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Hunting down the eagle killer: Vacuolar myelinopathy is a neurological disease affecting wildlife — including the iconic bald eagle — in the United States. Its cause has been elusive for decades, but its occurrence has been linked to the cyanobacterium Aetokthonos hydrillicola colonizing the invasive aquatic plant Hydrilla verticillata. In a recent study, we found that A. hydrillicola produces a novel highly toxic biindole alkaloid (aetokthonotoxin), and proved that it is causing the disease.

In order to solve the problem of low accuracy and efficiency of soil moisture content prediction in tea plantations and improve the level of soil water content prediction, a soil moisture content prediction model for tea plantations based on the support vector machine (SVM)‐optimised bald eagle search (BES) algorithm (BES‐SVM) is proposed. Soil data and environmental data of tea plantations were transmitted to the server using sensor nodes and weather station nodes. The prediction models of soil moisture content and natural environmental parameters such as soil electrical conductivity, soil temperature, air temperature, air humidity, light intensity, and rainfall were developed using the SVM model optimised by the bald eagle search algorithm, and the mean square error (MSE) and coefficient of determination (R2) were calculated to evaluate the model performance. Meanwhile, the performance of the BES‐SVM model is compared with the particle swarm algorithm optimisation SVM (PSO‐SVM) and genetic algorithm optimised SVM (GA‐SVM) models. Results show that the proposed model has a mean coefficient of determination of 95.65%, and the prediction performance is better than the PSO‐SVM and GA‐SVM model, indicating that the BES‐SVM model has good performance and is a feasible prediction method for soil water content prediction and guiding irrigation and fertilisation management in tea plantations.

The movement of individuals according to the availability of resources has a fundamental effect on animal distributions. In the Pacific Northwest, Bald Eagles (Haliaeetus leucocephalus (Linnaeus, 1766)) rely heavily on scavenging opportunities during the non-breeding period, and their distribution and movements are thought to be strongly influenced by the availability of post-spawning Pacific salmon (genus Oncorhynchus Suckley, 1861) carcasses. We surveyed the abundance of eagles and salmon on four adjacent rivers on Vancouver Island, British Columbia, Canada, during the 2017 fall spawning season. Salmon began to arrive in late September, peaked in abundance in mid-November, and were absent after early December. The seasonal progression of Bald Eagle abundance matched that of salmon carcass availability. The slope of proportional eagle–salmon relationship was significantly positive, though lower than the 1:1 match predicted by Ideal Free Distribution theory. The numerical response of Bald Eagles to salmon abundance was elevated on one of the rivers, potentially due to physical features such as sandbars and mudflats that increased the availability of carcasses and provided access points for eagles.

The construction of a road extension of Park Avenue through the Pennsylvania State University’s agricultural fields offered an opportunity to reinvestigate, in more detail, the Tudek jasper quarry site (36CE238). The original investigation was led by Dr. James Hatch and graduate students from the University’s Department of Anthropology. Initial studies yielded in excess of 27,000 artifacts that were used in this analysis. Our reinvestigation resulted in the construction of a detailed outline of the quarry site and the pattern of usage of the materials from the site. Additionally, radiocarbon dating indicated that the site was intensively utilized for a long period of time (3500 BC to 1500 AD) and confirmed that, like many quarry sites, the activities included primary materials collection and testing, reduction of the lithic materials for transport to another location where the final finishing of tools took place. Moreover, the availability of raw material likely changed through time and across the quarry. Observed color changes in the jasper suggest some heat treatment on site, primarily during later time periods.

We analyzed concentrations and trends of perfluoroalkyl substances (PFAS) in blood plasma samples of bald eagle (Haliaeetus leucocephalus) nestlings at 6 study areas in the upper Midwest of the United States, 2006 to 2015, and long‐term trends at 2 Lake Superior (USA/Canada) sites, 1995 to 2015. Nestling blood plasma concentrations of the sum of 15 PFAS analytes (∑PFAS) differed among study areas and were highest at the 3 industrialized river sites: pools 3 and 4 of the Mississippi River (pools 3 + 4; geometric mean [GM] = 754 μg/L; range = 633–2930), the Mississippi National River and Recreation Area (GM = 687 μg/L; range = 24–7371), and the lower St. Croix National Scenic Riverway (GM = 546 μg/L; range = 20–2400). Temporal trends in ∑PFAS in nestling plasma differed among study areas; concentrations decreased at pools 3 + 4, Mississippi National River and Recreation Area, and lower St. Croix National Scenic Riverway, but not at the most remote sites, the upper St. Croix River and Lake Superior. Overall, perfluorooctanesulfonate (PFOS) was the most abundant analyte at all study areas, and perfluorodecanesulfonate (PFDS) the second most abundant at industrialized river sites although not at Lake Superior; concentrations of both these analytes declined from 2006 to 2015 over the study area. In addition, nestling age significantly influenced plasma concentrations of ∑PFAS and 7 of the 12 analytes. For these analytes, concentrations increased by 1 to 2%/d as nestlings grew, indicating that age should be considered when using nestling plasma to assess PFAS. Environ Toxicol Chem 2021;40:754–766. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC., Concentrations of perfluoroalkyl substances (PFAS) in blood plasma of bald eagle nestlings declined at 3 industrialized river sites, but not at a remote river site or Lake Superior. Nestling age significantly influenced plasma concentrations of total PFAS and most analytes.

Monitoring programs can benefit from an adaptive monitoring approach, where key decisions about why, where, what, and how to monitor are revisited periodically in order to ensure programmatic relevancy.The National Park Service (NPS) monitors status and trends of vital signs to evaluate compliance with the NPS mission. Although abundant, The Southwest Alaska Network (SWAN) monitors bald eagles because of their inherent importance to park visitors and role as an important ecological indicator. Our goal is to identify an optimal monitoring program that may be standardized among participating parks.We gathered an expert panel of scientists and managers, and implemented a Delphi Process to gather information about the bald eagle monitoring program. Panelists generated a list of means objectives for the monitoring program: minimizing cost, minimizing effort, maximizing the ability to detect change in bald eagle populations, and maximizing the amount of accurate information collected about bald eagles.We used a swing‐weighting technique to assign importance to each objective. Collecting accurate information about bald eagles was considered the most important means objective.Combining panelist‐generated information with objective importance, we analyzed the scenarios and defined the optimal decision using linear value modeling. Through our analysis, we found that a “Comprehensive” monitoring scenario, comprised of all feasible monitoring metrics, is the optimal monitoring scenario. Even with greatly increased cost, the Comprehensive monitoring scenario remains the best solution.We suggest further exploration of the cost and effort required for the Comprehensive scenario, to determine whether it is in the parks’ best interest to begin monitoring additional metrics., The Southwest Alaska Network (SWAN) of the National Park Service monitors bald eagles as part of the Vital Signs Monitoring Plan. This study uses structured decision‐making techniques to evaluate an optimal long‐term bald eagle monitoring program that may be standardized among participating parks.

Ceremonialism is an integral part of human life but difficult to recover from archaeological remains. Among Native groups in Eastern North America, skins and feathers of birds were commonly used as part of ritual feast ceremonies, including those of the Thunderbird, a mythological creature associated with thunder, lightning, and the upper world. Physical evidence for the Thunderbird has been limited to ceramic, lithic, copper, and petroglyphic artifacts, but the recent discovery of a series of Bald eagle (Haliaeetus leucocephalus) wing bones from the Frisby Butler site may present the first faunal evidence for the myth in Native North America. Patterns of skeletal part representation within the assemblage and across the site suggest that the deposit is the remains of a ritual feast and the presence of multiple wings indicates intentional curation of eagles. If so, this is the earliest known Thunderbird association on the island of Martha's Vineyard, showing the spread of extant Algonquin cosmology to this area by at least 2,000 BP.

Freshwater fish in several regions of New York State (NYS) are known to contain concentrations of mercury (Hg) associated with negative health effects in wildlife and humans. We collected blood and breast feathers from bald eagle (Haliaeetus leucocephalus) nestlings throughout NYS, with an emphasis on the Catskill region to determine their exposure to Hg. We assessed whether habitat type (lake or river), region (Delaware–Catskill region vs. rest of NY) or sample site elevation influenced Hg concentrations in bald eagle breast feathers using ANCOVA. The model was significant and accounted for 41% of the variability in log10 breast feather Hg concentrations. Mercury concentrations in nestling breast feathers were significantly greater in the Delaware–Catskill Region (geometric mean: 14.5 µg/g dw) than in the rest of NY (7.4 µg/g, dw), and greater at nests located at higher elevations. Habitat type (river vs. lake) did not have a significant influence on breast feather Hg concentrations. Geometric mean blood Hg concentrations were significantly greater in Catskill nestlings (0.78 µg/g ww) than in those from the rest of NY (0.32 µg/g). Mercury concentrations in nestling breast feathers and especially blood samples from the Delaware–Catskill region were generally greater than those reported for most populations sampled elsewhere, including areas associated with significant Hg pollution problems. Bald eagles can serve as valuable Hg bioindicators in aquatic ecosystems of NYS, particularly given their broad statewide distribution and their tendency to nest across all major watersheds and different habitat types.

Web-based technologies have become a ubiquitous conservation tool in the last decade. Despite the popularity of wildlife webcams, websites, and social media, their potential to motivate en...

Bald eagles (Haliaeetus leucocephalus) were formerly endangered in the contiguous United States, but have since recolonized much of their past range. Maintaining bald eagle populations following recovery requires knowledge of factors that influence nesting success, including food habits during the brood-rearing period. We examined over 26,000 images from a high-resolution, above-nest digital camera to document the diet of a nesting bald eagle pair in north-central Indiana, U.S.A., during the 2018 brood-rearing period. After the hatch of two eaglets in April 2018, the camera was programmed to take still photos of the nest every 20 min, in addition to live-streaming video to YouTube for public audiences. Still images were used to quantify and identify all prey deliveries to the lowest taxonomic level possible, typically species. A total of 135 prey items and at least 26 prey taxa were recorded during the 75 d of the study, although daily prey count became uncertain in the final 20 d as fledglings began to move out of camera view. The majority of recorded prey items (73%) were fish, with redhorse suckers (Moxostoma spp.) representing the most numerous of the 13 fish taxa observed. Smaller numbers of birds (13%), mammals (10%), and reptiles (4%) were also observed. Although our results represent one nest across a single brood-rearing season, we gained novel insights through the analysis of high-frequency, high-definition images that provided increased temporal and taxonomic resolution of prey deliveries. The use of a camera not only avoided historical biases in bald eagle diet analysis, but also provided a valuable tool to engage public audiences.

Bald eagles (Haliaeetus leucocephalus) underwent a severe population bottleneck in the mid-1900s due to Dichlorodiphenyltrichloroethane (DDT) use as an insecticide. After its ban in 1972, the population began to recover with the increase being attributed to banning DDT and reintroduction/translocation programs. Although bald eagles have increased and may be in a phase of exponential growth, many populations continue to experience anthropogenic stressors. Assessing levels of standing genetic variation and the partitioning of genetic variation within and among populations is critical for the development of informed conservation management plans. To begin addressing these concerns, we developed a custom 50K Affymetrix Axiom myDesign single nucleotide polymorphism (SNP) array and performed preliminary population genomic analyses on geographically disparate populations of bald eagles to test the utility of this SNP array for assessing levels of standing genetic variation in the gene pool and determining the partitioning of genetic variation within and among populations. To develop the array, a combination of RAD-tag sequencing and genome sequencing was used with the final chip consisting of 50,789 SNPs in both genic and intergenic regions of the genome. After genotyping 169 hatchlings, 45,952 SNPs from the array were found to be of quality and were used in Structure, Admixture, and a discriminant analysis of principal components (DAPC) analyses. Results from all of these analyses indicate that despite the significant population bottleneck, sufficient genetic variation is detectable within the bald eagle gene pool. Moreover, based on our disparate geographic sampling of bald eagles, our preliminary analyses indicate statistically significant partitioning of the genetic variation among broad sampling areas.

The bald eagle (Haliaeetus leucocephalus) once experienced near-extinction but has since rebounded. For decades, bald eagles near the Wisconsin River, USA, have experienced a lethal syndrome with characteristic clinical and pathological features but unknown etiology. Here, we describe a novel hepacivirus-like virus (Flaviviridae: Hepacivirus) identified during an investigation of Wisconsin River eagle syndrome (WRES). Bald eagle hepacivirus (BeHV) belongs to a divergent clade of avian viruses that share features with members of the genera Hepacivirus and Pegivirus. BeHV infected 31.9% of eagles spanning 4,254 km of the coterminous USA, with negative strand viral RNA demonstrating active replication in liver tissues. Eagles from Wisconsin were approximately 10-fold more likely to be infected than eagles from elsewhere. Eagle mitochondrial DNA sequences were homogeneous and geographically unstructured, likely reflecting a recent population bottleneck, whereas BeHV envelope gene sequences showed strong population genetic substructure and isolation by distance, suggesting localized transmission. Cophylogenetic analyses showed no congruity between eagles and their viruses, supporting horizontal rather than vertical transmission. These results expand our knowledge of the Flaviviridae, reveal a striking pattern of decoupled host/virus coevolution on a continental scale, and highlight knowledge gaps about health and conservation in even the most iconic of wildlife species.

This study proposes a bald eagle search (BES) algorithm, which is a novel, nature-inspired meta-heuristic optimisation algorithm that mimics the hunting strategy or intelligent social behaviour of bald eagles as they search for fish. Hunting by BES is divided into three stages. In the first stage (selecting space), an eagle selects the space with the most number of prey. In the second stage (searching in space), the eagle moves inside the selected space to search for prey. In the third stage (swooping), the eagle swings from the best position identified in the second stage and determines the best point to hunt. Swooping starts from the best point and all other movements are directed towards this point. BES is tested by adopting a three-part evaluation methodology that (1) describes the benchmarking of the optimisation problem to evaluate the algorithm performance, (2) compares the algorithm performance with that of other intelligent computation techniques and parameter settings and (3) evaluates the algorithm based on mean, standard deviation, best point and Wilcoxon signed-rank test statistic of the function values. Optimisation results and discussion confirm that the BES algorithm competes well with advanced meta-heuristic algorithms and conventional methods.

We analyzed concentrations and trends of DDE, total PCBs, and mercury in bald eagle (Haliaeetus leucocephalus) nestlings at six study areas in the upper Midwest, 2006–2015, and long-term trends at two Lake Superior sites, 1989–2015. Eaglet plasma from the Apostle Islands in Lake Superior had the highest concentrations of DDE (geometric mean [GM] = 10.6 μg/L), and DDE concentrations decreased at 5.8% per year across the region from 2006 to 2015, and at 5.5% per year at Lake Superior sites from 1989 to 2015. Concentrations of the sum of 75 PCB congeners (ΣPCB75) were highest at Pools 3 and 4 of the Mississippi River (GM = 114.8 μg/L) and did not decline significantly region-wide (all study areas together) between the years of 2006 and 2011. However, at Lake Superior, ΣPCB75 declined from 1995 to 2011 along the south shore at 3.6% per year, with a non-significant decline at the Apostle Islands. Concentrations of mercury in nestling breast feathers were highest at the upper St. Croix River (GM = 6.66 μg/g wet weight). At Lake Superior study areas, mercury declined at 1.6% per year from 1991 to 2015; however, from 2006 to 2015 we found no significant trend at one of these same study areas and mercury concentrations apparently increased at two study areas. Mean concentrations of contaminants were below levels associated with significant impairment of reproduction at all sites and mean reproductive rates were > 1.4 young per nest. However, increasing concentrations of mercury in some areas, combined with relatively high concentrations at some nests, suggest that continued monitoring of mercury should be a management priority.

Sources of lead exposure of many bird species are poorly understood. We analyzed blood lead concentrations from osprey (n = 244; Pandion haliaetus) and bald eagles (n = 68; Haliaeetus leucocephalus) and documented potential sources of lead they may encounter. Adult bald eagles had higher blood lead concentrations than did adult osprey. However, blood lead concentrations of nestlings were similar for both species. Although 62% of osprey had detectable lead concentrations ( x¯ = 1.99 ± 4.02 μg/dL, mean ± standard deviation [SD]), there was no difference in the detection frequency or lead concentrations between osprey adults and nestlings. Likewise, we found no differences in the detection frequency or lead concentrations in osprey adults and nestlings from high- and low-salinity areas. Of the bald eagle samples tested, 55% had detectable lead levels ( x¯ = 6.23 ± 10.74 μg/dL). Adult bald eagles had more detectable and higher lead concentrations than did nestlings or pre-adults. Among environmental samples, paint had the highest lead concentrations, followed by sediment, blue catfish (Ictalurus furcatus), and gizzard shad (Dorosoma cepedianum). There was no correlation between blood lead concentrations of osprey adults and their offspring. Our results indicate that, in the Chesapeake Bay region of Maryland and Virginia (USA), there are multiple sources by which piscivorous raptors may be exposed to lead. Environ Toxicol Chem 2019;38:862-871. © Published 2019 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Bald eagle (Haliaeetus leucocephalus) populations in North America rebounded in the latter part of the twentieth century, the result of tightened protection and outlawing of pesticides such as DDT. An unintended consequence of recovery may be a negative impact on seabirds. During the 1980s, few bald eagles disturbed a large glaucous‐winged gull (Larus glaucescens) colony on Protection Island, Washington, USA, in the Salish Sea. Breeding gull numbers in this colony rose nearly 50% during the 1980s and early 1990s. Beginning in the 1990s, a dramatic increase in bald eagle activity ensued within the colony, after which began a significant decline in gull numbers. To examine whether trends in the gull colony could be explained by eagle activity, we fit a Lotka–Volterra‐type predator–prey model to gull nest count data and Washington State eagle territory data collected in most years between 1980 and 2016. Both species were assumed to grow logistically in the absence of the other. The model fits the data with generalized R 2 = 0.82, supporting the hypothesis that gull dynamics were due largely to eagle population dynamics. Point estimates of the model parameters indicated approach to stable coexistence. Within the 95% confidence intervals for the parameters, however, 11.0% of bootstrapped parameter vectors predicted gull colony extinction. Our results suggest that the effects of bald eagle activity on the dynamics of a large gull colony were explained by a predator–prey relationship that included the possibility of coexistence but also the possibility of gull colony extinction. This study serves as a cautionary exploration of the future, not only for gulls on Protection Island, but for other seabirds in the Salish Sea. Managers should monitor numbers of nests in seabird colonies as well as eagle activity within colonies to document trends that may lead to colony extinction.

Environmental enrichment is often offered to animals in captivity to aid in enhancing quality of life by providing appropriate environmental stimuli that improve psychological and physiological well-being. Due to the limited amount of research conducted on raptors and enrichment, I sought to determine raptor preferences of enrichment types through the observation of captive bald eagles (Haliaeetus leucocephalus) and red-tailed hawks (Buteo jamaicensis) in the education department at Elmwood Park Zoo. I predicted that the raptors would interact more with natural enrichment items compared to ones that were man-made. Although results showed only the female bald eagle to interact enough with the enrichment items to gather an adequate number of observations, she was found to interact significantly more frequently with natural enrichment items compared to ones that were man-made (p 0.0001, FET). These results are not meant to infer that all female bald eagles prefer natural enrichment items over man-made ones, or that all male bald eagles and female and male red-tailed hawks do not prefer any enrichment items. Nonetheless, they justify future research on environmental enrichment preferences involving many more individuals and many more taxa to determine more appropriate enrichment regimens for captive birds of prey.

The development and installation of renewable energy comes with environmental cost, including the death of wildlife. These costs occur locally, and seem small compared to the global loss of biodiversity. However, failure to acknowledge uncertainties around these costs affects local conservation, and may lead to the loss of populations or species. Working with these uncertainties can result in adaptive management plans designed to benefit renewable energy development and conservation. An example is the U.S. government's policy for managing bald (Haliaeetus leucocephalus) and golden (Aquila chrysaetos) eagle deaths at terrestrial wind facilities. Using records from 422 U.S. wind facilities we improved the precision of estimates of exposure (8.79 eagle minutes hr−1 km−3, SD: 13.64) and collision probability (0.0058 birds per minute of exposure, SD: 0.0038) currently used in U.S. policy. The new estimates for bald (exposure: 3.19 eagle minutes hr−1 km−3, SD: 2.583; collision probability: 0.007025 eagles per minute of exposure, SD: 0.004379) and golden (exposure: 1.21 eagle minutes hr−1 km−3, SD: 0.352; collision probability: 0.005648 birds per minute of exposure, SD: 0.004413) eagles had a smaller mean and standard deviation. Thus, their implementation within the government's adaptive management framework could help refine the balance between energy consumption and conservation.

Knowledge of the home range size (HRS) of species is critical for their effective management and conservation. We systematically searched the open literature for information on HRS for Bald Eagle (Haliaeetus leucocephalus), Golden Eagle (Aquila chrysaetos), Prairie Falcon (Falco mexicanus), and Ferruginous Hawk (Buteo regalis). We found 24 articles with HRS estimates and accompanying methodology and demographic information on sampled individuals. Most studies focused on Bald Eagles, followed by Golden Eagles, Prairie Falcons, and Ferruginous Hawks. HRS estimates for the Golden Eagle were the largest and had the greatest associated variance (m = 8797 km2; 95% CI, 0–47,284 km2). Estimates for Bald Eagle HRS were smaller, with a mean of 2215 km2 (95% CI, 0–12,472 km2). Prairie Falcon and Ferruginous Hawk HRS estimates were much smaller, with means of 156 km2 (95% CI, 0–415.22 km2) and 22 km2 (95% CI, 0–96.88 km2), respectively. HRS estimates varied substantially across period (breeding/nonbreeding), sex, age class, fix type, and estimation method for all species, and this finding points to the importance of accounting for the context of these estimates. The information can be used to inform other efforts to characterize the spatial use of these 4 raptors.

Bald Eagle (Haliaeetus leucocephalus) populations throughout North America have increased considerably since the ban of DDT in 1972 and eagles now inhabit suburban areas in large numbers. To better understand the ecology of urban populations living in south-coastal British Columbia, we compared nest-site characteristics, reproductive rates, and diets of more than 150 breeding pairs of rural-, suburban- and urban-nesting eagles in the Greater Vancouver area. Three-quarters of the nests were located within 230 m of buildings and roads, or within 31 m of a potential source of disturbance. Urban eagles nested in live, taller trees that were close to the edges of patches, whereas rural eagles used shorter trees and occasionally human-made structures such as transmission towers. Eagles at nests located close to patch edges and in areas with greater human land use had higher reproductive rates than those at isolated nests or in remote rural habitat. Waterfowl and gulls (family Laridae) were common in the diet across the study area, but urban eagles also used alternative sources such as C-O sole (Pleuronichthys coenosus), Bufflehead (Bucephala albeola), and Band-tailed Pigeon (Patagioenas fasciata). Eagles in the Vancouver area have adapted to human-altered landscapes; management strategies should focus on maintaining edge habitat, monitoring population expansion in urban areas, and protecting nest sites.

We measured concentrations of up to 17 polybrominated diphenyl ethers (PBDEs) in plasma of 492 bald eagle (Haliaeetus leucocephalus) nestlings between 1995 and 2017 from 12 study areas in Wisconsin and Minnesota, USA. Geometric mean concentrations of the sum of 9 PBDE congeners (∑PBDE) measured across all years ranged from 2.88 to 10.8 µg/L, and nestlings in urban areas had higher concentrations than those in remote locations. Region‐wide from 2006 through 2017, we found that ∑PBDEs declined by 3.8% annually and congeners BDE‐47, ‐99, and ‐100 declined by 5.6 to 6.5%, whereas BDE‐153 and ‐154 had no significant declines. When categorized by waterbody type, nestlings from Great Lakes and river study areas had higher concentrations of ∑PBDEs than those at inland lakes, but river study areas spanned the extremes. From 2006 to 2017, ∑PBDEs declined by 7.3% annually in Great Lakes nestlings and by 3.2% in nestlings along rivers, and increased by 32.7% at inland lakes. Using a longer dataset (1995–2015), we found that ∑PBDEs declined in Lake Superior nestlings by 3.3% annually. Our results show that PBDEs declined in bald eagle nestling plasma in most study areas since PBDE production was reduced, but that concentrations remain high near urban centers and that trends differ by congener, study area, and waterbody type. Environ Toxicol Chem 2021;40:1606–1618. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC., As apex predators, bald eagles can serve as biosentinels of environmental contamination to aquatic environments. Blood plasma from bald eagle nestlings is particularly useful for measuring the extent of local contamination. PBDE = polybrominated diphenyl ether. For study area acronym abbreviations, see Table 1 footnote.

Radiograph imaging is an important diagnostic tool for assessing cardiac size in avian patients. The bald eagle (Haliaeetus leucocephalis), once on the United States Federal List of Endangered and Threatened Wildlife and Plants, is now a thriving species in the United States. However, there is surprisingly little information regarding bald eagle cardiac reference values obtained through radiographic imaging for use in assessment of cardiac disease in this species. This study was performed to establish reference values of cardiac size in the bald eagle. Ventrodorsal radiographic images were taken from 9 healthy birds obtained from a raptor rehabilitation facility. Cardiac silhouette width to thorax width, cardiac silhouette width to sternum width, cardiac silhouette width to hepatic silhouette width, and cardiac silhouette width to coracoid width were obtained. Ratios were calculated between the respective areas measured. The results showed that the cardiac silhouette averages 44%-52% of the thoracic width, 71%-86% of the sternal width, 94%-117% of the width of the hepatic silhouette, and 500%-920% of the coracoid width. In the individuals studied there was a strong correlation between cardiac silhouette width to thoracic and sternal width whereas cardiac width with hepatic and coracoid widths had a moderate to weak correlation respectively. The values obtained in this study can be used to radiographically assess the cardiac size of bald eagles, thus aiding in the diagnosis of cardiomegaly in this species.

In this chapter Patrick details his time in the wilderness. He conquers his night terrors, becomes less anxious, and revels in the experience of nature and being alone. Patrick focuses on healing in the Canadian wilderness.

Bald Eagle (Haliaeetus leucocephalus) populations have been recovering throughout North America for the past several decades, and long-term monitoring efforts have been useful for understanding the ecological and anthropogenic drivers that influence population trajectories. We analyzed data on Bald Eagles in Kansas over 30 breeding seasons (1989–2018) to describe population growth, habitat selection, temporal trends in productivity, and predictors of nesting attempts. The breeding Bald Eagle population in Kansas recovered from a single documented nesting pair in 1989 to 137 documented nesting pairs in 2018. Habitat in and around large artificial reservoirs was important for early colonizing nesting pairs. However, as the population grew, nesting territories along river shorelines made up a majority of the total. Birds nesting in territories near rivers and large artificial reservoirs, newer territories, and territories closer to electrical lines were significantly more likely to have a nesting attempt compared to those in other territories. Capture-mark-resighting efforts allowed us to track productivity, recruitment, and site fidelity for a portion of the breeding population in Kansas (272 banded individuals). Growth of the breeding Bald Eagle population in Kansas has shown little sign of slowing in the first three decades following recolonization. Continued annual increases in the number of new nesting territories indicate that the availability of suitable habitat does not appear to be limiting population growth.

Bald eagles have returned from the brink of extinction and today serve as a reminder to our collective memory of not only what we can do to destroy a species, but what we can learn from its near loss. In our environmental ignorance, we almost lost the symbol of our identity as Americans and replaced it with a value system that saw our dominion over nature as a legitimate and proper role for mankind. Today, we more readily appreciate that our well-being is closely tied to that of nature and without intact ecosystems we all lose. Our willingness to pay to maintain populations of bald eagles is an important tool for assigning this charismatic bird value. Bald eagles now soar in places as varied as the rivers of Alaska to the highly developed coastline of the Chesapeake Bay, but in both locations, their presence reminds us of what we could have lost if we allowed the bald eagle to “blink out” and what we have gained from their conservation success.

From late February to early April the Central Platte River Valley in Nebraska is home to the largest gathering of Sandhill Cranes (Antigone canadensis) in the world and increasingly serves as a foraging ground for migrating Bald Eagles (Haliaeetus leucocephalus). On 7 March 2017, we documented a subadult Bald Eagle depredating an adult Sandhill Crane. Though evidence suggests that Bald Eagles depredate Sandhill Cranes on rare occasion, the process of that depredation has not been described in the scientific literature. The Sandhill Crane effectively defended itself several times against hovering attacks from the Bald Eagle by utilizing wing-spread displays and “bill stab” attacks. However, the Bald Eagle was eventually able to land on the Sandhill Crane's neck and back with its talons, push the crane's head under water, and drown its prey. Following submersion, the Sandhill Crane was only momentarily responsive before floating on its back down the river. We also documented 5 subadult Bald Eagles competing for access to a second Sandhill Crane carcass. As Bald Eagle populations continue to recover, Sandhill Cranes may become more frequently depredated by Bald Eagles during the spring migration-staging period in the Central Platte River Valley.

We examined the influence of biological and geographical factors on the levels and patterns of organohalogen contaminants in blood of adult common loons (Gavia immer) collected from 20 lakes in Alberta, Canada. The loons were captured in the 2006 and 2007 breeding seasons over a 900 m elevation gradient across the eastern slope of the Canadian Rocky Mountains. While PCBs dominated the composition of these contaminants in loons at all sites (∑PCBs > p,p’-DDE > ∑PBDEs > ∑Chlordanes > HCB), p,p’-DDE and ∑PBDEs were also important, averaging approximately 50% and 20% of total PCB concentrations, respectively. ∑PCBs and ∑PBDEs were higher in males than in females. Inter-lake variation was apparent for contaminant concentrations and patterns and were largely explained by dietary signatures (δ15N and δ13C) and proximity to a large hydroelectric dam. Mean ∑PCB (19.6 ng/g wet weight (ww)) and organochlorine pesticide (OCP) (p,p’-DDE: 11.8 ng/g, cis-nonachlor: 0.10 ng/g, trans-nonachlor: 0.32 ng/g, HCB: 0.34 ng/g ww) concentrations in loons were approximately 4- to 17-fold lower than average concentrations reported in common loons from Atlantic Canada and were well below concentrations which have been associated with impaired reproductive success and eggshell thinning in other piscivorous birds. Dominant PBDE congeners were BDE47, BDE99, and BDE100. The regional mean for ∑PBDEs (4.04 ng/g ww) in loons from the present study was within the range reported for ∑PBDEs in nestling bald eagle plasma from British Columbia. This is the first report of PBDEs in loons and the first report of PCBs and OCPs in common loons from Western North America.

Management or conservation targets based on demographic rates should be evaluated within the context of expected population dynamics of the species of interest. Wild populations can experience stable, cyclical, or complex dynamics, therefore undisturbed populations can provide background needed to evaluate programmatic success. Many raptor species have recovered from large declines caused by environmental contaminants, making them strong candidates for ongoing efforts to understand population dynamics and ecosystem processes in response to human‐caused stressors. Dynamic multistate occupancy models are a useful tool for analyzing species dynamics because they leverage the autocorrelation inherent in long‐term monitoring datasets to obtain useful information about the dynamic properties of population or reproductive states. We analyzed a 23‐year bald eagle monitoring dataset in a dynamic multistate occupancy modeling framework to assess long‐term nest occupancy and reproduction in Lake Clark National Park and Preserve, Alaska. We also used a hierarchical generalized linear model to understand changes in nest productivity in relation to environmental factors. Nests were most likely to remain in the same nesting state between years. Most notably, successful nests were likely to remain in use (either occupied or successful) and had a very low probability of transitioning to an unoccupied state in the following year. There was no apparent trend in the proportion of nests used by eagles through time, and the probability that nests transitioned into or out of the successful state was not influenced by temperature or salmon availability. Productivity was constant over the course of the study, although warm April minimum temperatures were associated with increased chick production. Overall our results demonstrate the expected nesting dynamics of a healthy bald eagle population that is largely free of human disturbance and can be used as a baseline for the expected dynamics for recovering bald eagle populations in the contiguous 48 states.

In this study, we measured the concentrations of 58 flame retardants (and related compounds) in bald eagle (Haliaeetus leucocephalus) egg and plasma samples from the Michigan. These analytes include polybrominated diphenyl ethers (PBDEs), novel flame retardants (nFRs), Dechlorane-related compounds (Decs), and organophosphate esters (OPEs). A total of 24 paired eaglet plasma and egg samples were collected from inland (IN, N = 13) and the Great Lakes (GL, N = 11) breeding areas from 2000 to 2012. PBDEs were the most abundant chemical group with a geometric mean of 181 ng/g wet weight (ww) in egg and 5.31 ng/g ww in plasma. Decs were barely found in plasma samples, but they were frequently found in eggs (geometric mean 23.5 ng/g ww). OPE levels were comparable to those of PBDEs in the plasma but lower than those of PBDEs in eggs. Dec and PBDE concentrations were significantly higher in GL than in IN (p 0.05). The ratio of egg to plasma concentrations (lipid normalized) varied with chemicals and correlated with the chemical's octanol-water partition coefficient. The lipid normalized bald eagle egg and plasma concentrations from Lake Superior and Huron were one to three orders of magnitude higher than concentrations measured in composite lake trout (Salvelinus namaycush) from the same lake, implying that they biomagnify in the environment.

Mercury (Hg) exposure was evaluated in bald eagles (Haliaeetus leucocephalus) in the lower Penobscot River watershed (PRW) in Maine to assess whether Hg discharges from a chlor-alkali plant (HoltraChem) influenced Hg concentrations in nestling tissues. Mean Hg concentrations in nestling blood and breast feathers sampled in marine and estuarine areas potentially contaminated with Hg from HoltraChem (the potential Hg impact zone) were significantly greater than those from reference sites spanning the Maine coast. To place Hg exposure in the potential Hg impact zone into a broader context, Hg exposure in bald eagle nestlings from four habitat types in the PRW was assessed. Mercury concentrations varied significantly across habitat types within the PRW, generally following the pattern: marine=estuarine

Organophosphate esters (OPEs) and other alternative flame retardants including 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) and bis(2-ethylhexyl) tetrabromophthalate (BEHTBP) are ubiquitous in the Great Lakes region, having been detected in air, water, and biota samples. In a recent study, however, we showed that concentrations of six OPEs in eagle eggs were generally low (geometric mean 24 ng/g ww), and the two main Firemaster (FM) components, EHTBB and BEHTBP, were below limits of detection. We therefore hypothesized that the low levels of these compounds in bald eagles may be due to a potential rapid metabolic transformation. We measured metabolites of triaryl and trialkyl phosphates and brominated Firemaster (FM) flame retardants in 21 addled bald eagle (Haliaeetus leucocephalus) eggs from 2000 to 2012 from the Michigan Bald Eagle Biosentinel Program archive. Sampling sites were divided into two groups: inland (IN) and Great Lakes (GL) based on breeding areas. Results suggest that the most abundant...

We explored changes in seasonal distribution and behavior of waterbirds in the Strait of Georgia, Canada, in response to increased presence of a major avian predator, the Bald Eagle (Haliaeetus leucocephalus). Eagles were widespread and their increase through fall and winter coincided with migratory movements of waterbirds. Many species of waterbird used inshore waters in early fall when eagles were scarce. Diving birds moved away from inshore waters when eagles returned in late fall and winter, whereas dabbling ducks formed large flocks in inshore waters and spent proportionally more time being vigilant as winter progressed. Flock sizes and avoidance flight distances of scoters and dabblers, but not gulls, increased with proximity to eagles. Waterbirds did not alter vigilance with distance to eagles. We discuss our findings in context of management issues regarding apparent declines and importance of understanding indirect effects of predators on prey for wildlife monitoring.