Bald eagles came close to extinction in the 1950s and 1960s as a result of more than a century of illegal shooting and the introduction of DDT, a pesticide that rendered the species virtually sterile. They were reduced to fewer than 500 nesting pairs in the lower 48 states and were finally listed as endangered in 1978.
Bald eagles have made one of the most spectacular recoveries of any endangered species and are no longer listed as such. Today, more than 10,000 nesting pairs occupy the lower 48 states, a number that has been increasing at roughly 5% annually in many states.
With such a robust recovery, what threats are jeopardizing the population of these birds today? And are wind turbines likely to pose a significant threat?
The most common source of human-induced fatalities of the species comes from collision with motor vehicles, although Amtrak trains have killed dozens of eagles. Although I could not locate a single statistic as to how many eagles are killed annually on U.S. highways, a soon-to-be-published study from Michigan State University reveals about 22 bald eagles were killed annually on Michigan highways during the period 2008-2012. A quick search on the Web reveals that road kills of this species occur in many other states.
Lead poisoning, resulting from ingestion of fragments of bullets and slugs or lead shot, is the second most commonly cited source of bald eagle fatalities. The same database from Michigan reveals that 10+ birds died annually between 2008 and 2012 in that state from ingesting lead fragments from ammunition dispersed by hunters. Similar numbers are being reported from Wisconsin, Minnesota, Iowa and elsewhere. In one study in Wyoming, 54 of 55 (98%) bald eagles that were captured during the hunting season had elevated levels of lead.
Other sources of bald eagle fatalities include gunshot wounds, fur trapping, pesticides/toxins, collisions/electrocutions with electrical lines and, finally, collisions with wind turbines.
As of this writing, fewer than 10 bald eagles had been documented as killed at wind energy facilities, and that number is the cumulative total for all wind turbines in the U.S since wind turbines have been operating. This number includes a bald eagle found dead at a wind turbine owned and operated by the U.S. Fish and Wildlife Service (FWS) at its Eastern Neck National Wildlife Refuge. Thus, it is likely that wind turbines account for far less than 1% of all annual human-induced fatalities of bald eagles in the U.S.
What is most interesting about the above facts is that of all the sources of human-induced fatalities of bald eagles, only wind turbines have been studied systematically.
Unfortunately, it is unknown how many eagles are killed on highways or via lead poisoning, and what we do know is from carcasses found by accident, rather than during systematic, quantitative studies, as are done at wind turbines. In other words, the number of eagles killed by lead poisoning in Michigan could be twice as high as the number provided above.
It is also ironic that the human activities that kill the most bald eagles, road kills and lead poisoning, are likely operating in violation of the Bald and Golden Eagle Protection Act (BGEPA) as cited by the FWS in the new Eagle Conservation Plan Guidance – Module 1 – Land-based Guidance – Version 2 (ECPG).
That act prohibits "take" of individual eagles "and their parts, nests or eggs" without a permit. The BGEPA defines "take" to include "pursue, shoot at, poison, wound, kill, capture, trap, collect, molest or disturb." Thus, agencies involved in funding and permitting of road building should, by law, apply for eagle take permits. The same is true for agencies funding or issuing hunting licenses because hunting ammunition that is sanctioned by these same agencies is the primary cause of lead poisoning.
In fact, the FWS subsidizes state hunting programs to the tune of hundreds of millions of dollars in excise taxes each year. In Michigan, where more than 10 bald eagles are poisoned each year by lead dispersed by hunters, the FWS provides $12 million to the state agency that licenses and promotes hunting.
In other words, the FWS and other agencies that fund and license these activities are violating the BGEPA. How can the agency that is entrusted with protecting bald eagles be taken seriously when it subsidizes and promotes hunting practices that are killing perhaps in excess of 100 bald eagles per year nationally?
If the wind industry is to make a conscientious effort to adhere to the new ECPG, the FWS must be a leader and scrutinize its own actions with respect to funding state hunting programs that distribute lead that kills eagles, endangered condors and other wildlife.
This may be difficult for the FWS because it distributes hundreds of millions of dollars to state hunting agencies, making examination of this issue better suited for the Inspector General of the U.S. Department of the Interior. Because the FWS is suggesting prosecution of wind energy companies if turbines kill even a single eagle, perhaps the U.S. Department of Justice, as well as solicitors within the FWS, should weigh in on highway fatalities and lead poisoning of eagles to help us understand why wind turbines are different.
Finally, a word of advice to all wind energy developers and turbine owners: If an eagle is found dead at a wind facility, turbine owners must insist that the federal authorities allow the carcass to be analyzed to determine whether lead poisoning was involved. Eagles having even slightly elevated lead levels can be weakened and fly erratically, causing them to collide with various objects. In the event that the bird has elevated lead levels, the ultimate responsibility for the fatality may not be the turbine. Instead, the agency that funded and licensed the lead dispersal should accept responsibility.
Paul Kerlinger, Ph.D., is senior scientist and principal at Curry & Kerlinger LLC, a consulting firm specializing in bird and bat issues. He can be reached at (609) 884-2842 or firstname.lastname@example.org.