PROTONYM: Falco Chrysaëtos Linnaeus, 1758. Systema Naturæ per Regna Tria Naturæ, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. Tomus I. Editio decima, reformata 1, p.88.
TYPE LOCALITY: Europe; restricted to Sweden by Linnaeus, 1761, Fauna Svecica, ed. 2, p. 19.UPPERCASE: current genus Uppercase first letter: generic synonym ● and ● See: generic homonyms lowercase: species and subspecies ●: early names, variants, misspellings ‡: extinct †: type species Gr.: ancient Greek L.: Latin : derived from syn: synonym of /: separates historical and modern geographic names ex: based on TL: type locality OD: original diagnosis (genus) or original description (species)
More details: Guide to key entries Standard abbreviations and symbolsTodd E. Katzner, Michael N. Kochert, Karen Steenhof, Carol L. McIntyre, Erica H. Craig, and Tricia A. Miller
Version: 2.0 — Published September 17, 2020
Although the Golden Eagle has special conservation status and appears on Red Lists in many parts of its range it is ranked by IUCN as a species of Least Concern on a global scale. The species is listed in CITES Appendix II and has legal protections within most countries in which it occurs. Globally, the Golden Eagle is an iconic and culturally important flagship species ( 615 Katzner, T. E., and R. E. Tingay (2010). Eagle diversity, ecology and conservation. In The Eagle Watchers (R. E. Tingay and T. E. Katzner, Editors), Cornell University Press, Ithaca, NY, USA. pp. 1–25. Close , 85 Doyle, J. M., T. E. Katzner, P. H. Bloom, Y. Ji, B. K. Wijayawardena, and J. A. DeWoody (2014). The genome sequence of a widespread apex predator, the Golden Eagle (Aquila chrysaetos). PLoS One 9: e95599. Close ). In ancient Egypt, eagle hieroglyphs were symbolic of the soul after death. In contemporary North America, native cultures incorporate eagle feathers into medicines and religious ceremonies. Eagles have long been trained for falconry in Central Asia and are still used to hunt prey as large as wolves in Mongolia.
Historically, in North America and Eurasia, the Golden Eagle was heavily persecuted, via shooting, trapping, or poisoning, causing reductions in population size. Recent reduction in persecution, likely is related to stable or increasing population trends in some countries. However, threats to the species remain due to habitat change and the potential for lead poisoning, collision with wind turbines, electrocution, illegal killing, and even negative interactions with reindeer herding in northern Scandinavia. Disjunct populations in Ethiopia may be rapidly declining.
Trade for eagles in North America is primarily focused on two areas. First, the U.S. Fish and Wildlife Service (USFWS) allows use of a small number of wild-caught eagles for falconry. There are rules that limit the number taken from the wild ( 616 U.S. Fish and Wildlife Service (1987). Draft environmental assessment-falconry and raptor propagation regulations. U.S. Department of the Interior, U.S. Fish and Wildife Service, Washington, DC, USA. Close ), and these rules change frequently. Second, there is a commercial market for Golden Eagle and their parts for legal use in Native American religious ceremonies and for other illegal uses.
The USFWS authorizes permits to allow Native Americans to take and possess eagles and their parts for religious purposes. The taking of up to 40 nestling eagles by Hopi tribes is authorized under a special permit from the USFWS ( 617 U.S. Fish and Wildlife Service (2016c). Programmatic environmental impact statement for the eagle rule revision. U.S. Fish and Wildlife Service, Department of the Interior, Office of Migratory Bird Management, Washington, DC, USA. Close ). However, authorized take does not necessarily reflect actual take, and the actual take by Hopi averages around 23 eagles per year ( 618 U.S. Fish and Wildlife Service (2016b). Native American Policy. U.S. Fish and Wildlife Service, Department of the Interior, Office of Migratory Bird Management, Washington, DC, USA. Close , 617 U.S. Fish and Wildlife Service (2016c). Programmatic environmental impact statement for the eagle rule revision. U.S. Fish and Wildlife Service, Department of the Interior, Office of Migratory Bird Management, Washington, DC, USA. Close ).
Eagle carcasses in the United States are sent to the USFWS National Eagle Repository for eventual distribution to Native American tribal members. The role of the repository is to “collect, process, and distribute, as expeditiously as possible, eagle feathers and remains to federally recognized tribal members for religious, ceremonial, and cultural purposes in accordance with Federal law” ( 618 U.S. Fish and Wildlife Service (2016b). Native American Policy. U.S. Fish and Wildlife Service, Department of the Interior, Office of Migratory Bird Management, Washington, DC, USA. Close ).
Illegal take of Golden Eagles happens in many places in the United States A sting operation by the USFWS in 2018 recovered parts from 143 Golden Eagles. The defendants in this case were mostly from the states of South Dakota, and North Dakota, Montana, and Wyoming ( 619 The Wildlife Society (2018). Black market eagle feather bust nets 31. Wildlife Professional 12: 12–13. Close ).
Because of their cultural and religious significance, Golden Eagles command a high black-market value that fuels illegal killing and trafficking of eagles ( 620 Pankratz, H. (2009). Boulder eagle’s mutilation part of trend, feds say. The Denver Post. Close , 619 The Wildlife Society (2018). Black market eagle feather bust nets 31. Wildlife Professional 12: 12–13. Close ). A whole Golden Eagle carcass can bring $1,000 to $1,500, a single tail feather from a young eagle, $100, and complete tail, $500 to $800 ( 620 Pankratz, H. (2009). Boulder eagle’s mutilation part of trend, feds say. The Denver Post. Close ). Collectors of headdresses, bustles, and other replicas of Native American regalia that include eagle feathers are marketed to non-native and Native Americans in the United States and overseas ( 619 The Wildlife Society (2018). Black market eagle feather bust nets 31. Wildlife Professional 12: 12–13. Close ).
Golden Eagle is listed in CITES Appendix II, which includes non-threatened species for which trade should be controlled to protect their survival.
Golden Eagles have legal and regulatory protection in most European countries.
Golden Eagles have legal protection in most of their range states in Asia. They appear in the "Red Data Books" of most central, east and south Asian countries.
Golden Eagles in the United States are provided federal protection in several other ways. Most important is the Migratory Bird Treaty Act (MBTA; 16 U.S.C. §§ 703–712). MBTA is similar to BGEPA in that it prohibits taking of migratory birds, including eagles, but the details and implementation of MBTA differ substantially from BGEPA.
The USFWS issues guidelines and regulations designed to protect eagles from take and to set thresholds for permitting take. In 2007, USFWS issued National Bald Eagle Management Guidelines to publicize how Bald Eagle is protected, to advise the public on how human activities may disturb eagles, and to encourage nonbinding management practices to benefit eagles ( 621 U.S. Fish and Wildlife Service (2007). Endangered and Threatened Wildlife and Plants; Removing the Bald Eagle in the Lower 48 States from the List of Endangered and Threatened Wildlife. Federal Register 72(130):37346–37372. Close ). No similar document was produced for the Golden Eagle.
In 2013, USFWS issued an Eagle Conservation Plan Guidance with the goal to help make wind energy facilities compatible with eagle conservation and the laws and regulations that protect eagles ( 622 U.S. Fish and Wildlife Service (2013). Eagle Conservation Plan Guidance. Module 1 Land-based wind energy, version 2. Division of Migratory Bird Management, Washington, DC, USA. Close ). In 2016, the USFWS published a final rule in the Federal Register that revised regulations for eagle incidental take and take of eagle nests. Permits issued under this and earlier rules provide a framework for permitting incidental take of eagles, an especially important topic for renewable energy development. Finally, USFWS has created a Bald Eagle and Golden Eagle Electrocution Prevention In-lieu Fee Program that sells compensatory mitigation credits for take of Bald and Golden Eagles. All these, together with many other rules and regulations, form the framework by which the United States Government protects and manages Golden Eagles. As these rules change frequently, readers interested in current protections in the United States should follow up with their local office of the USFWS Division of Migratory Bird Management.
In addition to federal protections, in the United States, Golden Eagles are protected by law in most states in which they occur. These protections take the form of specific laws or sometimes by including them on lists of endangered, threatened, or special concern species. Golden Eagles often are mentioned in planning documents such as state Wildlife Action Plans (SWAPs). Regulations vary widely among states, often in relation to the abundance of Golden Eagles in the state and the time of the year in which they are present (i.e., many eastern states do not have state laws that protect Golden Eagles because they do not nest in those states and are present only in winter).
Within Canada, Golden Eagles are not protected at the federal level by the Canadian Migratory Birds Convention Act of 1994. However, individual provinces and territories provide protections to Golden Eagles and other species of wildlife. For details on these and a list of the relevant acts, see here.
Habitat alteration has important, often negative effects on the Golden Eagle. Occasionally, such as when nesting sites are created, they can be beneficial to the species.
Climate change is associated with change in eagle habitat. One way climate change acts on habitat is by contributing to an increase in the number and size of wildfires ( 623 Westerling, A. L., H. G. Hidalgo, D. R. Cayan, and T. W. Swetnam (2006). Warming and earlier spring increase western U.S. forest wildfire activity. Science 313(5789):940–943. Close , 624 Westerling, A. L., M. G. Turner, E. A. H. Smithwick, W. H. Romme, and M. G. Ryan (2011). Continued warming could transform Greater Yellowstone fire regimes by mid-21st century. Proceedings of the National Academy of Sciences of the United States of America 108: 13165–13170. Close , 625 Marlon, J. R., P. J. Bartlein, M. K. Walsh, S. P. Harrison, K. J. Brown, M. E. Edwards, P. E. Higuera, M. J. Power, R. S. Anderson, C. Briles, A. Brunelle, C. Carcaillet, M. Daniels, F. S. Hu, M. Lavoie, C. Long, T. Minckley, P. J. Richard, A. C. Scott, D. S. Shafer, W. Tinner, C. E. Umbanhowar Jr., and C. Whitlock (2009). Wildfire responses to abrupt climate change in North America. Proceedings of the National Academy of Sciences 106: 2519–2524. Close ), which often lead to the subsequent invasion of exotic plant species ( 626 Chambers, J. C., R. F. Miller, D. I. Board, D. A. Pyke, B. A. Roundy, J. B. Grace, E. W. Schupp, and R. J. Tausch (2014). Resilience and resistance of sagebrush ecosystems: implications for state and transition models and management treatments. Rangeland Ecology and Management 67(5): 440–454. Close ). In the intermountain American West, since 1980 fires have caused large-scale loss of shrubs and jackrabbit habitat in areas used by eagles. For example, wildfires in the Morley Nelson Snake River Birds of Prey National Conservation Area (NCA) burned 43% (approximately 53,000 ha) of the shrubland habitat between 1979 and 1994 ( 627 U.S. Department of the Interior (1996). Effects of military training and fire in the Snake River Birds of Prey National Conservation Area. U.S. Geological Survey, Biological Resources Division, Snake River Field Station, Boise, ID, USA. Close ). Nesting success at burned territories in the NCA declined after major fires but subsequently increased again, 10–11 years afterwards ( 604 Kochert, M. N., K. Steenhof, L. B. Carpenter, and J. M. Marzluff (1999). Effects of fire on Golden Eagle territory occupancy and reproductive success. Journal of Wildlife Management 63: 773–780. Close ). The number of occupied territories in the NCA has declined significantly after burning, but productivity of the remaining nests has not changed although there have been dietary shifts in the burned territories ( 348 Heath, J. A., and M. N. Kochert (2016). Golden Eagle dietary shifts in response to habitat alteration and consequences for eagle productivity in the Morley Nelson Snake River Birds of Prey National Conservation Area. Cooperator Final Report to the U. S. Fish and Wildlife Service. Boise State University, Raptor Research Center, Boise, ID, USA. Close , 603 Kochert, M. N., K. Steenhof, C. Pozzanghera, and J. A. Heath (2018). Monitoring of Golden Eagle nesting territory occupancy and reproduction in the Morley Nelson Snake River Birds of Prey National Conservation Area, Owyhee Survey Area, and Comparison Survey Areas, Idaho, 2011-16: Administrative report. U.S. Geological Survey, Reston, VA, USA. Close ). Combined, these data suggest a possible reduction in carrying capacity for Golden Eagle in the NCA that is driven by climate change mechanisms ( 604 Kochert, M. N., K. Steenhof, L. B. Carpenter, and J. M. Marzluff (1999). Effects of fire on Golden Eagle territory occupancy and reproductive success. Journal of Wildlife Management 63: 773–780. Close , 603 Kochert, M. N., K. Steenhof, C. Pozzanghera, and J. A. Heath (2018). Monitoring of Golden Eagle nesting territory occupancy and reproduction in the Morley Nelson Snake River Birds of Prey National Conservation Area, Owyhee Survey Area, and Comparison Survey Areas, Idaho, 2011-16: Administrative report. U.S. Geological Survey, Reston, VA, USA. Close ).
Energy development is also associated with changes to eagle habitat. In western North America, modern energy development of all types (e.g., wind and solar, oil and gas) could potentially affect > 40 million ha of shrublands and > 70 million ha of grasslands ( 628 Copeland, H. E., A. Pocewicz, and J. M. Kiesecker (2011). Geography of energy development in western North America: Potential impacts on terrestrial ecosystems. In Energy Development and Wildlife Conservation in Western North America (D. E. Naugle, Editor). Island Press, Washington, DC, USA. pp. 7–22. Close ). Wind energy development in Wyoming is not expected to affect nesting habitat for Golden Eagle ( 629 Tack, J. D., and B. C. Fedy (2015). Landscapes for energy and wildlife: Conservation prioritization for Golden Eagles across large spatial scales. PLoS ONE 10(8): e0134781. Close ), but there is documented potential for conflict between eagle flight habitat and wind turbines ( 8 Smallwood, K. S., and C. Thelander (2008). Bird mortality in the Altamont Pass Wind Resource Area, California. Journal of Wildlife Management 72(1): 215–223. Close , 405 Katzner, T. E., D. Brandes, T. Miller, M. Lanzone, C. Maisonneuve, J. A. Tremblay, R. Mulvihill, and G. T. Merovich Jr. (2012). Topography drives migratory flight altitude of Golden Eagles: Implications for on-shore wind energy development. Journal of Applied Ecology 49: 1178–1186. Close , 630 Miller, T. A., R. P. Brooks, M. Lanzone, D. Brandes, J. Cooper, K. O’Malley, C. Maisonneuve, J. Tremblay, A. Duerr, and T. Katzner (2014). Assessing risk to birds from industrial wind energy development via paired resource selection models. Conservation Biology 28: 745–755. Close , 403 Duerr, A. E., T. A. Miller, L. Dunn, D. A. Bell, P. H. Bloom, R. N. Fisher, J. A. Tracey, and T. E. Katzner (2019). Topographic drivers of flight altitude over large spatial and temporal scales. Auk: Ornithological Advances 136(2): 1–11. Close ).
Golden Eagle nesting and wintering areas occur in habitats where coal and other mineral development occurs ( 7 Craig, E. H., T. H. Craig, and M. R. Fuller (2018a). Using TreeNet, a machine learning approach to better understand factors that influence elevated blood lead levels in wintering Golden Eagles in the western United States. In Machine Learning for Ecology and Sustainable Natural Resource Management (G. Humphries, D. R. Magness, and F. Huettmann, Editors). Springer International Publishing, Cham, Switzerland. pp. 243–260. Close ). Mine high walls can provide nesting sites for eagles ( 631 Fala, R. A., A. Anderson, and J. P. Ward (1985). Highwall-to-pole Golden Eagle nest site relocations. Raptor Research 19: 1–7. Close ), but surface coal mines can threaten scarce nesting sites in Wyoming ( 632 Phillips, R. L., and A. E. Beske (1984). Resolving conflicts between energy development and nesting Golden Eagles. In Issues and Technology in the Management of Impacted Western Wildlife (R. D. Comer, J. M. Merino, J. W. Monarch, C. Pustmueller, M. Stalmaster, R. Stoecker, J. Todd and W. Wright, Editors). Thorne Ecological Institute, Boulder, CO, USA. pp. 214–219. Close ). This interaction may become less relevant if less coal is mined when coal-fired power plants are decommissioned ( 633 U.S. Energy Information Administration (2019). More U.S. coal-fired power plants are decommissioning as retirements continue. U.S. Energy Information Administration, Today in Energy. Accessed 31 August 2019. Close ).
Urbanization and human population growth also alter eagle habitat. These processes have rendered many historical eagle use areas unsuitable, particularly in southern California ( 634 Scott, T. A. (1985). Human impacts on the Golden Eagle population of San Diego County. M.S. thesis, San Diego State University, San Diego, CA, USA. Close ) and the Colorado Front Range ( 597 Boeker, E. L. (1974). Status of Golden Eagle surveys in the western states. Wildlife Society Bulletin 2: 46–49. Close ). In one study, abandoned territories in San Diego County, California, had more dwellings within 2 km and higher human populations within 5 km than territories that continued to be occupied ( 634 Scott, T. A. (1985). Human impacts on the Golden Eagle population of San Diego County. M.S. thesis, San Diego State University, San Diego, CA, USA. Close ). In addition, widespread agricultural development and urban sprawl in the western United States is known to reduce jackrabbit populations and makes areas less suitable for nesting and wintering eagles ( 473 Beecham, J. J., and M. N. Kochert (1975). Breeding biology of the Golden Eagle in southwestern Idaho. Wilson Bulletin 87: 506–513. Close , 347 U.S. Department of Interior (1979). Snake River Birds of Prey Special Research Report to the Secretary of the Interior. U.S. Department of Interior, Bureau of Land Management, Boise, ID, USA. Close , 234 Craig, E. H., T. H. Craig, and L. R. Powers (1986). Habitat use by wintering Golden Eagles and Rough-legged Hawks in southeastern Idaho. Raptor Research 20: 69–71. Close ).
The most widespread anthropogenic alteration of habitat now occurring in eastern North America results from hydraulic fracturing (“fracking”) associated with shale gas development ( 635 Kiviat, E. (2013). Risks to biodiversity from hydraulic fracturing for natural gas in the Marcellus and Utica shales. Annals of the New York Academy of Sciences 1286: 1–14. Close ). Wintering Golden Eagles in this region are associated with forested landscapes, but they also use open areas within those forests ( 144 Miller, T. A., R. P. Brooks, M. J. Lanzone, J. Cooper, K. O’Malley, D. Brandes, A. Duerr, and T. E. Katzner (2017). Summer and winter space use and home range characteristics of Golden Eagles (Aquila chrysaetos) in eastern North America. Condor 119: 697–719. Close ). Fracking creates forest openings, but it is not known how the effects of fracking on forest cover will influence Golden Eagle numbers.
Landscapes in eastern North America have changed dramatically over the past 100 years as forest cover has increased and suburban landscapes have grown in prominence. These combined effects have had important consequences for numbers of white-tailed deer and wild turkey, both important prey species for eastern Golden Eagle ( 5 Katzner, T., B. W. Smith, T. A. Miller, D. Brandes, J. Cooper, M. Lanzone, D. Brauning, C. Farmer, S. Harding, D. E. Kramar, C. Koppie, C. Maisonneuve, M. Martell, E. K. Mojica, C. Todd, J. A. Tremblay, M. Wheeler, D. F. Brinker, T. E. Chubbs, R. Gubler, K. O'Malley, S. Mehus, B. Porter, R. P. Brooks, B. D. Watts, and K. L. Bildstein (2012). Status, biology, and conservation priorities for North America's eastern Golden Eagle (Aquila chrysaetos) population. Auk 129: 168–176. Close ).
Invasive predators have few impacts on the Golden Eagle. The species sometimes feed on non-native prey (e.g., Ring-necked Pheasant, Rock Pigeon; 304 Bedrosian, G., J. W. Watson, K. Steenhof, M. N. Kochert, C. R. Preston, B. Woodbridge, G. E. Williams, K. R. Keller, and R. H. Crandall (2017). Spatial and temporal patterns in Golden Eagle diets in the western United States, with implications for conservation planning. Journal of Raptor Research 51(3): 347–367. Close ) that may be considered invasive. Parasites that are invasive or expanding their distribution also may be consequential to eagles. See Demography and Populations: Disease and Body Parasites for additional details. Changing weather patterns associated with global warming contribute to an increase in wildfires and the subsequent spread of invasive grasses (e.g., cheatgrass [Bromus tectorum]) plant species ( 626 Chambers, J. C., R. F. Miller, D. I. Board, D. A. Pyke, B. A. Roundy, J. B. Grace, E. W. Schupp, and R. J. Tausch (2014). Resilience and resistance of sagebrush ecosystems: implications for state and transition models and management treatments. Rangeland Ecology and Management 67(5): 440–454. Close , 636 Creutzburg, M. K., J. E. Halofsky, J. S. Halofsky, and T. A. Christopher (2015). Climate change and land management in the rangelands of central Oregon. Environmental Management 55(1): 43–55 Close ). These exotics can dramatically alter fire regimes of shrublands and affect important habitats ( 637 Knick, S. T., D. S. Dobkin, J. T. Rotenberry, M. A. Schroeder, W. M. Vander Haegen, and C. Van Riper III (2003). Teetering on the edge or too late? Conservation and research issues for avifauna of sagebrush habitats. Condor 105(4): 611–634. Close ), affecting prey species, such as jackrabbits, which in turn affects Golden Eagle distribution and subsequent eagle territory occupancy, reproductive success, and distribution patterns during their annual cycle ( 604 Kochert, M. N., K. Steenhof, L. B. Carpenter, and J. M. Marzluff (1999). Effects of fire on Golden Eagle territory occupancy and reproductive success. Journal of Wildlife Management 63: 773–780. Close ).
Historically, eagles have been shot in parts of North America where depredation of domestic livestock was suspected, and to supply the trade in eagle-related Native American artifacts. Unregulated but legal aerial hunting of eagles began in California as early as 1936, with > 200 killed that winter. From 1941 to 1961, 20,000 Golden Eagles may have been shot from airplanes in southwestern states ( 417 Spofford, W. R. (1964). Golden Eagle in the Trans-Pecos and Edwards Plateau of Texas. National Audubon Society, New York, NY, USA. Close ). Hunting clubs in western Texas shot nearly 5,000 eagles between 1941 and 1947, likely reducing the number of breeding pairs in parts of Texas and New Mexico ( 638 Phillips, R. L. (1986). Current issues concerning the management of Golden Eagles in western U.S.A. In Birds of Prey Bulletin no. 3. (R. D. Chancellor and B. U. Meyburg, Editors). World Working Group on Birds of Prey and Owls, Berlin, Germany. pp. 149–156. Close ). In 1971, > 500 eagles were killed in Colorado and Wyoming by helicopter gunmen hired by sheep ranchers ( 639 Beans, B. E. (1996). Eagle's plume. Scribner, New York, NY, USA. Close ).
Even after legal protections were enacted (see Conservation Status: Legal and Regulatory Protections), eagles continue to be killed and shooting appears to be a common cause of death of eagles in North America and elsewhere in the world ( 611 Whitfield, D. P., A. H. Fielding, D. R. A. McLeod, and P. F. Haworth (2004). Modelling the effects of persecution on the population dynamics of Golden Eagles in Scotland. Biological Conservation 119(3): 319–333. Close , 640 Whitfield, D. P., A. H. Fielding, D. R. A. McLeod, and P. F. Haworth (2004). The effects of persecution on age of breeding and territory occupation in golden eagles in Scotland. Biological Conservation 118: 249–259. Close , 574 Whitfield, D. P., and A. H. Fielding (2017). Analyses of the fates of satellite tracked Golden Eagles in Scotland. Scottish Natural Heritage Commissioned Report Number 982. Close , 422 U.S. Fish and Wildlife Service (2016a). Bald and Golden Eagles: Population Demographics and Estimation of Sustainable Take in the United States, 2016 Update. U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Washington, DC, USA. Close ).
Native Americans harvest Golden Eagles for cultural and religious purposes ( 641 Fewkes, J. W. (1900). Property-right in eagles among the Hopi. American Anthropologist 2: 690–707. Close , 642 Hough, W. (1971). The Hopi Indians. Shorey Book Store, Seattle, WA, USA. Close ). Historically, this harvest was widespread, and it pre-dated other forms of human-caused mortality in North America ( 29 Palmer, R. S. (Editor) (1988). Diurnal raptors. In Handbook of North American Birds. Yale University Press, New Haven, CT, USA. pp. 324–380. Close , 422 U.S. Fish and Wildlife Service (2016a). Bald and Golden Eagles: Population Demographics and Estimation of Sustainable Take in the United States, 2016 Update. U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Washington, DC, USA. Close ). Some tribal cultural and religious activities involve the taking of live eagles. For example, members of the southwestern Hopi tribe remove nestlings from nests in April, raise them in captivity, and sacrifice them in July, when they are fully feathered. Recent research indicates that harvest may negatively affect local fledgling production ( 643 Stahlecker, D. W., Z. P. Wallace, D. G. Mikesic, and C. S. Smith (2017). Does Hopi religious harvest of eaglets affect Golden Eagle territory occupancy and reproduction on the Navajo Nation? Journal of Raptor Research 51: 305–318. Close ).
Incidental trapping resulting in death of eagles has probably occurred as long as people have been trapping mammals. Eagles are incidentally captured in traps set for mammalian predators for predator control, and in traps set to capture furbearing mammals for commercial and other purposes.
There is peer-reviewed published evidence that eagles and other raptors are attracted to exposed bait associated with leg-hold traps, snares, and poison sets designed to catch wild furbearers and other vertebrate animals ( 575 Bortolotti, G. R. (1984). Trap and poison mortality of Golden and Bald eagles. Journal of Wildlife Management 48: 1173–1179. Close , 644 U.S. Environmental Protection Agency (EPA) (1996). R.E.D. Facts: Strychnine (No. EPA-738-F-96-033), Prevention, Pesticides and Toxic Substances (7508W). United States Environmental Protection Agency, Washington, DC, USA. Close , 645 Fournier, G., A. St-Louis, G. Fitzgerald, P. Tambourgi, and A. Forest (2014). Les aigles et le piégeage: Comment éviter les captures accidentelles. Fédération des Trappeurs Gestionnaires du Québec, Québec, QC, Canada. Close , 573 Russell, R. E., and J. C. Franson (2014). Causes of mortality in eagles submitted to the National Wildlife Health Center 1975–2013. Wildlife Society Bulletin 38:697–704. Close ). Most trapping or poisoning deaths occur in winter when eagles are more likely to scavenge. Females may be more susceptible to incidental trapping or poisoning than are males ( 575 Bortolotti, G. R. (1984). Trap and poison mortality of Golden and Bald eagles. Journal of Wildlife Management 48: 1173–1179. Close ).
There are numerous anecdotal reports that illustrate the diversity of ways that eagles may be inadvertently captured in traps for mammals. In western North America, two adult females were incidentally killed in a marten trap in April 1901 in the Forty-Mile region of western Yukon Territory, Canada ( 646 Grinnell, J., F. Stephens, J. Dixon, and E. Heller (1909). Birds and mammals of the 1907 Alexander expedition to southeastern Alaska. University of California Publications in Zoology 5: 171–264. Close ). Much more recently, 3 telemetered eagles from south-central Alaska were incidentally killed in wolf snares in central British Columbia in winter (December, January) in 2016 and 2018 (T. Booms, personal communication).
In the eastern United States and Canada, Golden Eagles are sometimes caught in and killed in both snares and leg-holds ( 647 Fitzgerald, G., J. Tremblay, J. Lemaître, and A. St-Louis (2015). Captures accidentelles d’aigles royaux et de pygargues à tête blanche par les trappeurs d’animaux à fourrure au Québec. Le Naturaliste Canadien 139: 82–89. Close , TEK, TAM). Of 95 Golden Eagles tracked in eastern North America, 6 were captured in snares or leg-hold traps (TAM, TEK). In recent years, several Golden Eagles and Bald Eagles have been photographed at migration count sites, at bait over carrion, or simply in flight, with broken-off snares hanging around their necks (TAM), or with leg-hold traps attached to one foot (TEK).
Strychnine is highly toxic to birds, including eagles ( 648 Littrell, E. E. (1990). Effects of field vertebrate pest control on nontarget wildlife (with emphasis on bird and rodent control). In Proceedings of 14th Vertebrate Pest Conference (L. R. Davis and R. E. Marsh, Editors), Vertebrate Pest Council, Davis, CA, USA. pp. 59–61. Close ), and has been used to control animals in the United States since before 1947. However, because of threats to non-target species such as raptors, above-ground use of the toxicant has been prohibited in the United States since 1988 ( 644 U.S. Environmental Protection Agency (EPA) (1996). R.E.D. Facts: Strychnine (No. EPA-738-F-96-033), Prevention, Pesticides and Toxic Substances (7508W). United States Environmental Protection Agency, Washington, DC, USA. Close ). At least 10 eagles died in 1971 from eating thallium sulfate–laced antelope set out by sheep ranchers in Wyoming. Poisoning of this type by sheep ranchers continued into the 1980s ( 639 Beans, B. E. (1996). Eagle's plume. Scribner, New York, NY, USA. Close ). Carbofuran, which kills raptors frequently in Africa ( 649 Ogada, D. L. (2014). The power of poison: Pesticide poisoning of Africa’s wildlife. Annals of the New York Academy of Sciences 1322: 1–20. Close ), also can present risk to Golden Eagles ( 650 Mineau, P. (1993). The hazard of carbofuran to birds and other vertebrate wildlife. Technical Report Series no. 177. Canadian Wildlife Service, National Wildlife Research Centre, Ottawa, ON, Canada. Close ) if it is used inappropriately within their range. In Scotland, this toxicant is used illegally to kill Golden Eagles ( 651 Whitfield, D. P., D. R. A. McLeod, J. Watson, A. H. Fielding, and P. F. Haworth (2003). The association of grouse moor in Scotland with the illegal use of poisons to control predators. Biological Conservation 114: 157–163. Close ). Carbofuran was banned in granular form in the United States in 1999 because of its lethal effects on migratory birds. The U.S. Environmental Protection Agency issued a final rule in May 2009 banning all use of carbofuran (marketed as Furadan) on food crops in the United States It is also banned in Canada.
Susceptibility of Golden Eagles to organochlorine pesticides appears to depend on the degree to which birds in a given region feed on birds or mammals. In the western United States where the species feeds primarily on mammals, data suggest that Golden Eagles are not highly exposed to DDT poisoning. For example, eggs collected after 1946 had shell thicknesses similar to those collected in earlier years ( 519 Anderson, D. W., and J. J. Hickey (1972). Eggshell changes in certain North American birds. In Proceedings of the XVth International Ornitholological Congress (K. H. Voous, Editor). E. J. Brill, Leiden, Netherlands. pp. 514–540. Close ; for additional details, see Breeding: Eggs: Eggshell Thickness). Likewise, from 1964 to 1975, when many organochlorine pesticides were still legal, DDE and dieldrin levels in eggs and tissues from Golden Eagles in western North America were below thresholds known to cause reproductive problems (for exact levels, see 358 Reynolds, H. V., III (1969). Population status of the Golden Eagle in south-central Montana. M.S. thesis, University of Montana, Missoula, MT, USA. Close , 199 Kochert, M. N. (1972). Population status and chemical contamination in Golden Eagles in southwestern Idaho. M.S. thesis, University of Idaho, Moscow, ID, USA. Close , 652 Reidinger, R. F., Jr., and D. G. Crabtree (1974). Organochlorine residues in Golden Eagles, United States, March 1964–July 1971. Pesticides Monitoring Journal 8: 37–43. Close , 653 Noble, D. G., J. E. Elliott, and J. L. Shutt (1993). Environmental contaminants in Canadian raptors 1965–1989. Canadian Wildlife Service, National Wildlife Research Centre, Ottawa, ON, Canada. Close ). From 1990 to 1993, 48% of migrant eagles in west-central Montana had detectable levels of DDE in their blood, but the maximum concentration was < 0.021 ppm wet weight ( 654 Harmata, A. R., and M. Restani (1995). Environmental contaminants and cholinesterase in blood of vernal migrant Bald and Golden eagles in Montana. Intermountain Journal of Sciences 1: 1–15. Close ). Of 14 territorial Golden Eagles captured and tested in the Columbia Basin, Washington from 2005-2013, six had DDE levels below detection levels, and the remaining eight had low but detectable DDE concentrations ( 316 Watson, J. W., and R. W. Davies (2015). Lead, mercury, and DDE in the blood of nesting Golden Eagles in the Columbia Basin, Washington. Journal of Raptor Research 49: 217–221. Close ). Dieldrin was not detected in eggs in that study. Finally, DDT poisoning was not the cause of death for any of the 139 tracked and recovered Golden Eagles considered in the U.S. Fish and Wildlife Service analysis noted previously ( 422 U.S. Fish and Wildlife Service (2016a). Bald and Golden Eagles: Population Demographics and Estimation of Sustainable Take in the United States, 2016 Update. U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Washington, DC, USA. Close ).
In the northeastern United States, a region where Golden Eagles may eat more birds, long periods of reproductive failure followed by territory vacancy suggest that DDT poisoning had a role in the local extirpation of the species ( 5 Katzner, T., B. W. Smith, T. A. Miller, D. Brandes, J. Cooper, M. Lanzone, D. Brauning, C. Farmer, S. Harding, D. E. Kramar, C. Koppie, C. Maisonneuve, M. Martell, E. K. Mojica, C. Todd, J. A. Tremblay, M. Wheeler, D. F. Brinker, T. E. Chubbs, R. Gubler, K. O'Malley, S. Mehus, B. Porter, R. P. Brooks, B. D. Watts, and K. L. Bildstein (2012). Status, biology, and conservation priorities for North America's eastern Golden Eagle (Aquila chrysaetos) population. Auk 129: 168–176. Close ). Numbers of adult eagles counted at migration count sites in eastern North America declined during the DDT era ( 195 Todd, C. S. (2000). Golden Eagle Assessment. Maine Department of Inland Fisheries and Wildlife, Augusta, ME, USA. Close ), and chronic nesting failures in New York were attributed to DDT poisoning ( 216 Spofford, W. R. (1971). The breeding status of the Golden Eagle in the Appalachians. American Birds 25: 3–7. Close ). Finally, a single unhatched egg collected from one of the last occupied eagle territories in Maine, in 1996, contained levels of DDE and PCBs adequate to impair reproduction ( 195 Todd, C. S. (2000). Golden Eagle Assessment. Maine Department of Inland Fisheries and Wildlife, Augusta, ME, USA. Close ).
Lead poisoning has long been recognized as a threat to Golden Eagles in North America ( 656 Craig, T. H., J. W. Connelly, E. H. Craig and T. L. Parker (1990). Lead concentrations in Golden and Bald eagles. Wilson Bulletin 102: 130–133. Close ) and more recently in Europe ( 13 Kenntner, N., Y. Crettenand, H.-J. Fünfstück, M. Janovsky, and F. Tataruch (2007). Lead poisoning and heavy metal exposure of Golden Eagles (Aquila chrysaetos) from the European Alps. Journal of Ornithology 148(2): 173–177. Close , 18 Madry, M. M., T. Kraemer, J. Kupper, H. Naegeli, H. Jenny, L. Jenni, and D. Jenny (2015). Excessive lead burden among Golden Eagles in the Swiss Alps. Environmental Research Letters 10(3): 034003. Close ). It is thought to cause about 2–3% of Golden Eagle deaths in the United States ( 422 U.S. Fish and Wildlife Service (2016a). Bald and Golden Eagles: Population Demographics and Estimation of Sustainable Take in the United States, 2016 Update. U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Washington, DC, USA. Close ), although elevated but sublethal blood lead levels are widespread across the continent ( 657 Haig, S. M., J. D’Elia, C. Eagles-Smith, J. M. Fair, J. Gervais, G. Herring, J. W. Rivers, and J. H. Schulz (2014). The persistent problem of lead poisoning in birds from ammunition and fishing tackle. Condor 116: 408–428. Close , 658 Herring, G., C. A. Eagles-Smith, and J. Buck (2017). Characterizing Golden Eagle risk to lead and anticoagulant rodenticide exposure: A review. Journal of Raptor Research 51(3): 273–292. Close ). Data from individual field studies support these observations. Elevated blood-lead levels (> 0.20 ppm; 659 Kramer, J. L., and P. T. Redig (1997). Sixteen years of lead poisoning in eagles, 1980–1995: An epizootiologic view. Journal of Raptor Research 31:327–332. Close , 660 Cruz-Martinez, L., P. T. Redig, and J. Deen (2012). Lead from spent ammunition: A source of exposure and poisoning in Bald Eagles. Human–Wildlife Interactions 6: 11. Close ) occurred in 36% of 162 eagles from southern California, 1985–1986 ( 661 Pattee, O. H., P. H. Bloom, J. M. Scott, and M. R. Smith (1990). Lead hazards within the range of the California Condor. Condor 92: 931–937. Close ), 46% of 281 wintering eagles from Idaho, 1990–1997 ( 443 Craig, E. H., and T. H. Craig (1998). Lead and mercury levels in Golden and Bald eagles and annual movements of Golden Eagles wintering in east central Idaho 1990–1997. Idaho State Office, U.S. Department of the Interior, Bureau of Land Management, Boise, ID, USA. Close ), 56% of 86 spring migrants in Montana, 1985–1993 ( 654 Harmata, A. R., and M. Restani (1995). Environmental contaminants and cholinesterase in blood of vernal migrant Bald and Golden eagles in Montana. Intermountain Journal of Sciences 1: 1–15. Close ), 33% of 178 autumn migrants in Montana, 2006–2012 ( 662 Langner, H. W., R. Domenech, V. A. Slabe, and S. P. Sullivan (2015). Lead and mercury in fall migrant golden eagles from western North America. Archives of Environmental Contamination and Toxicology 69(1): 54–61. Close ), and 30% of 66 eagles captured during winter in the eastern United States 2010–2016 (J. Cooper, M. Lanzone, S. Van Arsedale, W. Perrone, unpublished data; TAM, TEK). Lead poisoning is also a frequent cause of illness or death of eagles admitted to rehabilitation centers ( 656 Craig, T. H., J. W. Connelly, E. H. Craig and T. L. Parker (1990). Lead concentrations in Golden and Bald eagles. Wilson Bulletin 102: 130–133. Close , 659 Kramer, J. L., and P. T. Redig (1997). Sixteen years of lead poisoning in eagles, 1980–1995: An epizootiologic view. Journal of Raptor Research 31:327–332. Close , 663 Stauber, E., N. Finch, P. A. Talcott, and J. M. Gay (2010). Lead poisoning of Bald (Haliaeetus leucocephalus) and Golden (Aquila chrysaetos) eagles in the U.S. inland Pacific Northwest region—An 18-year retrospective study: 1991–2008. Journal of Avian Medicine and Surgery 24: 279–287. Close ) or necropsied at wildlife health labs ( 664 Wayland, M., and T. Bollinger (1999). Lead exposure and poisoning in Bald Eagles and Golden Eagles in the Canadian prairie provinces. Environmental Pollution 104: 341–350. Close ).
A recent large-scale analysis of Golden Eagles from across the United States provides the most comprehensive look at the extent to which eagle populations are exposed to lead ( 665 Slabe, V. A. (2019). Lead exposure of North American raptors. Ph.D. dissertation, West Virginia University, Morgantown, WV, USA. Close ). Of 384 eagles whose blood was tested, only 13% had no evidence of lead exposure (lead levels were below the level of detection of the instrument), and 9% had blood lead levels above the threshold for clinical poisoning (> 50 ug/dL). Liver data from 171 eagles told a similar story: only 10% had no evidence of lead exposure, and 7% were above the threshold for clinical poisoning. However, lead levels in eagle bone, an indicator of chronic subclinical lead exposure ( 664 Wayland, M., and T. Bollinger (1999). Lead exposure and poisoning in Bald Eagles and Golden Eagles in the Canadian prairie provinces. Environmental Pollution 104: 341–350. Close , 18 Madry, M. M., T. Kraemer, J. Kupper, H. Naegeli, H. Jenny, L. Jenni, and D. Jenny (2015). Excessive lead burden among Golden Eagles in the Swiss Alps. Environmental Research Letters 10(3): 034003. Close ), provided a different perspective on lead exposure. Of 223 individuals sampled, only one had no evidence of lead exposure, and nearly 50% had levels above the threshold for clinical poisoning. This study also provided evidence of seasonal, regional, and age-related variation in lead exposure. Finally, although this study detected no sex-related differences in lead exposure, other studies have identified potential differences in lead exposure of male and female eagles ( 238 Craig, E. H., M. R. Fuller, T. H. Craig, and F. Huettmann (2018b). Assessment of potential risks from renewable energy development and other anthropogenic factors to wintering Golden Eagles in the western United States. In Machine Learning for Ecology and Sustainable Natural Resource Management (G. Humphries, D. R. Magness, and F. Huettmann, Editors). Springer International Publishing, Cham, pp. 379–407. Close ).
There is good evidence that eagles are exposed to lead via their diet ( 666 Katzner, T. E., M. J. Stuber, V. A. Slabe, J. T. Anderson, J. L. Cooper, L. L. Rhea, and B. A. Millsap (2018). Origins of lead in populations of raptors. Animal Conservation 21: 232–240. Close ). Sources of lead are predominantly fragments of ammunition in hunter-killed mammals and birds ( 664 Wayland, M., and T. Bollinger (1999). Lead exposure and poisoning in Bald Eagles and Golden Eagles in the Canadian prairie provinces. Environmental Pollution 104: 341–350. Close , 667 Wayland, M., L. K. Wilson, J. E. Elliott, M. J. R. Miller, T. Bollinger, M. McAdie, K. Langelier, J. Keating, and J. M. W. Froese (2003). Mortality, morbidity, and lead poisoning of eagles in western Canada, 1986–98. Journal of Raptor Research 37: 8–18. Close , 668 Clark, A., and A. M. Scheuhammer (2003). Lead poisoning in upland-foraging birds of prey in Canada. Ecotoxicology 12: 23–30. Close , 657 Haig, S. M., J. D’Elia, C. Eagles-Smith, J. M. Fair, J. Gervais, G. Herring, J. W. Rivers, and J. H. Schulz (2014). The persistent problem of lead poisoning in birds from ammunition and fishing tackle. Condor 116: 408–428. Close ), particularly deer ( 661 Pattee, O. H., P. H. Bloom, J. M. Scott, and M. R. Smith (1990). Lead hazards within the range of the California Condor. Condor 92: 931–937. Close ) and ground squirrels ( 654 Harmata, A. R., and M. Restani (1995). Environmental contaminants and cholinesterase in blood of vernal migrant Bald and Golden eagles in Montana. Intermountain Journal of Sciences 1: 1–15. Close , 669 Herring, G., C. Eagles-Smith, and M. Wagner (2016). Ground squirrel shooting and potential lead exposure in breeding avian scavengers. PLoS ONE 11: e0167926. Close , 670 McTee, M., M. Young, A. Umansky, and P. Ramsey (2017). Better bullets to shoot small mammals without poisoning scavengers. Wildlife Society Bulletin 41: 736–742. Close ). Blood-lead levels vary with season ( 661 Pattee, O. H., P. H. Bloom, J. M. Scott, and M. R. Smith (1990). Lead hazards within the range of the California Condor. Condor 92: 931–937. Close , 238 Craig, E. H., M. R. Fuller, T. H. Craig, and F. Huettmann (2018b). Assessment of potential risks from renewable energy development and other anthropogenic factors to wintering Golden Eagles in the western United States. In Machine Learning for Ecology and Sustainable Natural Resource Management (G. Humphries, D. R. Magness, and F. Huettmann, Editors). Springer International Publishing, Cham, pp. 379–407. Close ), and they decreased regionally after a ban on lead ammunition was implemented in parts of California ( 671 Kelly, T. R., P. H. Bloom, S. G. Torres, Y. Z. Hernandez, R. H. Poppenga, W. M. Boyce, and C. K. Johnson (2011). Impact of the California lead ammunition ban on reducing lead exposure in Golden Eagles and Turkey Vultures. PLOS One 6(4): e17656. Close ). Seasonal variation in blood lead levels and the correspondence of the timing of eagle scavenging with the timing of hunting seasons provide good evidence of the link between human hunting behavior and lead exposure of eagles ( 672 Bedrosian, B., D. Craighead, and R. Crandall (2012). Lead exposure in Bald Eagles from big game hunting, the continental implications and successful mitigation efforts. PLOS One 7: e51978. Close , 665 Slabe, V. A. (2019). Lead exposure of North American raptors. Ph.D. dissertation, West Virginia University, Morgantown, WV, USA. Close ).
Eagles that consume prey items contaminated with lead may experience only temporary elevations in blood lead levels ( 654 Harmata, A. R., and M. Restani (1995). Environmental contaminants and cholinesterase in blood of vernal migrant Bald and Golden eagles in Montana. Intermountain Journal of Sciences 1: 1–15. Close ), but the linkages between routes and intensity of exposure and consequent tissue lead levels are poorly understood ( 673 Fallon, J. A., P. Redig, T. A. Miller, M. Lanzone, and T. Katzner (2017). Guidelines for evaluation and treatment of lead poisoning of wild raptors. Wildlife Society Bulletin 41: 205–211 Close ). Blood-lead levels of 67% (n = 33) of wintering eagles in east-central Idaho, increased or stayed the same when recaptured (from 1–5 years after initial capture), suggesting repeated exposure to lead ( 443 Craig, E. H., and T. H. Craig (1998). Lead and mercury levels in Golden and Bald eagles and annual movements of Golden Eagles wintering in east central Idaho 1990–1997. Idaho State Office, U.S. Department of the Interior, Bureau of Land Management, Boise, ID, USA. Close ). Chronic subclinical lead exposure may alter movement behavior of Golden Eagles ( 674 Ecke, F., N. J. Singh, J. M. Arnemo, A. Bignert, B. Helander, Å. M. M. Berglund, H. Borg, C. Bröjer, K. Holm, M. Lanzone, T. Miller, Å. Nordström, J. Räikkönen, I. Rodushkin, E. Ågren, and B. Hörnfeldt (2017). Sublethal lead exposure alters movement behavior in free-ranging Golden Eagles. Environmental Science & Technology 51: 5729–5736. Close ) and also may weaken birds and predispose them to injury, predation, starvation, disease, or reproductive failure ( 659 Kramer, J. L., and P. T. Redig (1997). Sixteen years of lead poisoning in eagles, 1980–1995: An epizootiologic view. Journal of Raptor Research 31:327–332. Close , 443 Craig, E. H., and T. H. Craig (1998). Lead and mercury levels in Golden and Bald eagles and annual movements of Golden Eagles wintering in east central Idaho 1990–1997. Idaho State Office, U.S. Department of the Interior, Bureau of Land Management, Boise, ID, USA. Close ).
Secondary poisoning occurs when individuals consume prey killed or sickened by chemical pesticides such as those used to protect crops or kill rodents. Recent evidence suggests that anticoagulant rodenticides may be an important source of increased mortality rates for many birds of prey ( 675 Thomas, P. J., P. Mineau, R. F. Shore, L. Champoux, P. A. Martin, L. K. Wilson, G. Fitzgerald, and J. E. Elliott (2011). Second generation anticoagulant rodenticides in predatory birds: Probabilistic characterisation of toxic liver concentrations and implications for predatory bird populations in Canada. Environment International 37(5): 914–920. Close , 422 U.S. Fish and Wildlife Service (2016a). Bald and Golden Eagles: Population Demographics and Estimation of Sustainable Take in the United States, 2016 Update. U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Washington, DC, USA. Close ). Golden Eagle is susceptible to several different first- and second-generation anticoagulant rodenticides ( 676 Stone, W. B., J. C. Okoniewski, and J. R. Stedelin (1999). Poisoning of wildlife with anticoagulant rodenticides in New York. Journal of Wildlife Diseases 35: 187–193. Close , 675 Thomas, P. J., P. Mineau, R. F. Shore, L. Champoux, P. A. Martin, L. K. Wilson, G. Fitzgerald, and J. E. Elliott (2011). Second generation anticoagulant rodenticides in predatory birds: Probabilistic characterisation of toxic liver concentrations and implications for predatory bird populations in Canada. Environment International 37(5): 914–920. Close , 677 Elliott, J. E., B. A. Rattner, R. F. Shore, and N. W. Van Den Brink (2016). Paying the pipers: mitigating the impact of anticoagulant rodenticides on predators and scavengers. Bioscience 66(5): 401–407 Close ). From 1990 to 1993, heptachlor epoxide levels in plasma of spring migrants in west-central Montana were < 0.039 ppm wet weight ( 654 Harmata, A. R., and M. Restani (1995). Environmental contaminants and cholinesterase in blood of vernal migrant Bald and Golden eagles in Montana. Intermountain Journal of Sciences 1: 1–15. Close ). Three eagles that died in Oregon from 1977–1980 had lethal (> 8 ppm) levels of heptachlor epoxide ( 678 Henny, C. J., L. J. Blus, and T. E. Kaiser (1984). Heptachlor seed treatment contaminates hawks, owls, and eagles of Columbia Basin, Oregon. Raptor Research 18: 41–48. Close ). Those poisoned eagles apparently ate prey that had eaten heptachlor-treated seed. Anticoagulant rodenticide also was detected in the liver of the single Golden Eagle whose carcass was submitted to the New York Department of Environmental Conservation ( 679 Stone, W. B., J. C. Okoniewski, and J. R. Stedelin (2003). Anticoagulant rodenticides and raptors: Recent findings from New York, 1998–2001. Bulletin of Environmental Contamination and Toxicology 70(1):34–40. Close ).
Often are injured or killed by collisions with cars, fences, wires, and wind turbines ( 422 U.S. Fish and Wildlife Service (2016a). Bald and Golden Eagles: Population Demographics and Estimation of Sustainable Take in the United States, 2016 Update. U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Washington, DC, USA. Close ). Of these, collisions with vehicles may be the most common. As an example, nearly 100 Golden Eagles were killed on highways near Rock Springs, Wyoming in winter 1984–1985 ( 638 Phillips, R. L. (1986). Current issues concerning the management of Golden Eagles in western U.S.A. In Birds of Prey Bulletin no. 3. (R. D. Chancellor and B. U. Meyburg, Editors). World Working Group on Birds of Prey and Owls, Berlin, Germany. pp. 149–156. Close ).
Eagle mortality from blade strikes at wind energy facilities is of substantial interest within the United States and in Europe (see, e.g., 8 Smallwood, K. S., and C. Thelander (2008). Bird mortality in the Altamont Pass Wind Resource Area, California. Journal of Wildlife Management 72(1): 215–223. Close , 680 Bright, J., R. Langston, R. Bullman, R. Evans, S. Gardner, and J. Pearce-Higgins (2008). Map of bird sensitivities to wind farms in Scotland: a tool to aid planning and conservation. Biological Conservation 141(9): 2342–2356. Close , 681 Martínez, J. E., J. F. Calvo, J. A. Martínez, I. Zuberogoitia, E. Cerezo, J. Manrique, G. J. Gómez, J. C. Nevado, M. Sánchez, R. Sánchez, and J. Bayo (2010). Potential impact of wind farms on territories of large eagles in southeastern Spain. Biodiversity and Conservation 19(13): 3757–3767 Close , 682 Pagel, J. E., K. J. Kritz, B. A. Millsap, R. K. Murphy, E. L. Kershner, and S. Covington (2013). Bald Eagle and Golden Eagle mortalities at wind energy facilities in the contiguous United States. Journal of Raptor Research 47: 311–315. Close ). At least 79 Golden Eagles were killed at 10 facilities in the United States from 1997–2012, with most fatalities occurring towards the end of that period as turbines became more numerous ( 682 Pagel, J. E., K. J. Kritz, B. A. Millsap, R. K. Murphy, E. L. Kershner, and S. Covington (2013). Bald Eagle and Golden Eagle mortalities at wind energy facilities in the contiguous United States. Journal of Raptor Research 47: 311–315. Close ). However, this study almost certainly underestimates actual fatalities because it relies on incidental finds and voluntary reporting, and it ignores some of the facilities in California where many recorded fatalities have occurred. For example, during the period 1998–2002, an average of 67 Golden Eagles were killed each year by turbine blade strikes at the Altamont Pass Wind Resource Area, California ( 8 Smallwood, K. S., and C. Thelander (2008). Bird mortality in the Altamont Pass Wind Resource Area, California. Journal of Wildlife Management 72(1): 215–223. Close ). That number appears to have declined with repowering and installation of larger turbines ( 683 Alameda County Community Development Agency (2014). Altamont Pass Wind Resource Area Repowering Draft Program Environmental Impact Report. State Clearinghouse #2010082063. June (ICF 00323.08.) Hayward, CA. With technical assistance from ICF International, Sacramento, CA, USA. Close ).
Golden Eagle fatalities at wind turbines have occurred in most western U.S. states, especially Wyoming. Of 113 deaths of eagles tagged from 1994 to 2000 in and around Altamont Pass ( 6 Hunt, W. G. (2002). Golden Eagles in a perilous landscape: Predicting the effects of mitigation for wind turbine bladestrike mortality. California Energy Commission (CEC) Consultant Report P500-02-043F, CEC Sacramento, California. July 2002. Prepared for CEC. Public Interest Energy Research (PIER), Sacramento, CA, by University of California, Santa Cruz, CA, USA. Close ), 37% were turbine strikes, 11% were electrocutions, and 6% were non-anthropogenic in origin. The remainder of fatalities were unknown in origin or were from poisonings, collisions or shootings. In another study, > 25% of fatalities at Altamont were of birds that grew their feathers long distances away, suggesting that demographic impacts extend far beyond the region where the turbines are located ( 684 Katzner, T. E., D. M. Nelson, M. A. Braham, J. M. Doyle, N. B. Fernandez, A. E. Duerr, P. H. Bloom, M. C. Fitzpatrick, T. A. Miller, R. C. E. Culver, L. Braswell, and J. A. DeWoody (2017). Golden Eagle fatalities and the continental-scale consequences of local wind-energy generation. Conservation Biology 31: 406–415. Close ).
Golden Eagle is vulnerable to electrocution when they land on power poles and they are among the most frequently electrocuted raptors in North America ( 685 Lehman, R. N., P. L. Kennedy, and J. A. Savidge (2007b). The state of the art in raptor electrocution research: A global review. Biological Conservation 136(2): 159–174. Close , 686 Lehman, R. N., J. A. Savidge, P. L. Kennedy, and R. E. Harness (2010b). Raptor electrocution rates for a utility in the intermountain western United States. Journal of Wildlife Management 74 (3): 459–470. Close ). Pole configuration is the most frequently identified risk factor associated with electrocution of eagles ( 687 Mojica, E. K., J. F. Dwyer, R. E. Harness, G. E. Williams, and B. Woodbridge (2018). Review and synthesis of research investigating Golden Eagle electrocutions. Journal of Wildlife Management 82(3): 495–506 Close ). Younger birds appear more susceptible to electrocution, possibly because they are less skilled fliers and more likely to make contact with wires when landing ( 685 Lehman, R. N., P. L. Kennedy, and J. A. Savidge (2007b). The state of the art in raptor electrocution research: A global review. Biological Conservation 136(2): 159–174. Close , 686 Lehman, R. N., J. A. Savidge, P. L. Kennedy, and R. E. Harness (2010b). Raptor electrocution rates for a utility in the intermountain western United States. Journal of Wildlife Management 74 (3): 459–470. Close , 422 U.S. Fish and Wildlife Service (2016a). Bald and Golden Eagles: Population Demographics and Estimation of Sustainable Take in the United States, 2016 Update. U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Washington, DC, USA. Close , 687 Mojica, E. K., J. F. Dwyer, R. E. Harness, G. E. Williams, and B. Woodbridge (2018). Review and synthesis of research investigating Golden Eagle electrocutions. Journal of Wildlife Management 82(3): 495–506 Close ). Risk also appears to increase when inclement weather hampers flight or when wet feathers increase electrical conductivity ( 688 Avian Power Line Interaction Committee (1996). Suggested practices for raptor protection on power lines: the state of the art in 1996. Edison Electric Institute and Raptor Research Foundation, Washington, DC, USA. Close , 685 Lehman, R. N., P. L. Kennedy, and J. A. Savidge (2007b). The state of the art in raptor electrocution research: A global review. Biological Conservation 136(2): 159–174. Close ). A large proportion of electrocutions appear to occur during winter and in areas in western states where there are relatively fewer natural perches ( 689 Benson, P. C. (1981). Large raptor electrocution and powerpole utilization: A study in six western states. Ph.D. dissertation, Brigham Young University, Provo, UT, USA. Close , 690 Harness, R. E., and K. R. Wilson (2001). Electric-utility structures associated with raptor electrocutions in rural areas. Wildlife Society Bulletin 29 (2): 612–623. Close ).
Human release of pharmaceuticals and other environmental contaminants may have indirect effects that are not well understood. Antibiotic resistant bacteria have been found in Bald Eagles in Alaska ( 691 Ahlstrom, C. A., J. Bonnedahl, H. Woksepp, J. Hernandez, B. Olsen, and A. M. Ramey (2018). Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfll as inferred through genomic analysis. Scientific Reports 8: 7361. Close ). The demographic consequence of these infections, whether direct or indirect, are not understood and it is not clear whether Golden Eagle is also exposed to these drug-resistant bacteria.
Beyond indirect effects of pharmaceutical products via drug-resistant bacteria, these chemicals may also have direct effects. In particular, non-steroid anti-inflammatory drugs have caused widespread declines in vultures in south Asia ( 692 Green, R. E., I. Newton, S. Shultz, A. A. Cunningham, M. Gilbert, D. J. Pain, and V. Prakash (2004). Diclofenac poisoning as a cause of vulture population declines across the Indian subcontinent. Journal of Applied Ecology 41: 793–800. Close ), several are toxic to many raptor species ( 693 Cuthbert, R., J. Parry-Jones, R. E. Green, and D. J. Pain (2007). NSAIDs and scavenging birds: potential impacts beyond Asia’s critically endangered vultures. Biology Letters 3: 90–93. Close ) and at least one of these, Diclofenac, is known to be toxic to congeneric Steppe Eagles (Aquila nipalensis; 694 Sharma, A. K., M. Saini, S. D. Singh, V. Prakash, A. Das, R. B. Dasan, S. Pandey, D. Bohara, T. H. Galligan, R. E. Green, D. Knopp, and R. J. Cuthbert (2014). Diclofenac is toxic to the Steppe Eagle Aquila nipalensis: widening the diversity of raptors threatened by NSAID misuse in South Asia. Bird Conservation International 24(3): 282–286. Close ).
Human activity near nests can prevent nesting and cause failure of breeding attempts by Golden Eagles. Human activity close to nesting sites was thought to be the main reason that several eagle pairs did not nest in a northern Colorado study area ( 695 D’Ostilio, D. O. (1954). Nesting status and food of the Golden Eagle in northern Colorado. M.S. thesis, University of Colorado, Boulder, CO, USA. Close ). As of 1985, abandoned Golden Eagle territories in San Diego County, California, had more dwellings and higher human populations nearby than did territories that continued to be occupied ( 634 Scott, T. A. (1985). Human impacts on the Golden Eagle population of San Diego County. M.S. thesis, San Diego State University, San Diego, CA, USA. Close ). Two studies in western North America attributed 46–85% of Golden Eagle nesting failures to human disturbance ( 472 Camenzind, F. J. (1969). Nesting ecology and behavior of the Golden Eagle Aquila chrysaetos L. Brigham Young University Science Bulletin, Biological Series 10(4):4–15, 35–36. Close , 268 Boeker, E. L., and T. D. Ray (1971). Golden Eagle population studies in the Southwest. Condor 73: 463–467. Close ), and nesting success in Scotland is related inversely to human disturbance around nests ( 2 Watson, J. (2010). The Golden Eagle. Second edition. T. & A. D. Poyser, London, United Kingdom. Close ).
Human activity near nests also can interfere with and reduce parental care. Adult Golden Eagles in Alaska spend less time at nests and feed their young less often and a smaller amount of food per day when observers are camped close by ( 696 Steidl, R. J., K. D. Kozie, G. J. Dodge, T. Pehovski, and E. R. Hogan (1993). Effects of human activity on breeding behavior of Golden Eagles in Wrangell-St. Elias National Park and Preserve; A preliminary assessment. National Park Service, Wrangell-St. Elias National Park Preserve, Copper Center, AK, USA. Close ). That study suggested that vulnerability of nesting eagles to human disturbance likely depends on topography and physical characteristics of the nest ( 696 Steidl, R. J., K. D. Kozie, G. J. Dodge, T. Pehovski, and E. R. Hogan (1993). Effects of human activity on breeding behavior of Golden Eagles in Wrangell-St. Elias National Park and Preserve; A preliminary assessment. National Park Service, Wrangell-St. Elias National Park Preserve, Copper Center, AK, USA. Close ).
Outdoor recreation, whether on foot or by off-road vehicle can influence the nesting biology of eagles adversely. Golden Eagle territory occupancy rates in northern Finland are lower near tourist communities and are associated negatively with the length of nearby skiing and snowmobile trails ( 697 Kaisanlahti-Jokimἄki, M.-L., J. Jokima¨ki, E. Huhta, M. Ukkola, P. Helle, and T. Ollila (2008). Territory occupancy and breeding success of the Golden Eagle (Aquila chrysaetos) around tourist destinations in northern Finland. Ornis Fennica 85: 2–12. Close ). In southwestern Idaho, occupancy and success of territories near recreational trails and parking areas declined from 1999 to 2009 after a dramatic increase in off-highway vehicle (OHV) use ( 546 Steenhof, K., J. L. Brown, and M. N. Kochert (2014). Temporal and spatial changes in Golden Eagle reproduction in relation to increased off highway vehicle activity. Wildlife Society Bulletin 38: 682–688. Close ). In contrast, occupancy and success of territories not impacted by OHVs did not change. In that same study area, a 2-year follow-up study indicated that OHV use was associated with a reduction in the probability of both territory occupancy and nest survival ( 419 Spaul, R. J., and J. A. Heath (2016). Nonmotorized recreation and motorized recreation in shrub-steppe habitats affects behavior and reproduction of Golden Eagles (Aquila chrysaetos). Ecology and Evolution 6(22): 8037–8049. Close ). In addition, early season pedestrian use and other nonmotorized use reduced the probability of egg-laying, and pedestrians, who often arrived near eagle nests via motorized vehicles, were associated with a reduction in time that eagles spent at the nest. A more recent study in the same area concluded that recreation can be a significant threat to occupancy of eagle territories and reproduction ( 698 Davis, C. M. (2019). Recreation, Fire and Disease Create a Mosaic of Threats for Golden Eagles in Southwestern Idaho. Boise State University Theses and Dissertations 1590, Boise, ID, USA. Close ). Modeling indicated that recreation effects on eagle reproduction can have population-level consequences, through a process whereby marginal territories become vacant and reproductive potential of eagles is reduced in areas with high levels of recreation activities ( 699 Pauli, B. P., R. J. Spaul, and J. A. Heath (2017). Forecasting disturbance effects on wildlife: tolerance does not mitigate effects of increased recreation on wildlands. Animal Conservation 20(3): 251–260. Close ).
Nesting Golden Eagles were not affected adversely by helicopter passes during heli-skiing and military operations in the Wasatch Mountains of Utah ( 430 Grubb, T. G., D. K. Delaney, W. W. Bowerman, and M. R. Wierda (2010). Golden Eagle indifferences to heli-skiing and military helicopters in northern Utah. Journal of Wildlife Management 74: 1275–1285. Close ). There were no differences in nesting success or productivity the year of the helicopter activity, or in occupancy in following years, at territories that were visited and not visited by helicopters. In that study, most (66%) eagles either showed no response or watched (30%) the 227 helicopters passing by. The few cases eagles responded (2% of passes), were all after hatching and the responses were that eagles would either flatten in the nest or fly away from the nest. These data are consistent with anecdotal observations from biologists who have conducted surveys of eagle nests from helicopter (MNK, P. Bloom, personal observations).
An anecdotal account from a single nest in Arizona suggests that birds do not respond to sonic booms or low-level jets flights ( 700 Ellis, D. H., C. H. Ellis, and D. P. Mindell (1991). Raptor responses to low-level jet aircraft and sonic booms. Environmental Pollution 74: 58–83. Close ). However, a larger-scale study in Idaho suggested that when military training was occurring, birds were less frequently seen attempting to capture prey, and, in years when prey levels were low, flew at higher altitudes during training than when training did not occur ( 701 Schueck, L. S., J. M. Marzluff, and K. Steenhof (2001). Influence of military activities on raptor abundance and behavior. Condor 103(3): 606–615. Close ).
Golden Eagle may grow habituated to presence of humans (CLM, MNK, 702 Ruddock, M., and D. P. Whitfield (2007). A review of disturbance distances in selected bird species. Report to Scottish Natural Heritage. Close ) as is the case for other related species (habituation, the reduction of a response to a frequent stimulus is to be distinguished from tolerance, which does not require repeated exposure to a stimulant). Bald Eagle is reported to habituate to human activity ( 703 Stalmaster, M. V., and J. R. Newman (1978). Behavioral responses of wintering Bald Eagles to human activity. Journal of Wildlife Management 42:506–513. Close , 704 Steidl, R. J., and R. G. Anthony (2000). Experimental effects of human activity on breeding Bald Eagles. Ecological Applications 10: 258–268. Close ). Similarly, nest defense by Spanish Eagle in response to research visits grows more intense over time, as the birds gain experience with researchers ( 705 Ferrer, M., L. Garcia, and R. Cadenas (1990). Long-term changes in the nest defense intensity of the Spanish Imperial Eagle Aquila adalberti. Ardea 78: 395–398. Close ).
Putatively benign or beneficial research activities also can influence survival and behavior of Golden Eagle. For example, climbers entering nests for research purposes can kill eggs or nestlings when they: (1) spend too much time at a nest and cause parents to abandon eggs or nestlings; (2) keep parents off a nest long enough to subject eggs or young nestlings (incapable of thermoregulation) to overheating or cooling; (3) flush an adult, who accidentally knocks an egg or nestlings out of nest; (4) cause a nest to collapse; or (5) cause nestlings to fledge prematurely. These cases are rare and can be avoided with proper precautions ( 706 Pagel, J. E., and R. K. Thorstrom (2007). Ch. 10: Accessing nests. In Raptor Research and Management Techniques (D. M. Bird and K. L. Bildstein, Editors), Hancock House Publishers, Blaine, WA, USA. Close ; USGS, unpublished data). Likewise, as noted above for closely related Spanish Imperial Eagles, repeated visits to nests, conducted at territories over many years, resulted in increased intensity of nest defense ( 705 Ferrer, M., L. Garcia, and R. Cadenas (1990). Long-term changes in the nest defense intensity of the Spanish Imperial Eagle Aquila adalberti. Ardea 78: 395–398. Close ). Furthermore, nestling Imperial Eagles handled by ungloved human hands were more likely to have Staphylococcus infections than were those handled by scientists wearing gloves ( 707 Ferrer, M., and F. Hiraldo (1985). Human-associated staphylococcal infection in Spanish Imperial Eagles. Journal of Wildlife Diseases 31: 534–536. Close ).
There is other evidence from North America of research impacts on Golden Eagle. Of 76 eagle pairs monitored in the states of Colorado, Montana and Wyoming, the 23 whose nests were visited and whose young were banded were more likely to switch nests and less likely to attempt breeding in the subsequent year, than were those whose nests were not visited ( 549 Harmata, A. R. (2002). Encounters of Golden Eagles banded in the Rocky Mountain West. Journal of Field Ornithology 73: 23–32. Close ). At a single nest in Montana, nestlings lost weight when parents temporarily abandoned nests following a prolonged visit to a nest by researchers ( 529 Ellis, D. H. (1973b). Behavior of the Golden Eagle: an ontogenic study. Ph.D. dissertation, University of Montana, Missoula, MT, USA. Close ). All these nestlings later fledged at or above normal weights ( 529 Ellis, D. H. (1973b). Behavior of the Golden Eagle: an ontogenic study. Ph.D. dissertation, University of Montana, Missoula, MT, USA. Close ).
As is the case for recreational or military aircraft, surveys conducted by aircraft also do not seem to influence behavior or productivity of eagles. Early studies from fixed-wing aircraft in the Rocky Mountains caused no desertions or mortalities, despite the fact that the pilots deliberately passed close to the nest in an attempt to drive eagles away (to check nest contents; 708 Boeker, E. L. (1970). Use of aircraft to determine Golden Eagle, Aquila chrysaetos, nesting activity. Southwestern Naturalist 15: 136–137. Close ). In later studies in Montana, close approaches with fixed-wing aircraft and helicopters never caused adults or nestlings to flush from cliff nests ( 709 Dubois, K. (1984). Rocky Mountain Front Raptor Survey, December 1982–November 1983. Final Report. Montana Department of Fish, Wildlife, and Parks, Helena, MT, USA. Close ). During 906 helicopter passes by nests with incubating adults in southwestern Idaho and interior Alaska (n = 20 yr), only 11 adults flushed from nests. However, behavior differs when birds are not on the nest. In the Idaho study area, adults perched away from nests flushed in 121 times of 227 passes. No nestlings were flushed prematurely from nests during 778 helicopter checks in southwestern Idaho and Denali National Park and Preserve, Alaska (USGS, unpublished data; CLM).
Eagles may respond to aircraft in other ways. Coyle ( 323 Coyle, A. M. (2008). An investigation of the ecology of nesting Golden Eagles in North Dakota. Ph.D. dissertation, University of North Dakota, Grand Forks, ND, USA. Close ) observed “aggressive territorial behavior” toward a Piper PA-18 Super Cub fixed-wing aircraft on numerous occasions during nest surveys in North Dakota. In contrast, eagles rarely attack helicopters during nest surveys or flyovers in southern Idaho ( 3 Kochert, M. N., K. Steenhof, C. L. McIntyre, and E. H. Craig. 2002. Golden Eagle (Aquila chrysaetos). In The Birds of North America, No. 684 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA. Close , EHC; T. Craig, personal communication), interior Alaska (n = 30 years, > 90 territories; CLM), the Brooks Range, Alaska, (EHC; T. Craig, personal communication), or Utah ( 430 Grubb, T. G., D. K. Delaney, W. W. Bowerman, and M. R. Wierda (2010). Golden Eagle indifferences to heli-skiing and military helicopters in northern Utah. Journal of Wildlife Management 74: 1275–1285. Close ).
Capture and marking of eagles (wing tags, transmitters, rings/bands) almost certainly influence birds and may have negative consequences for individuals. It is not known how these factors influence populations, although individual birds are known to have been injured or killed by nest entry, or errors in capture, handling, or marking (TEK, MNK, KS, CLM, EHC, TAM).
However, in southwestern Idaho, wing markers had no adverse effects on individuals marked as nestlings ( 710 Kochert, M. N., K. Steenhof, and M. Q. Moritsch (1983). Evaluation of patagial markers for raptors and ravens. Wildlife Society Bulletin 11: 271–281. Close ). Likewise, in Wyoming, six adults wearing colored wing markers exhibited normal reproductive behavior and above-average reproductive success ( 711 Phillips, R. L., J. L. Cummings, and J. D. Berry (1991). Effects of patagial markers on the nesting success of Golden Eagles. Wildlife Society Bulletin 19: 434–436. Close ). In southwestern Idaho, nine nesting pairs with adults wearing backpack radio transmitters had similar productivity and success rates as control pairs (n = 3 yr; 176 Marzluff, J. M., S. T. Knick, M. S. Vekasy, L. S. Schueck, and T. J. Zarriello (1997). Spatial use and habitat selection of Golden Eagles in southwestern Idaho. Auk 114(4): 673–687. Close ).
Importantly, other studies suggest the potential for negative effects on reproduction and survival from trapping territorial adults and fitting them with wing-markers or telemetry devices (MNK, M. Lochkart, unpublished data). Furthermore, these markers potentially can alter drag and airflow, thus influencing flight behavior, migratory performance, metabolic rate, and survival as has been shown for other species ( 712 Obrecht H., C. Pennycuick, and M. Fuller (1988) Wind tunnel experiments to assess the effect of back-mounted radio transmitters on bird body drag. Journal Experimental Biology 135: 265−273. Close , 713 Gessaman, J. A., and K. A. Nagy (1988). Transmitter loads affect the flight speed and metabolism of homing pigeons. Condor 90: 662–668. Close , 383 Gessaman, J. A., M. R. Fuller, P. J. Perkins, and G. E. Duke (1991). Resting metabolic rate of Golden Eagles, Bald Eagles, and Barred Owls with a tracking transmitter or an equivalent load. Wilson Bulletin 103: 261–265. Close , 714 Gessaman, J. A., G. W. Workman, and M. R. Fuller (1991b). Flight performance, energetics and water turnover of Tippler pigeons with a harness and dorsal load. Condor 93: 546–554. Close , 715 Pennycuick C., P. L. Fast, N. Ballerstädt, and N. Rattenborg (2012) The effect of an external transmitter on the drag coefficient of a bird’s body, and hence on migration range, and energy reserves after migration. Journal of Ornithology 153: 633−644 Close , 716 Kay, W. P., D. S. Naumann, H. J. Bowen, S. J. Withers, B. J. Evans, R. P. Wilson, T. B. Stringell, J. C. Bull, P. W. Hopkins, and L. Borger (2019). Minimizing the impact of biologging devices: Using computational fluid dynamics for optimizing tag design and positioning. Methods in Ecology and Evolution 10: 1222–1233. Close ). This is especially true when tail-mount transmitters are used (e.g., 717 Hupp, J. W., S. Kharitonov, N. M. Yamaguchi, K. Ozaki, P. L. Flint, J. M. Pearce, K. Tokita, T. Shimada, and H. Higuchi (2015). Evidence that dorsally mounted satellite transmitters affect migration chronology of Northern Pintails. Journal of Ornithology 156(4): 977–989. Close , 718 Harmata, A. R. (2016). Retention, effect and utility of tail-mounted satellite tracked transmitters on Golden Eagles. Journal of Raptor Research 50: 265–275. Close ), as these have well-documented negative effects ( 719 Reynolds, R. T., G. C. White, S. M. Joy, and R. W. Mannan (2004). Effects of radiotransmitters on northern goshawks: do tailmounts lower survival of breeding males? Journal of Wildlife Management 68(1): 25–32. Close , 720 Vandenabeele, S. P., E. Grundy, M. I. Friswell, A. Grogan, S. C. Votier, and R. P. Wilson (2014) Excess baggage for birds: Inappropriate placement of tags on Gannets changes flight patterns. PLoS ONE 9(3): e92657. Close ). Finally, although there are few data to evaluate strengths and weaknesses of different designs of harnesses for attachment of telemetry units to birds, this likely influences the effect of telemetry units on birds (CLM, TAM, TEK). Appropriate positioning of telemetry devices near the center of mass of the animal, reductions in size related to technological development, and advances in form factor to reduce drag ( 716 Kay, W. P., D. S. Naumann, H. J. Bowen, S. J. Withers, B. J. Evans, R. P. Wilson, T. B. Stringell, J. C. Bull, P. W. Hopkins, and L. Borger (2019). Minimizing the impact of biologging devices: Using computational fluid dynamics for optimizing tag design and positioning. Methods in Ecology and Evolution 10: 1222–1233. Close ), and improvements in harness design, all may reduce the effects of tagging on research animals.
In conjunction with the Eagle Conservation Plan Guidance and the framework for permits for incidental take, the USFWS established a policy of “no net loss’’ for Golden Eagles in the United States. As such, any permitted take must be offset by actions that either reduce Golden Eagle mortality from another source or increase Golden Eagle productivity ( 622 U.S. Fish and Wildlife Service (2013). Eagle Conservation Plan Guidance. Module 1 Land-based wind energy, version 2. Division of Migratory Bird Management, Washington, DC, USA. Close ). Currently there are limited approved options to compensate for take ( 622 U.S. Fish and Wildlife Service (2013). Eagle Conservation Plan Guidance. Module 1 Land-based wind energy, version 2. Division of Migratory Bird Management, Washington, DC, USA. Close , 721 Allison, T. D., J. F. Cochrane, E. Lonsdorf, and C. Sanders-Reed (2017). A review of options for mitigating take of Golden Eagles at wind energy facilities. Journal of Raptor Research 51(3): 319–333. Close ). However, the USFWS has a stated policy of willingness to approve credible and defensible forms of mitigation that will offset added mortality, such as nest site improvements demonstrated to increase productivity (B. Millsap, personal communication). As of 2020, several proposals for mitigation options are being considered. Most prominent of these is to mitigate take of eagles by reducing lead poisoning rates of eagles. This would be implemented via efforts to convince hunters to voluntarily switch from lead to non-lead hunting ammunition (“lead abatement”; 722 Cochrane, J. F., E. Lonsdorf, T. D. Allison, and C. A. Sanders-Reed (2015). Modeling with uncertain science: estimating mitigation credits from abating lead poisoning in Golden Eagles. Ecological Applications 25: 1518–1533. Close ). Other similar proposals include removal of ungulate roadkill where eagle scavenging can result in collision mortality, prey habitat improvement, nest site enhancement, and rehabilitation of injured birds ( 721 Allison, T. D., J. F. Cochrane, E. Lonsdorf, and C. Sanders-Reed (2017). A review of options for mitigating take of Golden Eagles at wind energy facilities. Journal of Raptor Research 51(3): 319–333. Close ).
Despite these alternatives, mitigation to offset take for the Golden Eagle is primarily accomplished via retrofitting power poles that pose the risk of electrocution. Over the past 40 years, biologists, engineers, and government officials have cooperated in developing and publicizing power-pole designs that reduce raptor electrocutions. Some new power lines in non-urban areas have been built to raptor-safe construction standards ( 688 Avian Power Line Interaction Committee (1996). Suggested practices for raptor protection on power lines: the state of the art in 1996. Edison Electric Institute and Raptor Research Foundation, Washington, DC, USA. Close ). Since the early 1970s, utility companies have modified poles to prevent eagle electrocutions and such retrofitting is an important component of mitigation to offset take at wind energy facilities. Retrofitting may be an effective way to reduce fatalities of eagles due to electrocution, though this can be difficult to demonstrate ( 685 Lehman, R. N., P. L. Kennedy, and J. A. Savidge (2007b). The state of the art in raptor electrocution research: A global review. Biological Conservation 136(2): 159–174. Close , 686 Lehman, R. N., J. A. Savidge, P. L. Kennedy, and R. E. Harness (2010b). Raptor electrocution rates for a utility in the intermountain western United States. Journal of Wildlife Management 74 (3): 459–470. Close ); nonetheless, birds can still be electrocuted when retrofitting is done incorrectly ( 723 Dwyer, J. E., R. E. Harness, and D. Eccleston (2017). Avian electrocutions on incorrectly retrofitted power poles. Journal of Raptor Research 51(3): 293–304. Close ).
Because of the risks to eagles and other birds associated with leg-hold and snare traps for mammals, many U.S. states have regulations governing their use. Typical approaches to minimizing take of birds is to prohibit use of exposed baits, or to require baits to be located away from traps to avoid capturing non-target species ( 645 Fournier, G., A. St-Louis, G. Fitzgerald, P. Tambourgi, and A. Forest (2014). Les aigles et le piégeage: Comment éviter les captures accidentelles. Fédération des Trappeurs Gestionnaires du Québec, Québec, QC, Canada. Close ); see online trapping regulations published by state wildlife agencies for additional information. Nevertheless, eagles are still captured in such traps when they are set illegally or in states without these regulations. Snares appear to be particularly dangerous to eagles in Quebec because there are no regulations requiring stops that prevent the snare from fully closing around an eagle’s neck ( 647 Fitzgerald, G., J. Tremblay, J. Lemaître, and A. St-Louis (2015). Captures accidentelles d’aigles royaux et de pygargues à tête blanche par les trappeurs d’animaux à fourrure au Québec. Le Naturaliste Canadien 139: 82–89. Close ).
Mitigation and management for take of eagles at wind energy facilities is, as of 2020, an important research focus within the United States. The U.S. Department of Justice has prosecuted two wind companies for killing eagles in Wyoming ( 724 U.S. Department of Justice (2013). Utility Company Sentenced In Wyoming For Killing Protected Birds At Wind Projects. U.S. Department of Justice Press Release, 22 November 2013. Accessed 31 August 2019. Close , 725 U.S. Department of Justice (2014). Utility Company Sentenced in Wyoming for Killing Protected Birds at Wind Projects. U.S. Department of Justice Press Release, 19 December 2014. Accessed 31 August 2019. Close ). These prosecutions resulted in fines for these companies and some of the money generated from those fines was used to establish research and mitigation funds to support conservation of Golden Eagles in Wyoming. The U.S. Fish and Wildlife service has issued permits to allow take of eagles at wind facilities, but take requires offsetting mitigation or management actions ( 721 Allison, T. D., J. F. Cochrane, E. Lonsdorf, and C. Sanders-Reed (2017). A review of options for mitigating take of Golden Eagles at wind energy facilities. Journal of Raptor Research 51(3): 319–333. Close ). Because there are limited options for mitigation of take of eagles, the U.S. Department of Energy has funded research programs focused on developing detection and deterrent technologies that would reduce frequency of eagle-turbine collisions. Detection technologies often involve computer vision solutions such as IdentiFlight or DTBird. As of spring 2020, no deterrents are commercially available, although loud noises and bright lights have been tested to scare away birds. These technologies are nascent but, in many cases, promising, and their development, in conjunction with the development of mitigation options described above, has the potential to have broad benefits for eagle conservation.
Hacking techniques have been used to establish or re-establish populations of raptors ( 726 Dzialak, M. R., M. J. Lacki, K. M. Carter, K. Huie, and J. J. Cox (2006). From the field: an assessment of raptor hacking during a reintroduction. Wildlife Society Bulletin 34(2): 542–547. Close ). Hacking involves placing nestlings in artificial cages at sites where they will eventually be released. Humans care for the young until they are of fledging age, at which point the cage is opened and birds are allowed to leave and begin feeding themselves. Often, fledglings will continue return to be fed at hack sites for 4–6 weeks until they achieve independence. Hacking has been used for the Golden Eagle in North America in the southern Appalachians (see Introductions in the Southern Appalachians, below), in Kansas ( 727 May, R., and M. Weigel (1989). Golden Eagle reintroduction on the Wilson Wildlife Area in western Kansas: 1989 report. Prairie Raptor Project, Brooksville, KS, USA. Close ), and possibly elsewhere.
Golden Eagle is occasionally responsible for losses of newborn domestic sheep on the open range in the western United States ( 425 Phillips, R. L., J. L. Cummings, and J. D. Berry (1991). Responses of breeding Golden Eagles to relocation. Wildlife Society Bulletin 19: 430–434. Close ), particularly in cool, wet springs when rabbit populations are low ( 728 Matchett, M. R., and B. W. O'Gara (1987). Methods of controlling Golden Eagle depredation on domestic sheep in southwestern Montana. Journal of Raptor Research 21: 85–94. Close ). In the past, some of these birds have been trapped and relocated. In 1975, for example, 145 Golden Eagles were trapped and relocated ( 729 U.S. Fish and Wildlife Service (1982). Eagle permits; Permits for falconry purposes, Proposed rule. Federal Register 47: 46866–46868. Close ). A later study of marked and relocated resident eagles suggested that most (12 of 14) returned to their original territories after relocation 400–500 km away ( 425 Phillips, R. L., J. L. Cummings, and J. D. Berry (1991). Responses of breeding Golden Eagles to relocation. Wildlife Society Bulletin 19: 430–434. Close ). In another study, relocation of migratory eagles as far as 322 km was successful in reducing depredation on a short-term basis ( 730 Waite, B. C., and R. L. Phillips (1994). An approach to controlling Golden Eagle predation on lambs in South Dakota. In Proceedings of the 16th Vertebrate Pest Conference (W. S. Halverson and A. C. Crabb, Editors), Vertebrate Pest Conference, Davis, CA, USA. pp. 227–232. Close ). However, translocations are expensive and sometimes may only move the depredation problem from one place to another ( 728 Matchett, M. R., and B. W. O'Gara (1987). Methods of controlling Golden Eagle depredation on domestic sheep in southwestern Montana. Journal of Raptor Research 21: 85–94. Close ). As a consequence of these concerns, translocations are rarely used for management of eagles. Recent rules allow a small number of master falconers to apply for a permit to take, remove, and possess a Golden Eagle suspected of killing livestock (50 CFR 22.24).
Golden Eagle nests have been relocated to move them away from human activity. Nests with broods have been relocated up to 1.4 km in Wyoming to move young from proposed mining areas or from existing mine high walls scheduled for elimination ( 731 Postovit, H. R., J. W. Grier, J. M. Lockhart, and J. Tate Jr. (1982). Directed relocation of a Golden Eagle nest site. Journal of Wildlife Management 46: 1045–1048. Close , 631 Fala, R. A., A. Anderson, and J. P. Ward (1985). Highwall-to-pole Golden Eagle nest site relocations. Raptor Research 19: 1–7. Close ). Pairs at relocated nests have been successful for > 20 years (H. Postovit, personal communication).
Management for individual Golden Eagles can include rehabilitation of sick or injured animals. Wildlife rehabilitation centers treat eagles that have been injured (see Demography and Populations: Causes of Mortality: Free-flying Eagles for summaries from wildlife rehabilitation centers and wild populations). Effective treatments are available for many of these illnesses ( 732 Redig, P.T., L. Arent, H. Lopes, and L. Cruz (2007). Rehabilitation. In Raptor Research and Management Techniques (D. M. Bird and K. L. Bildstein, Editors). Hancock House Publishers, Blaine, WA, USA. Close , 733 Franson, J. C., M. Friend, S. E. J. Gibbs, and M. A. Wild, Editors (2015). Field Manual of Wildlife Diseases: Techniques and Methods 15. U.S. Geological Survey, U.S. Fish and Wildlife Service, and National Park Service, Washington, DC, USA. Close , 673 Fallon, J. A., P. Redig, T. A. Miller, M. Lanzone, and T. Katzner (2017). Guidelines for evaluation and treatment of lead poisoning of wild raptors. Wildlife Society Bulletin 41: 205–211 Close , 569 Dudek, B. M., M. N. Kochert, J. Barnes, P. H. Bloom, J. Papp, R. Gerhold, K. E. Purple, K. V. Jacobson, C. R. Preston, C. R. Vennum, J. W. Watson, and J. A. Heath (2018). Prevalence and risk factors of Trichomonas gallinae and trichomonosis in Golden Eagle (Aquila chrysaetos) nestlings in western North America. Journal of Wildlife Diseases 54: 755–764. Close , 603 Kochert, M. N., K. Steenhof, C. Pozzanghera, and J. A. Heath (2018). Monitoring of Golden Eagle nesting territory occupancy and reproduction in the Morley Nelson Snake River Birds of Prey National Conservation Area, Owyhee Survey Area, and Comparison Survey Areas, Idaho, 2011-16: Administrative report. U.S. Geological Survey, Reston, VA, USA. Close ). Recent studies have used point-of-care technologies developed for humans to assess lead poisoning of eagles caught in the course of field research, and to determine when it may be appropriate to remove a sick bird from the wild for treatment before releasing it ( 673 Fallon, J. A., P. Redig, T. A. Miller, M. Lanzone, and T. Katzner (2017). Guidelines for evaluation and treatment of lead poisoning of wild raptors. Wildlife Society Bulletin 41: 205–211 Close ).
Despite good evidence that Golden Eagle has not bred in the southern Appalachians in recent times ( 190 Lee, D. S., and W. R. Spofford (1990). Nesting of Golden Eagles in the central and southern Appalachians. Wilson Bulletin 102: 693–698. Close ), there have been numerous attempts to release non-migratory eagles into these landscapes. These actions are mistakenly called “reintroductions.”
Efforts to establish exotic nesting populations in the southern Appalachians began in 1981 at the Pisgah National Forest, North Carolina ( 734 Hammer, D. A., and G. K. Reed (1983). Restoration of Golden Eagle in the southern Appalachians. Tennessee Valley Authority, Knoxville, TN, USA. Close ). Eagles were subsequently introduced to Tennessee (B. Anderson, personal communication) and Georgia ( 735 Touchstone, T. (1997). Golden Eagle recovery techniques and success in the southern Appalachian Region. M.S. thesis, State University of West Georgia, Carrollton, GA, USA. Close ). Released birds were either free-flying birds taken to mitigate depredation, young from nests in Wyoming and Colorado, or captive bred. At least one individual hacked in Georgia later successfully fledged 7 young between 1991 and 2000, 5 km from the hacking site (T. Touchstone, personal communication). Another successfully fledged 4 young between 1993 and 1996 in Tennessee > 200 km from the hacking site (B. Anderson, personal communication). Introductions continued in Tennessee until 2006 when the state agency halted them.
There is no evidence that these introduced birds ever became part of the migratory population. However, sporadic nesting appears to continue in the region (TAM, TEK). An adult and juvenile were recorded sitting together on a branch over the Cumberland River in Tennessee in 2010, a recently fledged juvenile was found starving in Tennessee in 2012, and a juvenile was found emaciated in August 2016 in southwestern Virginia. Isotope analysis of a feather from the latter bird was consistent with it growing its first set of feathers in the southeastern United States (D. Nelson, personal communication).
Research suggests that reducing eagle exposure to human activity can benefit eagles. One study recommended buffer zones for activity and no-stopping zones for vehicles to protect nesting Golden Eagles ( 736 Spaul, R. J. (2015) Recreation disturbance to a shrub-steppe raptor: Biological consequences, behavioral mechanisms, and management implications. Boise State University Theses and Dissertations 995, Boise, ID, USA. Close ). Simulation modelling ( 737 D'Acunto, L. E., R. J. Spaul, J. A. Heath, and P. A. Zollner (2018). Simulating the success of trail closure strategies on reducing human disturbance to nesting Golden Eagles. Condor 120(3): 703–718. Close ) predicts that reducing trail densities or recreation levels use around occupied nests can reduce the frequency of disturbance experienced by Golden Eagles.
Although the effectiveness of closures or disturbance buffers has not been formally evaluated, they likely benefit eagles and numerous state and federal agencies use them to protect nesting eagles from human disturbance. The USFWS and many state agencies suggest restrictions on activity around eagle nests during the nesting season (see examples in Wyoming and North Dakota. Denali National Park and Preserve sometimes restricts human activity near occupied Golden Eagle nests during the nesting season (CLM). Eagle nesting cliffs have been closed to rock climbing on a seasonal basis in in Oregon and Colorado (F. Isaacs, W. Keeley, personal communication). In 2009, the Bureau of Land Management (BLM) permanently closed approximately 75 km of motorized trails to reduce disturbance to nesting Golden Eagles in southwestern Idaho ( 738 U.S. Department of the Interior (2009). Murphy Subregion travel management plan. Environmental Assessment (2009). ID-130-2007-EA-3431. U.S. Department of the Interior, Bureau of Land Management, Washington, DC, USA. Close ), and the BLM implemented seasonal trail closures in 2011 near the most vulnerable territories ( 739 Sutter, J. (2011). Owyhee Front Golden Eagle Monitoring 2011. U.S. Bureau of Land Management, Owyhee Field Office, Marsing, ID, USA. Close ).
Early analyses suggest that detection by automated camera systems may be effective at detecting more eagles than human observers ( 740 McClure, C. J., L. Martinson, and T. D. Allison (2018). Automated monitoring for birds in flight: Proof of concept with eagles at a wind power facility. Biological Conservation 224: 26–33 Close ).
A successful example of effective local eradication of Golden Eagles via relocation occurred at the Channel Islands, off the southern coast of California. The Golden Eagle had not historically bred or wintered on these islands ( 741 Coonan, T. J. (2001). Jumping the gun: island fox recover efforts at Channel Islands National Park. In Crossing Boundaries in Park Management: Proceedings of the 11th Conference on Research and Resource Management in Parks and Public Lands (D. Harmon, Editor). The George Wright Society, Hancock, MI, USA. Close , 742 Coonan, T. J., C. A. Schwemm, G. W. Roemer, D. K. Garcelon, and L. Munson (2005). Decline of an island fox subspecies to near extinction. Southwestern Naturalist 50: 32–41. Close ). However, the nesting Bald Eagles that once inhabited the islands were driven to local extirpation by a combination of organochlorine poisoning and persecution. Golden Eagles were first sighted on the islands in the 1980s, and the first nesting attempt was recorded in 1999. The low levels of genetic diversity of these eagles suggested that a small number of colonization events led to the establishment of this population ( 89 Sonsthagen, S. A., T. J. Coonan, B. C. Latta, G. K. Sage, and S. L. Talbot (2012). Genetic diversity of a newly established population of golden eagles on the Channel Islands, California. Biological Conservation 146: 116–122. Close ). Unlike the Bald Eagles on the island, the Golden Eagles preyed on mammals, primarily feral pigs, but secondarily on other species. Their predation on native and rare island fox (Urocyon littoralis), caused fears that they may cause its extinction. As a consequence, at least 45 Golden Eagles on the Channel Islands were trapped and relocated to mainland California ( 742 Coonan, T. J., C. A. Schwemm, G. W. Roemer, D. K. Garcelon, and L. Munson (2005). Decline of an island fox subspecies to near extinction. Southwestern Naturalist 50: 32–41. Close ). Removal of Golden Eagles from the Channel Islands happened in conjunction with removal of the pigs that provided the most important food source for the birds. Telemetry on a subset of the eagles released in northern California suggested that they did not attempt to return to the islands ( 741 Coonan, T. J. (2001). Jumping the gun: island fox recover efforts at Channel Islands National Park. In Crossing Boundaries in Park Management: Proceedings of the 11th Conference on Research and Resource Management in Parks and Public Lands (D. Harmon, Editor). The George Wright Society, Hancock, MI, USA. Close ).