iberica 2000.org

Birds and windfarms – Bird and Bat Behavior at windfarm sites.



Above picture: the turbines APPEAR to turn slowly. But it is deceitful: due to the length of their arms, the speed at the tip may reach 292 Km/h (about 180 mph).


(source: www.gepower.com/dhtml/wind/en_us/products/15/15specs.jsp )

model: 1.5S

- 70.5 m diameter 1.5MW model:
rotor speed: 11-22 rpm
rated wind speed: 14 m/s
cut-in speed: 4 m/s
cut-out speed: 25 m/s

My calculations based on the above specifications from General Electric:

- 70.5 m diameter 1.5MW model at 11 rpm:
70.5m x 3.14 =221.37m x 11rpm = 2,435m x 60 minutes = 146kmh

-- 70.5 m diameter 1.5MW model at 22 rpm:
70.5m x 3.14 =221.37m x 22 rpm = 4.870m x 60 minutes = 292kmh

It is a known fact that an intelligent animal like the dog can easily misjudge the time needed to cross the road safely. The higher the speed of approaching cars, the greater the chances of miscalculation.

As a matter of fact children, and even grown men, happen to err in their appreciation. Many accidents on our roads attest to the fact. It is therefore no wonder that millions of birds get killed by the blades of wind turbines*.

* See: Birds and windfarms - Bird Genocide at windfarm sites


a) Even a man looking at a wind turbine will be tempted to say it rotates slowly. Indeed the blades turn slowly near the center of the rotor; and one needs to focus on the tip of a single blade to realize how much distance it covers in a rotation - thereby deducting its speed.

b) Unlike approaching cars, the blades of a turbine do not maintain a straight course: they travel on orbit. The result is that their flying victims do not notice the blade-tip until it suddenly appears above their heads, or underneath them, and strikes in a split second.

Dr. Lekuona, who studied bird mortality at windfarm sites in Navarre, Spain, found numerous dead birds. And he actually witnessed two "hits":
- a close call: the bird losing some feathers.
- a strike: the small bird being projected out of sight like a base-ball.

(source: www.iberica2000.org/documents/LEKUONA_REPORT.pdf) - For an English translation, ask the RSPB. I am told they have one by now.

These incidents reinforce the statement made by some biologists in their reports, to the effect that mortality estimates based on recovered carcasses are conservative. Indeed, birds losing feathers may or may not survive more than a few days, depending on how important their loss is in regard to the ability to travel long distances (migrating birds), evade attacks from raptors, or successfully catch prey.

As for the birds that are projected outside the immediate area around the turbines, they will never be found by researchers. For these must limit their seach zone in relation to the available manpower, time and funding - apart from the difficulty offered by those areas away from the turbines, where the vegetation has not been cleared.


The eyes of most birds are located on each side of the head, covering a field of vision nearing 360°- to see predators coming from any angle. On the downside, quality of perception is mediocre at the limit of the 180° covered by each eye, i.e. right in front of the animal, right behind, right above and right below. This is compensated by the flexibility of their neck, which they can twist easily. But unless their heads happen to be twisted around to see what´s above, or sideways to see what''''''''s in front, their vision of the wind turbines they are flying into will be rather poor. - Rabbits, and non-predatory mammals in general, have the same problem: for this it is easy to capture them in nets.

And this explains why swans, storks, cranes, bustards, starlings and countless other species of day-flying birds regularly run into high-tension lines, wind turbines or other obstacles.

Then you have the birds that are active at night. Low-flying nocturnal migrants, such as many species of songbirds, are especially prone to collision with man-made structures - even when these obstacles are lit for aviation safety (in overcast conditions, lights attract the birds, disorient them, sometimes to the point of making them circle the light source in total confusion). The guy wires of a single television tower are known to have killed 5,408 birds in one night (356. *Purrington, R.D. 1969)

"Nocturnal bird kills are virtually certain wherever an obstacle extends into the air space where birds are flying in migration" (445. *Weir, R.D. 1976)

Birds are known to crash into all kinds of obvious obstacles such as buildings, smokestacks, moving cars etc. - even by day.


Where a single bird may luckily pass unharmed through overhead cables, or the maze of a windfarm, those flying in flocks will often leave a percentage of casualties behind. The reasons are obvious: 1) law of numbers 2) breadth and depth of the flock 3) the birds flying behind others have a reduced vision of what´s in front.


Humans have more accidents on the road, or as pedestrians, in bad weather. How do we expect birds will not accidentally venture on the trajectory of a turbine blade when visibility is impaired by rain or darkness, or when strong winds sends them off course their chosen flight path?

This witnessed account of the flight of 5 whooper swans speaks for itself:
Birds and Windfarms - The flight of the whooper swans


Birds, like any other animal, identify living creatures, not objects, as possible dangers. Their instinct doesn´t warn them about television towers, tension lines, or wind turbines.

A 100 feet-long blade travelling at 100 miles an hour or more at the apex will kill any creature it hits along much of its length - see pictures of a beheaded eagle, of a vulture sliced in half: Birds and windfarms - Critical analysis of 4 reports on bird mortality at windfarm sites.

At Altamont Pass, California, 40 to 60 golden eagles and "hundreds" of hawks and kestrels, among other birds, fall victims to the turbines on a yearly basis (Grainger Hunt, 2001). The estimates from the latest study by Dr. Smallwood are even higher (100+ eagles, and 500 other raptors a year - see Chilling Statistics. And further south another windfarm kills 4.000 to 7.000 birds a year (McCrary et al. 1993).

Small birds, more numerous and often travelling in flocks, are slaughtered in greater numbers. In Nasudden, Norway, researchers Winkelman and Karlsson found 49 dead birds at the foot of one turbine during a single night of migration.

In Tarifa, Spain, we have documented evidence that the "farms" victimize 13 protected bird species (source: Windpower Monthly - a magazine edited by the windpower industry itself).

In Navarre, 368 turbines killed 409 vultures, 24 eagles and other raptors, 650 bats and 6000 small birds in a single year - see Birds and windfarms - Bird Genocide at windfarm sites

New bird-kill data is coming in from Germany, Australia, the US, in spite of efforts by the wind industry to carefully select consultants doing the research. Only in the UK is the situation "under control". A handful of specialists, always the same, consistently find zero or near-zero bird fatalities. Impressed by this record, the French hired one of them to do a five-year study in their country: as expected, he found zero fatalities.


Wind turbines create powerful air disturbances in their wake, and around the blades themselves. These can easily throw a bird or a bat to the ground, or otherwise impair its flight.


Above picture: white-tailed sea eagle.

- vision:

Birds of prey, like humans and predators in general, have their eyes located in front of the head, for an in-depth perception of what´s in front of them. Their vision is superior to that of other animals: a peregrine falcon can spot a pigeon flying 10 miles away.

As they hunt, they often focus their eyes at great distances, allowing them to detect the prey before it can see them.

Anyone using a camera knows that when the lens is focused on a far-away point, twigs moving in the forefront are barely visible. And so it is with the arms of a giant turbine when the eyes of a raptor are focused on an area past them. The danger is heightened by the fact that, in the attack, they "lock-in" on the prey.

Proving this point we have documented evidence of peregrine falcons crashing into perfectly visible, stationary cables of high-tension lines - as well as being killed by wind turbines.

- flight patterns:

Birds of prey glide most of the time, to save energy. They use ascending air currents which often form along slopes and ridges, where windplants are often located for the same reason. And they drift on the wind itself, the same wind that flows through the turbines.

Some, like the golden eagle, practice "contour flying", i.e. close to the ground. Often they pass under the turbines, but sometimes they are not low enough, especially if a gust of wind sends them upwards. Hawks too, and harriers, and owls: they often fly below the reach of the rotors. But they will eventually go up to perch, or to soar, not always calculating that a blade above their heads slashes 100 meters in less than 1.5 seconds.

- perching:

Birds of prey commonly perch on tall structures. On days without wind, when the blades are standing still, turbines become perching sites, and will attract raptors. Having perched once, they will tend to come back to the site, whether the blades are moving or not.
Even tubular-tower turbines may attract them for that purpose: sea-gulls were seen perching on turbine nacelles at Tuno Knob offshore windfarm, Denmark (Birdlife/Bern report //mitglied.lycos.de/WilfriedHeck/wf&birds.pdf - section 2E).

- perfect hunting ground:

Another reason for being attracted by the "farms" is that the area has been cleared of its original vegetation. It is ideal for supporting a population of rodents: the ground, freshly broken by earth-moving equipment, allows for easy burrowing; and grass grows more abundant in the open area, providing plenty of seeds and grass-stems for food. Grouse, partridge, pheasants and other prey-birds also favour these habitats.

Rabbits and grouse attract eagles; smaller prey-birds attract pergerine falcons; voles attract buzzards, kestrels, kites, harriers. The open field and presence of prey makes windfarms a perfect hunting territory for raptors.

- vicious circle:

As the giant blades kill airborne predators, rodents tend to proliferate on windfarm grounds. Besides, bird carcasses provide them with a diet rich in protein - in his second report, using night-vision cameras, Dr. Lekuona was able to document mice eating dead birds (Lekuona 2002).

And the abundance of rodents attracts more raptors to be slaughtered. It is a vicious circle, a "black-hole" into which entire raptor populations may disappear. Kestrels, among others, die in numbers at windfarm sites : it was documented at Altamont Pass, California (over 100 yearly) at Tarifa (over 50), and in Navarre, Belgium, and Germany.

- further-reaching black-hole effect:

When a resident bird of prey (or the pair) has been killed by the turbines installed on its range, that breeding area becomes vacant. Sooner or later another raptor will claim the territory as its own. It may be a young specimen coming from hundreds, or even thousands of kilometers away*, in which case the black-hole would have a national, or international effect on certain bird populations.

* In Spain, a radio transmitter fixed on a young imperial eagle evidenced that this non-migrating bird flew from Spain to Senegal and back, before selecting a territory to call its own (Quercus - a Spanish wildlife magazine).

Altamont Pass, California, is a perfect example of the black-hole effect on golden eagles and red-tailed hawks - see: Birds and windfarms - Critical analysis of 4 reports on bird mortality at windfarm sites. . There, the turbines happen to be erected in a "dispersion area", i.e. a territory unsuitable for nesting but with abundant prey: this is where juveniles, immatures and floaters go to feed, the place not being defended by breeding adults.

Any suitable hunting ground containing prey that is not occupied by a territorial pair is a potential dispersion area. Occupied by a windfarm, it will become a population sink for raptors. The Edinbane/Ben Aketil windplant, to be built in Scotland, will be just that.


From Navarre, Spain, we have evidence that bats are being killed in large numbers by wind turbines (Dr. Lekuona* estimated that 368 turbines had killed 650 bats in one year). This shows that even radar-like perception systems are unable to save flying creatures from these machines.

And here is the evidence we received from Professor Hans Erkert, University of Tuebingen, Institute for Zoology, Tübingen, Germany:

"In Germany up to now only a few studies on the effect of wind turbines on the bat fauna have been carried out. However, these few studies already show that wind turbines indeed may have fatal consequences for migrating bats and/or local bat populations. So, below wind turbines a considerable number of dead bats have been found.

In Sweden and Germany the collected victims of windplants belonged to 10 bat species. Since many of the victims found in late summer and autumn belonged to migrating species bat specialists assume that they are mainly killed while migrating to their winter quarters. And during migration these bats probably do not use their ultrasound sonar system intensely for orientation but may rely more on vision or on any other yet unknown sense of orientation (e.g. the use of the magnetic field of earth like some birds). However, besides such migrating species also a considerable number of non-migrating bats have been found among the victims collected below wind turbines.

Starting from this observation specialists have asked the question whether wind turbines may attract hunting bats – probably because the waste heat of the hub or the navigation lights may attract insects of prey which then accumulate in the danger zone of the rotor. A hypothesis proposed by some bat specialists who tried to explain why bats are killed by windplants despite their usually very effective echolocation system is that, due to the special shape of the rotor blades, the bats’ ultrasound pulses may be not reflected towards the ears of the animals but deflected into other directions so that the animals are “acoustically blind” in this specific orienting situation.

As already mentioned by our Spanish colleague, the extremely high rotation speed of tips of rotor blades is another very critical safety hazard for hunting bats. Not (completely) understood is furthermore the observation that many bats found dead below large wind turbines did not show any signs of injuries pointing to a hit produced by the rotor. Because of some other observations made in such bats several scientists now assume that the rotating windmill sails produce a sub-pressure which causes the bats’ death when they are passing this decompression zone (principle: decompression sickness in divers coming up too fast).

In summary: We now know that many of our strongly protected bats are killed by wind turbines, however, we do not yet know the true reasons of this disaster. Nevertheless, the bat specialists among our animal conservationists therefore claim that, in case of planning large windplants also their possible effect on migrating bats and the local bat fauna should no longer be ignored because, at least in Europe, bats belong to the most endangered mammals."

Source: Brinkman, R. and Schauer-Weisshahn, H. (2002): Welche Auswirkungen haben Windenergieanlagen auf Fledermäuse? In: "Der Flattermann", Mitteilungen der Arbeitsgemeinschaft Fledermausschutz Baden-Württemberg e.V.,
Vol. 14, pp 21-22. Robert.Brinkmann@t-online.de and Horst
Schauer-Weisshahn (weisshahn@arcor.de).

More bat kill evidence came from Blackbone Mountain, in the Eastern United States: 2.700 bats were killed bt 44 wind turbines in one year - I shall post the reference promptly.


Erecting wind turbines on migration routes is particularly dangerous for the birds. Night-flyers, with greatly reduced visibility, may not even see the rotors. Daytime migrants, which tend to fly higher and out of reach in good weather, become more vulnerable in poor weather conditions. They also get closer to the ground when they skirt mountain crests, which are preferred locations for windfarms.

And then there is the take-off and the landing. Just imagine a whooper swan having just crossed the Atlantic from Greenland, and making a landing with its compagnons on the isle of Lewis, in Scotland, at dusk, in the middle of a windfarm...

If the Scottish Executive gets his way - and who is to stop him? - in a few years there will be thousands of bird killing machines spread all over Scotland. On eagle territory (three windfarms were built on golden eagle ranges already - more are planned) in wildlife designated areas (new planning policy PPS22 permits it) even in national parks (PPS22 again). Scotland will become a minefield for migrating birds, raptors, and anything that flies including delta-planers and helicopters.

Back to migrations: a migration route may be as wide as a country. Spain, Italy, Israel are the natural highways to Africa for most European birds; and many regions of the United States are flown over by migrating birds, especially the Appalachian Mountains.

So wide are these routes that even if we wanted to site windfarms away from them, we couldn´t. In addition, says the Birdlife/Bern report*: "very little is known on night migration routes" - which applies to so many songbirds. And a preliminary research of one year, two years or more would be insufficient to make sure a proposed location is not potentially dangerous: who is to say that one day, because of some weather front, large groups of birds will not happen to fly where consultants had "predicted" they would not?

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

There is no guarantee that migration routes will not vary from one year to another, if only because of the weather. A deviation of 1000 meters would be enough to throw the birds into a windfarm previously analysed as "safe" or "out of the way of migrating birds".


In May 1998, the newspaper USA Today quoted a Sierra Club official who had labeled wind turbines: "The Cuisinarts of the Air". But nowadays, practically conservation organizations actively promote windpower, even bird societies. Apart from the wind industry itself, they are often the most ardent supporters of the bird-mincers.

Officially, the buzzwords are: global warming, climate change, Kyoto protocol, renewable energy. But financial considerations also bear on the issue: such organizations thrive on subventions, grants, and donations. This entails that the donors must be kept happy. In addition, some organizations are now directly involved in the development of windfarms (Greenpeace) or getting royalties from endorsing renewable energy schemes with their name (RSPB - see www.southern-electric.co.uk/home/home_rspb_energy_welcome.asp?sMenu=rspb go to page bottom, enter 1.000.000 customers in the first square, move curser to 6 (years), press the equal sign, and see the millions of pounds that will flow to the bird society).

The simple truth is that, the more wind turbines there are, marring the landscape and killing birds, the more affluent these organizations become.

Another reason for their silence on the bird massacre is that a number of ecologists, biologists and ornithologists are contracted by the windpower industry to perform field-study assignments, and write environmental impact assessments. For some, this is a livelihood.

And each windfarm normally generates one or two field studies: one before construction, and sometimes one after. As an example: SEO/Birdlife were paid $48,000 in 1995 for their study on the windfarms at the Straits of Gibraltar (Tarifa). In 2003, an environmental impact assessment fetched $150,000 in Israel.

In 1995, the SEO study evidenced a high mortality of protected species at Tarifa. But nevertheless it strongly encourages the proliferation of these bird-killing machines throughout the Spanish territory, including migration routes. Their only caveat: that proper ornithological studies be conducted (and paid for - isn´t that a conflict of interest?) so that care is exercised in choosing the location - a care that is often absent in the hard reality. To wit: the subsequent installation of 930 wind turbines in Navarre, on migration routes and near "buitrerías" (vulture colonies) where they kill many thousands of birds a year.

And now we are about to witness the "turbinisation" of Europe´s stronghold of the remaining Bonelli´s eagle population in Europe. Over one thousand 2 MW turbines will be installed in the Valencia region, which is home to 82 breeding pairs of Bonelli´s eagle, in addition to 80 pairs of golden eagles, as many peregrines, some booted eagles and short toed eagles, and recently reintroduced griffon vultures and lesser kestrels. The area is also an important migration corridor: ospreys have been observed, and even the odd spotted eagle.

Above picture: Bonelli´s eagle

But Spain and Scotland are not alone: other busy highways of the sky are presently being targeted by windpower developers - Morocco, Egypt, Israel, Bulgaria, the Appalachian Mountains. If the bird societies and other organizations do not change tack rapidly, they will be responsible for the destruction of our bird life... for nothing.

When I say "nothing", I weigh my words: for windfarms save next to nothing in greenhouse gases, if they save at all. A critical view, presented in various articles - see Windfarms - Submission to the House of Lords and other links - reveals pitfalls unforeseen by Kyoto enthusiasts: 1) gases emitted by conventional power plants cushioning the sudden variations of wind-produced electricity, or running in spinning reserve for when the wind drops; 2) gases emitted for the construction and long term maintenance of the vast windfarm and power line networks, which will NOT eliminate the need to build more conventional plants as these are needed for back-up; 3) additional delays in the development of the clean-coal, solar, geothermal, wavepower, and other alternative technologies, as subsidies go preferably to the inefficient windfarms.

Windfarms are not only harmful to birds, landscapes and people: they are useless. Worse: they are slowing down the conversion to a really clean economy, by the subventions they receive and of which they are depriving other technologies.

Mark Duchamp

LATE NEWS: 13 sea eagles and 38 red kites found dead in Germany, killed by wind turbines; 2 wedge-tailed eagles found in Australia in similar circumstances.


more information on this webpage - click:

The negative effects of windfarms: links to papers published by Mark Duchamp

Related información on Internet - click:

* www.oism.org/pproject
(19.000 scientists speak-up against the theory of anthropogenic global warming)

* www.co2science.org
(web page on CO2)

* www.ecotrop.org
(web page on Kyoto)

* www.spaceflightnow.com/news/n0304/05climate
(Harvard scientists speak-up against the theory of anthropogenic global warming)

* http://www.sepp.org/leipzig.html
(Declaration of Leipzig against the theory of anthropogenic global warming)

Insertado por: Mark Duchamp (02/10/2002)
Fuente/Autor: Mark Duchamp