First-Year Dispersal of Golden Eagles from Natal Areas in the Southwestern United States and Implications for Second-year Settling

Murphy, Regina M.; Dunk, Jeffrey R.; Woodbridge, Brian; Stahlecker, Dale W.; LaPlante, David W.; Millsap, Brian A.; Jacobson, Kenneth V.

doi:10.3356/jrr-16-80.1

Cited by 27 publications

(48 citation statements)

References 49 publications

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“…We divided published estimates by two to get total abundance of females, assuming a 1:1 sex ratio; (B) estimated from helicopter survey of nests used by Golden Eagles in the DRECP area in 2012 (Latta and Table 8); (F) estimated from mean monthly 95% convex hull home ranges from eight Golden Eagles marked with GPS-GSM transmitters (Braham et al 2015); (G) estimated from 63 juvenile Golden Eagles marked with satellite transmitters in the southwestern U.S. (Murphy et al 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Development Focal Areas were added to the baseline mortality risk map by increasing the risk of mortality in these areas. We used estimated turbine blade-strike collision probabilities calculated for Golden Eagles (0.0037 6 0.0015 [SD]) by New et al (2015) to approximate increases in fatalities within DFAs. We also simulated the potential for degradation of foraging habitats in DFAs by subtracting 25% of baseline hexagon scores of the underlying prey availability map.…”

Section: Methodsmentioning

confidence: 99%

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Spatial Demographic Models to Inform Conservation Planning of Golden Eagles in Renewable Energy Landscapes

Wiens

Schumaker

Inman

et al. 2017

Journal of Raptor Research

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Spatial demographic models can help guide monitoring and management activities targeting at-risk species, even in cases where baseline data are lacking. Here, we provide an example of how site-specific changes in land-use and other anthropogenic stressors can be incorporated into a spatial demographic model to investigate effects on population dynamics of Golden Eagles (). Our study focused on a population of Golden Eagles exposed to risks associated with rapid increases in renewable energy development in southern California, USA. We developed a spatially-explicit, individual-based simulation model that integrated empirical data on demography of Golden Eagles with spatial data on the arrangement of nesting habitats, prey resources, and planned renewable energy development sites. Our model permitted simulated eagles of different stage-classes to disperse, establish home ranges, acquire resources, prospect for breeding sites, and reproduce. The distribution of nesting habitats, prey resources, and threats within each individual's home range influenced movement, reproduction, and survival. We used our model to explore potential effects of alternative disturbance scenarios, and proposed conservation strategies, on the future distribution and abundance of Golden Eagles in the study region. Results from our simulations suggest that probable increases in mortality associated with renewable energy infrastructure (e.g., collisions with wind-turbines and vehicles, electrocution on power poles) could have negative consequences for population trajectories, but that site-specific conservation actions could reduce the magnitude of negative impacts. Our study demonstrates the use of a flexible and expandable modeling framework to incorporate spatially dependent processes when determining relative risks of proposed management options to Golden Eagles and their habitats.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Spatial Demographic Models to Inform Conservation Planning of Golden Eagles in Renewable Energy Landscapes

Wiens

Schumaker

Inman

et al. 2017

Journal of Raptor Research

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“…) and settlement on a breeding territory, judged by changing patterns of spatial movement (after Murphy et al . ) and field confirmation of nest‐building activities (e.g. Hayhow et al .…”

Section: Methodsmentioning

confidence: 97%

“…Tags were deployed at nests across several regions of Scotland at a range of altitudes (Whitfield & Fielding 2017: table 2.2, for details). Only data from the dispersal phase of young eagles were included, as defined by departure from the natal territory (Method 7 of Weston et al 2013) and settlement on a breeding territory, judged by changing patterns of spatial movement (after Murphy et al 2017) and field confirmation of nest-building activities (e.g. Hayhow et al 2017).…”

Section: Gps Telemetrymentioning

confidence: 99%

A simple topographical model to predict Golden Eagle Aquila chrysaetos space use during dispersal

Fielding¹,

Haworth²,

Anderson

et al. 2019

Ibis

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Many large raptors exploit or rely on anabatic and orographic winds which provide vertical lift, to supplement or provide the energy fuelling flight. Airspace is therefore a critical habitat for such large raptors and its use is subject to the underlying terrestrial topography, because particular topographical features are more likely to provide wind‐energetic lift. Accordingly, ridges and/or ‘rugged topography’ are common preferred features in habitat use by large raptors. Our study aimed to provide a simple model of space use for a large raptor, the Golden Eagle Aquila chrysaetos, based on thousands of GPS telemetry records during juvenile dispersal of 92 birds tagged as nestlings between 2007 and 2016 across upland Scotland. Model development was based on the hypothesis that four topographical variables would be influential: slope, aspect, altitude and distance from ridge. The telemetry dataset was divided into training and two testing components. The first testing set was derived by a temporal split resulting in approximately equal sample size on records and some temporal overlap in individuals’ records with training data. The second testing set involved no individuals from the training set. Aspect was removed early in training model development because it was not influential. The model found that young Golden Eagles preferred, or used according to availability, space above slopes greater than 10°, at an altitude of ≥ 300 m, and within 300 m of a ridge. The test data were highly correlated with those from the training data in the model variables, and performance as regard to expected preferences from the model was improved in both test datasets, indicating the model was robust. Given the apparent universal nature of large raptor dependence on topography, that topography is relatively immutable according to time and use, and that topographical data are readily available, we commend our approach to other habitat preference studies of Golden Eagles and other large raptors elsewhere.

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“…Juvenile dispersal is considered to have three distinct phases: (1) departure from parental care, (2) transience, during which individuals investigate the landscape, and (3) settlement, where individuals first defend a breeding territory (Bowler & Benton 2005, Murphy et al 2017). The first phase of dispersal has been well studied for some avian species; however, most studies have focused on small-scale, post-fledging movements of species that exhibit short-duration parental care in only the first year of life (White & Faaborg 2008, Small et al 2015.…”

mentioning

confidence: 99%

Juvenile Sandhill Cranes exhibit wider ranging and more exploratory movements than adults during the breeding season

Wolfson

Fieberg

Andersen

2019

Ibis

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Sandhill Cranes Antigone canadensis exhibit delayed sexual maturity and breeding, and therefore juvenile Cranes searching for suitable territories to occupy have different ecological constraints on movements than adults, which must defend a territory and raise young. We used fine‐scale GPS telemetry data to characterize and compare movements of adult and juvenile Cranes near the boundary between two populations in Minnesota, USA, from arrival on natal areas in the spring until staging prior to autumn migration. Juvenile and adult Cranes had marked differences in movement patterns throughout the breeding season. Juveniles were more likely than adults to display long‐distance movements: they revisited areas less frequently throughout the breeding season and they had lower average residence times.

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First-Year Dispersal of Golden Eagles from Natal Areas in the Southwestern United States and Implications for Second-year Settling

Cited by 27 publications

References 49 publications

Spatial Demographic Models to Inform Conservation Planning of Golden Eagles in Renewable Energy Landscapes

Spatial Demographic Models to Inform Conservation Planning of Golden Eagles in Renewable Energy Landscapes

A simple topographical model to predict Golden Eagle Aquila chrysaetos space use during dispersal

Juvenile Sandhill Cranes exhibit wider ranging and more exploratory movements than adults during the breeding season

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