Audible Bird Scarers and Other Bird Scaring Alternatives

Bird Management Plans

Bird Management Plans can be developed where an occupier wants to demonstrate they are complying with best practice, for more information on drafting a Best Management Plan contact the Environmental Services Team on 06 306 9611.

Noise and Audible Bird Scaring Devices

Different sources produce different types of noise (including gas guns, audible avian distress alarms, and firearms). Different types of noise such as intermittent, tonal, or impulsive noise are more likely to cause complaints.

The noise generally associated with audible bird scaring devices such as gas guns is impulse noise which consists of one or more bursts of sound energy, each of duration of less than about 1 second. Impulsive noise provides a brief and abrupt startling effect which may cause greater annoyance than would be expected from a simple measurement of sound pressure level.

Noise Level For Bird Scaring Devices

Reasonable noise level emitted by audible impulse devices (including gas guns, audible avian distress alarms, and firearms) is limited to be at or below 65 dBA (SEL) at the notional boundary of rural dwellings or at any point within a residential zone. This may mean a buffer distance of 300 metres, or more is needed to ensure enough sound reduction via distance to nearest houses.

Audible Bird Deterrents

Where sensitive crops are grown in proximity to housing, hospitals, and schools, there can be a conflict between the growers seeking to protect their crop, and the amenity of the area.

The best practical option is defined as the best method for preventing or minimising the adverse effects on the environment having regard to:

  • The nature of the discharge or emission and the sensitivity of the receiving environment to adverse effects; and
  • The financial implications, and the effects on the environment, of that option when compared with other options; and
  • The current state of technical knowledge and the likelihood that the option can be successfully applied.

Types of Audible Bird Deterrents

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.

Audible Bird Deterrents Best Practices

  • Use auditory scarers only when their use can be justified.
  • Limit the hours of operation as far as possible. A guideline is to use audible bird scaring devices for a maximum of four hours per property, per day, during the hours of daylight.
  • Use scarers as infrequently as possible. Determine when the crop is most vulnerable and only use scarers then – the use of audible bird scaring devices to be limited to a maximum of two months per crop.
  • If guns are hired from an outside party take some time to learn how the guns work.

Position and Direction of Devices

  • 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.

Number of Noise Devices & Discharges

  • 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.

Alternative Bird Deterrents

The following deterrents could be incorporated along with an audible device to maximise the efficiency of your intended bird management plan or may act as an alternative if your audible deterrents are causing issues.

Visual Bird Deterrents

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 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.

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.

Bird Exclusion Devices

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.

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.

How do I Lodge a Noise Complaint?

Before making a complaint to Council, it is recommended you discuss the complaint with the grower who operates the device. If this is not an option or there is no resolution, the South Wairarapa District Council Environmental Health Officer should be contacted.

When providing information regarding a complaint, please make sure you explain the problem fully, giving full contact details and as much information regarding the complaint as possible.

All complaints are treated confidentially. We do not tell the noisy party who complained. Your details are required by the Council in order for Noise Control Officers to monitor ongoing noise problems.

Useful Links

Noise and Noise Management

Wairarapa Combined District Plan

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