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In March 2021, the U.S. Fish and Wildlife Service announced that the newest population estimate of bald eagles had quadrupled in just over a decade! The bald eagle population climbed to an estimated 316,700 individual eagles, which included 71,400 nesting pairs. The recovery of the bald eagle from all-time low of 417 estimated breeding pairs to 10,000 pairs in 2007 when it was removed from Endangered Species Act protection, to its continued population growth across the country, truly does make this one of the most successful conservation stories of all time.
How then are golden eagles doing?
Golden Eagle Biology
Golden eagles (Aquila chrysaetos canadensis) can be found from the tundra, through grasslands, forested habitat and woodland‐brushlands, south to arid deserts, including Death Valley, California. As aerial predators, golden eagles eat small to midsize reptiles, birds, and mammals up to the size of mule deer fawns and coyote pups. They also are known to scavenge on carrion.
One finds golden eagle nests on cliffs or in the largest trees of forested stands that often afford an unobstructed view of the surrounding habitat. Their nests are usually sticks and soft material added to existing nests, or new nests that are constructed to create strong, flat or bowl shaped platforms. Golden eagles avoid nesting near urban habitat and do not generally nest in densely forested habitat. Individuals will occasionally nest near semi-urban areas where housing density is low and in farmland habitat, but the bird seems sensitive to some forms of human presence.
The species lays one to four eggs, with two eggs being most common and four eggs most rare. The laying interval between eggs ranges between three to five days.
Golden eagles will migrate from Alaska and the northern Canadian provinces to areas that are milder in the winter and/or may have less snow cover. During winter, golden eagles are found throughout the continental United States and much of Mexico. Golden eagles tend to migrate during midday along north-south oriented cliff lines, ridges, and escarpments, where they are buoyed by uplift from deflected winds. Golden eagles will forage during migration flights and use lift from heated air to move efficiently during migration and seasonal movements, gliding from one thermal to the next and sometimes moving in groups with other raptor species.
Protection of Golden Eagles
Bald and golden eagles are protected by three federal laws: the Bald and Golden Eagle Protection Act, the Migratory Bird Treaty Act and the Lacey Act. These laws prohibit the possession, use, and sale of eagle feathers and parts as well as the transport of eagles and feathers and parts that have been illegally obtained.
The Bald and Golden Eagle Protection Act makes take (killing, injuring, disturbing, or possessing) bald and golden eagles or their parts illegal in most situations in the United States. It does recognizes several legitimate uses of eagles, allowing the Service to authorize and permit the take of eagles in some cases.
The Eagle Protection Act explicitly identifies incidental take of eagles as a prohibited act, and the authorization of incidental take is one of the cases where permits may be issued. However, Congress specified that the Service’s authority to permit take requires a determination that the take is compatible with the preservation of the eagle species being taken. Thus, the Service has to make scientific determinations regarding the sustainability of any take of eagles that it authorizes.
As part of implementing these laws, the Service published a Programmatic Environmental Impact Statement (PEIS), in December 2016, in which the Service committed to updating population size estimates and take limits for both bald and golden eagles no less than once every six years.
This means that the Service monitors the health of bald and golden eagles, provides updated information on population size, productivity, and survival rates, and manages the effects of both authorized and unauthorized take on eagles.
Status of Golden Eagles
The Service and our colleagues have regularly surveyed golden eagles since 2006. We look closely at the interior western United States as that supports the majority of the population. The last time the Service published the population status included data through 2014.
The newest population estimate, based on data through 2016, for the interior western U.S. golden eagle population is 31,800, very similar to the estimate in 2014.
The total population size for the golden eagle throughout the United States (including Alaska) in 2014 was estimated to be 40,000. Given that the numbers for the interior western U.S. have remained the same, we believe that total population estimate is still about the same.
This population estimate was recently published in the scientific journal Ecological Applications.
What’s happening to Golden Eagles?
Even though golden eagle populations appear stable, the current rate of golden eagle mortality raises concerns as to whether they can remain stable. Based on this most recent published research, human activities still account for the majority of golden eagle mortality (74% of deaths after their first year). This rate of human-caused mortality is likely at the upper extreme of the level of take that is sustainable. In addition, many juvenile eagles die from starvation during their first year. Golden eagles are also unintentionally killed in conjunction with many activities such as electrocution on power poles or collision with wind turbines.
However, intentional activities, including illegal shooting and poisoning, continue to be substantial causes of adult golden eagle mortality.
In fact, according to this research, the leading cause of adult golden eagle mortality in the western U.S. is illegal shooting, accounting for nearly 700 golden eagle deaths annually. This finding is consistent with other recent work documenting high rates of illegal shooting of raptors and other species. Golden eagles are the target of poachers selling feathers on the black market, and farmers and ranchers that shoot the birds thinking they are protecting livestock. Service law enforcement agents across the western U.S. are involved with numerous cases every year involving golden eagles.
In addition to the issues of shooting, this research found that poisoning accounts for nearly 427 golden eagle deaths annually, along with about 506 electrocutions and 611 collisions with automobiles, wind turbines, and power lines.
Purposeful killing of golden eagles is a criminal violation under the Eagle Act, yet it is apparent that prosecution and penalties have not been able to curtail widespread shooting. The Service is currently supporting a human dimensions research project through Colorado State University — Pueblo to gather information from a wide range of sources to better understand what is motivating this illegal shooting. Our hope is that by better understanding why eagles are being shot, novel solutions can be identified to counteract it.
So what happens to those dead golden eagles?
Many of those dead eagles go to the Service’s National Fish and Wildlife Forensics Laboratory in Oregon, where they are analyzed by forensic specialists. The Forensics Lab is the world’s leading full-service crime laboratory devoted exclusively to supporting wildlife law enforcement; and, by treaty, is the official crime lab of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Scientists at the laboratory identify the species, source of wildlife parts, and products seized as evidence. They link suspect, “victim,” and crime scene through the examination and comparison of physical evidence; determine the cause of death of wildlife crime victims; and help analyze crime scenes. Laboratory scientists also conduct research to develop new analytical techniques needed in wildlife forensics and provide training on species identification and evidence handling to Service law enforcement officers and their global counterparts. Scientists at the Forensics Lab are the most definitive source of how the Service identifies the actual cause of death to wildlife, including golden eagles.
For eagles that did not die from suspected foul play, and for those eagles that have already been analyzed at the Forensics Lab, there is another unique place that eagle remains go to: the National Eagle Repository.
The Service has long recognized the religious and cultural significance of eagles to Native Americans and works to accommodate these needs. The Service operates the National Eagle Repository in Colorado as a clearinghouse for eagles and eagle parts that are shipped to Native Americans and Alaska Natives enrolled in federally recognized tribes for use in Indian cultural and religious ceremonies.
It is illegal for any individual to possess a bald or golden eagle, including its parts (feathers, feet, etc.). The distribution of bald and golden eagles and their parts to Native Americans is authorized by the Bald and Golden Eagle Protection Act and Regulations found in 50 CFR 22.
Federal and state conservation agencies, zoological parks, federal rehabilitators, and others who may legally possess and transport dead bald and golden eagles are either mandated or encouraged to send them to the National Eagle Repository where they will be distributed to Native Americans as well.
The collection efforts of the Service provides a legal means for Native Americans to acquire eagle feathers for religious purposes, which in turn, reduces the pressure to take birds from the wild and thereby protects eagle populations. It also promotes a government-to-government relationship with federally recognized tribes, and fulfills the U.S. government’s trust responsibilities to Native Americans.
What’s next for golden eagles?
The Service will continue to monitor golden eagle populations, paying close attention to any signs of population decline. In addition, the Service and many collaborators are carefully considering how to reduce the amount of human-caused mortality the species faces. Unlike illegal shooting, where a solution to the problem has so far evaded us, some other forms of mortality have known solutions that can be implemented. Electrocution, vehicle collisions, and secondary poisoning are causes of mortality that are the focus of efforts to reduce golden eagle mortality. This is important work, because some forms of golden eagle mortality will likely increase over the coming decade. Reducing existing forms of manageable golden eagle mortality will be critical if the species is going to persist for the enjoyment and benefits of future generations.
This story was originally published via the USFWS Medium blog on January 27, 2022.
