By: Annie Klodd, University of Minnesota Extension
Good bird control measures are expensive. They are also a key part of growing grapes anywhere birds are found.
Last year during a site visit, a grower told me they would be forgoing bird control because of the time and labor it takes. Instead of giving up on bird control, I encouraged them to find a solution that worked better for their business than their current methods. That conversation inspired me to develop a bird control guide to help growers find strategies that work for them.
I dug into the research on bird control to find out which methods have had the most success in vineyards. Among the 10 or so bird control tools out there, some are much more effective than others.
Netting Remains the Most Effective Bird Control Technique
No surprise here. According to comparative research studies in vineyards, bird netting is still the most effective bird management tool. When used correctly, growers can expect 90-100% bird control with netting. For example, a 2007 study in California found 97.8% control compared to uncovered vines.
There is a reason that netting works best. Netting offers nearly equal opportunity exclusion of birds regardless of the species simply by keeping them out. Birds cannot adapt to physical exclusion like they can with behavior-based deterrents like cannons, predatory calls, and visual threats, which I will discuss shortly.
The downsides of netting are the high upfront cost and time required to apply and remove it. However, growers will have an easier time with netting by following these tips:
1. Use netting with holes 3/4 inch wide or smaller so that birds cannot sneak through it.
2. Invest in a net applicator implement (e.g. Netter Getter or similar) for applying and removing nets. They drastically decrease labor costs and fatigue.
3. Do not stretch out the net. For high cordon trellised vines, just drape the net loosely over the vines. Growers often tend to pull it tightly and snugly, but this actually stretches and expands the holes, making it easier for birds to peck through them. Keeping it loose actually protects the berries better.
4. On high cordon vines, use netting that is wide enough to reach the ground on both sides of the row. You can use zip ties to pin the bottoms of the net together so it doesn’t blow away.
5. Finish all skirting, hedging, or other canopy management before applying nets.
6. Keep up your spray program once the net is on; netting does not stop spray droplet from reaching the vines.
7. Remove all jewelry before handling netting!
Sound-based Deterrents
Some growers prefer to use “behavior-based” sound deterrents: propane scare cannons, and speakers that play predator calls and bird distress calls. Controlled vineyard trials have found that these work well, but not quite as well as netting.
It is hard to predict how well sound-based deterrents will work in a specific vineyard, because their effectiveness depends on the bird species and how they are used. They are designed to trigger fear responses in the birds, which works better for some species than others. They remain effective for anywhere from 1 to 6 weeks, until the birds realize they present no real threat.
However, sound deterrents can work moderately to very well if used properly. They also work best in areas with moderate or smaller bird populations.
The best thing you can do to improve success with sound makers is to move them around. Change their location and time intervals frequently before the birds become accustomed to them. The biggest mistake growers make is to keep them stationary.
Here Are Some Other Key Tips:
• Since most bird species get used to sound deterrents within 2-6 weeks, wait to set them up until after veraison or until you notice bird activity in the vineyard.
• Move the equipment throughout the vineyard at least 1 time per week.
• Program your equipment to have variable time intervals between calls or blasts. Cannon blasts should vary between every 3-10 minutes.
• Turn on the sound machines at sunrise and turn them off at sunset.
• Observe local noise ordinances. Avoid using cannons at wineries when customers are present.
What Doesn’t Work for Birds?
Based on current field research, visual deterrents like balloons and ribbons are far less effective than either netting or sound deterrents. A 2007 study in the Carneros AVA in California found that vineyards using visual deterrents alone had 13% bird damage, compared to only 2.3% damage when netting was used. In a 2018 study, even inflatable tubemen – like the tall inflatables at car dealerships – failed to significantly decrease bird damage.
Visuals may help when used in combination with other more effective methods, and in areas with few birds. Like the sound deterrents, they work better when moved throughout the vineyard weekly rather than kept in one spot.
Additionally, methyl anthranilate sprays have not been found effective in controlled, published trials. Methyl anthranilate is artificial grape flavoring which is considered distasteful to birds. However, it does not seem to work in practice. The three studies I found, one as recent as 2018, suggested little to no benefit of methyl anthranilate sprays in vineyards – vines that were sprayed with methyl anthranilate had similar bird damage to the unsprayed vines. I suspect that if this chemical were effective, it would be quite popular by now.
Bird Control Lasers
Bird control lasers are beginning to emerge in some grape-growing regions and are sparking growers’ interest across the US. They emit lasers throughout the vineyard to scare birds without harming any wildlife.
I look forward to seeing how well lasers work for vineyards. Existing systems have not yet been thoroughly tested by objective in-field research, and we cannot say how effective they are until more research is done. For example, we need to learn how long they remain effective and which species they control best. Right now, lasers may be best suited for growers willing to experiment and able to afford the upfront cost.
My main take from all of this is: Netting is still the most effective bird control method, and you can make it easier by following a few key tips. If you have sworn off netting, investigate sound-based deterrents next. Alter their location and frequency for best results. Don’t count too hard on visual deterrents or sprays, which are unlikely to give adequate bird control.
To read more analysis of bird control methods, download Comparing Bird Control Methods for Vineyards and Berry Farms from University of Minnesota Extension.
