// Maja the eagle owl helps reconcile wind energy with wildlife conservation

[Translate to Englisch:] Der Ornithologe Dr. Herbert Stark mit Rotmilan Lise

[Translate to Englisch:] Rotmilan Lise sammel fleißig Daten für das ZSW

[Translate to Englisch:] Falkner Michael Schanze mit Uhu Maja

[Translate to Englisch:] Uhu Maja wartet auf die Rotmilane

Nature conservation research on the world’s first wind energy test site.

Maja has been sitting on the meadow for half an hour without moving. There is a bird couple circling above her. They are red kites. They spotted the eagle owl some time ago but they have not attacked it yet, although it is only a few metres away from the nest with their young birds. They keep circling and putting off the decision as to whether and when to drive their biggest enemy away from the vicinity of their nest. But this is what everyone standing at the edge of the field is waiting for, eagerly watching the spectacle. The female eagle owl Maja is a decoy. She has been specially trained by a falconer for this job, and her role is to incite the red kites to launch an attack. The eagle owl is perched on a wooden pole with a net behind it. As soon as one of the red kites approaches Maja, it will get caught in the net. It will only be in captivity for a short time. Once it has been fitted with a small lightweight GPS transmitter, which will allow its flight patterns and habits to be studied, the bird will be released again quickly. The research work is in line with the requirements set out in the relevant nature conservation laws and has been approved by the nature conservation authorities.

The red kite couple is raising its offspring in a special place. It is the WINSENT wind energy research site which is being developed and operated by the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) at Stöttener Berg. The breeding location chosen by the red kite is ideal because the nature conservation research accompanying the wind energy test site will focus on the behaviour of the bird of prey which is not a rare species in the Swabian Alb. A radar device and several camera systems and microphones are also installed on the two wind measuring masts at the wind test site on the plateau near Stötten in order to record the movements of birds, bats and large insects during the day and at night. The research project is unique because it is adopting various approaches to help reconcile wildlife conservation and wind energy.

Preventing collisions with wind turbines

The research project “NatForWINSENT - Nature Conservation Research at the Wind Energy Test Site” is funded by the Federal Agency for Nature Conservation (Bundesamt für Naturschutz - BfN) with resources from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (Bundesministerium für Umwelt, Naturschutz und nukleare Sicherheit - BMU). Some funds have also been released by the Baden-Württemberg Ministry of the Environment (Umweltministerium Baden-Württemberg) for the process of fitting the red kites with transmitters.

The ZSW scientists will be assisted in their nature conservation research at Stöttener Berg by an international team of scientists from such organisations as the Freiburg Institute of Applied Animal Ecology (Freiburger Institut für angewandte Tierökologie - FrInaT) and Bio-Scouting Tübingen. The Swiss Ornithological Institute in Sempach (Schweizerische Vogelwarte Sempach) is in charge of the red kite survey. The goal of the conservationists is to study the movements of the birds in detail in order to be even better equipped in future to guard against collisions with wind turbines on the basis of the research results. Various technical systems designed to prevent birds from colliding with wind turbines are also being tested to this end. “It was a matter of priority for us to get a number of nature conservationists and scientists on board in order to benefit from their expertise and to establish a broad basis for our research,” said Frank Musiol who heads up the nature conservation research in the Wind Energy team at the ZSW. The project is attracting great interest among the population and has the support of regional nature conservation organisations.

Ornithologist Dr. Herbert Stark is following every step of the project and is back on site again this morning. The birdwatching expert points to the GPS transmitter which is ready to attach to the red kite once it has been captured. The small black transmitter with the solar module weighs only a few grams. “Red kites are creatures of habit. They come back to their nesting sites every spring after spending the winter in the south of Europe. And they do so for several years,” he said.

Three nests currently occupied by young birds are being watched over by breeding pairs in the immediate vicinity of the test site this year. The research scientists had installed cameras above two of the nests in February. This allowed them to observe the red kite pairs preparing their nests in the spring. One female laid her eggs very early and, despite the wintry spell in April, stayed in the nest in the snow and cold to hatch the eggs. The female barely leaves the nest in the first few weeks after the eggs have hatched, looking after the nestlings and feeding them with the food brought by the male, which consists mainly of small mammals and birds. The fledging period is between 48 and 54 days, depending on weather conditions and food supply. In extreme cases, the young birds will only fly the nest after 70 days.

Studying the behaviour of the birds

Two male red kites living in the vicinity of the test site were fitted with GPS transmitters back in June 2019. This does not curtail the freedom of the birds. The movements of the two birds of prey have been recorded continuously since then. The flight altitude data are particularly important to see whether the birds are flying at the height of the rotors, but the flight speed is another key factor – especially if detection systems are to be used as a means of preventing collisions. The information about the speed at which the birds fly is crucial in order to enable the rotors to coast to a standstill in time, for example. The research scientists also want to collect comparative data. They are therefore researching how the birds behave before the wind turbine is erected and while it is being operated. Other data are also being gathered which are of great interest to the bird conservationists in general and which will be useful for their research.

Meanwhile the two red kites have decided not to attack the eagle owl. Falconer Michael Schanze puts Maja back in her cage. She is allowed to take a rest before a new attempt at capture is started near another nest with young birds. Maayen Wigger, research assistant at the ZSW, sets up the net with the ornithologist; the decoy is then placed in front of it. The ZSW employee normally works on the 100-metre-high wind measuring masts erected by the ZSW on the WINSENT wind energy research test site. “My job is actually to collect and analyse the meteorological data and to install and operate the sensors, but everyone in the Wind Energy team helps the bird experts to catch the red kites,” he said.

The female eagle owl Maja has now arrived at the new location which, once again, is near a nest with young birds. This time the parents are bolder, circling around the eagle owl again and again. Then, all of a sudden, one of the red kites swoops down on the eagle owl and goes into the net. Herbert Stark is quick to react and takes it gently in his hand. The ornithologist weighs the bird, identifies its sex and age, and attaches a ring. It is a female and about four years old. Then the transmitter is fastened to its back like a lightweight backpack and the bird is immediately released again. Lise, as the research scientists have christened the female red kite, is now busy collecting movement data.

Using artificial intelligence to improve the protection of bird species

The information about the behaviour of the red kites is used by the ZSW research scientists in various ways, including as a basis for the development of a “BirdRecorder”, a camera system which uses artificial intelligence to identify protected bird species and trigger collision avoidance mechanisms, even to the point of stopping the wind turbine rotors. “The aim is to develop an inexpensive, robust and very reliable system which can eventually be used at wind farms and also retrofitted. One of the advantages of this would be dispensing with general shutdown times for the protection of birds of prey, which are being imposed more and more frequently. In this way, electricity production will be increased and the birds will be protected at the same time," explained Frank Musiol.

The world’s first research test site for wind energy in complex terrain is being developed in the Swabian Alb. Another distinctive feature is that the research scientists have full access to the turbine control system. This unique project is of great significance for the expansion of wind energy and consequently for the energy transition as well. Wind energy is the driving force behind the energy transition. The wind energy test site is intended to boost the expansion of wind energy, especially in the south of Germany. The ZSW is working with members of the Wind Energy Research Cluster WindForS, to which various universities and colleges belong. The scientists involved in the project “Wind Science and Engineering Test Site in Complex Terrain (WINSENT)” are investigating how wind turbines can be operated to optimum effect and their service life extended in mountainous terrain with irregular wind currents and air turbulence. They are hoping to make a number of technological improvements, such as developing quieter, lighter and more powerful rotors or optimised simulators and computer models. The results of the research at the wind energy test site can be transferred to large-scale commercial systems and provide new impe-tus for the industry.

Transparent system

Once fully erected, the non-commercial wind test site will have a total of two research wind turbines, each with a rated output of 750 kilowatts and a hub height of 73 metres, as well as four wind measurement masts on which various research modules will be fitted and tested. The WINSENT project is unique in that the research scientists have unrestricted access to the design data, the operational management and the controllers of the turbines, making them “transparent”. The meteorological measuring masts are optimally positioned on the platform to record the site conditions and to develop models – and all during opera-tion. The accompanying nature conservation research is intended to dovetail environmental protection with nature conservation and to increase public acceptance for the use of wind energy.

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