Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California

The status of golden eagles (Aquila chrysaetos) in coastal southern California is unclear. To address this knowledge gap, the U.S. Geological Survey (USGS) in collaboration with local, State, and other Federal agencies began a multi-year survey and tracking program of golden eagles to address questions regarding habitat use, movement behavior, nest occupancy, genetic population structure, and human impacts on eagles. Golden eagle trapping and tracking efforts began in September 2014. During trapping efforts from September 29, 2014, to February 23, 2016, 27 golden eagles were captured. During trapping efforts from February 24, 2016, to February 23, 2017, an additional 10 golden eagles (7 females and 3 males) were captured in San Diego, Orange, and western Riverside Counties. Biotelemetry data were collected between November 22, 2014 and February 23, 2016. Biotelemetry data for 26 of the 37 golden eagles that were transmitting data from February 24, 2016, to February 23, 2017 are presented in the reports. These eagles ranged as far north as northern Nevada and southern Wyoming, and as far south as La Paz, Baja California, Mexico. For more information on this study, please visit the USGS website: https://pubs.er.usgs.gov/publication/ds994 .

Monitoring
Vertebrate Species
completed
Project Groups
  • SDMMP_2025_574604 Golden Eagle (Aquila chrysaetos) Management and Monitoring

Project Focus

Golden eagle

San Diego Association of Governments

Robert N. Fisher

U.S. Geological Survey

Robert N. Fisher

Sarah McCutcheon

Kris Preston

Jeff Tracey

Strategic Elements
  • FY15-16 - 1.2
Project Location
Baja California, Orange, Riverside, San Bernardino, San Diego
Central-central, Central-east, Central-west, North-central, North-east, North-west, South-central, South-east, South-west
10, 11, 2, 3, 4, 5, 6, 8, 9

Golden eagle Aquila chrysaetos canadensis

Goal: Expand and then maintain a self-sustaining golden eagle population to ensure long term persistence (>100 years) on Conserved Lands in the MSPA by: improving reproductive success through protection of active and inactive nest sites from human disturbance; reducing anthropogenic mortality; managing large mosaics of grassland and open shrublands for optimal prey availability, especially during drought; and by minimizing human impacts to foraging eagles.

regional NFO 2017, 2018, 2019 SO
MON-RES-SPEC AQUCHR-1

Management units: 3, 4, 5, 6, 8, 9, 10, 11

From 2017 to 2019, continue the Golden Eagle Nesting, Foraging, and Habitat Use Study, begun in 2014, to monitor golden eagle territory occupancy and reproduction in the MSPA (see occurrence table) and to track eagle movements to identify important foraging, nesting and roosting areas. Continue to study the influence of human activity and land use on patterns of eagle movement and habitat use, measure the response of eagles to human activity while foraging, and determine whether locally produced floaters recruit into the breeding population.

Action Statement Action status Projects
RES-1 Monitor territory occupancy and reproduction in suitable golden eagle habitat within the MSPA. Identify any threats or disturbance to eagles and provide this information to land managers so that management actions can be taken to reduce impacts from human disturbance and other threats. in progress Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California
RES-2 Capture adult eagles at selected territories and attach GPS-transmitters that track eagle movements to identify important foraging areas and to study movement patterns relative to human activity within a landscape matrix of urban, rural, and undeveloped lands. Determine whether eagles switch territories and mates, document individual mortality, and track emigration or short term movements outside of the MSPA. Determine if there are multiple nesting sites within a territory and identify nest sites that are unstable or vulnerable to loss. in progress Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California , Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California
RES-3 Analyze golden eagle foraging habitat data and develop objectives with criteria for managing open areas (grasslands and suitable areas in coastal sage scrub and chaparral) to conditions preferred by foraging eagles and that support abundant prey (e.g., black-tailed jack rabbits, ground squirrels). unknown Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California
RES-4 Measure eagle behavioral responses to human activity at foraging areas. Identify the intensity and type of human activity that affects foraging behavior. in progress Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California , Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California
RES-5 Use the GPS and behavioral response data to model potential impacts to foraging eagles under different scenarios of human disturbance at important foraging areas. Prepare management recommendations to reduce human impacts on foraging eagles, including alignment of trails, restriction of activities, and educational outreach. in progress Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California , Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California
RES-6 Submit project metadata, datasets, and report with management recommendations to the MSP Web Portal. in progress Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California , Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California
Criteria Deadline year
Golden Eagle Nesting, Foraging, and Habitat Use Study Report with Management Recommendations Completed by 2020 2021
Code Obj. code Statement
AQUCHR-2 MON-RES-GEN From 2017 to 2019, continue the Golden Eagle Genetics Study begun in 2014 and collect genetic samples in conjunction with eagle captures for the Golden Eagle Nesting, Foraging, and Habitat Use Study. Analyze these samples to determine the population genetic structure of golden eagles within the MSPA (see occurrence table) and their relationship to eagle populations in other parts of the western United States.
AQUCHR-3 MGT-PRP-MGTPL In 2021, use the results and recommendations from the Golden Eagle Nesting, Foraging, and Habitat Use Study and the Golden Eagle Genetics Study to develop a comprehensive Golden Eagle Management Plan for managing golden eagle territories with nesting, roosting, and foraging habitat on Conserved Lands within the MSPA (see occurrence table). The plan should include recommendations for managing important foraging habitat to minimize human disturbance to foraging eagles and to improve habitat quality to enhance prey availability, especially during drought periods. The plan should also include specifications to control human disturbance that could discourage nesting, cause nest abandonment, or adversely affect the survival of nestlings, and for managing unstable nest ledges or tree nest sites that are critical to maintaining a breeding pair in territories with limited nesting sites.
AQUCHR-4 MON-PRP-MONPL In 2021, use the results and recommendations from the Golden Eagle Nesting, Foraging, and Habitat Use Study and the Golden Eagle Genetics Study to develop a comprehensive Golden Eagle Monitoring Plan for monitoring golden eagle status and assessing nesting, roosting, and foraging habitat on Conserved Lands within the MSPA (see occurrence table). The plan should include standardized monitoring protocols to track the status of eagles at nesting territories, to monitor use of important foraging areas, and to collect habitat and threats covariate data to inform needed management actions.

Golden eagle Aquila chrysaetos canadensis

Goal: Expand and then maintain a self-sustaining golden eagle population to ensure long term persistence (>100 years) on Conserved Lands in the MSPA by: improving reproductive success through protection of active and inactive nest sites from human disturbance; reducing anthropogenic mortality; managing large mosaics of grassland and open shrublands for optimal prey availability, especially during drought; and by minimizing human impacts to foraging eagles.

regional NFO 2017, 2018, 2019 SO
MON-RES-GEN AQUCHR-2

Management units: 3, 4, 5, 6, 8, 9, 10, 11

From 2017 to 2019, continue the Golden Eagle Genetics Study begun in 2014 and collect genetic samples in conjunction with eagle captures for the Golden Eagle Nesting, Foraging, and Habitat Use Study. Analyze these samples to determine the population genetic structure of golden eagles within the MSPA (see occurrence table) and their relationship to eagle populations in other parts of the western United States.

Action Statement Action status Projects
RES-1 Collect blood samples from captured birds to include in a larger study of golden eagle population genetics in the western United States to determine the population genetic structure within the MSPA. Genetic parameters that can be measured include gene flow between territories, relatedness of individuals, effective breeding population size, and overall genetic diversity. Determine whether eagles produced outside the MSPA immigrate into the MSPA to establish breeding territories and evaluate genetic relationships to other eagle populations in the western United States. in progress Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California , Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California
RES-2 Submit project metadata, datasets, and Golden Eagle Genetics Study report to the MSP Web Portal. in progress Five Year Site Occupancy, Nesting Success, Movement Behavior, and Genetic Structure of Golden Eagles in Western San Diego County, California , Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California
Criteria Deadline year
Golden Eagle Genetic Study with Report Completed by 2020 2021
Threat Name Threat Code
Loss of connectivityLOSCON
Urban developmentURBDEV
Code Obj. code Statement
AQUCHR-1 MON-RES-SPEC From 2017 to 2019, continue the Golden Eagle Nesting, Foraging, and Habitat Use Study, begun in 2014, to monitor golden eagle territory occupancy and reproduction in the MSPA (see occurrence table) and to track eagle movements to identify important foraging, nesting and roosting areas. Continue to study the influence of human activity and land use on patterns of eagle movement and habitat use, measure the response of eagles to human activity while foraging, and determine whether locally produced floaters recruit into the breeding population.
AQUCHR-3 MGT-PRP-MGTPL In 2021, use the results and recommendations from the Golden Eagle Nesting, Foraging, and Habitat Use Study and the Golden Eagle Genetics Study to develop a comprehensive Golden Eagle Management Plan for managing golden eagle territories with nesting, roosting, and foraging habitat on Conserved Lands within the MSPA (see occurrence table). The plan should include recommendations for managing important foraging habitat to minimize human disturbance to foraging eagles and to improve habitat quality to enhance prey availability, especially during drought periods. The plan should also include specifications to control human disturbance that could discourage nesting, cause nest abandonment, or adversely affect the survival of nestlings, and for managing unstable nest ledges or tree nest sites that are critical to maintaining a breeding pair in territories with limited nesting sites.
AQUCHR-4 MON-PRP-MONPL In 2021, use the results and recommendations from the Golden Eagle Nesting, Foraging, and Habitat Use Study and the Golden Eagle Genetics Study to develop a comprehensive Golden Eagle Monitoring Plan for monitoring golden eagle status and assessing nesting, roosting, and foraging habitat on Conserved Lands within the MSPA (see occurrence table). The plan should include standardized monitoring protocols to track the status of eagles at nesting territories, to monitor use of important foraging areas, and to collect habitat and threats covariate data to inform needed management actions.
File name Lead Author Year Type
A Clarification on the Effects of Urbanization on Golden Eagle (Aquila chrysaetos) Habitat Selection Tracey, Jeff; Madden, Melanie; Bloom, Peter; Fisher, Robert N. 2020 report
Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California, February 2016-February 2017 Bloom, Peter; Fisher, Robert N.; Katzner, Todd; Madden, Melanie; Sebes, Jeremy; Tracey, Jeff 2017 report
Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California, February 2017-December 2019 Tracey, Jeff; Madden, Melanie; Molden, James; Sebes, Jeremy; Bloom, Peter; Fisher, Robert N. 2020 report
Biotelemetry Data for Golden Eagles (Aquila chrysaetos) Captured in Coastal Southern California, November 2014-February 2016 Bloom, Peter; Fisher, Robert N.; Katzner, Todd; Madden, Melanie; Sebes, Jeremy; Tracey, Jeff 2016 report
Golden Eagle Habitat Selection as a Function of Land Use and Terrain, San Diego County, California Tracey, Jeff; Madden, Melanie; Bloom, Peter; Katzner, Todd; Fisher, Robert N. 2018 report
Topographic drivers of flight altitude over large spatial and temporal scales Bloom, Peter; Fisher, Robert N.; Tracey, Jeff; Katzner, Todd; Duerr, Adam; Miller, Tricia; Dunn, Leah; Bell, Douglas 2019 journal article