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Birds and windfarms - Critical analysis of 4 reports on bird mortality at windfarm sites.



ESPAÑOL: Aves y Eolica - Análisis crítica de 4 informes sobre mortandad de aves en parques eólicos.

This paper has been peered reviewed by Belgian biologist Joris Everaert, a leading expert in the matter : ---> PEER REVIEW

Above picture: Old model lattice-type wind turbines (Tarifa, California etc.) - Note: in favourable weather conditions, migrating birds generally fly high enough to be out of reach (although it is more difficult now, as bigger wind turbines reach higher in the sky, up to 140 meters ). But when cloud cover is low, or when a headwind is blowing, migrating birds fly closer to the ground. This puts them within reach of the turbines´ blades.

There are also periods of fog, when the turbines are invisible. And then there are bird species that fly during the night, to cool their high body temperatures (most songbirds migrate at night).


Dr. Lekuona estimates fatalities to be in excess of 6,450 birds and 650 bats a year. These figures do not appear in the report. They must be reconstructed from pages 88/89:

Windfarm of Salajones: 35.05 fatalities/turbine/year x 33 turbines = 1,156 fatalities/year
Izco: 25.72 x 75 = 1,929 fatalities/year
Alaiz 3.56 x 75 = 267 fatalities/year
Guerinda 8.47 x 145 = 1,228 fatalities/year
El Perdón: 64.26 x 40 = 2,570 fatalities/year
---------- ----------
Total ……………………..19.43 fatalities/turbine/year x 368 turbines = 7,150 fatalities/y.

Note: This is a conservative figure - the resources allocated to Dr. Lekuona for the performance of his study did not permit a thorough job (p.15, p.125).

In any event, there is enough data to induce reflection, provided that: 1) The report be disclosed to the public in its entirety, and 2) Figures are not tampered with.

But there has been deception on both counts. First, the report was shelved, and the public was denied access: GURELUR, a Navarran association of ecologists, asked for a copy. But its right to be informed was violated: "to obtain the said report, GURELUR had to resort to a person outside Navarra, for the Department of the Environment denied it to us, in spite of our asking several times through different channels, under the peculiar pretext that it was not finished" (www.gurelur.org).

Then there was falsification of the key figures. Few people have the time to read through 147 (or even 89) pages of technical observations, tables, and graphs, let alone get into calculations of their own (as we did above); therefore a summary was made, and placed at the beginning. And this is where the most significant figure, that of the total estimated mortality, has been tampered with: "It has been estimated that the mortality per turbine/mo was 0.03 specimen" (line 10). Nothing more is said about fatalities as estimated by Dr. Lekuona .

How much of a falsification? – This much: 0.03 x 368 turbines = 11 fatalities. And if the reader pays attention to the "/mo" at the end of the word "turbine": 11 x 12 = 132 fatalities.

In short, the Summary reports 132 fatalities where there have been 7,150.


Above photo: new model tubular column wind turbine, Navarre, and 2 griffon vultures freshly killed, one of them sliced in 2 pieces by the fast moving blade-tip - up to 292 km/h ... see: Birds and windfarms – Bird and Bat Behavior at windfarm sites.

The 7,150 fatalities include 409 griffon vultures - and 24 other protected raptors: golden eagles, eagle owls, booted eagles, sparrow hawks and kestrels. Moreover, specimens of lammergeyers, Bonelli´s eagles, black storks, etc. have been sighted in "situations of risk" flying close to the turbines (1) – a fact that the author has statistically linked to mortality (p.66) - yet no remains have been found of these endangered species. But the limited means that were put at the disposal of Dr. Lekuona did not permit him to find all of the carcasses, not by a long shot.

Indeed, 65% of the turbines remained out of the sampling zone. An employee of the Navarran government, acting alone and once a week, performed the search in the selected 35% in those areas that were "more or less free of shrub vegetation"(p.15). In addition, some of the sampled mills stood near a cliff, and that´s another area that stayed out of the search. And most important: the presence of "numerous opportunistic predators", some of which were seen dragging away carcasses of the heaviest birds (p.122), makes it a certainty that much of the evidence disappeared before the weekly visit.

Estimates of total mortality do take such parameters into account. However, in cases where you have zero carcass recovered for any given specie, your mortality estimate for that particular specie will remain zero, no matter what coefficient is applied. This places a serious limit on the validity of all field studies as far as rare species are concerned. For you may have several yearly deaths affecting, say, the black stork; but if none of the carcasses happen to be found (for the reasons outlined in the previous paragraph) your total estimate will reflect: zero black stork. Besides, in cases where the person performing the search may be submitted to pressures from his employer (loss of job), it must be kept in mind that carcasses of endangered species may fail to be reported for the scandal that would cause.

(1) Says the report: "Of the 37 species involved in situations of risk, 10 have presented high values of interspecific risk level (also called level of exposure) and they are the following: Black Stork, White Stork, Black Kite, Lammergeyer, Egyptian Vulture, Hen Harrier, Montagu´s Harrier, Booted Eagle, Bonelli´s Eagle, Common Kestrel, Merlin, and Greenfinch." (p.56).

Aside: The Valencian Government, whose territory harbors the second largest European population of the rare Bonelli´s eagle (82 pairs), and lies on the migration route to Africa of millions of birds – some of them on the endangered species list – authorized a Plan which permits the installation of 2,750 wind turbines precisely where they do great carnage: on mountain crests.

Extrapolation: There are about 1,000 wind turbines in Navarra, and 6,000 in Spain, many of them "old generation" (100 Kw to 250 Kw). To produce 20% of Spain´s electricity fifteen years from now, an additional 19,000 turbines will be needed, averaging 1,000 Kw each. That´s 25.000 wind turbines in total.

Extrapolations are inexact by definition, but they have the merit of providing an order of magnitude. Using the conservative estimate of 7,150 fatalities, i.e. 19.43 per turbine – say 20 – over a period of 30 years, and all things being equal:

20 fatalities per turbine x 25,000 turbines = 500,000 x 30 years = 15 million fatalities in Spain alone. If the mix of new turbines averaged 1,500 Kw per turbine, total turbine numbers would be 18,666, and fatalities 11,2 million – all things being equal.

Note: the claim that larger turbines are more benevolent to birds is not based on fact. The contrary is likely to hold true. For if the revolutions per minute are reduced, the arms length is increased, and the tips of the blades still travel at speeds up to 180 mph. They also reach higher in the sky, endangering new classes of birds. Finally, the swept area is much larger. All in all, fatalities per turbine may well be poised for a substantial increase, and the above estimates may need to be revised upwards.

That´s for wind turbines alone, without counting the fatalities associated with the new tension lines rendered necessary by a network of hundreds of windfarms throughout the land. Now let´s add to this the electrocutions, the collisions with existing tension lines, the murderous guy wires of television and other telecommunication towers, the loss of habitat, and all the other pressures man brings to bear upon birdlife: it is to be feared that windfarms will put an intolerable additional strain on many bird species, bringing some to extinction levels. This is particularly evident in the case of raptors, but hardly exclusive of others.


Says the report: "we have witnessed large flocks refusing to cross (the lines of turbines).... The effects were the dispersal into smaller groups, the presence in the vicinity of the windfarms of disoriented birds unable to follow their original flight trajectory, and in some cases situations of risk of collision for the smaller bands". ----- (Among the 6,450 dead birds, Dr. Lekuona evaluates that 40% were migrating, i.e. 2,580) ------ "This … is bound to entail higher energetic costs for these individuals, which must fly to the sides, away from their normal course, so as to avoid the lines of wind turbines, or to reach a higher altitude in order to go over the windfarms" (p. 143 -144)

This implies that the weaker specimens will not reach their destination, especially if there are more windfarms along the way (i.e. more energetic costs for the birds). These fatalities are not accounted for – and neither are those of the birds which, wounded by the blades, or having lost essential flight feathers, will not finish their journey: "on several occasions we have witnessed loss of feathers…" (p.92). - The author also witnessed reactions of panic, and deadly collisions.


"We have detected the presence of numerous opportunistic predators in the vicinity of the turbines (foxes, martens, polecats, cats and dogs)"..... "stray hunting dogs, famished, collarless, and prowling between the turbines". And indeed, "carcass permanency tests" revealed that the bodies of small birds disappear at a fast rate (p. 80). As for those of medium and large birds: "in one occasion we are certain that a fox dragged the carcass of a beheaded Griffon Vulture out of the Salajones windfarm... On another occasion a fox dragged the body of yet another vulture 30 meters, hiding it into the bush, and in the case of the Eagle Owl, only the severed wing was found" (p.122). And Dr. Lekuona goes on saying that another study documented the fact that dogs are an "important" factor in the disappearance of carcasses of large raptors (p.130).

At this juncture it is worth recalling the American study "Crawford, R.L. 1971. Predation on birds killed at TV tower Oriole 36(4)", in which the author performed various overnight carcass permanency tests. And here are the results: "the nightly loss of test birds to scavengers was between 64 percent and 100 percent".

An image will help visualize the extent of the scavenging factor, and the hidden nature of the damage done to birdlife: in a way, the windfarms act as fastfood outlets for the foxes*, stray dogs, cats and other opportunistic predators. Dr. Lekuona confirms this when he reports the presence of "very busy fox tracks" and the abundance of domestic species such as cats and dogs on windfarm grounds (p.133) *and coyotes in America

It is for this reason that we do not find thousands of dead birds on windfarm grounds; and for this reason that ecologists and ornithologists think that the danger to birdlife is minimal – when in fact it is great.

For this reason and for the fact that all field studies that were ever made on the subject are commissioned and published by the windpower industry itself or by the Administration, which has clearly demonstrated its partiality towards windfarms: we have just seen how easily they can falsify a report, when it happens to have been made by an honest biologist.


Here, the actual body count was: 65 large or medium-size birds for 34% of the 256 turbines surveyed "generally twice a week", and 54% of the tension lines surveyed once a week. Two short-toed eagles were among them, as well as 30 griffon vultures, 15 kestrels (3 of them on the endangered list), 2 eagle owls, 1 black kite, 1 "unidentified raptor" (it could be an endangered imperial eagle, for all we know) and one egret. Based on this, the summary estimates total mortality to be: 89 large and medium size birds – whereas a weighted extrapolation from 64 bodies on 34% of the windfarm area, and 1 on 54% of the tension lines area, would yield 190 bird carcasses for 100% of the area. So, in effect, we are asked to believe that the estimated mortality is less than half the estimated body count.

The surveyors justify their calculations by saying that extrapolation was only applied to kestrels. They want the reader to accept that 1) although they only surveyed 34% of the territory, "generally twice a week", they would have spotted all carcasses other than those of kestrels on 100% of the territory (256 turbines) 2) and, although we know that foxes and stray dogs take away birds carcasses of all sizes, including heavy vultures, no scavenger removal factor has been applied to vultures, eagles, black kites, eagle owls, "unidentified raptors" and egrets. Such methodology is totally unacceptable. What is more, these important irregularities do raise the question of whether the report has been tampered with at time of publication. - In such circumstances, should we trust the body-count figures themselves?

We read: "the survey was centered on the detection of medium to large size birds only". Yet, millions of small birds cross the Straits of Gibraltar twice a year, most of them at night, when wind turbines a lot harder to see and cross safely. Why wasn´t their mortality surveyed? This is possibly Europe´s busiest migration corridor, and a thousand wind turbines stand in the way…


Above photo: golden eagle beheaded by a wind turbine at Altamont Pass, California.

In the executive summary we read: "Estimates are that wind turbines kill 40-60 sub-adult and adult golden eagles each year, on average"... plus "other protected species...including several hundred red-tailed hawks and American kestrels each year". The impreciseness of the figures, the undisclosed methodology (percentage of surveyed area, number of visits, number of surveyors, detectability factor, scavenger removal factor, non-consideration of small birds, etc.) reveal that no bird-mortality survey was conducted. Indeed, that was not the purpose of the study.

Yet, a bird mortality estimate is provided. And as we compare it to information available in the body of the report, we find it only shows the tip of the iceberg, as may be ascertained from page 6: "In 1994 alone, 348 raptor fatalities in the WRA* were reported to Alameda County, 35 of which were golden eagles an 194 red-tailed hawks (Alameda County 1998)" (119 American kestrels and other raptors are left out of the text: 348 – (194 + 35) = 119). Now, this is not the result of a survey: just carcasses that happen to have been found in 1994.
*Wind Resource Area

It is further reported on page 6 that up to 42 carcasses of golden eagles have been found in a single year by "wind industry employees who, while servicing the turbines, happened upon" (them). The author then adds: "However, these likely represented only a fraction of the total fatalities present, considering the lack of surveys and the incidental nature of the reports". - A "fraction" says the author, but the summary misleads us into a definite 40-60 a year.

For all we know, one hundred young golden eagles may die each year at Altamont, and 600 other raptors. It is not proven, but then again we have 42 eagle carcasses and 313 dead hawks and falcons casually reported to the authorities in 1994 and another undisclosed year.

Then the summary tries to demonstrate, through a bizarre mathematical model, that these numerous kills do not affect the overall population of golden eagles from one year to the next. Yet we read earlier in the summary: "Golden eagles, being naturally slow to reproduce, are particularly sensitive to changes in adult and sub-adult survival rates". This is contradictory.

In fact, what we have here is a good example of the dreaded black- hole effect, where the entire California population of golden eagles is being thinned down by a large windfarm which happens to have been erected on a juvenile dispersion area, i.e. a rich hunting ground free of territorial adults. It is a fact well known to ornithologists that young eagles will travel hundreds of miles to find such an area. As for red-tail hawks, some of which migrate from Canada, the effect is felt even further. – But the report´s objective is to study the population of breeding golden eagles within a circle of 30 kms around the windfarm. Given the abundance of sub-adults and floaters* concurring to the Altamont dispersion area from far away places, it is only natural that the immediate surrounding adult populations be replenished when an adult dies. But it is on far-away eagle populations that the attrition effect of Altamont will bring to bear – precisely those that were not studied. *non-breeding adults

Now, the windpower industry claims that Altamont is an exception. But the opposite is more likely: any area cleared of dense vegetation is a potential hunting ground for raptors, and windfarms typically create such environments.


POSTCRIPT NOTE: the following analysis is based on the Sept/Oct. 2002 edition of the report. A new, revised edition was released in Sept. 2003, from which the objects of my critiques had been corrected. The fact remains that, when I wrote the lines below, the Birdlife report WAS misleading. The other conclusion to draw is that I did the right thing when I denounced the slant. - end of note. BIRDLIFE - corrected version

The summary emphasizes the low impact on birdlife: 2.25 "The majority of studies have so far demonstrated very low collision mortality rates attributable to wind farms". – But the body of the report fails to substantiate that; and the use of the word "demonstrated" is questionable, at best, as most reports emphasize the underestimation of bird mortality.

Then the summary suggests that no judgment should be attempted on the newer, larger models:
2.26 "Most studies have been of small turbines; the implications of newer, larger turbines may be different, but it is too early to tell ". Yet, we read in the body of the report (2.77): " Conversely, larger turbines may pose more of a problem because of the greater height range through which the rotor blades travel". - Here again, the summary plays down the negative points of the report. (Note: two different paragraphs re numbered "2.77" - it is the second one, under the heading "The Future Offshore")

On page 9 we find alarming information on migratory birds: a great many fly by night, a great many fly at wind-turbine height, a great many are attracted and confused by lights – and we know that turbines must be lit, for airplane and/or sea-traffic safety. We are also told that hilltops and mountain crests are more dangerous because this is where migrants fly closer to the ground – and this is precisely where many windfarms are located. We are told that high flying migrants effect stopovers, and that the heavier the bird, the longer its descending flight, and the greater the danger (swans, bustards, geese, cranes, storks, herons, egrets, ducks, eagles, ospreys, honey buzzards, kites, falcons etc.). – We thus learn that wind turbines threaten high flyers as well. Finally, it is conceded that very little is known about nocturnal migration routes, which we know from the above statements to be very busy, and within turbine range.

In paragraphs 2.59/60, we are surprised to read that a long-term study on golden eagle populations (Hunt et al) at Altamont Pass is "in its early stages at present". This was written in September 2002. Yet, Grainger Hunt, commissioned by the California Energy Commission, published a long-term study on golden eagle populations at Altamont in July 2002 - Oversight?

Paragraph 2.54 it is said "In Belgium…. corpse searches, at three wind farms, identified herring gull, lesser black-backed and black-headed gulls… common terns, little terns kittiwake and raptors (kestrel, sparrow hawk and peregrine falcon)". But the Birdlife team fails to quote the most important data: "We found that the estimated collision numbers varied from 0 to 125 birds/wind turbine/year. The mean number was 23 (East dam), 12 (Pathoekeweg) and 4 (Schelle) birds/wind turbine/year. At 12 sea-directed wind turbines on the ‘East dam’ in the port of Zeebrugge the mean number was 39 birds/wind turbine/year" – signed: Joris Everaert*, biologist, author of the report. These figures are comparable to those reported by Dr Lekuona in Navarra, and researcher Winkelman in Holland: hardly benign.
* He wrote a summary in English which I published with his permission: see Birds and Windfarms - Wind turbines and birds in Flanders (Belgium) - Preliminary results 2000/01

Effectively, on Paragraph 2.50 we read: "At Urk (Winkelman 1989) and Oosterbierum (Winkelman 1992a) in The Netherlands… mean corrected daily collision rates per turbine were <0.1 in autumn and spring. The number of corpses in autumn was 2 –3 times that recorded in winter or spring (Winkelman 1989)". Confusing as that may be (winter seems to be included in the mean average, but what about summer then?) we tentatively obtain: 0.1 x 365 = 36.5 birds/turbine/year. Again, an alarming figure that would translate into 2.2 million dead birds per year if applied to the 60,000 turbines Western Europe is proceeding to erect in its airspace.

2.56 "Mortality at Tarifa, Spain …… Real (mortality) rate is: 106 / 256 turbines = 0,41". First we have the questionable nature of the methodology of the survey (see Tarifa analysis above); then, the 106 dead birds estimate curiously includes 17 small birds that were not surveyed but
"happened to have been found" – and quite incorrectly counted on the basis: one happened-to-have-been-found-without-being-surveyed-dead-body = one estimated death per year). Yet Birdlife quotes this highly irregular figure, and fails to mention that small birds were not surveyed in this study, which is a paramount qualification of the results.

In fact, anybody who doesn´t happen to have studied the Tarifa report throughout, and with a critical eye, will get the impression from the Birdlife/Bern report that 106 birds is all that 256 wind
turbines kill yearly at a crucial location above the Straits of Gibraltar.

2.53: At Blyth, in the UK (Still et al. 1996): "31 wind farm collision victims (of four species) were recorded, equivalent to 1.34 bird strikes per turbine per year". – Here it would appear that "bird strikes per year" are based on the sole body count, which we know is a tiny fraction of actual mortality. And yet, that body count itself is underestimated, as we read: " This experiment
confirmed expectations that few corpses were likely to be washed ashore, illustrating the limitations of corpse searches for assessing collision mortality". – So, in effect, the 1.34 figure would appear to be a highly underestimated body count. As for the actual mortality estimate, it is not even reported.

Conclusion: the Birdlife/Bern report deceives the reader by using a variety of methods, ranging from picking irrelevant and misleading figures to failing to report significant data.

Offshore: some of the data seems to have been left intact, though, for we saw that the dangers to migrating birds have not been minimized (p.9 above). And neither have the risks associated
with offshore wind farms:

2.65 " both common eiders and common scoter were active at night"… (at sea)

2.67 "Lighting of turbines has the potential to attract birds, thereby potentially increasing the risk of collision (Winkelman 1992b)"

2.75 "It is thought unlikely that the turbines will offer many roosting or nesting sites for birds as turbine design now offers minimal opportunity for perching and, offshore, the platforms will be largely submerged. However, access walkways may attract occasional birds to settle, bringing
them into close proximity to the turbines. Large gulls are attracted to loaf on top of the flat-topped nacelles in the Tunø Knob wind farm, Denmark (pers. obs.) and cormorants have been observed on landing platforms at offshore installations (Sundberg, pers. comm.)".

Comment: If large gulls are attracted by the flat-topped nacelles, so may ospreys and sea-eagles, including the American bald eagle. And so will the girfalcon in northern regions – a bird that has been radio-monitored in open seas over 20 miles off the coast of Greenland.


A double crime is being committed: 1) a bird slaughter in the millions that includes protected species as well as endangered ones 2) a cover-up job. The Lekuona report is but one of the smoking guns: all four reports are dishonest in their summaries, which too often is the only part that is actually read.

Mark Duchamp..........................................January 28th, 2003

UPDATE: German authorities in the state of Brandenburg recorded windfarm victims that were reported to them : 28 white-tailed sea eagles, 91 red kites, 10 common storks, 1 black stork, 12 swans, 12 geese, 91 buzzards, 29 sundry falcons, etc. ( as at Dec 14 2007 ). It is the tip of the iceberg...

Evidence of alarming bird and bat mortality has been coming in from many countries : Sweden, Norway, the US, Japan, Australia, etc. - see --> Chilling Statistics.

Here is more : 6,000 bats and 2,000 birds killed in one year at the Tug Hill windfarm ( New York ) --> TUG HILL -----> SEE PAGES 41-42

and... 2,000 bats killed in only 2 months by the Mountaineer windfarm in West Virginia --> BACKBONE MOUNTAIN

And in Scotland, windfarms are being built on eagle territories, without much opposition from the RSPB - see --> RSPB executives are causing severe harm to bird life.
We can expect the extinction of the Scottish eagles within a couple of generations, if not sooner - see --> Windfarms to wipe out Scottish eagles.

Spain is another disaster area, with about 2,000 griffon vultures killed by wind turbines yearly, plus eagles, cranes etc.

More information on the windfarm fiasco : The negative effects of windfarms: links to papers published by Mark Duchamp

Pictures of windfarm victims ( eagles etc. ), of turbines on fire, of collapsed turbines, of soil & water contamination etc.

Insertado por: Mark Duchamp (26/12/2003)
Fuente/Autor: Mark Duchamp



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Well done Mark Duchamp!!
Nombre: Mal Davies  (05/03/2005) E-mail: mal_davies@tiscali.co.uk
The stubborn politicians in Wales UK are not listening to any of this. Neither is the RSPB (UK Bird Protection Society). It makes you wonder - are they stupid or in business with the Wind Moguls. Keep up the good work Mark.
Nombre: Ioan M. Richard  (08/11/2005) E-mail: ioan.richard@swansea.gov.uk
Glad you pointed out the incredible loss of beautiful flying creatures caused by the windfarms. The public should be informed to call for a serious review of this whole industry
otherwise more nature is going to be extinct.
Nombre: J M Krippendorf  (26/12/2005) E-mail: info@ramrod-tm.de
Public enquiry coming soon for Harestanes (Forest of Ae) and Clyde Windfarms. Proposal for Clyde is 161 turbines, 125m high. I'm using some of the information. Thanks.
Nombre: Mr. A. R. Nelson  (07/04/2006) E-mail: andrewrushfordnelson@hotmail.com

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