Bird scarer
From Wikipedia, the free encyclopedia
A bird scarer is any one of a number devices designed to scare birds, usually employed by farmers to dissuade birds from eating recently planted arable crops.
They are also used on airfields to prevent birds accumulating near runways and causing a potential hazard to jet aircraft.
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[edit] Visual scarers
[edit] Scarecrow
One of the oldest designs of bird scarer is the scarecrow in the shape of a human figure.
[edit] Bird Kite
Many species of bird are also naturally afraid of predators such as birds of prey. A bird kite is designed to fly in low winds and hover above the field to be protected. They are usually painted with the sillouette of a bird of prey such as a hawk.
[edit] Lasers
The use of lasers can be an effective method of bird scaring, although there is some evidence to suggest some birds are laser-resistant. The equipment is expensive and specialised training is required, adding to the costs. As the effectiveness of the laser decreases with increasing light levels, it is likely to be most effective at dawn and dusk. Its usefulness may therefore be confined to night time roosts and feeding sites at dawn.
The method relies on Birds being startled by the strong contrast between the ambient light and the laser beam. During low light conditions this technique is very selective and can be attuned to frequencies that individual bird species don't like, but at night the light beam is visible over a large distance and can cause widespread (non-species specific) disturbance.
[edit] Dead Birds
The use of model or actual dead birds is used to signal danger to others. Initially birds often approach the corpse but usually leave when they see the unnatural position of the bird. This approach has been frequently used in attempts to deter gulls from airports.
[edit] Balloons
Balloons are an inexpensive but somewhat ineffectual long term deterrent. This method relies on the movement of the balloons, something to which birds can become used to. The addition of eye illustrations on the balloons has been shown to increase this methods effectiveness.
In the United Kingdom the use of balloons is subject to approval from the Civil Aviation Authority, especially around airfields.
[edit] Auditory scarers
[edit] Propane gas gun
Towards the end of the 20th century, one of the most popular types of bird scarer used by farmers in Europe and America is the propane gas powered gas gun which produces a periodic loud explosion. The audible bang can reach volumes in excess of 150 decibels near the gun.
One of the problems with gas gun scarers is that the loud bangs can also irritate people living on nearby properties, or other people using the countryside.
[edit] Ultrasonic scarers
Ultrasonic scarers are electronic devices that produce high volume ultrasound. The sound is designed to be too high pitched for people to hear, but audible to most birds. This has the advantage to preventing disturbance to neighbouring households. However, these can be heard by some people, particularly females and the young, and although this ability is generally lost with age it can cause discomfort and even headaches for those in proximity who have sensitive high-range hearing.
[edit] Cartridge scarers
Cartridge scarers include a wide variety of noise-producing cartridges usually fired from rockets or rope bangers, or on aerodromes from modified pistols or shotguns, which produce a loud bang and emit flashes of light. They include shellcrackers, screamer shells and whistling projectiles, exploding projectiles, bird bangers and flares.
Cartridges are projected from a shotgun with a range of 45-90m, or pistol (range approximately 25m), and then explode. Bird scaring cartridges can produce noise levels of up to 160dB at varying ranges but both the cartridges and the gun require a firearms certificate in some countries.
Pyrotechnics have proved effective in dispersing birds at airports, landfill sites, agricultural crops and aquaculture facilities. At airports in the UK, shellcrackers fired from a modified pistol are the commonest means of dispersing birds, as they allow the bird controller to have some directional control over birds in flight, so they can be steered away from runways.
[edit] Other
[edit] Dogs
The control of birds and other wildlife such as deer through harassment by trained border collies has been used at aerodromes, golf courses and agricultural land. The dogs represent an actual, not perceived threat, and so elicit flight reactions. Habituation is unlikely as they can continually pursue and change their behaviour. Border collies are used as they are working dogs bred to herd animals and to avoid attack, and they respond well to whistle and verbal commands. A single border collie and its handler can keep an area of approximately 50 square kilometres free of larger birds and wildlife and although they are effective at deterring ground foraging birds such as waders and wildfowl, they are not so useful for species that spend most of their time flying or perching, such as raptors and swallows.
In 1999 Southwest Florida International Airport became the first commercial airport in the world to employ a border collie in an airfield wildlife control programme. After the use of the collie, numbers and species of birds on the airport declined and most birds that remained congregated in a drainage ditch away from the runway. The number of bird strikes dropped to zero compared to 13 for the same period the previous year. Several other airports and airbases have now started similar programmes.
At Dover Air Force Base, Delaware, bird strike damage to aircraft caused by birds has been reduced from an average of US $600,000 / year for the proceeding two years to US$24 000/year after the initiation of a bird control programme that included the use of border collies.
[edit] Predators
The success of this method of bird control is based on the fact that many birds have a natural fear of falcons and hawks as predators, so their presence in the area encourages problem species to disperse. The natural reaction of most prey species is to form a flock and attempt to fly above the falcon. If this fails, they will attempt to fly for cover and leave the area.
[edit] Radio controlled aircraft
Radio-controlled model aircraft have been used to scare or 'haze' bird pests since the early 1980s, mainly over airfields, but have also been used over agricultural areas, fisheries and landfill sites. This method has been shown to be very effective and birds habituate more slowly to a treatment in which they are being actively hazed. At Whiteman Air Force Base, Missouri, balsa wood radio-controlled aircraft are one of the primary bird harassment methods used to keep the airfield clear of raptors and other large birds, and they have also proved effective at dispersing the base’s redwing blackbird roost.
[edit] References
- J. Bishop, H. McKay, D. Parrott, J. Allan (2003). Review of international research literature regarding the effectiveness of auditory bird scaring techniques and potential alternatives. (PDF). DEFRA. Retrieved on 2007-01-30.
[edit] External links
- NFU online Code of Practice for using bird scarers.
