By Jim Wiegand, wildlife biologist, University of California, Berkeley.
The controversy surrounding wind farms in America has been brewing for over 25 years. The debate centers around the use of the deadly propeller style wind turbines and the large death toll to what are supposedly protected species. One of these species, the federally protected golden eagle, has been at the forefront of this debate from the beginning.
For the wind industry, environmental analysis basically comes down to disclosing as few impacts as possible to an ignorant audience. The biological assessments are either paid by the industry for or created from wind industry influence in political arena. These grossly incompetent documents are produced solely to manipulate and expedite the permitting process for wind farm approval.
As I will point out, there are some very good reasons to discard these surveys. It does not matter how skilled the observer, the fact is that identification of the golden eagle and determining age class is not easy. It is a well documented fact that the golden eagle is very often confused with immature bald eagles. With the West Inc observers flying around in an airplane I can imagine there being a lot of confusion between the two
because it appears that results of these yearly surveys have to be contaminated with immature bald eagle sightings counted as golden eagles.
Mistakenly identifying golden eagles is common. I even witnessed this with UC Berkeley staff on college on field trips.These surveys have been broken up into four geographic regions. One is called the Northern mountain region of the Western U.S. This is the area of the survey overlaps that overlaps primary bald eagle Western habitat(see image). Over the last two years the West inc. survey reports the most golden eagles in this area even though this region represents only secondary golden eagle habitat. Much of the habitat in this region of the survey cannot even support a population of golden eagles because of the abundance of cover and lack of prey species.
This area has also been under drought conditions for years(see image). This further affects the available food supply for the golden eagle.
Yet if we are to believe the estimates put out by West Inc for entire 193,000 square mile region of what they classify as Northern Mountain habitat, there is a golden eagle every 25 square miles. In actuality there is not even one golden eagle every 200 square miles for this region.
In the past I conducted my own golden eagle research. This intermountain habitat had an elevation ranging between 3000-5000 feet. The habitat included juniper woodland, forest, semi desert, and grasslands. I found that this habitat will support a nesting pair of nesting golden eagles in about a 100 square mile territory under the best of conditions. I observed one pair that actually hunted over a 200 square mile territory during the spring and summer months exploiting pockets in the habitat where their preferred prey lived. [singlepic id=331 w=286 h=375 float= right]
Eagles aren’t the only birds falilng prey to razor-sharp turbine blades. In Italy, red kites brought back from the brink of extinction have been decimated by wind turbines, experts report.
Over the last 40 years there have been intense ground and air surveys of some of the very best golden eagle habitat that exists in the Western US. These are habitats in Northern Nevada, Northwestern Utah, the Snake River drainage of Idaho, and the Thunder Basin area of Wyoming. These are areas that support large populations of either rabbits, ground squirrels or prairie dogs. These are the pockets of habitat that can actually support an eagle every 25 square miles.
When considering just these prime pockets of golden eagle habitat and include all the surrounding lesser habitat in their respective counties, the golden eagle populations still only come out to about one pair of nesting golden eagles every 80-100 square miles in less than 10% of the counties of the 13 western states surveyed. None of these counties exist in the Northern Mountain Habitat region of the survey.
The Thunder Basin National Grassland was surveyed in 2006 by the USDA and they only reported 18 golden eagle nests for the entire 893 square mile National Park. This works out to one eagle nest for every 49.6 sq. miles in this prime habitat. In 2003 the West Inc survey of the 757,883 sq miles region of the Western U.S. reported a total golden eagle population of an astounding 27392 eagles. This figure represents one eagle existing for every 27 square miles of every bit of the western habitat. These reported figures are ridiculous.
In Southern Nevada, Arizona, New Mexico, the Rocky Mountains there are vast areas of poor habitat included in the survey where there is not even one pair of eagles every 400-500 square miles. There are also1000’s of square miles of cities, towns, farms and industrial areas no eagle habitat exists. This too must be factored in to any population estimates. I have provided a map to show where the highest year round populations and densities golden eagles actually exist in the Western U.S.
The proportion and number of juvenile golden eagles in the reported in surveys are also erroneous. I say this because when identifying young juvenile golden eagles one must keep in mind that they look nearly identical to those birds that have not completed their first molt. This would make the juvenile eagles counted in the survey are actually a mix of two different years of golden eagle offspring. Thus the actual fledged or juvenile golden eagles reported by the West Inc are actually lower than those stated in the surveys. Photographs are the best way to tell them apart and to document what is really an eagle recently fledged from the nest vs. an eagle from the previous year.
When considering the amount of juvenile eagles accounted for in this series of surveys, I will now point out the most damming or contradictory fact of the West Inc golden eagle surveys. The age classes of the given eagle population in the surveys contradict their own total population conclusions. This further invalidates the survey results. The West Inc surveys state a population that is made up of approximately 12,000 adult golden eagles. These adults are reported to be producing fewer than 2000 young each of the last 4 years.
In reality a population of 12,000 adult eagles would easily produce 5000-6000 offspring for each of these years. It is well documented from decades of research that nesting Golden Eagles on average produce between .75 and 1.25 fledged young per year. Even if we were to accept the inflated 2000 number of juveniles given in the survey, it would indicate a population of half the size given.
As I have pointed out in this report, there are not nearly as many golden eagles as reported in the West Inc surveys. The population of golden eagles in the 13 western states has been exaggerated 3-4 times.
I find it ironic that these extensive surveys were contracted out to private industry even though under the employment of the USFWS there are many qualified people that could conduct a much more accurate analysis of the golden eagle. Many biologists who are currently under the employment of the USFWS, USDA, and State wildlife departments that will agree with this report. Unfortunately they must answer to the policies dictated by industry and remain silent.
It is also my understanding that these surveys are planned for 20 years. That’s just about long enough to get to get the planned 150,000- 200,000 turbines and the needed transmission lines installed into this region of the Western U.S. So if this gauntlet of turbines is installed and the golden eagle population is found to be in a nose dive…. Then what? Who will be responsible? Not the wind industry because they will be protected by the “no surprises clause” conveniently written into the Federal law pertaining to incidental take permits.
This report represents the true state of the golden eagle population and it should be circulated to every in planning department in the Western U.S. I have been paid nothing to write this and have been influenced by no one.