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Movements by animals can serve different functions and occur over a variety of spatial and temporal scales. Routine movement types, such as residency (localized movements) and migration, have been well studied. However, nonroutine movement types, such as dispersal, prospecting, and nomadism, are less well understood. Documenting these rarely detected events requires tracking large numbers of individuals across all age classes. We studied >500 golden eagles (Aquila chrysaetos) tracked by telemetry over a 10‐year period in western North America, of which 160 engaged in nonroutine, long‐distance (>300 km) movements. We identified spatial and temporal correlates of those movements at both small and large scales, and we quantified movement timing and direction. We further tested which age and sex classes of eagles were more likely to engage in these movements. Our analysis of 88,093 daily tracks suggested that distances traveled by eagles were responsive to the updraft potential of the spatial and temporal landscape they encountered. Tracks covered longer distances at locations and times of higher updraft potential, and older birds traveled farther than younger birds. By contrast, after decomposing daily tracks into 563 nonroutine, long‐distance movements measured at a multiday scale, only the duration of travel was responsive to environmental conditions encountered by eagles. Multiday trips that were longer were those initiated in open and warm landscapes and those that ended in mountainous regions. Finally, long‐distance movements were more frequently made in seasons other than winter, in north–south directions, and by young birds. We documented clear correlates of nonroutine, long‐distance movements by golden eagles at small, local scales but found little evidence of such correlates at larger, regional scales. Most long‐distance movements we documented fit patterns associated with traditional definitions of prospecting and nomadism but not migration. Our study is the first to describe these movement types by golden eagles, and as such provides a foundation for subsequent study into the movement ecology of other species. [ABSTRACT FROM AUTHOR]

Lead poisoning occurs worldwide in populations of predatory birds, but exposure rates and population impacts are known only from regional studies. We evaluated the lead exposure of 1210 bald and golden eagles from 38 US states across North America, including 620 live eagles. We detected unexpectedly high frequencies of lead poisoning of eagles, both chronic (46 to 47% of bald and golden eagles, as measured in bone) and acute (27 to 33% of bald eagles and 7 to 35% of golden eagles, as measured in liver, blood, and feathers). Frequency of lead poisoning was influenced by age and, for bald eagles, by region and season. Continent-wide demographic modeling suggests that poisoning at this level suppresses population growth rates for bald eagles by 3.8% (95% confidence interval: 2.5%, 5.4%) and for golden eagles by 0.8% (0.7%, 0.9%). Lead poisoning is an underappreciated but important constraint on continent-wide populations of these iconic protected species. [ABSTRACT FROM AUTHOR]

Wildlife conservation strategies focused on one season or population segment may fail to adequately protect populations, especially when a species' habitat preferences vary among seasons, age-classes, geographic regions, or other factors. Conservation of golden eagles (Aquila chrysaetos) is an example of such a complex scenario, in which the distribution, habitat use, and migratory strategies of this species of conservation concern vary by age-class, reproductive status, region, and season. Nonetheless, research aimed at mapping priority use areas to inform management of golden eagles in western North America has typically focused on territory-holding adults during the breeding period, largely to the exclusion of other seasons and life-history groups. To support population-wide conservation planning across the full annual cycle for golden eagles, we developed a distribution model for individuals in a season not typically evaluated-winter-and in an area of the interior western U.S. that is a high priority for conservation of the species. We used a large GPS-telemetry dataset and library of environmental variables to develop a machine-learning model to predict spatial variation in the relative intensity of use by golden eagles during winter in Wyoming, USA, and surrounding ecoregions. Based on a rigorous series of evaluations including cross-validation, withheld and independent data, our winter-season model accurately predicted spatial variation in intensity of use by multiple age- and life-history groups of eagles not associated with nesting territories (i.e., all age classes of long-distance migrants, and resident non-adults and adult "floaters", and movements of adult territory holders and their offspring outside their breeding territories). Important predictors in the model were wind and uplift (40.2% contribution), vegetation and landcover (27.9%), topography (14%), climate and weather (9.4%), and ecoregion (8.7%). Predicted areas of high-use winter habitat had relatively low spatial overlap with nesting habitat, suggesting a conservation strategy targeting high-use areas for one season would capture as much as half and as little as one quarter of high-use areas for the other season. The majority of predicted high-use habitat (top 10% quantile) occurred on private lands (55%); lands managed by states and the Bureau of Land Management (BLM) had a lower amount (33%), but higher concentration of high-use habitat than expected for their area (1.5-1.6x). These results will enable those involved in conservation and management of golden eagles in our study region to incorporate spatial prioritization of wintering habitat into their existing regulatory processes, land-use planning tasks, and conservation actions., Competing Interests: We have read the journal’s policy and the authors of this manuscript have the following competing interests: Author, Dave LaPlante, owns Natural Resource Geospatial. Author, Jessi Brown, owns Sparrowhawk Data Science. Author, Mike Lockhart, owns Wildlands Bio-Consulting. Author, Dale Stahlecker, is a partner in Eagle Environmental, Inc. None of these companies funded the study or influenced the decision to publish. There are no patents, products in development or marketed products to declare. None of our interests alter our adherence to all the PLOS ONE policies on sharing data and materials., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

ABSTRACT Populations of greater sage-grouse ( Centrocercus urophasianus; sage-grouse) have been in a decline since the nineteenth century. We used our research, unpublished reports, and scientific literature to identify which predators kill sage-grouse and to assess whether lethal control of these predators benefited the species. We also asked state wildlife biologists and scientists whether they had ever witnessed a predator kill sage-grouse. We identified 266 instances where the predator responsible for depredating nests or killing juvenile or adult sage-grouse could be ascertained. Most adult sage-grouse were killed by eagles (Accipitridae), owls (Strigiformes), coyotes ( Canis latrans), or red foxes ( Vuples vulpes). Based on nest cameras, most depredated eggs are taken by common ravens ( Corvus corax), badgers ( Taxidae taxus), or coyotes. There are too few studies to conclude that predator removal increases survival rates of juvenile or adult sage-grouse. No study has been conducted to determine whether badger removal increases nest success of sage-grouse, and the only study on coyote removal produced ambiguous results. Several studies reported that more sage-grouse nests are successful (i.e., >1 eggs hatched) in areas where common ravens were removed or in areas where raven densities were lower than in other areas. The data we reviewed did not indicate predators played a role in the decline during the past century, but increasing numbers of ravens since the 1970s may have contributed to the declining sage-grouse populations in recent decades. We conclude that removing common ravens can increase nest success, although not necessarily sage-grouse abundance. Without a better understanding of sage-grouse and their predators, wildlife biologists will be handicapped in their efforts to prevent sage-grouse populations from continuing to decline. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

The bald eagle (Haliaeetus leucocephalus) is a culturally and ecologically vital species in North America that embodies conservation success but continues to face threats that include emerging pathogens. The introduction of A/goose/Guangdong/1/1996 lineage highly pathogenic (HP) clade 2.3.4.4b H5N1 influenza A virus (IAV) in North America in late 2021 resulted in high rates of mortality among bald eagles. Here we show an alarming rate of bald eagle nest failure and mortality attributed to HP IAV. We documented fatal, systemic HP IAV infection in breeding adult and nestling bald eagles along the southeastern U.S. coast. Concurrently, annual bald eagle nest surveys in Georgia and Florida revealed a precipitous drop in success in coastal counties compared with previous years, portending negative impacts on population recruitment. As an apex predator and efficient scavenger, it is likely that bald eagles become infected through consumption of infected waterfowl. These results and similar reports of raptor mortality in Europe, Asia, and Africa, indicate a clear threat to raptor health. The possible long-term persistence of HP H5N1 IAV in North America poses an impending threat to bald eagle populations not only related to direct mortality but also decreased recruitment and warrants continued efforts to understand these potential impacts., (© 2023. The Author(s).)

To maximize fitness, flying animals should maximize flight speed while minimizing energetic expenditure. Soaring speeds of large-bodied birds are determined by flight routes and tradeoffs between minimizing time and energetic costs. Large raptors migrating in eastern North America predominantly glide between thermals that provide lift or soar along slopes or ridgelines using orographic lift (slope soaring). It is usually assumed that slope soaring is faster than thermal gliding because forward progress is constant compared to interrupted progress when birds pause to regain altitude in thermals. We tested this slope-soaring hypothesis using high-frequency GPS-GSM telemetry devices to track golden eagles during northbound migration. In contrast to expectations, flight speed was slower when slope soaring and eagles also were diverted from their migratory path, incurring possible energetic costs and reducing speed of progress towards a migratory endpoint. When gliding between thermals, eagles stayed on track and fast gliding speeds compensated for lack of progress during thermal soaring. When thermals were not available, eagles minimized migration time, not energy, by choosing energetically expensive slope soaring instead of waiting for thermals to develop. Sites suited to slope soaring include ridges preferred for wind-energy generation, thus avian risk of collision with wind turbines is associated with evolutionary trade-offs required to maximize fitness of time-minimizing migratory raptors. [ABSTRACT FROM AUTHOR]

A recent summary of raptor migration count data concluded that the status of Golden Eagles (Aquila chrysaetos) in western North America warranted concern (Hoffman and Smith 2003). Our analysis of these data did not lead us to the same conclusion. We have three specific concerns. First, the regional characterizations of eagle migration in Hoffman and Smith (2003) are based on a very small sample of sites. Therefore, we recommend that these characterizations be considered as hypothetical in nature. Second, we suggest that the population cycles and patterns of age-specific population change described by Hoffman and Smith (2003) are neither as general nor as clear-cut as they indicated. Finally, although the authors expressed concern about the status of Golden Eagles based upon both their findings and data from other sources, we did not find compelling evidence for population declines in our inspection of those same data. [ABSTRACT FROM AUTHOR]

The article focuses on the research conducted by W. W. Bowerman IV and colleages regarding the abnormalities of the jawbones of bald eagles. It states that the researchers had observed the documentation of nesting of bald eagles across Great Lakes Basin in North America from 1966 to 1989. Researchers also performed a comparison between the bill malformation cases and the banding of cuddling the eagles in the Great Lakes area.

In Hoffman and Smith (2003), we summarized two decades of raptor migration count data from western North America. McCaffery and McIntyre (2005) offer an extensive critique of the "conclusions" we drew from these data concerning the migration ecology and status of western Golden Eagles (Aquila chrysaetos). Many of their specific points about data limitations are well taken. Contrary to the flavor of their critique, however, we were not offering any definitive conclusions about the status or habits of eagles. Rather, we merely sought to describe the tendencies in the data and offer reasonable speculation about potential underlying causes of the documented patterns and trends. Our primary goal was to challenge colleagues to help us carefully consider our data and help formulate reasonable hypotheses about causal factors. We welcome and applaud McCaffery and McIntyre's (2005) thorough review of our work and genuine concern for guarding against unwarranted speculation. We believe, however that the depth of their critique was unjustified because the precision of the migration count data we presented simply is not sufficient to support detailed inspection of every annual change. Moreover, while we cannot disagree with them concerning the limits of the migration data we presented, we stand firmly behind our contention that there are indeed reasons to be concerned about the status of Golden Eagles in western North America, particularly within the sagebrush-steppe ecoregion. [ABSTRACT FROM AUTHOR]

Three bald eagles (Haliaeetus leucocephalus) and 1 golden eagle (Aquila chrysaetos) were admitted to rehabilitation facilities with emaciation, lethargy, and an inability to fly. Intravascular schizonts and merozoites were present in 2 bald eagles, mainly in the lung tissue, whereas the third bald eagle and the golden eagle had lymphohistiocytic encephalitis with intralesional schizonts and merozoites. In all eagles, protozoal tissue cysts were present in skeletal musculature or heart. The protozoal organisms were morphologically compatible with a Sarcocystis sp. By immunohistochemistry, the protozoal merozoites were positive for Sarcocystis falcatula antigen in all cases when using polyclonal antisera. Furthermore, the protozoa were confirmed to be most similar to S. falcatula by polymerase chain reaction in 3 of the 4 cases. To the authors' knowledge, this report presents the first cases of natural infection in eagles with S. falcatula as a cause of mortality.