Frightening Birds Away As A Means Of Control

Techniques to frighten predators rely on visual and/or auditory stimuli to produce fear and thus discourage birds from remaining in the area. Although most northeastern aquaculture producers have consistently rated frightening as relatively ineffective, it may be useful where barrier systems and other techniques are impractical. To be effective, frightening procedures must be actively and aggressively pursued in a carefully planned program. If possible, the regime should start before birds establish a regular feeding pattern at the site.

Many devices are commercially available for scaring birds, including pyrotechnics, gas-operated exploders, electronic noisemakers, bird distress calls, stationary and pop-up effigies, eyespot balloons, raptor models, strobe or flashing lights, reflective tapes, and water-spray devices.

Although use of one technique may produce positive results in the short term, longer term results are best achieved by using a combination of methods and by alternating the devices used. Effectiveness of these devices can also be enhanced if they are activated upon arrival of the avian predator. Motion sensors or infrared beams can be used to detect the predator and activate many of these devices, thus increasing their effectiveness.

Pyrotechnic Devices: Pyrotechnic devices are effective against most birds. They are fired with a breech-opening, open-bore 12-gauge shotgun or a specially designed pistol. Shell crackers are shotgun shells that contain a firecracker that is projected 50 to 100 yards before exploding. This produces two loud noises, one when the gun is fired and another when the firecracker explodes. Because wads from the shell may stick in the gun, it is important to check the barrel after each shot. Other pyrotechnic devices called screamer sirens and bird bombs are fired from a 15-mm pistol launcher using .22-caliber blanks. Although the range of these projectiles is only 35 to 75 yards, they are less expensive and more convenient to use.

Automatic Exploder: The automatic exploder is effective in deterring most birds if combined with other techniques. Propane or acetylene gas is used to operate this small cannon, which is equipped with an electronic timing device. The cannon emits loud explosions at adjustable intervals and can be heard over areas of up to 5 acres. For best results, exploders should be elevated above vegetation and moved to different locations every 1 or 2 days.

Alarm or Distress Calls: Broadcasting recordings of alarm or distress calls has been shown to be effective in frightening black-crowned night herons but not great blue herons. For best results, distress calls should be broadcast as birds begin to arrive, and the time interval between broadcasts should be as long as possible.

Lights: Strobe lights, barricade lights and revolving beacons have been used to frighten birds. Of these, strobe lights appear to be the most effective in frightening night-feeding birds, particularly the black-crowned night heron.

Water-Spray Devices: Water spray from strategically placed rotating sprinklers can deter birds from feeding. In some cases, water aeration systems can be modified for this purpose. Best results are obtained when sufficient water pressure is used and sprinklers are operated on an on ­off cycle.

Human Effigies: Human effigies or scarecrows rely on the innate fear most birds have of humans. For this reason, effigies that best simulate human appearance or that exhibit movement usually are more effective. Successful use of effigies at aquaculture facilities has been demonstrated when effigies are periodically replaced with humans firing live ammunition or pyrotechnics.

Dogs: The use of dogs to deter birds at northeastern aquaculture facilities has met with variable success, depending on the motivation, training, and temperament of the dog. Physical characteristics of the facility, such as total size and layout, also influence effectiveness. For example, dogs obtained from animal shelters proved marginally effective in reducing predation at a large State facility in New York.

Harassment Patrols: Harassment patrols by persons on foot or in vehicles are widely used for frightening birds at aquaculture facilities, particularly larger facilities. Such patrols typically involve the use of pyrotechnic devices. The effectiveness of the technique is largely related to the fear response birds have to human presence. However, this technique can become highly labor intensive because of the need for patrols throughout the day and night. For this reason, human effigies, automatic exploders, and other devices are needed to supplement these patrols when personnel cannot be present.