Bird Control in Horticultural Crops
Table of Contents
Bird damage in horticultural crops is a serious problem for many growers. Unchecked, birds can completely destroy an entire crop. If each bird eats just 4 grapes/day, a flock of 5,000 starlings will consume 1,000 kg (1 tonne) of food over a 10-day period. This factsheet identifies problem birds on Ontario farms, discusses common bird-control methods and outlines steps to develop an effective bird-control strategy for horticultural crops.
Growers want a simple, cost-effective way to keep birds away from their crops. Neighbours want a solution that does not involve noise-producing devices. Finding a balance is difficult. Even modern equipment and the best effort will not prevent all bird damage, and some devices can create a social disturbance if they are not managed properly. However, the right tools and good management can reduce bird pressure and preserve more crops, while minimizing the impact on neighbours.
Follow these five steps to develop an effective bird-control strategy that balances the needs of the crop with those of the surrounding neighbourhood:
Appendix B provides a sample control strategy for a hypothetical 4-ha vineyard, based on the bird-pressure level. This is an example only; every farm is different, and there are many possible options. Create each strategy to suit the particular farm, crop and surrounding area.
To solve the bird-control problem, start by understanding which birds are causing damage, where they are coming from, how they behave and where the highest-risk areas are located.
Identify Problem Bird Species
Table 1 lists the main birds that cause damage to horticultural crops in Ontario. Figure 1 shows pictures of these birds for easier identification.
Table 1. Common bird pests in Ontario's horticultural crops
Figure 1. Common bird pests affecting Ontario's horticultural crops. Source: Wikimedia Creative Commons, reprinted under the Creative Commons license as noted under each image.
Understand Bird Behaviour
Birds act based on instincts and environment. Observe birds in the crops, and identify key behaviours. Look for ways to disrupt these behaviours to make feeding more difficult.
Estimate Bird Pressure
To understand the risk of bird damage and opportunities for control on a specific farm, create a property map for each crop area. On the map, identify relevant features within a few hundred metres of the crop.
Property features relevant to bird damage
Nearby sensitive areas
Using the property map and the checklist below, evaluate bird pressure in each area of the farm. Place a checkmark beside each situation that applies. The number of checkmarks indicates the potential bird pressure level:
0 or 1: Low bird pressure
2 or 3: Medium bird pressure
4 or more: High bird pressure
Situations present in and around the crop:
Identify How Much Crop Is Lost to Birds
Bird damage is not always obvious. Crops with physical damage (bird pecks) are easy to spot, but crops eaten completely by birds can only be estimated. At harvest time, it can be difficult to know the impact of bird damage on the crop. Use the property map and the bird-pressure assessment to identify areas with a higher risk of bird damage. Estimate potential bird losses in these areas with field tests, depending on the type of crop (see Appendix A). Calculate the value of the lost crop to determine a budget for bird-control equipment.
Keep records of all assessments. Use these assessments to identify locations where control equipment is needed. Look for other opportunities to limit bird damage, such as making habitats less attractive or eliminating water sources.
The most effective bird control uses a combination of deterrent methods at the same time. Even netting does not provide 100% protection and can be improved with other devices. There are three categories of bird deterrent methods currently available:
Chemical deterrents (e.g., methyl anthranilate) are also available. These products must be approved for use on the specific crop and used according to the label instructions. These products can leave unwanted flavours on fresh food. As a result, their use in agricultural applications is very limited.
Acoustic deterrents use sound to scare birds away. Birds have a hearing range similar to humans; if people can hear it, so can birds. Birds cannot hear ultrasonic sounds.
Propane-Fired Cannons (Bird Bangers)
Bird bangers ignite propane to produce loud, random, unexpected sound blasts (Figure 2). Modern devices fire sets of 3 blasts while rotating to cover a larger area. They must be used in compliance with best management practices (see Best Practices for Use of Acoustic Bird Deterrents and the OMAFRA factsheet, Using Propane-Fired Cannons to Keep Birds Away from Vineyards).
Figure 2. A propane-fired canon.
Electronic Sound Devices (Squawkers)
Electronic sound devices broadcast either electronic noises to irritate birds and disrupt their sensory system, or distress calls of specific bird species and predatory attack calls (Figure 3). The latter sound like real birds and are usually more acceptable to neighbours than propane-fired cannons. Some farmers report the distress calls actually attract birds of prey, which can help scare problem birds away.
Electronic sound devices and propane-fired cannons are often used together. The electronic devices keep birds irritated and edgy, while the cannon provides stimulus to drive them away.
Pyrotechnic Pistol Cartridges
Pyrotechnic cartridges are launched from a handheld pistol and "fly" directly into a flock of birds, where they explode and produce a loud sound and/or visual effects. They can quickly scare away an entire flock. However, they must be manually operated. Take care when using cartridges near neighbours and observe the same setbacks (from where the cartridges explode) and guidelines as propane-fired cannons.
Shotguns pose a serious safety risk and must never be used without a licence and proper training. A shotgun is not as effective at scaring birds as a pyrotechnic cartridge. Lethal control is usually ineffective because of the large bird numbers. Obtain permission from governing authorities before using shotguns.
Other Sound-Producing Devices
Devices such as air horns, clanging metal or Mylar humming lines generally work for a few days before birds start to ignore them. They can also be disruptive to neighbours. These devices may provide the most benefit when used only in the days just before harvest, when bird pressure is highest.
Figure 3. An electronic sound device (squawker)
* See the OMAFRA factsheet, Using Propane-Fired Cannons to Keep Birds Away from Vineyards, for specific details.
Birds react both to movement and things resembling their enemies. However, visual deterrents rarely provide enough protection by themselves and are usually combined with acoustic systems for better results.
Flying Visual Deterrents
Scare-Eye Balloons - Coloured balloons the size of beach balls move freely with the wind and appear like the gaping mouth of a hawk (Figure 4). Yellow balloons have shown the best results in Ontario, especially with blackbirds.
Tapes and Streamers - Strips of shiny plastic tape reflect sunlight and move with the slightest wind. Viewed from above, the entire field appears to be in motion. Use along perimeter rows or in other areas where the most severe damage occurs. Two-colour red/silver tapes deter a broad range of species.
Kites Shaped Like Birds of Prey - Kites wave in the wind and appear like predators hunting in the field (Figure 5). The flying presence is threatening and can keep birds away. Tether kites to poles high above the crop so they wave freely in the wind.
Falconry - Trained falcons and hawks can be very effective, but these services are very expensive. The predators must be airborne to create the scaring effect. Trials using birds of prey tethered to a post have failed because other birds quickly realize the predator is unable to attack.
American Kestrel Nest Boxes - Small birds of prey native to Ontario, American kestrels feed on insects, voles, mice and some smaller birds. Bird-feeding pressure can be reduced while the kestrels are airborne. Kestrels leave the area by early August, limiting their effectiveness in later-ripening crops (e.g., grapes).
Kestrels can be attracted to an area by building nest boxes (Figure 6). Mount boxes 5-6 m high on poles, away from wooded areas, with the box entrance facing southeast. Check boxes regularly to prevent unwanted birds from taking up residence.
Model aircraft and UAVs - Radio-controlled model aircraft and unmanned aerial vehicles (UAVs) can be used to scare birds (Figure 7). Flying devices must be airborne to have a scaring effect. They are costly, labour intensive and require skilled operators. Weather conditions and battery life may limit their use. Operators must follow all aviation regulations and may require a Special Flight Operations Certificate (SFOC) from Transport Canada.
Figure 4. A scare-eye balloon with flash tape
Figure 5. A kite shaped like a bird-of-prey
Figure 6. American kestrel with nest box. Source: Jim Willwerth and Mary Jasinski, Brock University, St. Catharines, Ontario
Figure 7. UAV with built-in acoustic device. Source: Bird-X, Inc., Chicago IL USA
Ground-Based Visual Deterrents
Mirrors, Reflectors, Lights and Lasers - Visual effects and reflected sunlight can disrupt birds, particularly starlings. Reflectors only work when the sun is shining. Lights or lasers work best when natural light is dim, need power close by and can bother nearby neighbours.
Artificial Predators and Scarecrows - Scarecrows and artificial predators present a threatening presence. However, birds quickly realize the threat is not real. Some birds will nest right on these devices. To improve effectiveness, they must be moved constantly.
Air Dancers - Large inflatable "dancing men" waving randomly will keep birds on edge. Power is needed close by. For the best effect, move them regularly.
Dogs - Trained working dogs (e.g., border collies) can be excellent deterrents, especially for ground-foraging birds (such as robins, geese). Dogs need direction by a trained handler to be most effective.
Human Activity - Human activity disrupts birds both directly (chasing birds) and indirectly (movement and presence). Many deterrents (e.g., pyrotechnics) rely on direct human use. It is difficult to separate the effects of these devices from the human presence.
Physical Exclusion (Netting)
Physically excluding birds from the crop using netting is the best way to ensure crop protection. Unfortunately, it is usually the most expensive option and will not guarantee 100% protection. Desperate birds can still find a way into the crop (Figures 8 and 9).
Nets are available in many sizes, colours and materials. The choice depends on the crop, field layout, expected life and installation equipment. Netting material costs have dropped over the years, and systems for applying the netting are improving. The high value of some horticultural crops makes netting a worthwhile investment.
Figure 8. Netting installed directly on grapes
Netting Installed Directly on the Crop
Direct installation is best suited for crops that do not require multiple pickings (e.g., grapes). Coloured nets may also act as camouflage, making it harder for birds to see ripening fruit.
For ice wine grapes, netting is a necessity. Ice wine netting is draped completely around the vines and fastened tightly under the lowest bunches of grapes. This protects the crop from birds and keeps grapes from dropping on the ground during the long period until harvest in mid-winter.
Netting fastened to overhead structure
Overhead netting is best suited for crops picked more than once (e.g., blueberries). Overhead systems allow work to occur beneath the nets, while still protecting the crop from birds. Overhead nets must be removed or retracted at the end of the season to prevent ultraviolet degradation and snow load damage.
Figure 9. Bird damage to grapes through netting.
Costs and Effectiveness
Table 2 ranks each deterrent on effectiveness, annual costs (including labour) and potential to create nuisance. Rankings are high (H), medium (M), low (L). High effectiveness, low cost and low nuisance are the most desirable characteristics.
The rankings are based on published studies and available research. Characteristics can change considerably depending on fields, crops, bird species, weather conditions and management.
Table 2. Relative effectiveness, annual costs (including labour) and nuisance potential of common bird deterrents
Legend: H = high, M = medium, L = low
Bird control must be started early, before birds get a foothold in the area. Growers often start their bird-control program too late, after the birds have already tasted the crop.
During the Nesting Season
During the Growing Season
Birds are intelligent and will quickly get used to regular, repeated, consistent control methods. Use a variety of strategies and change both the timing and locations of these devices regularly to get the best control:
Appendix B provides an example strategy for bird control in a 4-ha (10-acre) vineyard. The strategy uses more aggressive methods for higher levels of bird pressure.
Unfortunately, any device that annoys birds can also irritate nearby neighbours. Most complaints about bird-scaring devices involve propane-fired cannons. Complaints can increase over time if nothing is done.
Be proactive! Avoid problems before they develop. Manage cannons properly to reduce the impact on neighbours. See the OMAFRA factsheet, Using Propane-Fired Cannons to Keep Birds Away From Vineyards, for best management practices, minimum setback distances and operating tips. See the OMAFRA factsheet, Understanding and Reducing Noise Nuisance From Stationary Farm Equipment, for noise measurement and abatement information.
Before setting up cannons, explain to your neighbours why cannons are needed and answer any questions they have. Give them your contact information so they know whom to call if there is a problem. Modify the sample letter in Appendix C and send it to nearby neighbours each year. Giving neighbours a chance to have input may not eliminate complaints entirely, but it can reduce their feelings of helplessness.
For neighbours living near farms using bird-control devices, take the time to understand the farmers' reason for using the deterrent. They are trying to protect their valuable crops, as farming is their business and the birds are a threat to their livelihood.
The OMAFRA factsheet, Using Propane-Fired Cannons to Keep Birds Away From Vineyards, explains how this equipment works and the best management practices for using them. A calm, two-way conversation can help create a solution that meets everyone's needs. Maintaining good neighbourly relations is important to resolving any nuisance issues.
Speak to the farmer and obtain permission to walk through the crops and take pictures of bird activity. Monitor bird activity to better understand the scale of the farmer's problem.
If a neighbour and farmer cannot resolve the conflict on their own, initiate OMAFRA's Farm Practices Conflict Resolution Process (ontario.ca/omafra and search on the title) by calling OMAFRA at 1-877-424-1300. An OMAFRA specialist will work with both parties to try to resolve the issue.
If this is not successful, the next step is to apply to the Normal Farm Practices Protection Board (NFPPB). See OMAFRA's Citizen's Guide to the Normal Farm Practices Protection Board (ontario.ca/omafra and search on the title) for more information.
The most effective bird control balances the needs of the crop, the effectiveness and costs of various control methods and the best interests of the environment and the neighbourhood.
Ongoing research continues to investigate new methods of bird control. Contact OMAFRA crop specialists (ontario.ca/omafra) or local bird-control suppliers for the latest information.
Perform these field tests to estimate the percentage of crop lost to birds.
Bush or Vine Crops (eg. blueberries, grapes)
Just prior to ripening:
Estimated bird loss: (10/50) x 100 = 20% loss
Tree Crops (eg. cherries, apples)
Three weeks before harvest:
Estimated bird loss: (36/180) x 100 = 20% loss
Field Crops (e.g., sweet corn)
Estimated bird loss: (4/20) x 100 = 20% loss
Table 3 shows an example strategy for bird control in a 4-ha (10-acre) vineyard. The vineyard has 50 rows of grapes that are 290 m (950 ft) long, spaced 2.75 m (9 ft) apart. The strategy uses more aggressive methods for higher levels of bird pressure (see checklist).
Table 3. Suggested bird control for a 4-ha vineyard based on bird pressure
This is a sample letter that can be used as a template to inform nearby neighbours about the bird-control devices being used near their homes.
Include a copy of the OMAFRA factsheet, Using Propane-Fired Cannons to Keep Birds Away From Vineyards, with the letter to give the neighbours more information about bird-control devices.
To our neighbour,
Thank you for your patience with our farming practices. We own the vineyard at the address [farm address here]. Our grapes are ripening, so we plan to place propane-fired cannons (bird bangers), bird netting and electronic scaring devices (squawkers) in our vineyards to protect against the onslaught of birds. These devices will not harm the birds, only frighten them away from the crops. These measures are necessary to stop the birds from eating all our ripening crops.
This equipment will be set to operate no earlier than 30 minutes before sunrise and no later than 30 minutes after sunset. We will locate them at least [XX] metres from your home, based on the best management practices described in the Ontario Ministry of Agriculture, Food and Rural Affairs factsheet, which is attached to this letter.
If you do hear this equipment operating outside the time frames above, it means something is not right. Please call us, no matter what the hour, so we can fix this as soon as possible. Please do not try to turn off the devices yourself as you may hurt yourself or damage the device. If you have any questions, concerns or comments about any part of our bird-control program, please call us at: [phone number] .
Thank you again for your patience and understanding, because we cannot earn our living if the birds eat all our crops.
Bishop, J., McKay, H., Parrott, D., Allan, J. (2003) Review of International Research Literature Regarding the Effectiveness of Auditory Bird Scaring Techniques and Potential Alternatives. (PDF), United Kingdom Department for Environment, Food and Rural Affairs.
Comfort, T. (2012) The Spartan: a nestbox for the American Kestrel.
Fraser, H. Bird Banger Videos, Ontario Ministry of Agriculture, Food and Rural Affairs.
Fraser, H. (2010) Using Propane-Fired Cannons to Keep Birds Away From Vineyards. OMAFRA Factsheet. Ontario Ministry of Agriculture, Food and Rural Affairs.
Fraser, H. (2012) Understanding and Reducing Noise Nuisance From Stationary Farm Equipment. OMAFRA Factsheet. Ontario Ministry of Agriculture, Food and Rural Affairs.
Harris, R., and Davis, R. (1998) TP 13029 - Evaluation of the Efficacy of Products and Techniques for Airport Bird Control. Transport Canada.
Tracey, J., Bomford, M., Hart, Q., Saunders, G., and Sinclair, R. (2007) Managing Bird Damage to Fruit and Other Horticultural Crops. Bureau of Rural Sciences, Canberra Australia.
This factsheet was revised by James Dyck, P.Eng., Engineering Specialist, Crop Systems and Environment, OMAFRA, Vineland, and John Warbick, P.Eng., Engineering Specialist, Horticultural Crop Systems, OMAFRA, Vineland, and reviewed by Hugh Fraser, P.Eng., OTB Farm Solutions, St. Catharines, Ian Frensch, P.Eng., C. Frensch Ltd., Beamsville, and Dr. Wendy McFadden-Smith, Fruit Crop Specialist, OMAFRA, Vineland.
For more information:
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