Can a Model of Avian Electrocution from Southern California be Useful in Guiding Power Pole Retrofitting for Golden Eagles Elsewhere?

A previously published model of avian electrocution risk, “the 2014 model,” was developed by comparing power poles that electrocuted birds (electrocution poles; including 21 golden eagle Aquila chrysaetos electrocutions) to poles not known to have electrocuted birds (comparison poles). The 2014 model produces pole-specific risk index scores between 0 and 1. The scores rank relative risk so electric utilities can maximize conservation benefits per dollar spent by focusing retrofitting on poles with greatest risk. Although the 2014 model was created from a study population of birds and poles in southern California, the 2014 model has potential to be used in managing a target population of raptors including golden eagles throughout the western United States. Use beyond southern California is only appropriate if the study population is similar enough to the target population for the 2014 model to predict risk effectively. To evaluate similarity, we examined five sources of evidence. Two were the relative consistency in electrical safety codes for power poles and body sizes of golden eagles in the study and target populations. Three more were consistency in structure-specific factors associated with 1) golden eagle electrocutions in other studies, 2) other avian electrocutions, and 3) previously unreported golden eagle electrocutions. We found that although the study population in the 2014 model included relatively few golden eagles, data were sufficient to create a model that can be applied to a target population throughout the western United States. The model can also be useful in helping determine equivalencies between pole types if utilities seek to compare benefits of retrofitting small numbers of high-risk poles to large numbers of low-risk poles.

Ecosystem Functioning Influences Species Fitness at Upper Trophic Levels

Global change is severely affecting ecosystem functioning and biodiversity globally. Remotely sensed ecosystem functional attributes (EFAs) are integrative descriptors of the environmental change—being closely related to the processes directly affecting food chains via trophic cascades. Here we tested if EFAs can explain the species fitness at upper trophic levels. We took advantage of a long-term time series database of the reproductive success of the Golden Eagle (Aquila chrysaetos)—an apex predator at the upper trophic level—over a 17-year period across a bioclimatic gradient (NW Spain; c. 29,575 km2). We computed a comprehensive database of EFAs from three MODIS satellite-products related to the carbon cycle, heat dynamics and radiative balance. We also assessed possible time-lag in the response of the Golden Eagle to fire, a critical disruptor of the surface energy budget in our region. We explored the role of EFAs on the fitness of the Golden Eagle with logistic-exposure nest survival models. Our models showed that the reproductive performance of the Golden Eagle is influenced by spatiotemporal variations in land surface temperature, albedo and vegetation productivity (AUC values from 0.71 to 0.8; ΣWi EFAs from 0.66 to 1). Fire disturbance also affected ecological fitness of this apex predator—with a limited effect at 3 years after fire (a time-lagged response to surface energy budget disruptions; ΣWi Fire = 0.62). Our study provides evidence for the influence of the matter and energy fluxes between land surface and atmosphere on the reproductive success of species at upper trophic levels.

Removal of foreign bodies from the proventriculus in a young golden eagle (Aquila chrysaetos)

This paper presents a clinical case report of a golden eagle (Aquila chrysaetos) with foreign bodies (stones) in its proventriculus. The case deals with the identification, management and removal of foreign objects identified in the gastrointestinal tract. A surgical removal by proventriculotomy under general anaesthesia was attempted. The surgery and the recovery were uneventful, and the follow-up after six months revealed no complications. To the best of our knowledge, there are no other reports of successful foreign body removal by proventriculotomy in the golden eagle.

Golden Eagle Abundance in Alaska: Migration Counts and Movement Data Generate a Conservative Population Estimate

ABSTRACT Estimating species density and abundance is challenging but important for establishing conservation and management strategies. Significant progress has been made toward estimating Golden Eagle (Aquila chrysaetos) abundance in the conterminous United States of America (USA) but much less is known about eagle abundance in Alaska. Here, we paired migration count and GPS-tracking data collected near Gunsight Mountain, Alaska, in a Bayesian framework to estimate the number of Golden Eagles in south-central Alaska. We estimated 1204 (95% credible interval: 866, 1526) potentially breeding (≥4 yr old) Golden Eagles annually moved through the Gunsight Mountain migration corridor and summered over an area of 150,325 km2 in south-central Alaska, equating to a density of 0.80 potentially breeding eagles/100 km2. By extrapolating across the species' nesting range in Alaska (1,180,489 km2) and incorporating published productivity and age-specific survival rates for eagles <4 yr old into our hierarchical model, we estimated 12,717 (95% credible interval: 9043, 16,349) Golden Eagles of all ages occur in Alaska, annually. We propose this as a conservative statewide population estimate because we used methods that likely underestimated population size. Even so, our estimate is three to five times larger than previous estimates and likely represents about one quarter of the USA's population.

Hunting for the Mythic Female Shaman Eagle Featuring the Golden Eagle (Aquila chrysaetos)

<p>This essay explores different intonations of the episode of the Female Shaman Eagle that is found in European versions of the Bear’s Son tale. It will be shown that a retelling of this episode can be detected in other myths and legends. It has left traces in the myth of Prometheus as summarized in Hesiod, as well as more explicitly in the legends surrounding the Caucasian hero Amirani. Further to the east the episode surfaces in tales recorded among the Tuvan people while evidence for the entrenchment of the episode along with its mythical ramifications in imagery can be identified in Iran. In the pages that follow we discover that the eastern reach of variants of the Bear’s Son tale takes us into Turkey, the Caucasus, south into Iran and even further to the east into the westernmost steppes of Mongolia. In all these geographic locations it is the figure of the Female Shaman Eagle that is highlighted and acquires mythic proportions, not just in narrative form but also as a highly esteemed bird of prey, celebrated in dance and expressed in striking visual imagery. In these materials the eagle in question is regularly identified as a Golden Eagle (Aquila chrysaetos). In addition, these are zones in which there have been strong traditions of raising and training Golden Eagles as hunting companions</p>