Audible Bird Scarers and Other Bird Scaring Alternatives

The following are examples of noise-emitting bird deterrents that could be employed.

1. Gas Guns
   Gas guns (or cannons) are mechanical devices that produce loud banging noises by igniting either acetylene or propane gas.
   
   Their scaring effect is probably related to the similarity of the noise to that of a shotgun, startling the birds into flight. Birds quickly become ‘habituated’ to the noise, especially where the bang is too frequent.
   
   Gas guns emit noise which can be problematic for neighbouring residents, including livestock and horses. Measurements with reference to the Wairarapa Combined District Plan indicate excessive noise levels can occur when gas guns are located less than 300m from noise sensitive sites.
   
2. Pyrotechnics
   This method includes a wide variety of noise-producing cartridges usually fired from shotguns, rockets, or rope bangers, which produce a loud bang and emit flashes of light.
   
3. Firearms
   The use of shot guns etc. There are strict laws relating to ownership and use of firearms (refer Arms Act 1983). Further information should be obtained from the New Zealand Police.
   
4. Ultrasonic and high Intensity Sound
   Bio-acoustic deterrents are sonic devices that transmit recorded bird alarm and distress calls.

• Noise levels decrease as the distance from the source increases, hence provide buffer distance of greater than 300m between the device and noise sensitive sites.
• Aim to provide a buffer distance of at least 300m i.e. dwellings, horse stables, hospitals, schools etc. Remember that livestock especially horses are easily frightened and can bolt or unseat their riders.
• Gas guns produce noise, which is highly directional, point the gun away from neighbouring residential properties, schools etc.
• Take account of the prevailing wind when siting scarers. Remember that noise travels much further downwind.
• Try placing a scarer inside a brightly coloured container and place several similar, but empty containers in the field. Occasionally move the scarer from one container to another.

If possible, use a noise barrier to assist in concentrating the sound on to your property and away from neighbours wherever potential nuisance could be caused. These can be very effective in reducing noise levels in the required direction. A barrier can be effective for a fixed device when installed close to the source.

Setting up successful barriers includes:

1. The barrier(s) should be a minimum height and width which blocks line of sight with surrounding noise sensitive sites i.e. the barrier should be higher than the gas guns turret by around 1 metre.
2. There should be no gaps in (or under) the barrier(s). A noise barrier must be solid to work.
3. The minimum superficial mass shall be no less than 10 kg/m2.
4. The length of the barrier(s) should be continuous all the way around (no gaps)
5. The barrier(s) should be portable and durable etc.

• Aim to provide a maximum ratio of devices per unit area (e.g. 1 device per 4 Ha).
• Liaison with other neighbouring growers to try and avoid an overlap of machines in one area.
• Set the device so as to have a maximum number of discharges per time period (e.g. 4- 6 shots per hour). Using the device more frequently means the birds get used to the sound. Some machines fire three reports in a cycle; this should be counted as one “bang” or shot. Birds can take much more than 15 minutes to regroup.

Ensure that scarers are properly maintained and checked regularly to detect any malfunctions that could cause complaints.

These rely on the birds’ fear of other predatory birds, humans or of sudden movement.

Human Scarer
Human activity can disturb birds from specific areas either deliberately, or indirectly through, for example, leisure activities.

Predator Models
Predator models, such as scarecrows, are common, traditional methods used in attempts to scare avian pests.

In general, however, motionless devices either provide only short-term protection or are ineffective as the threat from them is only perceived rather than real.

Balloons
Balloons tethered in a crop are an inexpensive method of bird deterrence, but studies show that they are not very effective, and birds quickly habituate to them.

Falconry
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.

Flags and Streamers
Flags, rags, and streamers are a useful bird scaring technique, being cheap, and easy to deploy. Although not totally effective in completely eliminating bird pests, reducing numbers by dispersing birds over an area can reduce localised crop damage.

Nets
The use of nets to cover crops and totally exclude birds is considered one of the most effective bird deterrents. There are no associated adverse environmental impacts with the use of netting.

Wires
Overhead wires or lines strung over the area from which birds are to be excluded can be an effective deterrent, and a less expensive method than full exclusion. Many types of lines can be used.