Bird strike

from Wikipedia, the free encyclopedia
A Sikorsky UH-60 helicopter after a bird strike with a crane

Bird strike describes the collision of birds with objects. Like other living things, birds sometimes fail to recognize natural or man-made obstacles in their flight space (such as window panes, noise barriers, and power lines), misinterpret them or fail to avoid them and collide with them. This can lead to injuries and death to the animals. The damage to the obstacle is usually minor; however, bird strikes can create serious hazardous situations for fast moving vehicles, and especially aircraft. For this reason, tests with the chicken cannon are required for aircraft approval .

Birds killed annually by polluter in the United States
cause Number of deaths in millions
Wind turbines 0.1-0.44
building 0.1-1000
Transmission towers 5-6.8
Overhead lines 0.1-175
Motor vehicles 60-80
Pesticides in Agriculture 67-90
Cats ( domestic and wild cats ) 365-1000

Bird strike on stationary objects

Supermarket parking lot in Feldkirch-Levis, delimited with glass panes and provoking bird strikes

problem

Typical obstacles to bird flight are overhead lines for electricity and telephones, window panes, winter gardens, glass facades and noise barriers. Over 250,000 birds in Europe die every day from bird strikes on such objects. Glass surfaces that allow an unobstructed view of the landscapes behind (for example, soundproof walls or glass bus shelters) or highly reflective glass panes, as are often used in modern buildings, are particularly dangerous for birds, because of the mirror-like effect, the landscape behind the panes seems to “continue” ". In both cases the bird does not recognize the obstacle (the disc). As a rule, head injuries, internal bleeding or fractures in the wing skeleton occur as a result of the impact. These injuries can lead to the death of the animals, which can only occur some time later (e.g. due to internal bleeding).

Contraceptive methods

Don't clean windows

Not having to clean the windows leads to a decrease in the mirror effect of the panes: dust and dirt scatter the light, the pane “becomes matt” and can be seen directly.

Birds of prey silhouettes

Bird of prey silhouette on the window pane of a residential building

Birds of prey silhouettes (also known as warning birds ) are stickers attached to glass surfaces to prevent birds from flying against (transparent or highly reflective) panes. From the 1970s on, large window panes were often stuck with stickers in the form of silhouettes of birds of prey . Smaller birds, which belong to the prey of the birds of prey, should be kept away from the disc. The underlying thesis is that songbirds recognize the outlines of their natural enemies and dodge out of fear. This succeeds to a small extent with colored, but hardly with black or white silhouettes. Studies have shown that the bird of prey silhouettes did not result in a statistically significant reduction in bird strikes. The birds perceive the sticker as an obstacle, but only try to fly around it and hit the glass surface in the immediate vicinity of the silhouette.

Stripe pattern, close-meshed stickers

Instead, it has been shown that glass surfaces effectively keep birds away if they are provided with a close-meshed striped pattern from the outside (advantageous when shining through and reflecting) (transverse or longitudinal stripes at a distance of no more than 10 cm). Other objects stuck to the outside of the pane also reduce the risk of bird impact, provided the object density is high. Basically, also for birds of prey silhouettes, the stickers on the glass surface must be very tight so that birds can safely perceive the pane as an obstacle.

Spider web effect

The frequency of light that birds can still perceive is higher than that of humans; many species of birds are able to see UV light that is invisible to humans . So you can z. B. Recognize UV ​​light (matt) reflecting surfaces, plumage drawings and excretions from prey.

This fact protects cobwebs from being destroyed by birds. The nets reflect the UV light, which is why they are visible obstacles for birds' eyes, which birds avoid. The " spider web effect" can be used against bird strikes on window panes:

Films, stickers or similar that are transparent in the spectrum visible to humans, but reflect or absorb in the UV range (preferably matt), can provide birds with visual aids without impairing human vision. A contrasting pattern of UV-absorbing and reflecting surfaces on the pane, which is still transparent and colorless to humans, can warn the birds of the glass pane as an obstacle.

Effects through UV absorption

Window areas that absorb UV radiation create a “color cast” for the bird in the mirrored or translucent area and can therefore help the approaching bird avoid the mirrored / translucent area. If only parts of the window are absorbent in the UV range, their UV absorption can then create a “color contrast” to the otherwise mirrored / translucent area - the image is partly “tinged” for the bird, partly not. By parallax during the approach of the bird that can then perceive the window itself.

Effects through UV reflection

If the bird perceives the UV-reflecting window predominantly as translucent (non-reflecting), the image reflected in the UV-area overlays the translucent area and the bird avoids this confusing space. If the window appears to be predominantly reflective to the bird, the UV reflection increases the realism of the image and is therefore rather counterproductive. If only parts of the window are reflective in the UV range, they can create a "color contrast" (case "reflective") or a "reflection contrast" (case "translucent") to the other mirrored / translucent area - the picture is for the bird partly “colored” / “reflective”, partly not. By parallax during the approach of the bird that can then perceive the window itself.

Methods of UV reflection / absorption

Bird protection felt pen

With a special felt-tip pen that contains a UV dye that is invisible to humans, it is possible to mark window panes accordingly in order to significantly reduce bird strikes without disturbing the human observer. This method is particularly suitable for private households and existing window panes. The effectiveness of the felt-tip pen against bird strikes on window panes has been experimentally confirmed under laboratory conditions at the Max Planck Institute for Ornithology (Radolfzell Vogelwarte). However, the avoidance factor of approx. 70:30 (50:50 means “no effect at all”) determined in the process is considered too low by critics.

Bird protection glass

For permanent installation, there is a bird protection glass developed in 2005 that has the same effect. Bird protection glass is a standard window glass with a special coating that reflects UV light . This glass is particularly suitable for large glass facades, which then become a recognizable obstacle for birds . A layer is applied to the glass at the factory that reflects the UV light that birds can perceive. The birds recognize the panes of glass as an obstacle and avoid them. Like ordinary glass, this glass is almost transparent to humans. The effectiveness of the glass has been experimentally confirmed under laboratory conditions at the Max Planck Institute for Ornithology (Radolfzell Vogelwarte). But here, too, the degree of avoidance is only 76:24 (50:50 means “no effect at all”), which critics (as with the bird protection felt pen) consider to be too low. The Bavarian State Office for the Environment also advises against using “bird protection glass” and recommends alternatives.

UV protective film

Films and stickers that are transparent in the human-visible spectrum, but which emit or absorb in the UV range.

Creaming with sunscreen

Another option is sun cream with a high sun protection factor (approx. 30). After cleaning the window, a fingertip of the lotion is dabbed onto the pane every ten centimeters, creating a grid that is visible to birds.

Bird strikes on moving objects

Bird strike on ICE 3

Modern means of transport represent a sometimes considerable danger for birds. Due to the high speeds, a collision usually leads to serious injuries, but mostly to the death of the bird.

The impact of birds on aircraft, automobiles or high-speed trains is also a danger for the vehicles themselves and their occupants, since in the simplest case the driver is distracted and frightened by the impact, in the worst case can be injured by the windshield bursting and then is no longer able to control the vehicle.

Aircraft (like most high-speed trains) are therefore examined in special test facilities for their resistance to bird strikes. The effects of a bird strike are also increasingly being simulated using computer calculations. For example, at the German Aerospace Center in Stuttgart, aircraft structures are exposed to an artificial bird strike both in experiments and in computer analysis, and the consequences for the aircraft are investigated. Artificial substitute birds are used here.

Bird strikes on aircraft

problem

The cockpit of an F-16 after a bird strike
Jet engine after bird strike (cleaned)

Particular attention is paid to the problem of bird strikes in aviation , where damage totaling over a billion US dollars is caused annually worldwide and flight safety is in some cases considerably endangered.

For example, if birds get caught in the engines of aircraft , known in aviation as Foreign Object Damage (FOD), an engine failure can result. Bird collisions with aircraft occur during the take-off or landing phase and at altitudes below about 300 meters. If all engines fail at such a low altitude, this situation is particularly critical as there is little time left to prepare for an emergency landing .

Modern engines must be resistant to bird strikes. They are tested with birds up to 3.6 kg , depending on the inside diameter of their inlet . In doing so, their damage must “remain within limits” (ie not have catastrophic consequences for the aircraft). The requirements are defined by the building regulations for aircraft propulsion systems. The speed of rotation of the engine is decisive for the impact. The speed difference between the aircraft and the bird is also dictated by the building regulations.

The same applies to the aircraft structure, where a bird strike must not lead to a catastrophic flight situation. Appropriate tests (or tests verified and validated analyzes) for the engine and structure of an aircraft are prescribed by the approval authorities such as the Luftfahrt-Bundesamt in Germany , EASA in Europe and the FAA in the USA .

Avoiding bird strikes on aircraft

Short documentation of the United States Air Force on the prevention of bird strikes on Bagram Air Base , Afghanistan

In Germany, the German Committee for the Prevention of Bird Strikes in Air Traffic (DAVVL) has been dealing with this problem since the mid-1960s. Among other things, it publishes a bird migration forecast and distributes bird migration warnings , so-called BIRDTAMs (based on NOTAMs ), which are issued by the Federal Armed Forces Office for Geographic Information . This provides information on the risk of bird strikes in a region on the basis of bird migration observations made by radar. The DAVVL also publishes the online journal “Vogel und Luftverkehr” and maintains a list of serious aviation accidents caused by bird strikes.

In addition to forecasting and bird strike warning, the biotope management instrument is mainly used to prevent bird strikes. Airports and their surroundings are designed in such a way that large bird species that endanger flight operations or occur in large flocks do not meet their ecological requirements for a habitat. Small, often rare species that hardly stand a chance in the predominantly industrialized agriculture environment, however, find a suitable habitat there. In Germany, deterrence technology is only used in situations in which biotope management does not have a sufficient effect to ensure biological flight safety, which may be the case after snowfall or mowing, etc. As a rule, it is pyrotechnics that are fired from signal revolvers. The generated bang drives away the birds. In contrast to North America, no lethal measures are taken in Germany to solve the bird strike problem at airports.

At large airports abroad, attempts are made to keep the terrain free of birds with the help of birds of prey and other measures ( sound through sound carriers with animal voices ). The birds are also deprived of the opportunity to breed there (no bushes or trees).

Large aircraft under 3000 meters (10,000 ft) generally switch on the landing lights (also during the day) in order to be more visible to birds (and other aircraft).

In order to escape an oncoming aircraft, birds dodge down by swooping down as they can change altitude much faster than when climbing . To avoid bird strikes, the pilot should avoid birds upwards or to the side (if the reaction time is sufficient).

With a horizontal and vertical radar and specially developed software, it is possible to automatically detect all objects in flight within a radius of approx. 6–8 NM . The software classifies the objects in flight based on their typical flight behavior and calculates whether the flight routes with aircraft taking off or landing are on a collision course. Measuring the reflectivity of the radar also makes it possible to measure the mass in the air. Since 10,000 sparrows can be just as dangerous for an aircraft as 10 wild geese, this risk can be adequately depicted. Radar technology makes it possible to manage the risk of bird strikes, which is finding its way into more and more airports with the term Operational Risk Management (ORM).

Since military aircraft are particularly affected due to the low proportion of gliding, bird strikes are a problem, especially for the military.

Bird strike on railway trains

Seven different studies (on German and other European railway lines), which lasted 70 days to several years and were published between 1982 and 2002, showed that there are between 0.29 and 61 bird strikes per kilometer and year. On routes that were only driven at a speed of up to 160 km / h, this value was a maximum of 20, on routes with a maximum speed of 200 km / h and more, at least 38.1. If mammals are also recorded, the number of mammals killed is as high as that of birds.

Statements on bird strikes should also be extended to bats. The cause of the high frequency of bird strikes on trains is seen as the fact that trains with pantographs are 8 m above the top of the rails and thus twice as high as motor vehicles on motorways. Smaller birds often only fly 4–6 m high. In addition, higher maximum speeds are regularly driven on trains than on motorways.

A bird strike on the pantograph of an intercity train can block both tracks on a route for several hours, as happened in Germany on August 12, 2016.

Bird strike on road vehicles

Motor vehicles can also suffer from bird strikes. This can damage the windshield so severely that it needs to be replaced. Bird strikes are also possible with two-wheelers.

If cyclists are traveling more slowly and penetrate areas of birds, however, it can also lead to false attacks flown by birds.

Alan Stacey died in a car race from a bird strike through his helmet visor.

Bird strike on wind turbines

Bird strikes on wind turbines are also a problem. According to a study by NABU in 2005, around one thousand birds per year in Germany die when they collide with a wind turbine. Birds of prey are particularly affected. In addition, many dead bats are repeatedly found in the vicinity of wind turbines . In contrast, there are around ten million birds killed by road traffic and power lines ( BUND estimate). NABU evaluated 127 international studies and came to the conclusion that no bird species was endangered by wind energy in Germany. However, red kites and, increasingly, sea ​​eagles can be affected locally to a considerable extent.

These issues are being actively addressed. By choosing the crop rotation of the fields at wind power plants and in the surrounding area, the hunting grounds of the birds of prey are relocated to the area around the wind power plants. The choice of crop rotations and the design of the wind farms and their surroundings make hunting in the wind farm considerably more difficult and easier outside. This makes it unattractive for the robbers to fly through the facilities. After the harvest, the wind power plants are switched off for several days. There are also ongoing research projects on how to repel bats. The most extensive study to date on bird strikes on wind turbines (Progress study by the University of Bielefeld 2016) already speaks of a development that could threaten the existence of the common buzzard due to the high number of victims.

literature

  • Reza Hedayati, et al .: Bird Strike - An Experimental, Theoretical and Numerical Investigation. Woodhead Publ. Cambridge 2016, ISBN 9780081000939 .

Web links

Wiktionary: bird strike  - explanations of meanings, word origins, synonyms, translations
Commons : Bird Strikes  - Collection of images, videos and audio files

Individual evidence

  1. ↑ The trouble with turbines: An ill wind . In: Nature , June 20, 2012. Retrieved June 25, 2012.
  2. ↑ a b c  ( page no longer available , search in web archives )@1@ 2Template: Dead Link / www.spinnennetz-effekt.de
  3. ↑ a b c  ( page no longer available , search in web archives )@1@ 2Template: Dead Link / www.spinnennetz-effekt.de
  4. ↑ Trybus
  5. ↑ Deadly Glass
  6. ↑ State Association for Bird Protection - Bird Strikes on Glass Surfaces ( Memento from March 25, 2010 in the Internet Archive ).
  7. ↑ a b c http://www.vogelabwehr.de/vogelschutzglas.php
  8. ↑ http://www.spinnennetz-effekt.de/
  9. ↑ Experimental examination of the effectiveness of a sample disk coated with birdpen against bird strikes ( Memento from July 11, 2009 in the Internet Archive )
  10. ↑ http://70085.forumromanum.com/member/forum/entry.user_70085.2.1108643231.birdpen_wie_wirksam_ist-bird_at.html?onsearch=1
  11. ↑ http://www.bauletter.de/archiv/2007/2007-09-20.php
  12. ↑ http://70085.forumromanum.com/member/forum/entry.user_70085.2.1108643231.birdpen_wie_wirksam_ist-bird_at.html?onsearch=1
  13. ↑ Friederike Bleckmann, Bernd-Ulrich Rudolph: Avoid bird strikes on glass surfaces. Bavarian State Office for the Environment, January 8, 2014, accessed on November 2, 2017 .
  14. ↑ Black vulture crashes against Lufthansa flyer mallorcazeitung.es over Mallorca , September 15, 2016, accessed October 3, 2016.
  15. ^ German Committee for the Prevention of Bird Strikes in Air Traffic
  16. ↑ Complete table of contents VOGEL and AIR TRAFFIC from 1986
  17. ↑ Heavy bird strikes
  18. ↑ http://www.birdstrike.de/
  19. ↑ Notes on the ecological impact prognosis in EIA, LBP and FFH compatibility assessments for expansion and new construction measures on railways by the Federal Railway Authority (Germany), March 2004, Note 2006, accessed August 13, 2016. Including table on p. 41 f.
  20. ↑ 1 2 Statement on the regional planning procedure for the new Rhine / Main - Rhine / Neckar line of Deutsche Bahn AG BUND, undated (approx. 2003), accessed August 13, 2016. 61 p., Here: p. 29–31.
  21. ↑ Vogel stops Intercity in Germany August 13, 2016, accessed August 13, 2016.
  22. ↑ NABU - Effects of regenerative energy generation on biological diversity using the example of birds and bats
  23. ↑ Lübecker Nachrichten, Lübeck, Schleswig-Holstein, Germany: Kastorf - deflecting surfaces to protect red kites from rotors - LN - Lübecker Nachrichten. Retrieved March 5, 2017 .
  24. ↑ FOCUS Online: Myth: Wind turbines kill tons of birds . In: FOCUS Online . ( focus.de [accessed on March 5, 2017]).
  25. ↑ Wind power and birds (bird species sensitive to wind power). Pro Windkraft Niedernhausen, accessed on March 5, 2017 .
  26. ↑ Falken Study