The Status Of Golden Eagles In The West: Migration, Breeding, And Energy Infrastructure

Golden Eagles (Aquila chrysaetos), are widespread raptors, breeding predominately in western North America, from northern Alaska to central Mexico, occupying a wide range of habitats from arctic tundra to deserts. Several studies have recently indicated decreasing population estimates for migrant and wintering Golden Eagles in the western US. Longterm point count surveys of migrating raptors along the Rocky Mountain Front flyway have indicated approximately a 50-percent decline in total autumnal and vernal Golden Eagle migrants observed over the past 15 yrs and suggest the rate of decline has been increasing. Regionally, specific populations in the Lower 48 and parts of Alaska have been well studied on their breeding grounds. Some of these populations appear to be stable, while others show declines. Observed declines, appear to be associated with habitat alterations. Oil and gas resource extraction has increased noticeably across many areas of the West. The demand for resource extraction is growing and now includes renewable energy facilities such as wind farms. Due to the greater than ever human presence on the landscape and projected increases in development, it is critical to assess eagle response to these changes within their current and historic breeding, migration and winter ranges. Mapping current Golden Eagle habitat use, locally and at the landscape level to better understanding the relationships between human activities and eagle ecology, are the vital first steps to creating a balance between maintaining viable Golden Eagle populations and sustainable development

Tracking New Species: An Update on Satellite Telemetry Data from Raptors Captured on the MPG Ranch

We have studied the fall migration of raptors at the MPG Ranch near Florence, Montana, since 2011. Our banding efforts during this period have yielded modest totals, but impressive species diversity, with a relatively high proportion of Red-tailed Hawks and large falcons. After several successful years outfitting Golden Eagles and Ospreys with satellite transmitters, we decided to expand these efforts to other species. To date, we have outfitted 8 Red-tailed Hawks, 4 Cooper’s Hawks, 3 Peregrine Falcons and 1 Prairie Falcon with satellite transmitters captured on the MPG Ranch during fall migration. We will share what we’ve learned from these individuals and give a telemetry update on our Osprey study

Blood-Lead Levels of Wintering Golden and Bald Eagles of the Bitterroot Valley Montana (Poster)

Lead has long been documented as a serious environmental hazard to eagles and other predatory, opportunistic and scavenging avian species. The use of lead shotgun pellets for waterfowl hunting on federal and state lands was banned in 1991 due to lead poisoning in Bald Eagles (Haliaeetus leucocephalus), Golden Eagles (Aquila chrysaetos) and numerous waterfowl species. At that time, this was thought to be the major source of the lead exposure. More recently, lead poisoning from ingested lead-bullet fragments and shotgun pellets has been identified as the leading cause of death in California Condors (Gymnogyps californianus), leading to a ban of lead ammunition within the “California Condor Recovery Zone.” Another on-going study on Common Ravens (Corvus corax) and Bald Eagles in Wyoming has shown a direct correlation between very high blood-lead levels and the on-set of rifle hunting season. Indeed, there is overwhelming evidence showing that lead toxicity is still prevalent in the environment and mounting data points to fragmented rifle bullets as the source. We sampled blood from 32 Golden Eagles and 11 Bald Eagles captured on wintering grounds in the Bitterroot Valley from 2011 - Present. Eighty-six percent of eagles tested showed blood-lead concentrations higher than natural background levels. These preliminary results suggest exposure to lead is prevalent among eagles from northern latitudes wintering in the Bitterroot Valley

Wing-Tagged Encounters of Goldens Eagles Captured in Montana (Poster)

Recently, there has been an increase in concern for Golden Eagle (Aquila chrysaetos) populations in the western United States. The concern stems from a marked decrease in the number of migrants and concern over an increase in future threats from a variety of anthropogenic factors including, but not limited to, energy development. Thus, there is a need for more information on Golden Eagles including: where they winter, longevity, causes of mortality and critical habit needs. Standard banding offers low encounter rates (<7%) and satellite telemetry is cost prohibitive. We began auxiliary marking Golden Eagles with vinyl wing-tag markers as a cost effective means to gather information on the species. Since 2004, we have wing-tagged over 214 eagles, and re-encountered 46 individuals, giving us a 21% encounter rate. This technique is proving considerably more effective than banding alone as a means of identifying individuals and receiving re-encounter information. We attribute this success, in part to internet information sharing and the increasing use of remote cameras set up on carcasses to view scavenger activity

Estimating Natal Origins of Migratory Juvenile Northern Goshawks Using Stable Hydrogen Isotopes

From 2004 to 2007, we collected hatch-year feathers from 44 juvenile Northern Goshawks (Accipiter gentilis) captured at our Rocky Mountain Front banding station near Lincoln, Montana. Due to the relative scarcity and secretive nature of goshawks, little is understood about their migration patterns or the geographic origins of birds encountered at research sites. Most studies suggest goshawks are partial migrants, often moving <100km, but select band returns and radio and satellite telemetry have shown some individuals occasionally travel thousands of kilometers. We performed a stable hydrogen isotope analysis on the feathers we collected from young goshawks to determine their predicted natal origin. We found that 68% of goshawks had predicted natal origins relatively close to our capture site, 25% from areas in northwestern Canada and eastern Alaska, and 7% somewhere significantly south or east of our capture site. We did not find any significant patterns with sex and passage date or latitudinal origin, nor did we find a meaningful relationship between latitudinal origin and passage date. Our findings support the current understandings of goshawk migration, with a majority of individuals traveling short distances from their natal grounds and a few outliers traveling great distances, not always in a southerly direction

Determining Sex In Golden Eagles Using Foot Displacement

The Golden Eagle (Aquila chysaetos) is one of the most widespread raptors in the world. Attempts have been made in the past to determine sex in Golden Eagles (GOEA) through individual and combined morphometric measurements. Due to the gender overlap within these measurements, the GOEA is one of several diurnal raptor species in North America that cannot be conclusively sexed in the hand. Sex in GOEAs is currently determined only through DNA analysis. Determining sex in the hand would increase the value of information collected by banders in the field, unable to devote time or resources to conduct blood or tissue assays. David Ellis, the author of the GOEA monograph, has developed an instrument under the assumption that foot volume could be definably different between male and female GOEA’s. This method measures the volume of the eagle’s foot, hallux claws, and lower part of the tarsus by the amount of water (cc) displaced. The technique is in its infancy and will be refined as needed. Since 2008, Raptor View Research Institute (RVRI) has measured foot displacement on 36 GOEAs captured on migration in Montana. Our preliminary data shows a 3 cc separation in foot displacement between male and female GOEAs

Habitat Use of Over-Wintering Adult Godlen Eagles in the Western U.S.

A number of studies show declining migration count trends and breeding abundance in Golden Eagles (Aquila chrysaetos) in the West. We outfitted 13 adult, migrant Golden Eagles with transmitters from 2007-2012 with battery powered Argos Platform Terminal Transmitters (PTT) or 70-g solar-powered GPS/PTTs. Eagles wintered across the West, from central Montana to Arkansas. We gathered data on winter territory size, time spent on wintering grounds, and the habitat use of eagles during the winter. We measured a large degree of variability in both winter home range size and duration of winter range use. We found an average 50-percent Minimum Convex Polygon (MCP) home range estimate of 1680 km2 (range 8-14,881 km2) and an average 95-percent MCP of 6578 km2 (range 85- 36,143 km2). Winter home range estimates were extremely variable between individuals and even within the same individual between years. Eagles spent an average of 105 days on their wintering territories (range 60-179 days). We found the most common habitat types were pinyon-juniper, coniferous forest, grassland, shrub, and sagebrush habitats which all comprised ?10 percent of core wintering areas. Several habitat types were correlated to latitude and longitude: the percentage of coastal habitat within winter home ranges increased as eagles wintered further south, riparian and logged habitats increased to the north and west, and shrub habitat percentage of the home range decreased with an increase in latitude. Understanding wintering needs of Golden Eagles is essential to the long-term health of this species across the West

Blood-Lead Levels Of Fall Migrant Golden Eagles In West- Central Montana

Lead has long been documented as a serious environmental hazard to eagles and other predatory, opportunistic and scavenging avian species. The use of lead shotgun pellets for waterfowl hunting on federal and state lands was banned in 1991 due to lead poisoning in Bald Eagles (Haliaeetus leucocephalus), Golden Eagles (Aquila chrysaetos) and numerous waterfowl species. At that time, this was thought to be the only major source of the lead exposure. More recently, lead poisoning from ingested lead-bullet fragments and shotgun pellets has been identified as the leading cause of death in California Condors (Gymnogyps californianus), leading to the recent ban of lead ammunition within the “California Condor Recovery Zone.” Another on-going study on Common Ravens (Corvus corax) and Bald Eagles in Wyoming has shown a direct correlation between very high blood-lead levels and the on-set of rifle hunting season. Indeed, there is overwhelming evidence showing that lead toxicity is still prevalent in the environment and mounting data points to fragmented rifle bullets as the source. We sampled blood from 131 Golden Eagles captured on migration during the fall from 2006 and 2010 to quantify a suite of possible heavy metal contaminants, with an emphasis on lead

Estimating Natal Origins of Migratory Juvenile Golden Eagles Using Stable Hydrogen Isotopes

We used stable hydrogen isotope analysis to estimate the natal origins of juvenile Golden Eagles (Aquila chrysaetos) captured during fall migration along the Rocky Mountain Front in Montana, U.S.A. We collected feather samples from 50 hatch-year (juvenile) Golden Eagles at several fall migration sites from 2004 – 2007. We analyzed feathers for their ratio of deuterium (?2Hf) described in parts per thousand [‰]. A simple linear regression model was used to calibrate our isotope ratios of migrating eagles to a raptor-specific deuterium base map. This enabled us to make inferences about the natal origins of juvenile Golden Eagles captured during fall migration. Our analysis indicated natal origins ranged from the Brooks Range in Alaska to northern Montana. However, 66% (range 50-76%) of the individuals we sampled likely originated from natal areas located in the Yukon and Northwest Territories, Canada, and a small portion of eastern Alaska (? -140 ?2Hf). We did not observe any passage date differences regarding gender or natal latitudinal origins. Our study supports that stable isotope analysis is effective in aiding researchers to understand natal origins of migratory, juvenile Golden Eagles captured during fall migration, or found as mortalities on wintering grounds. It may also be a useful tool for linking Golden Eagle migration count and trend data with population status when utilized among multiple migration sites and wintering areas throughout North America

The Bird’s-Eye View Education Program: Using Bird Research To Educate The Public On The Importance Of Healthy Riparian Systems

The Upper Clark Fork River Basin (UCFRB) has been degraded by over 100 yrs of mining and smelting activities. The UCFRB is the largest contiguous complex of federal Superfund sites in the nation. Restoration and remediation efforts were initiated in the late 1980s and will continue, at a minimum, through 2030. Any restoration activity should include public education and outreach so that land-use decisions in the future do not compromise the integrity of the ecosystems that support the region. We have developed a program, the Bird’s-eye View Education Program, which integrates public education and research on the ecological health of the UCFRB. Specifically we focus on birds, inviting the public to observe research at songbird banding stations and Osprey (Pandion haliaetus) nests. Riparian-associated birds are likely to respond positively to riparian restoration activities and can be used as bio-indicators to measure success. In 2010 we operated three bird banding stations and monitored 19 Osprey nests. We captured 595 songbirds, collected 43 blood and feather samples from Osprey chicks, and served nearly 1000 participants. The program was an outstanding success and results from an assessment show that participants leave with a positive attitude toward the outdoor science experience and a general knowledge of Upper Clark Fork restoration, history, and its riparian ecosystems