.8

31.0

0.00

Constant survival

15,840.4

0.0

0.35

Early winter precipitation

15,842.0

1.6

0.16

Late winter precipitation

15,842.1

1.7

0.15

Sex

15,842.3

2.0

0.13

Total winter precipitation

15,842.3

2.0

0.13

Early winter precipitation+late winter precipitation

15,843.5

3.1

0.07

Year

15,857.4

17.0

0.00

Sex+year

15,859.8

19.4

0.00

Focal species

Model Migrants—Continued

Orange-crowned Warbler Sex

Yellow-breasted Chat

Yellow Warbler

30 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Common Yellowthroat

0.9 0.8

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Female survival Male survival

Adult survival

0.7

0.6 0.5

0.4 20

0.3 0.2

Precipitation, in centimeters

1.0

0.1

** *

* * * *

19 98 –1 99 9 19 99 –2 00 0 20 00 –2 00 1 20 01 –2 00 2 20 02 –2 00 3 20 03 –2 00 4 20 04 –2 00 5 20 05 –2 00 6 20 06 –2 00 7 20 07 –2 00 8 20 08 –2 00 9 20 09 –2 01 0 20 10 –2 01 1 20 11 –2 01 2 20 12 –2 01 3 20 13 –2 01 4 20 14 –2 01 5 20 15 –2 01 6 20 16 –2 01 7 20 17 –2 01 8 20 18 –2 01 9 20 19 –2 02 0 20 20 –2 02 1

0.0

Year

Song Sparrow

0.9 0.8

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Female survival Male survival

0.7

Adult survival

0.6 30

0.5 0.4

0.3 0.2

Precipitation, in centimeters

1.0

0.1

* *

** * *

0.0

Year

Figure 13. Model averaged annual adult survival (table 7) of focal species by sex (male versus female) and winter precipitation for the associated bio-year (total winter is October–March, early winter is October–December, and late winter is January–March) at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. Intervals affected by lack of banding denoted by * and intervals with only migration banding denoted by **.

Adult survival 0.9

0.8

0.9

0.8

Least Bell's Vireo

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Female survival Male survival

0.7 40

0.6

0.5 30

0.4

0.3 20

0.2

0.0

* *

0.0

Figure 13.—Continued

* * * *

1.0

** * *

Orange-crowned Warbler

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Female survival Male survival

0.7 40

0.6

0.5 30

0.4

0.3 20

0.2

0.1

** * *

Year

Precipitation, in centimeters

1.0

Precipitation, in centimeters

Adult survival

Results 31

0.1

Year

32 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Yellow-breasted Chat

0.9 0.8

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Female survival Male survival

0.7

Adult survival

0.6 30

0.5 0.4

0.3 0.2

Precipitation, in centimeters

1.0

0.1

* * *

** * *

19 98 –1 99 19 9 99 –2 00 20 0 00 –2 00 20 1 01 –2 00 20 2 02 –2 00 20 3 03 –2 00 20 4 04 –2 00 20 5 05 –2 00 20 6 06 –2 00 20 7 07 –2 00 20 8 08 –2 00 20 9 09 –2 01 20 0 10 –2 01 20 1 11 –2 01 20 2 12 –2 01 20 3 13 –2 01 20 4 14 –2 01 20 5 15 –2 01 20 6 16 –2 01 20 7 17 –2 01 20 8 18 –2 01 20 9 19 –2 02 20 0 20 –2 02 1

0.0

Year

Yellow Warbler

0.9 0.8

Total winter precipitation (Oct–Mar) Early winter precipitation (Oct–Dec) Late winter precipitation (Jan–Mar) Female survival Male survival

0.7

Adult survival

0.6 0.5

0.4 20

0.3 0.2

0.1

* * *

** * *

0.0

Year

Figure 13.—Continued

Precipitation, in centimeters

1.0

Results 33

Table 8. Results of multiple regression analyses to predict population size for six bird species captured at Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. [Population estimates accounted for effort. Abbreviations: β, Parameter estimates; SE, standard error; P, p-values; R2, model explaining population trends over time; —, no data; ≤, less than or equal to]

Intercept

27.9

9.2

0.01

0.38

Survival (yearx−1 to yearx)

−30.7

23.5

0.22

—

1.5

3.4

0.67

—

Focal species

Parameter Residents

Common Yellowthroat

Productivity (yearx−1) Song Sparrow

Population estimate (yearx−1)

0.2

0.4

0.60

—

Intercept

−8.2

10.6

0.45

0.66

Survival (yearx−1 to yearx)

29.0

17.5

0.13

—

Productivity (yearx−1)

0.6

2.0

0.78

—

0.5

0.3

10.09

—

Intercept

3.4

1.4

0.03

0.15

Survival (yearx−1 to yearx)

0.4

1.2

0.73

—

Productivity (yearx−1)

0.5

1.1

0.64

—

Population estimate (yearx−1)

−0.2

0.5

0.77

—

Intercept

6.2

2.1

0.01

0.58

Survival (yearx−1 to yearx)

6.2

2.9

10.05

—

Productivity (yearx−1)

0.3

1.1

0.81

—

Population estimate (yearx−1)

−0.1

0.2

0.44

—

Intercept

2.8

0.6

0.00

0.67

Survival (yearx−1 to yearx)

0.5

0.8

0.54

— —

Population estimate (yearx−1) Migrants Least Bell's Vireo

Orange-crowned Warbler

Yellow-breasted Chat

Yellow Warbler

Productivity (yearx−1)

0.8

0.3

10.01

Population estimate (yearx−1)

−0.2

0.2

0.38

—

Intercept

1.2

0.4

0.02

0.61

Survival (yearx−1 to yearx)

−1.1

1.4

0.43

—

Productivity (yearx−1)

−1.0

1.9

0.62

—

0.2

10.03

—

Population estimate (yearx−1) 1Significant parameter (P≤0.10).

0.5

34 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Discussion Species richness and the number of individual captures at both MAPS stations at MCBCP were above the annual means in 2021. The peak in captures and species richness at both stations in 2021 was in early to mid-May and coincided with migration. One additional peak was observed at De Luz in mid-July, also coinciding with migration. Return rate was 48 percent lower than the 20-year mean at De Luz and 11 percent lower but approaching the 18-year mean at the Santa Margarita station. The low return rate of birds to De Luz could be a result of a gradual decline in habitat quality at the station; a habitat quality decline is suggested by anecdotal evidence. De Luz Creek is drier than the Santa Margarita River and crews have observed a decline in water flow (R. Pottinger, U.S. Geological Survey, oral commun., 2018). Furthermore, a fire burned most of the station in 2004. A nearby 5-year study (B. Kus, U.S. Geological Survey, unpub. data, 2019) of post-fire recovery found that habitat at that site may have converted to a different habitat type that doesn’t provide suitable resources for reproduction for some species, which is possibly what happened at De Luz. Slow habitat recovery may have been compounded by extended drought (2011–18; Vose and others, 2014) and flooding at the site in 2017 and 2019. The proportion of juveniles in the 2021 populations was 21 percent lower than the annual mean at De Luz but was 17 percent higher than the annual mean at Santa Margarita. Reproductive success at De Luz was likely affected by the decline in habitat. Furthermore, the winter of 2020–21 was relatively dry, with total winter precipitation 50 percent lower than the 1995–2020 mean (±SD; 32.5±19.0 centimeters [cm]) and was the sixth driest winter of the study. The combination of habitat degradation and dry vegetation could increase exposure of nests and result in increased nest predation at De Luz. The habitat at Santa Margarita is denser and more mesic and was likely not affected as severely by the dry winter. Comparable to the 2018 and 2019 seasons, the proportion of hummingbirds among all birds captured at De Luz was high; 75 percent of all juveniles captured, and 21 percent of all individuals captured were hummingbird species, including Anna’s Hummingbird, Costa’s Hummingbird, Allen’s Hummingbird, and Rufous Hummingbird (Selasphorus rufus), which was 197 percent above the 1995–2019 mean of 7 percent of all individuals captured. As in 2019, the proportion of orioles (Hooded Oriole [Icterus cucullatus] and Bullock’s Oriole) was also high, at 194 percent above the 1995–2019 mean of 2 percent. An increase in exotic tree tobacco (Nicotiana glauca) was observed in the creek bed and may have contributed to the increase in nectarivores (hummingbird species and orioles) at De Luz, which forage on the plant’s tubular yellow flowers.

Although half of focal species populations were above their annual means in 2021, several populations may be in decline at MCBCP. We found 25 percent of focal species (3/12) at De Luz (Common Yellowthroat, Song Sparrow, and Yellow-breasted Chat) and 31 percent (4/13) of focal species at Santa Margarita (American Goldfinch, Black-headed Grosbeak, Willow Flycatcher, and Yellow Warbler) to be showing significantly declining trends during the period of this study (De Luz: 1995–2021; Santa Margarita: 1998–2021). We compared population trends of focal species on MCBCP to trends from the North American Breeding Bird Survey at different scales: in the United States and Canada, in the state of California, and in the California coast bird conservation region (an ecologically distinct bird conservation region [Sauer and others, 2020]) to evaluate the extent to which trends on Base matched those at larger spatial scales or appeared to be localized effects. Consistent with their trends range wide in the United States, Willow Flycatcher, Yellow Warbler, and American Goldfinch are in decline on MCBCP. Willow Flycatcher and American Goldfinch are in decline range wide in the United States, but stable throughout California and the California coast bird conservation region, indicating the decline at the Santa Margarita station is a local effect. However, Willow Flycatchers were always rare at the station and mainly pass through on migration. The local American Goldfinch trend could be caused by the establishment of noxious, invasive plants at Santa Margarita. Giant reed (Arundo donax), black mustard (Brassica nigra), and poison hemlock (Conium maculatum) reduce habitat suitability for native species by outcompeting native plants for water, producing allelopathic chemicals, and overshading, preventing germination of native plants. These invasive species may be eliminating native seed-producing plants the American Goldfinch is dependent upon on Base, driving them to find food elsewhere. Although invasive species removal has been completed west of the Santa Margarita station, none has been done at the station and where the restoration has taken place, native vegetation struggles to fill in the gaps, possibly resulting from long-term drought. Yellow Warbler is in decline range wide in the United States and the California coast bird conservation region but stable throughout California, indicating the decline at the Santa Margarita station is not a local effect. Yellow-breasted Chat is in decline range wide and at De Luz on MCBCP but is stable at the Santa Margarita station, in California, and the California coast bird conservation region, indicating the decline at De Luz is localized. The habitat has declined at De Luz; in particular, wild grape (Vitis spp.) cover in areas previously inhabited by Yellow-breasted Chat has been reduced. Black-headed Grosbeak is in decline throughout the California coast bird conservation region and at the Santa Margarita station on MCBCP.

Discussion 35 Barring 2017 and 2021, when four individuals and one individual were captured, respectively, no Black-headed Grosbeak had been captured at Santa Margarita since 2010, and capture rate of Black-headed Grosbeak at the station has always been low (mean [±SD] adults captured per year: 2±2 adults). Song Sparrow is declining range wide in the United States and at De Luz. However, the trends in California, the California coast bird conservation region, and at the Santa Margarita are stable, indicating the decline at De Luz is a local effect. Common Yellowthroat also is declining range wide in the United States and at De Luz, but it is increasing in California and in the California coast bird conservation region and is stable at the Santa Margarita station, indicating the decline at De Luz also is a local effect. Declines of residents Common Yellowthroat and Song Sparrow at De Luz may be explained by anecdotal observations of loss of understory. Of the focal species and resident species, 23 percent (3/13) of at Santa Margarita had significantly increasing population trends (House Wren, Spotted Towhee, and Wrentit). House Wren is increasing range wide in the United States, whereas Spotted Towhee and Wrentit are declining range wide, in California, and (for the Spotted Towhee) in the California coast bird conservation area. These three species are stable at De Luz, indicating that increases in Spotted Towhee and Wrentit are localized at the Santa Margarita. We captured no juveniles of focal species at De Luz in 2021. In contrast, productivity at Santa Margarita was higher than the annual means for all focal species except Yellow-breasted Chat. Several studies have found that winter precipitation is an important predictor of productivity (Nott and others, 2002; Bolger and others, 2005; DeSante and others, 2005; Zarzycki, 2017). We found that total winter precipitation increased productivity of all focal species except Least Bell’s Vireos at both MCBCP stations. Lack of precipitation, combined with a decline in habitat quality, may be resulting in a combined negative effect on productivity of focal species at De Luz. Increased precipitation results in increased plant (Birtwistle, 2015) and arthropod abundance (Bolger and others, 2005), which increases fledging success and adult survival (Bolger and others, 2005). Results indicate that the relationship may be further affected by the timing of winter precipitation (for example, if it occurs early or late in the season). Productivity of Black-headed Grosbeak and Song Sparrow at De Luz was predicted by early winter precipitation. Except for the Common Yellowthroat, which is strictly insectivorous, these species are all insectivores that also eat fruits when they are available. Increased precipitation in the early winter may jump-start primary productivity, increasing availability of fruits during important breeding activities for these species. Productivity of Common Yellowthroat was

predicted by late winter precipitation at both stations. This is likely an effect of arthropod abundance boosting food availability during their breeding activities. Survival was highly variable among focal species and years at MCBCP. Winter precipitation has been found to be an important predictor of survival in species such as Wrentits, warblers, Swainson’s Thrush (Catharus ustulatus), Spotted Towhee, California Towhee, and Rufous-Crowned Sparrow (Aimophila ruficeps; Sillett and Holmes, 2002; Bolger and others, 2005; LaManna and others, 2012; Rockwell and others, 2017). There is a gap in our understanding of survival of focal species at De Luz for 2021 because the station was not operated in 2020, but we found that winter precipitation affected survival of some but not all species at Santa Margarita. A model based on total winter precipitation was among the best supported models of survival of resident Common Yellowthroat, whereas two models (one based on early precipitation, and the other based on a combination of two precipitation variables, early plus late precipitation) were the best supported models for resident Song Sparrow survival. Sex was the top predictor of survival for Common Yellowthroat, Least Bell’s Vireo, Orange-crowned Warbler, and Yellow-breasted Chat, where females had lower probability of survival than males. More research is needed to determine drivers of survival for our focal species. Several studies have found that precipitation during migration drives the survival of migrant species (Sillett and Holmes, 2002; LaManna and others, 2012; Rockwell and others, 2017; Zarzycki, 2017; Saracco and Rubenstein, 2020). Future studies could examine the effects of precipitation on migratory stop-over and wintering grounds of species that breed at MCBCP (Mexico, Central America, and South America). Access to updated local temperature and El Niño/Southern Oscillation data would be useful to inform the interactions between local precipitation and temperature on local avian populations as well. We investigated previous-year adult population size, survival, and productivity as predictors of adult population size for focal species at Santa Margarita in the survey year. Population size of four of the six bird species was positively associated with either population size the previous year (Song Sparrow and Yellow Warbler), breeding productivity the previous year (Yellow-breasted Chat), or adult survival from the previous year (Orange-crowned Warbler). These population models would also benefit from the inclusion of winter temperature data on MCBCP for resident species and on wintering grounds for migrants. Woodworth and others (2017) found that temperature on the wintering grounds limited population growth for Savannah Sparrows (Passerculus sandwichensis) by limiting survival.

36 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Conclusions The Monitoring Avian Productivity and Survivorship (MAPS) Program provides insight into important questions regarding avian population trends by examining key demographic parameters. This year’s research detected population declines in multiple species on Marine Corps Base Camp Pendleton (MCBCP or Base), and a plummet in productivity at De Luz Creek, potentially driven by habitat changes. With continued MAPS station operations on Base, the following actions could improve our understanding of the factors driving these declines: 1. Investigate the ongoing declines at De Luz relative to possible vegetation change resulting from heavy precipitation, drought, floods, and fire. a. Changes in vegetation over time can be analyzed using measurements from the Landsat Normalized Difference Vegetation Index (NDVI), which is used to quantify vegetation greenness and understand changes in plant health. b. Over time, NDVI values can be used to analyze the response of vegetation to precipitation, drought, flooding, and fire relative to demographic parameters of our focal species (Birtwistle, 2015). 2. Evaluate the relationship between weather variables, nesting initiation, and resulting demographic consequences for avian species that breed at Camp Pendleton. a. Investigate how the timing of the onset of breeding (determined from morphological metrics) relates to local precipitation and temperature and how that timing affects productivity and survival of focal species. 3. Investigate range-wide population declines of Yellow Warbler relative to conditions on overwintering and stopover sites, such as weather patterns and habitat alteration. 4. Perform periodic syntheses of multi-year periods to better grasp big-picture trends occurring with breeding birds on Base. The MAPS Program on Base also contributes to our understanding of emerging new threats to riparian birds; for example, the invasive Kuroshio Shot Hole Borer (Euwallacea Kuroshio; KSHB) has caused massive and widespread loss of riparian habitat in the Tijuana River and has been detected in multiple other rivers in San Diego County. Although the KSHB hasn’t yet been detected on Base, the MAPS stations on Base provide an invaluable reference point to understand the effects of KSHB on riparian habitat and associated birds at infested sites.

Continued research through the MAPS Program is a valuable way to support the Base’s commitment to environmental stewardship. The two stations on MCBCP are two of the longest operating MAPS stations in the nation, with nearly concurrent operation at De Luz since 1995 and at Santa Margarita since 1998. Decades of MAPS Program monitoring on Base provided the data needed to analyze the effects of precipitation, and fire on local bird populations. The knowledge gained by the MAPS Program’s continent-wide, collaborative avian monitoring effort helps to maximize the return on Marine Corps investment in environmental compliance and conservation by enhancing the effectiveness of conservation efforts and providing the data to analyze that effectiveness.

References Cited Allen, K.S., and Kus, B.E., 2014, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2013 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Allen, K.S., and Kus, B.E., 2015, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2015 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Barton, K., 2020, MuMIn—Multi-model inference—R package version 1.43.17: Vienna, Austria, The Comprehensive R Archive Network (CRAN), accessed February 1, 2024, at https://cran.r-project.org/web/ packages/MuMIn/MuMIn.pdf. Birtwistle, A.N., 2015, Linking riparian vegetation to precipitation using NDVI at Yuma Proving Ground, Arizona: Fort Collins, Colo., Colorado State University, Ph.D. dissertation. Bolger, D.T., Patten, M.A., and Bostock, D.C., 2005, Avian reproductive failure in response to an extreme climatic event: Oecologia, v. 142, no. 3, p. 398–406, accessed February 1, 2024, at https://doi.org/10.1007/s00442-004-1734-9. Burnham, K.P., and Anderson, D.R., 2002, Model selection and multimodel inference—A practical information-theoretic approach (2d ed.): New York, N.Y., Springer-Verlag. DeSante, D.F., Burton, K.M., Kaschube, D.R., Velez, P., Froehlich, D., and Albert, S., 2021, MAPS manual—2021 protocol: Petaluma, Calif., The Institute for Bird Populations, 90 p., accessed February 1, 2024, at https://www.birdpop.org/docs/misc/MAPSManual21.pdf.

References Cited 37 DeSante, D.F., Nott, M.P., and Kaschube, D.R., 2005, Monitoring, modeling, and management—Why base avian management on vital rates and how should it be done?, in Ralph, J.C., and Rich, T.D., eds., Bird conservation implementation and integration in the Americas—Proceedings of the Third International Partners in Flight Conference, Asilomar, Calif., March 20–24, 2002: Albany, Calif., v. 1 and 2, U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, General Technical Report PSW-GTR-191, p. 795–804, accessed February 1, 2024, at https://www.fs.usda.gov/research/treesearch/32069. Froehlich, D., Michel, N., DeSante, D.F., and Velez, P., 2006, MAPSPROG version 4.1 user’s guide and manual: Point Reyes Station, Calif., The Institute for Bird Populations, 172 p., accessed February 1, 2024, at https://www.birdpop.org/docs/misc/MAPSPROG- Manual.pdf. Hall, K.S., and Kus, B.E., 2016, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2016 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Hall, K.S., and Kus, B.E., 2017, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2017 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Howell, S.L., Wellik, M.J., and Kus, B.E., 2007, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2006 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Howell, S.L., Wellik, M.J., and Kus, B.E., 2008, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2007 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Kus, B.E., 1995, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—First progress report, 1995—Prepared for the U.S. Marine Corps, Environmental and Natural Resources Office: Camp Pendleton, Calif., U.S. Geological Survey Report, 18 p. Kus, B.E., 1996, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—Second annual progress report, 1996—Prepared for the U.S. Marine Corps, Environmental and Natural Resources Office: Camp Pendleton, Calif., U.S. Geological Survey Report, 27 p.

Kus, B.E., and Beck, P.P., 1997, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—Third annual progress report, 1997—Prepared for the U.S. Marine Corps, Environmental and Natural Resources Office: Camp Pendleton, Calif., U.S. Geological Survey Report, 29 p. Kus, B.E., and Beck, P.P., 1999, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—Fourth annual progress report, 1998—Prepared for the U.S. Marine Corps, Environmental and Natural Resources Office: Camp Pendleton, Calif., U.S. Geological Survey Report, 45 p. Kus, B.E., and Beck, P.P., 2000, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—Fifth annual progress report, 1999—Prepared for the U.S. Marine Corps, Environmental and Natural Resources Office: Camp Pendleton, Calif. Kus, B.E., and Beck, P.P., 2001, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—Case Springs Station, 1995–1999—Prepared for AC/S Environmental Security, Marine Corps Base Camp Pendleton, California: Camp Pendleton, Calif., Marine Corps Base Camp Pendleton, U.S. Geological Survey Report. Kus, B.E., and Falcone, J.F., 2006, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2004 annual report—Prepared for Assistant Chief of Staff: Camp Pendleton, Calif., Environmental Security, Marine Corps Base Camp Pendleton. Kus, B.E., and Kisner, D.A., 2003, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2002 annual report—Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton: Camp Pendleton, Calif., U.S. Geological Survey Report. Kus, B.E., and Sharp, B.L., 2002, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2001 annual report—Prepared for Assistant Chief of Staff: Camp Pendleton, Calif., Environmental Security, Marine Corps Base Camp Pendleton, U.S. Geological Survey Report. Laake, J.L., 2013, RMark—An R interface for analysis of capture-recapture data with MARK: Seattle, Wash., Alaska Fisheries Science Center Processed Rep 2013–01, National Oceanic and Atmospheric Administration, National Maritime Fisheries Service, 25 p., accessed February 1, 2024, at https://repository.library.noaa.gov/view/noaa/4372. LaManna, J.A., George, T.L., Saracco, J.F., Nott, M.P., and DeSante, D.F., 2012, El Niño— Southern Oscillation influences annual survival of a migratory songbird at a regional scale: The Auk, v. 129, no. 4, p. 734–743, accessed February 1, 2024, at https://doi.org/10.1525/auk.2012.12017.

38 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Madden, M.C., Allen, K.S., and Kus, B.E, 2015, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2014 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton.

Rogne, M.M., Howell, S.L., and Kus, B.E., 2008, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2008 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton.

Madden-Smith, M.C., Lynn, S., and Kus, B.E., 2012, Fall monitoring of neotropical migratory and resident birds at Marine Corps Base Camp Pendleton, California—2011 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton.

Rogne, M.M., and Kus, B.E., 2009, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2009 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton.

Mendia, S.M., Lynn, S., and Kus, B.E, 2018, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2018 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Mendia, S.M., and Kus, B.E., 2019, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2019 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Nott, M.P., and Michel, N., 2005, Management strategies for reversing declines in landbirds of conservation concern on military installations—Predictive modeling of landbird populations on military installations: Point Reyes Station, Calif., Institute for Bird Populations, accessed February 1, 2024, at https://doi.org/10.21236/ADA541508. Nott, M.P., Desante, D.F., Siegel, R.B., and Pyle, P., 2002, Influences of the El Niño/Southern Oscillation and the North Atlantic Oscillation on avian productivity in forests of the Pacific Northwest of North America: Global Ecology and Biogeography, v. 11, no. 4, p. 333–342, accessed February 1, 2024, at https://doi.org/10.1046/j.1466-822X.2002.00296.x. Office of Water Resources, 2021, Lake O’Neill Station precipitation summary: Camp Pendleton, Calif., Prepared for the Assistant Chief of Staff, Facilities, Marine Corps Base Camp Pendleton. Pyle, P., 1997, Identification guide to North American birds, part I: Bolinas, Calif., Slate Creek Press. R Core Team, 2021, R—A language and environment for statistical computing: Vienna, Austria, R Foundation for Statistical Computing, accessed September 24, 2021, at https://www.R-project.org/. Rockwell, S.M., Wunderle, J.M., Jr., Sillett, T.S., Bocetti, C.I., Ewert, D.N., Currie, D., White, J.D., and Marra, P.P., 2017, Seasonal survival estimation for a long-distance migratory bird and the influence of winter precipitation: Oecologia, v. 183, no. 3, p. 715–726, accessed February 1, 2024, at https://doi.org/10.1007/s00442-016-3788-x.

Rogne, M.M., and Kus, B.E., 2010, Neotropical migratory bird monitoring study at Marine Corps Base Camp Pendleton, California—2010 annual data summary: Prepared for Assistant Chief of Staff, Environmental Security, Marine Corps Base Camp Pendleton. Saracco, J.F., and Rubenstein, M., 2020, Integrating broad‐scale data to assess demographic and climatic contributions to population change in a declining songbird: Ecology and Evolution, v. 10, no. 4, p. 1804–1816, accessed February 1, 2024, at https://doi.org/10.1002/ece3.5975. Sauer, J.R., Link, W.A., and Hines, J.E., 2020, The North American Breeding Bird Survey, analysis results 1966–2019: U.S. Geological Survey data release, accessed February 28, 2023, at https://doi.org/10.5066/P96A7675. Sillett, T.S., and Holmes, R.T., 2002, Variation in survivorship of a migratory songbird throughout its annual cycle: Journal of Animal Ecology, v. 71, no. 2, p. 296–308, accessed February 1, 2024, at https://doi.org/10.1046/j.1365-2656.2002.00599.x. Vose, R.S., Applequist, S., Squires, M., Durre, I., Menne, M.J., Williams, C.N., Jr., Fenimore, C., Gleason, K., and Arndt, D., 2014, NOAA Monthly U.S. Climate Divisional Database (NClimDiv)—Gridded Climate Divisional Dataset (CLIMDIV): National Oceanic and Atmospheric Administration, National Climatic Data Center, accessed October 11, 2019, at https://doi.org/10.7289/V5M32STR. White, G.C., and Burnham, K.P., 1999, Program MARK—Survival estimation from populations of marked animals: Bird Study, v. 46, no. sup1, p. S120–S139, accessed February 1, 2024, at https://doi.org/10.1080/00063659909477239. Woodworth, B.K., Wheelwright, N.T., Newman, A.E., Schaub, M., and Norris, D.R., 2017, temperatures limit population growth rate of a migratory songbird: Nature Communications, v. 8, article no. 14812, 9 p., accessed February 1, 2024, at https://doi.org/10.1038/ncomms14812. Zarzycki, M.C., 2017, Evidence for cross-seasonal effects— Insights from long-term sata on Northern Pintail: Corvallis, Oreg., Oregon State University, Master’s thesis.

Appendix 1. 39

Appendix 1. Alpha Codes, Common Names, and Scientific Names for Species Captured at De Luz Creek and Santa Margarita River, Camp Pendleton, California Table 1.1. Species captured at De Luz Creek and Santa Margarita River, Camp Pendleton, California. [—, no data]

Alpha code

Common name

Scientific name

SSHA

Sharp-shinned Hawk

Accipiter striatus

COHA

Cooper's Hawk

Accipiter cooperii

AMKE

American Kestrel

Falco sparverius

CAQU

California Quail

Callipepla californica

MODO

Mourning Dove

Zenaida macroura

COGD

Common Ground-Dove

Columbina passerina

BCHU

Black-chinned Hummingbird

Archilochus alexandri

ANHU

Anna's Hummingbird

Calypte anna

COHU

Costa's Hummingbird

Calypte costae

CAHU

Calliope Hummingbird

Selasphorus calliope

RUHU

Rufous Hummingbird

Selasphorus rufus

ALHU

Allen's Hummingbird

Selasphorus sasin

USHU

Unidentified Selasphorus Hummingbird species

Selasphorus spp.

UNHU

Unidentified Hummingbird species

—

ACWO

Acorn Woodpecker

Melanerpes formicivorus

DOWO

Downy Woodpecker

Dryobates pubescens

NUWO

Nuttall's Woodpecker

Dryobates nuttallii

HAWO

Hairy Woodpecker

Leuconotopicus villosus

RSFL

Red-shafted Flicker

Colaptes auratus cafer

WEWP

Western Wood-Pewee

Contopus sordidulus

WIFL

Willow Flycatcher

Empidonax traillii

HAFL

Hammond's Flycatcher

Empidonax hammondii

DUFL

Dusky Flycatcher

Empidonax oberholseri

PSFL

Pacific-slope Flycatcher

Empidonax difficilis

UEFL

Unidentified Empidonax Flycatcher species

Empidonax spp.

BLPH

Black Phoebe

Sayornis nigricans

ATFL

Ash-throated Flycatcher

Myiarchus cinerascens

CAKI

Cassin's Kingbird

Tyrannus vociferans

WEKI

Western Kingbird

Tyrannus verticalis

LBVI

Least Bell's Vireo

Vireo bellii pusillus

HUVI

Hutton's Vireo

Vireo huttoni

CAVI

Cassin's Vireo

Vireo cassinii

WAVI

Warbling Vireo

Vireo gilvus

LOSH

Loggerhead Shrike

Lanius ludovicianus

CASJ

California Scrub-jay

Aphelocoma californica

OATI

Oak Titmouse

Baeolophus inornatus

NRWS

Northern Rough-winged Swallow

Stelgidopteryx serripennis

TRES

Tree Swallow

Tachycineta bicolor

VGSW

Violet-green Swallow

Tachycineta thalassina

40 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 1.1. Species captured at De Luz Creek and Santa Margarita River, Camp Pendleton, California.—Continued [—, no data]

Alpha code

Common name

Scientific name

CLSW

Cliff Swallow

Petrochelidon pyrrhonota

BUSH

Bushtit

Psaltriparus minimus

WREN

Wrentit

Chamaea fasciata

RCKI

Ruby-crowned Kinglet

Corthylio calendula

WBNU

White-breasted Nuthatch

Sitta carolinensis

BGGN

Blue-gray Gnatcatcher

Polioptila caerulea

HOWR

House Wren

Troglodytes aedon

BEWR

Bewick's Wren

Thyromanes bewickii

EUST

European Starling

Sturnus vulgaris

CATH

California Thrasher

Toxostoma redivivum

NOMO

Northern Mockingbird

Mimus polyglottos

SWTH

Swainson's Thrush

Catharus ustulatus

HETH

Hermit Thrush

Catharus guttatus

PHAI

Phainopepla

Phainopepla nitens

HOFI

House Finch

Haemorhous mexicanus

PUFI

Purple Finch

Haemorhous purpureus

LEGO

Lesser Goldfinch

Spinus psaltria

LAGO

Lawrence's Goldfinch

Spinus lawrencei

AMGO

American Goldfinch

Spinus tristis

CHSP

Chipping Sparrow

Spizella passerina

BCSP

Black-chinned Sparrow

Spizella atrogularis

BRSP

Brewer's Sparrow

Spizella breweri

BTSP

Black-throated Sparrow

Amphispiza bilineata

LASP

Lark Sparrow

Chondestes grammacus

FOSP

Fox Sparrow

Passerella iliaca

ORJU

Oregon Dark-eyed Junco

Junco hyemalis oreganus

Appendix 1. 41 Table 1.1. Species captured at De Luz Creek and Santa Margarita River, Camp Pendleton, California.—Continued [—, no data]

Common name

Scientific name

WCSP

Alpha code

White-crowned Sparrow

Zonotrichia leucophyrs

GCSP

Golden-crowned Sparrow

Zonotrichia atricapilla

SOSP

Song Sparrow

Melospiza melodia

LISP

Lincoln's Sparrow

Melospiza lincolnii

CALT

California Towhee

Melozone crissalis

RCSP

Rufous-crowned Sparrow

Aimophila ruficeps

GTTO

Green-tailed Towhee

Pipilo chlorurus

SPTO

Spotted Towhee

Pipilo maculatus

YBCH

Yellow-breasted Chat

Icteria virens

HOOR

Hooded Oriole

Icterus cucullatus

BUOR

Bullock's Oriole

Icterus bullockii

OVEN

Ovenbird

Seiurus aurocapilla

OCWA

Orange-crowned Warbler

Leiothlypis celata

NAWA

Nashville Warbler

Leiothlypis ruficapilla

MGWA

MacGillivray's Warbler

Geothlypis tolmiei

COYE

Common Yellowthroat

Geothlypis trichas

HOWA

Hooded Warbler

Setophaga citrina

YWAR

Yellow Warbler

Setophaga petechia

AUWA

Audubon's warbler

Setophaga coronata

BTYW

Black-throated Gray Warbler

Setophaga nigrescens

TOWA

Townsend's Warbler

Setophaga townsendi

THWH

Townsend's x Hermit Warbler Hybrid

Setophaga townsendi x occidentalis

HEWA

Hermit Warbler

Setophaga occidentalis

WIWA

Wilson's Warbler

Cardellina pusilla

WETA

Western Tanager

Piranga ludoviciana

BHGR

Black-headed Grosbeak

Pheucticus melanocephalus

BLGR

Blue Grosbeak

Passerina caerulea

LAZB

Lazuli Bunting

Passerina amoena

42 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Appendix 2. Tables for De Luz Creek, Camp Pendleton, California Table 2.1. Number of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021. [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Year 1995

1996

1997

1998

1999

2000

2001

2002

2004

2006

2007

2008

COHA

AMKE

CAQU

MODO

COGD

BCHU

ANHU

COHU

CAHU

RUHU

ALHU

USHU

UNHU

ACWO

NUWO

DOWO

HAWO

RSFL

WEWP

WIFL

HAFL

DUFL

PSFL

BLPH

ATFL

CAKI

WEKI

LOSH

LBVI

HUVI

WAVI

CASJ

VGSW

NRWS

CLSW

OATI

Appendix 1. 43

Table 2.1. Number of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Year 2009

2010

2011

2013

2014

COHA

AMKE

2015

2016

2017

2018

Total

2019

2021

CAQU

MODO

COGD

BCHU

119

ANHU

261

COHU

115

CAHU

RUHU

ALHU

117

USHU

UNHU

ACWO

NUWO

DOWO

HAWO

RSFL

WEWP

WIFL

HAFL

DUFL

PSFL

158

BLPH

ATFL

172

CAKI

WEKI

LOSH

LBVI

174

HUVI

WAVI

CASJ

VGSW

NRWS

CLSW

OATI

44 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 2.1. Number of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Year 1995

1996

1997

1998

1999

2000

2001

2002

2004

2006

2007

2008

BUSH

WBNU

BEWR

HOWR

UNWR

BGGN

SWTH

HETH

WREN

NOMO

CATH

EUST

PHAI

OCWA

NAWA

YEWA

AUWA

BTYW

TOWA

THWH

MGWA

COYE

121

WIWA

YBCH

WETA

GTTO

SPTO

CALT

RCSP

CHSP

BCSP

LASP

BTSP

FOSP

SOSP

LISP

WCSP

GCSP

ORJU

BHGR

Appendix 2. 45 Table 2.1. Number of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Year

Total

2009

2010

2011

2013

2014

2015

2016

2017

2018

2019

2021

BUSH

428

WBNU

BEWR

260

HOWR

290

UNWR

BGGN

SWTH

101

HETH

WREN

629

NOMO

CATH

EUST

PHAI

OCWA

190

NAWA

YEWA

AUWA

BTYW

TOWA

THWH

MGWA

COYE

974

WIWA

119

YBCH

322

WETA

GTTO

SPTO

376

CALT

390

RCSP

CHSP

BCSP

LASP

BTSP

FOSP

SOSP

840

LISP

WCSP

GCSP

ORJU

BHGR

358

46 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 2.1. Number of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Year 1995

1996

1997

1998

1999

2000

2001

2002

2004

2006

2007

2008

BLGR

LAZB

HOOR

BUOR

PUFI

HOFI

LEGO

AMGO

UNBI

Total individuals

454

422

404

429

420

371

351

397

151

545

359

360

Total species1

1Unknown species not included in species total.

Appendix 2. 47 Table 2.1. Number of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 1995–2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Year

Total

2009

2010

2011

2013

2014

2015

2016

2017

2018

2019

2021

LAZB

HOOR

BLGR

BUOR

PUFI

HOFI

193

LEGO

282

AMGO

Total individuals

UNBI

368

468

350

252

225

255

246

238

527

395

8,053

Total species1

[MAPS, Monitoring Avian Productivity and Survivorship; mm-dd-yy, month-day-year]

MAPS period

Date (mm-dd-yy)

−3

04-07-21

−2

−1

04-14-21

04-21-21

05-05-21

05-12-21

05-26-21

06-02-21

06-16-21

06-23-21

07-08-21

Captures/ net-hour

Net 8

Totals by date

Net-hours

5:00

4:30

5:00

49:30

Captures

Captures/net-hour

0.2

0.8

0.2

1.0

0.4

1.1

0.8

0.4

1.6

0.7

Net-hours

4:00

40:00

Captures

Captures/net-hour

0.0

0.8

1.0

0.8

1.8

0.0

1.5

0.8

Net-hours

3:00

30:00

Captures

Captures/net-hour

1.7

0.0

0.3

2.0

0.3

0.7

0.0

0.7

0.8

Net-hours

5:42

5:00

50:42

Captures

Captures/net-hour

0.5

0.6

2.0

2.6

0.4

0.8

1.0

0.4

0.6

1.0

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.8

0.4

1.4

1.2

0.8

1.0

0.2

0.8

1.2

0.9

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.0

0.6

1.8

0.8

0.6

0.2

0.8

1.0

0.7

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.6

0.2

1.2

0.8

0.6

0.0

0.2

0.5

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.0

0.6

0.2

0.4

1.0

0.4

0.2

1.4

0.2

0.5

Net-hours

5:00

4:18

5:00

4:18

47:54

Captures

Captures/net-hour

0.0

0.2

1.2

0.0

1.2

0.8

0.0

0.5

0.4

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.0

0.4

1.4

0.8

0.6

0.8

0.2

0.4

0.2

1.2

0.6

48 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Table 2.2. Capture rate by net and date: De Luz Creek, Marine Corps Base Camp Pendleton, 2021.

Table 2.2. Capture rate by net and date: De Luz Creek, Marine Corps Base Camp Pendleton, 2021.—Continued [MAPS, Monitoring Avian Productivity and Survivorship; mm-dd-yy, month-day-year]

MAPS period

Date (mm-dd-yy)

07-14-21

07-21-21

08-04-21

08-09-21

08-25-21

Totals by net

Captures/ net-hour

Net 8

Totals by date

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.0

1.0

0.4

2.4

1.4

0.0

1.4

0.8

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.0

0.8

0.4

0.2

0.6

1.0

0.0

0.6

Net-hours

4:00

5:00

4:30

5:00

4:30

5:00

47:00

Captures

Captures/net-hour

0.5

0.0

1.0

0.4

0.2

0.8

0.2

0.4

0.6

0.4

Net-hours

4:30

5:00

49:00

Captures

Captures/net-hour

0.4

0.2

0.6

0.4

0.2

0.0

0.3

Net-hours

4:00

5:00

4:30

5:00

4:00

5:00

46:30

Captures

Captures/net-hour

0.3

0.5

0.2

0.0

0.6

0.4

0.2

0.8

0.2

0.4

Net-hours

70:12

69:30

72:00

70:18

71:18

72:00

71:30

72:00

70:30

71:18

710:36

Captures1

438

Captures/net-hour

0.3

0.4

0.8

1.0

0.7

0.5

0.7

0.5

0.7

0.6

1Excludes five captures where net number was not recorded.

Appendix 2. 49

[See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Total captures1 Species

2016

2017

2018

2019

New individuals banded 2021

Total

2016

2017

2018

2019

Recaptured individuals2 in 2021

2021

Total

Year originally banded 2016

2017

2018

2019

Total

AMKE

CAQU

MODO

BCHU

ANHU

COHU

RUHU

ALHU

USHU

UNHU

ACWO

NUWO

WIFL

PSFL

ATFL

CAKI

LBVI

HUVI

WAVI

CASJ

WESJ

OATI

BUSH

WBNU

BEWR

HOWR

BGGN

SWTH

HETH

WREN

178

158

NOMO

50 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Table 2.3. Number of birds captured, banded, and recaptured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2016–21.

Table 2.3. Number of birds captured, banded, and recaptured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2016–21.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Total captures1 Species CATH

New individuals banded

Recaptured individuals2 in 2021

2016

2017

2018

2019

2021

Total

2016

2017

2018

2019

2021

Total

Year originally banded 2016

2017

2018

2019

Total

EUST

PHAI

OCWA

NAWA

YEWA

AUWA

BTYW

MGWA

COYE

102

101

WIWA

YBCH

WETA

SPTO

CALT

102

101

RCSP

BTSP

SOSP

147

141

LISP

WCSP

GCSP

BHGR

HOOR

BUOR

HOFI

LEGO

Total

290

260

253

585

443

1,831

197

191

148

385

273

1,738

1Includes multiple captures of some individuals. 2Excludes one escaped recapture (no band number recorded).

Appendix 2. 51

BLGR LAZB

52 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 2.4. Sex and age of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021. [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: HY, hatch-year; AHY, after-hatch-year; SY, second-year; ASY, after-second-year; TY, third-year; ATY, after-third-year; I, indeterminable age]

Female age

Male age

AHY

ASY

ATY

Female total

CAQU

MODO

ANHU

COHU

RUHU

ALHU

UNHU

ACWO

NUWO

PSFL

ATFL

CAKI

LBVI

CASJ

OATI

BUSH

BEWR

HOWR

SWTH

HETH

WREN

NOMO

CATH

PHAI

OCWA

YEWA

AUWA

BTYW

MGWA

COYE

WIWA

YBCH

WETA

SPTO

CALT

RCSP

SOSP

LISP

BHGR

HOOR

Species

AHY

ASY

ATY

Male total

Appendix 2. 53 Table 2.4. Sex and age of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: HY, hatch-year; AHY, after-hatch-year; SY, second-year; ASY, after-second-year; TY, third-year; ATY, after-third-year; I, indeterminable age]

Unknown sex age HY

AHY

ASY

ATY

Unknown total

Species total

CAQU

MODO

ANHU

COHU

RUHU

ALHU

UNHU

ACWO

NUWO

PSFL

ATFL

CAKI

LBVI

CASJ

OATI

BUSH

BEWR

HOWR

SWTH

HETH

WREN

NOMO

CATH

PHAI

OCWA

YEWA

AUWA

BTYW

MGWA

COYE

WIWA

YBCH

WETA

SPTO

CALT

RCSP

SOSP

LISP

BHGR

HOOR

Species

54 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 2.4. Sex and age of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: HY, hatch-year; AHY, after-hatch-year; SY, second-year; ASY, after-second-year; TY, third-year; ATY, after-third-year; I, indeterminable age]

Female age

Male age

AHY

ASY

ATY

Female total

BUOR

HOFI

Species

AHY

ASY

ATY

Male total

LEGO

Total

116

156

Appendix 2. 55 Table 2.4. Sex and age of individuals (banded and unbanded) captured: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: HY, hatch-year; AHY, after-hatch-year; SY, second-year; ASY, after-second-year; TY, third-year; ATY, after-third-year; I, indeterminable age]

Unknown sex age HY

AHY

ASY

ATY

Unknown total

Species total

BUOR

HOFI

Species

LEGO

Total

123

395

[See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: MAPS, Monitoring Avian Productivity and Survivorship; mm-dd, month-day]

MAPS period Total

Captures per 100 net-hours1

0.6

0.1

3.2

2.1

0.7

5.1

0.1

1.1

0.3

0.8

1.3

0.1

0.4

0.1

0.3

3.0

1.8

1.0

0.7

0.3

6.1

0.1

1.0

0.6

0.3

0.6

1.1

0.1

−3

−2

−1

04-07

04-14

04-21

05-05

05-12

05-26

06-02

06-16

06-23

07-08

07-14

07-21

08-04

08-09

08-25

CAQU

MODO

ANHU

COHU

RUHU

ALHU

UNHU

ACWO

NUWO

PSFL

ATFL

CAKI

LBVI

CASJ

OATI

BUSH

BEWR

HOWR

SWTH

HETH

WREN

NOMO

CATH

PHAI

OCWA

YEWA

AUWA

BTYW MGWA

Species

5 Date (mm-dd)

56 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Table 2.5. Number of captures by date: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021.

Table 2.5. Number of captures by date: De Luz Creek, Marine Corps Base Camp Pendleton, California, 2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: MAPS, Monitoring Avian Productivity and Survivorship; mm-dd, month-day]

MAPS period Total

Captures per 100 net-hours1

0.8

0.6

0.4

0.3

3.5

4.1

0.6

3.4

0.4

3.5

2.0

1.3

0.6

392

55.2

−3

−2

−1

04-07

04-14

04-21

05-05

05-12

05-26

06-02

06-16

06-23

07-08

07-14

07-21

08-04

08-09

08-25

COYE

WIWA

YBCH

WETA

SPTO

CALT

RCSP

SOSP

LISP

BHGR

HOOR

BUOR

HOFI

LEGO

Captures/day

Total species2

Species

5 Date (mm-dd)

1710:36 total net-hours. 2Total species excludes one unknown hummingbird species captured.

Appendix 2. 57

58 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Appendix 3. Tables for Santa Margarita River, Camp Pendleton, California Table 3.1. Number of individuals (banded and unbanded) captured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes] Species

Year 1998 1999 2000 2001 2002 2004 2006 2007 2008 2009 2010 2011 2013 2014 2015 2016 2017 2018 2019 2020 2021

Total

SSHA

AMKE

CAQU

MODO

COGD

BCHU

ANHU

COHU

RUHU

ALHU

USHU

UNHU

NUWO

DOWO

RSFL

WEWP

WIFL

PSFL

182

BLPH

ATFL

LBVI

503

CAVI

HUVI

WAVI

122

TRES

CLSW

BUSH

603

BEWR

349

HOWR

292

RCKI

BGGN

SWTH

153

HETH

WREN

578

NOMO

CATH

PHAI

Appendix 2. 59

Table 3.1. Number of individuals (banded and unbanded) captured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 1998–2021. —Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes] Species OCWA

Year 1998 1999 2000 2001 2002 2004 2006 2007 2008 2009 2010 2011 2013 2014 2015 2016 2017 2018 2019 2020 2021 28 102

Total 1,294

NAWA

YEWA

333

AUWA

BTYW

TOWA

HEWA

OVEN

MGWA

16 3,254

COYE HOWA

200 191 179 222 118 204 159

86 219 117 151

49 197

70 206 103 210 185 222

WIWA

YBCH

368

393

WETA

SPTO

402

CALT

RCSP

BRSP

FOSP

328 238 109

2,976

SOSP

54 135 154

84 121

62 108

62 236

99 186 146 200 167 236

LISP

WCSP

GCSP

BHGR

BLGR

LAZB

HOOR

BUOR

HOFI

117

LEGO

164

LAGO

AMGO

179

Total individuals

786 947 562 664 588 733 614 537 625 464 535 239 765 512 417 557 705 583 765 601 832 13,031

Total species1

1Unknown species not included in species total.

[MAPS, Monitoring Avian Productivity and Survivorship; mm-dd-yy, month-day-year]

MAPS period

Date (mm-dd-yy)

−3

04-06-21

−2

−1

04-13-21

04-27-21

05-04-21

05-18-21

05-25-21

06-08-21

06-15-21

06-22-21

07-07-21

Captures/ net-hour

Net 1

Total by date

Net-hours

5:00

50:00

Captures

Captures/net-hour

1.6

0.6

0.8

0.4

1.4

1.6

0.6

0.8

1.0

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.4

0.6

0.2

1.4

1.8

0.7

Net-hours

5:00

4:00

5:00

49:00

Captures

Captures/net-hour

0.6

0.8

0.0

1.0

0.6

1.0

1.4

0.2

0.6

0.7

Net-hours

5:00

50:00

Captures

Captures/net-hour

1.2

1.6

0.6

0.8

1.2

1.8

0.2

2.2

1.3

Net-hours

5:00

50:00

Captures

122

Captures/net-hour

2.0

3.8

2.2

2.4

3.0

1.8

2.2

2.0

2.6

2.4

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.8

3.6

2.6

1.8

2.2

1.8

1.6

1.0

1.4

2.2

1.9

Net-hours

5:00

50:00

Captures

101

Captures/net-hour

1.6

4.0

2.6

1.8

2.0

2.2

2.8

0.4

1.0

1.8

2.0

Net-hours

5:00

4:30

5:00

4:30

5:00

49:00

Captures

104

Captures/net-hour

1.6

3.8

3.0

2.0

1.8

2.8

2.4

1.2

1.4

2.1

Net-hours

5:00

50:00

Captures

111

Captures/net-hour

2.0

2.4

2.6

3.0

2.6

2.4

1.6

1.4

2.2

Net-hours

5:00

50:00

Captures

Captures/net-hour

2.2

3.8

1.4

2.2

1.4

1.8

0.4

0.8

1.7

60 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Table 3.2. Capture rate by net and date: Santa Margarita River, Marine Corps Base Camp Pendleton, 2021.

Table 3.2. Capture rate by net and date: Santa Margarita River, Marine Corps Base Camp Pendleton, 2021.—Continued [MAPS, Monitoring Avian Productivity and Survivorship; mm-dd-yy, month-day-year]

MAPS period

Date (mm-dd-yy)

07-13-21

07-27-21

08-03-21

08-10-21

08-24-21

Totals by net

Net

Captures/ net-hour

Total by date

Net-hours

5:00

50:00

Captures

Captures/net-hour

1.0

3.6

1.6

0.8

0.6

0.4

0.8

0.6

1.4

1.7

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.8

2.0

0.4

0.6

0.4

0.8

0.2

0.4

0.7

Net-hours

5:00

50:00

Captures

Captures/net-hour

1.2

0.4

0.8

0.4

3.0

0.6

0.8

Net-hours

5:00

50:00

Captures

Captures/net-hour

1.0

2.2

1.2

0.6

0.2

0.8

1.0

0.6

0.4

0.8

Net-hours

5:00

50:00

Captures

Captures/net-hour

0.8

2.4

2.0

0.4

1.0

0.2

0.6

1.0

1.4

1.0

1.1

Net-hours

80:00

79:00

80:00

79:30

80:00

79:30

80:00

798:00

Captures1

180

119

105

100

1,027

Captures/net-hour

1.1

1.2

1.1

1.0

2.3

1.5

1.3

1Excludes five captures where net numbers were not recorded.

Appendix 3. 61

62 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 3.3. Number of birds captured, banded, and recaptured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2017–21. [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Total captures1

New individuals banded

2017

2018

2019

2020

2021

Total

2017

2018

2019

2020

2021

Total

SSHA

AMKE

CAQU

MODO

COGD

BCHU

ANHU

COHU

RUHU

ALHU

USHU

UNHU

NUWO

DOWO

RSFL

WEWP

WIFL

PSFL

BLPH

ATFL

LBVI

181

108

CAVI

HUVI

WAVI

TRES

CLSW

BUSH

116

BEWR

HOWR

164

107

RCKI

BGGN

SWTH

HETH

WREN

226

120

NOMO

CATH

PHAI

OCWA

350

223

NAWA

YEWA

AUWA

Appendix 3. 63 Table 3.3. Number of birds captured, banded, and recaptured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2017–21.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Recaptured individuals2 in 2021 Species

Year originally banded 2013

2014

2015

2016

2017

2018

2019

2020

Total

SSHA

AMKE

CAQU

MODO

COGD

BCHU

ANHU

COHU

RUHU

ALHU

USHU

UNHU

NUWO

DOWO

RSFL

WEWP

WIFL

PSFL

BLPH

ATFL

LBVI

CAVI

HUVI

WAVI

TRES

CLSW

BUSH

BEWR

HOWR

RCKI

BGGN

SWTH

HETH

WREN

NOMO

CATH

PHAI

OCWA

NAWA

YEWA

64 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 3.3. Number of birds captured, banded, and recaptured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2017–21.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Species

Total captures1

New individuals banded

2017

2018

2019

2020

2021

Total

2017

2018

2019

2020

2021

Total

BTYW

TOWA

HEWA

OVEN

MGWA

COYE

244

133

292

225

286 1,180 184

HOWA

WIWA

YBCH

188

147

193

793

130

WETA

SPTO

137

CALT

RCSP

BRSP

304 1,149 166

111

169

131

181

758

FOSP

SOSP

210

183

247

205

LISP

WCSP

GCSP

BHGR

BLGR

LAZB

HOOR

BUOR

HOFI

LEGO

LAGO

1,032 4,227 599

473

627

448

682

2,829

AMGO

Total

825

695

950

725

1Includes multiple captures of some individuals. 2Excludes three escaped recaptures (no band number recorded) and two recaptured Least Bell’s Vireos that were banded at Marine Corps Base Camp Pendleton as nestlings in 2021.

Appendix 3. 65 Table 3.3. Number of birds captured, banded, and recaptured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2017–21.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes]

Recaptured individuals2 in 2021 Species

Year originally banded

Total

2013

2014

2015

2016

2017

2018

2019

2020

AUWA

BTYW

TOWA

HEWA

OVEN

MGWA

COYE

HOWA

WIWA

YBCH

WETA

SPTO

CALT

RCSP

BRSP

FOSP

SOSP

LISP

WCSP

GCSP

BHGR

BLGR

LAZB

HOOR

BUOR

HOFI

LEGO

LAGO

AMGO

Total

120

66 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary Table 3.4. Sex and age of individuals (banded and unbanded) captured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2021. [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: HY, hatch-year; AHY, after-hatch-year; SY, second-year; ASY, after-second-year; TY, third-year; ATY, after-third-year; I, indeterminable age]

Female age

Male age

AHY

ASY

ATY

Female total

AHY

ASY

ATY

Male total

MODO

ANHU

COHU

ALHU

UNHU

NUWO

DOWO

WEWP

WIFL

PSFL

ATFL

LBVI

HUVI

WAVI

TRES

CLSW

BUSH

BEWR

HOWR

SWTH

HETH

WREN

CATH

OCWA

YEWA

TOWA

MGWA

COYE

104

WIWA

YBCH

SPTO

SOSP

LISP

BHGR

LAZB

HOOR

HOFI

LEGO

AMGO

Total

190

268

Species

Appendix 3. 67 Table 3.4. Sex and age of individuals (banded and unbanded) captured: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: HY, hatch-year; AHY, after-hatch-year; SY, second-year; ASY, after-second-year; TY, third-year; ATY, after-third-year; I, indeterminable age]

Unknown sex age HY

AHY

ASY

ATY

Unknown total

MODO

ANHU

COHU

ALHU

UNHU

NUWO

DOWO

WEWP

WIFL

PSFL

ATFL

LBVI

HUVI

WAVI

TRES

CLSW

BUSH

BEWR

HOWR

SWTH

HETH

WREN

CATH

OCWA

YEWA

TOWA

MGWA

COYE

222

WIWA

YBCH

Species

Species total

SPTO

SOSP

124

156

236

LISP

BHGR

LAZB

HOOR

HOFI

LEGO

AMGO

Total

264

374

832

[See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: MAPS, Monitoring Avian Productivity and Survivorship; mm-dd, month-day]

MAPS period Species

−3

−2

−1

Date (mm-dd)

Total

Captures per 100 net-hours1

04-06

04-13

04-27

05-04

05-18

05-25

06-08

06-15

06-22

07-07

07-13

07-27

08-03

08-10

08-24

MODO

0.3

ANHU

0.2

COHU

0.2

ALHU

0.8

UNHU

0.3

NUWO

1.0

DOWO

0.8

WEWP

0.3

WIFL

0.2

PSFL

1.0

ATFL

0.3 8.8

LBVI

HUVI

1.0

WAVI

1.2

TRES

0.2

CLSW

0.2

BUSH

1.5

BEWR

1.0

HOWR

3.3

SWTH

2.3

HETH

0.3

WREN

7.2

CATH

0.7

OCWA

13.0

YEWA

4.3

TOWA

0.3

MGWA

0.2

COYE

243

40.6

68 Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary

Table 3.5. Number of captures by date: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2021.

Table 3.5. Number of captures by date: Santa Margarita River, Marine Corps Base Camp Pendleton, California, 2021.—Continued [See appendix 1 (table 1.1) for common and scientific bird names corresponding to four-letter species codes. Abbreviations: MAPS, Monitoring Avian Productivity and Survivorship; mm-dd, month-day]

MAPS period Species

−3

−2

−1

Date (mm-dd)

Total

Captures per 100 net-hours1

04-06

04-13

04-27

05-04

05-18

05-25

06-08

06-15

06-22

07-07

07-13

07-27

08-03

08-10

08-24

WIWA

3.7

YBCH

4.3

SPTO

4.3

SOSP

254

42.4

LISP

0.2

BHGR

0.2

LAZB

0.2

HOOR

0.3

HOFI

0.7

LEGO

1.3

AMGO

0.3

Captures/ day

122

101

104

111

896

149.6

Total species

6.5

1798:00 total net-hours.

Appendix 3. 69

For more information concerning the research in this report, contact the Director, Western Ecological Research Center U.S. Geological Survey 3020 State University Drive East Sacramento, California 95819 https://www.usgs.gov/centers/werc Publishing support provided by the Science Publishing Network, Sacramento Publishing Service Center

Mendia and Kus—Neotropical Migratory Bird Study at Marine Corps Base Camp Pendleton—2021 Summary—OFR 2024–1024

ISSN 2331-1258 (online) https://doi.org/10.3133/ofr20241024

Neotropical Migratory Bird Monitoring Study at Marine Corps Base Camp Pendleton, California—2021 Annual Data Summary

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