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May. 20, 2022 | Friday
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IN-DEPTH: 'Bird bangers' least effective choice long-term, researchers say


Propane cannons, commonly known as bird cannons or bird bangers, have been used for deterring birds from agricultural crops for years, but many experts say they are only effective in the short-term or when used in conjunction with other deterrents.

Birds and other animals are smart and adaptable. Using only loud explosions does not deter them for long, extensive studies have shown.

During harvest season from late summer through autumn, farmers use a wide variety of techniques to scare away birds and animals from crops.

Loud, auditory deterrents – which inevitably lead to complaints from some residential neighbours and to “the farmers were here first” push back from proponents – can include bird cannons, air horns, shotguns, electronic sound devices or pyrotechnic pistol cartridges.

Visual techniques such as tapes and streamers, balloons, scarecrows, falcons, American Kestrel nest boxes (a natural pest deterrent) and other methods are also used sometimes.

Most studies and researchers say there usually needs to be a combination of deterrents for the best success, experts say. But keeping birds away from crops is a real challenge.

“Deterring birds is difficult,” retired University of Guelph professor Helen Fisher said in an email response to The Lake Report.

“There are nets, cannons, squawkers and many visual deterrents – mylar tape, paper owls, light shows – and the use/encouragement of raptors in the immediate area. Nothing is perfect.”

Karen Steensma, a professor of biology and environmental studies at Trinity Western University in Langley, B.C., said the gold standard has now become the use of professional bird abatement techniques such as falconry.

“It may be inexpensive to light up a propane cannon and set it to go off every 10 to 20 minutes all day long but it won’t last for the long term,” Steensma said in a phone interview. “The birds will eventually learn and there have to be other techniques combined with that.”

As a farmer herself, Steensma said she understands all sides of the issue, but said propane cannons may now be an outdated technique.

“In some ways, it (cannon) seems to almost call the birds in. They learn: ‘Oh, this is where the fruit is.’ So, there’s some evidence for that,” Steensma said. “Birds are very smart to figure things out.”

Falconry, active shooting of pest birds, netting when feasible, habitat modification to encourage natural predators and habitat modification to discourage pest birds are the most effective methods, according to a 2009 pilot study headed by Steensma.

The research paper, titled “Efficacy of bird deterrent devices in agricultural areas of the Fraser Valley of British Columbia,” was prepared for the B.C. provincial government and the Fraser Valley Regional District.

It concluded that propane cannons, reflective tape, distress and predator callers, scarecrows and other visuals have limited effect.

Using lasers, lights, smoke, microwaves, high intensity, infra- or ultra-sounds were not recommended by Steensma.

“You get what you pay for, usually,” she told The Lake Report. 

“Ideally, if you can keep a good habitat around your farm for other wild animals, that might help,” she said, such as setting up nest boxes at the farm so large birds of prey can protect crops from fruit-eating birds.

For a small grower, netting also proved to be effective, she added.

Debbie Zimmerman, chief executive of the Grape Growers of Ontario, said some Niagara growers have tried using drones and predatory birds, such as falcons and owls. There is no “easy fix,” she said.

“The bird cannons are the most effective right now,” she told The Lake Report. “They’re necessary to keep the crops. It is necessary to maintain our vineyards and it (cannon) is a part of normal farm practice.”

Most Niagara farmers use netting and bird cannons, Zimmerman said.

In 2016, senior viticulturist Jim Willwerth and technician Mary Jasinksi of Brock University’s Cool Climate Oenology and Viticulture Institute worked on an award-winning project to test the effectiveness of new bird deterrents.

One of the methods, which involved installing American Kestrel nest boxes at several trial sites and monitoring bird pressure and damage, showed kestrels’ presence reduced the number of birds and their activity.

Research showed nuisance bird populations dropped 20 to 30 per cent at the sites where the nesting boxes for kestrels were installed, Brock’s marketing and communications officer Kaitlyn Little said in a media statement at the time.

The collaborative project among Brock, the Grape Growers of Ontario and Ontario Fruit and Vegetable Growers’ Association, won the Regional Premier’s Award for Agri-Food Innovation Excellence in 2016.

The best solution to reduce birds destroying grapes or other berry crops is using a variety of bird abatement techniques, Willwerth said.

“Acoustical types of deterrents such as propane cannons are normally used for short time periods and in conjunction with other types of deterrents, such as visual deterrents, as it is important to diversify and have randomness to keep birds from habituating to the deterrent,” Willwerth said in an email response to The Lake Report.

“Local research from (Brock) found that attracting natural predators such as birds of prey (kestrels, Cooper’s Hawks, etc.) can be beneficial for reducing birds from congregating and foraging in vineyards.”

“New technologies being explored for bird control worldwide include the use of UAVs (unmanned aerial vehicles, i.e. drones) or new types of visual deterrents (lights or lasers) to deter birds while minimizing impacts on neighbours. Local research has demonstrated mixed results so far from a practical or effectiveness standpoint.”

More than 20 years ago, a 1998 report, “Evaluation of the efficacy of products and techniques for airport bird control,” prepared by King City-based researchers Ross Harris and Rolph Davis for Transport Canada, said birds can get used to the sound of propane explosions.

“The loud bang of a propane cannon is known to be effective at scaring birds for short periods of time, but birds soon habituate to the noise,” the authors said in the report.

According to the study, the advantages of cannons are that they’re movable, effective during day and night, and direction, timing and volume of blasts can be controlled.

Falconry is also successful only if it is conducted by well-trained falconers, Harris and Davis said in their report.

The use of falconry is also expensive, so the crop has to be valuable enough to make it economically viable, Steensma said, and it might require sharing the expense of having a falconer with other nearby farmers.

Talking to growers in Washington State, Steensma said they found the use of falconry during harvest season, combined with a wine-tasting experience at the estate winery, can draw tourists.

“People are fascinated to watch the falcon, so it can actually be a part of their marketing. And it’s been shown by some of our research that economic incentives are there to use natural means or falconry because the public is willing to pay more for fruit that has been protected in that way as opposed to fruit that’s been protected by shooting or poison,” Steensma said.

Besides falconry, drones are another method being investigated, Steensma said, adding the research is still in the early stages but having drones that mimic falcons might be possible in the future.

The blueberry growers on the Washington side of the B.C. border use fewer propane cannons, after switching to falconry instead, and some farmers in B.C. also started using falcons and drones as well, Steensma said.

The lack of knowledge of cost-effective alternatives to bird cannons could contribute to the reason why “cannons are being widely used,” another report stated.

The 2003 study, “Review of international research literature regarding the effectiveness of auditory bird scaring techniques and potential alternatives,” written by Jack Bishop, Heather McKay, James Allan and David Parrott, suggested that auditory bird deterrents are seen to be cheap, portable and labour-free compared to other techniques, but they should be “intensively maintained and monitored.”

“Habituation seems to be the main reason for their loss of effectiveness.  A cannon firing repeatedly without any variation in timing or direction quickly loses its potential to scare birds.”

The provincial Farming and Food Production Protection Act safeguards farmers against nuisance complaints by neighbours when they are following “normal farm practices.”

According to a 2017 Ontario Ministry of Agriculture, Food and Rural Affairs factsheet, a flock of 5,000 starlings can consume 1,000 kilos or one metric tonne of food over a 10-day period.

The ministry recommends that farmers be proactive and start with identifying what bird species cause problems, where the birds are coming from and how they behave.

Some of the most common problem birds that target grapes in Ontario are sweet robins, starlings, orioles, mockingbirds and finches.

“The most effective bird control uses a combination of deterrent methods at the same time. Even netting does not provide 100 per cent protection and can be improved with other devices,” authors James Dyck and John Warbick said in the factsheet.

“During the growing season, do not operate equipment too frequently, or the effectiveness will be reduced.”

Propane-fired cannons are considered of medium effectiveness with medium costs but a high nuisance potential.

Among other auditory deterrents, pyrotechnic pistols have high effectiveness with medium annual costs and medium nuisance potential, the factsheet says. Netting and falconry when a bird is airborne are the most effective deterrents with low nuisance potential but high annual costs.

The least expensive deterrents are acoustical, but they are also the most annoying to neighbours, Dyck said in his online presentation.

Bird bangers can be used during daylight hours only, between 30 minutes before sunrise and 30 minutes after sunset from August to November. Using cannons adjacent, below or on the Niagara Escarpment can also cause echoing, another provincial factsheet states.

Research has shown there is no “one-size-fits-all” solution when it comes to finding a balance between neighbours’ complaints and protecting farmers’ crops.

Growers are advised to reach out to neighbours beforehand to inform them about bird-control devices being used near their homes. Neighbours are reminded that farmers need to protect their crops as birds are a threat to farmers’ businesses and livelihood, the factsheet says.

If common ground can’t be reached between farmers and residents, their disputes can be taken to the Normal Farm Practices Protection Board.