"Laser" scarecrows could revolutionize crop protection without harming wildlife

In the realm of agriculture, the battle against crop damage caused by birds is a never-ending challenge, with financial repercussions running into millions of dollars annually. Researchers have now introduced a high-tech solution to this problem: laser scarecrows.

The experts demonstrated that this innovative approach can drastically reduce crop damage.

Studying laser scarecrows

The study centers around the use of laser scarecrows to deter birds, specifically targeting the protection of sweet corn crops. 

European Starlings, a common pest for farmers, were presented with fresh ears of sweet corn, and the researchers observed the impact of moving laser beams on these birds. 

Remarkably, the lasers were found to significantly mitigate damage up to a distance of 20 meters from the device.

Study co-author Kathryn Sieving, professor of Wildlife Ecology and Conservation at the University of Florida, explained that more and more growers are seeking inexpensive and portable laser units, like the ones tested in the research.

“Growers need big effects for affordable prices, and if they can spend $300-$500 each for lasers to protect large fields for 1-3 weeks instead of more expensive options such as hiring people to patrol with dogs, falcons, or rifles, then lasers would be beneficial,” said Professor Sieving.

Vulnerability window 

One of the key advantages of lasers lies in their effectiveness during the “vulnerability window,” a critical period before harvest when crops are most susceptible to bird damage.

This short window reduces the likelihood of birds becoming accustomed to the lasers, maintaining their efficacy. 

“Lasers are being explored widely for crops with short vulnerability windows, like sweet corn. They seem to be performing very well and especially when different non-lethal deterrents are combined (e.g., lasers with loud noises),” said Professor Sieving.

“Birds only attack sweet corn during the brief ripening phase (called the milking stage) and it lasts only 5-10 days. So, as soon as it ripens, harvest begins.” 

“Therefore, in sweet corn, the protection does not need to last very long, and lasers seem to be working well – surprising birds such that they leave fields with lasers, and this reduces damage during milking stages by far more than 20%.”

Key insights from laser scarecrows

The research involved two types of experiments: stick trials and natural trials. In stick trials, corn ears were mounted on sticks at various distances from the lasers, while natural trials involved birds foraging on ripe corn grown in a flight pen.

These trials provided insights into the effectiveness of lasers under controlled conditions and in more natural settings. 

“We designed the stick trials to increase the sample size for more robust results. Natural corn matures over several weeks but then is only attractive to birds for two weeks – so our planted crop was not going to give us enough sample size,” explained Sieving.

“With the stick corn experiments we could study small scale effects and amp up the sample sizes.”

The findings revealed that while lasers reduced damage marginally in stick trials, their impact was significantly more pronounced in natural trials. 

Professor Sieving attributed this outcome to the sturdiness of the sticks used, which allowed birds to perch and feed while avoiding the laser.

By contrast, the natural corn stalks were more susceptible to the deterring effect of the lasers.

Distance from the laser source also played a crucial role in its effectiveness. While deterrence was effective up to 20 meters, it diminished beyond this range, with little impact observed at 30 meters. 

Implications and future study

However, Sieving pointed out that in true field settings, this effect seems to be unimportant. 

“In open fields, birds will simply leave a field that has detectable laser protection, and they fly far out of its influence. It seems that just one laser per field can often do the trick to keep birds mostly out of a field.”

“So, the fine scale spatial effects might only apply if birds were overly committed to feeding a small area – then a grower may need to add a couple of laser units with overlapping ranges.”

Professor Sieving hopes that laser scarecrows can offer a sustainable solution for the protection of crops with short vulnerability windows.

“Lasers are silent, unlike acoustic deterrents (loud bangs, other noises occurring several times per hour) which can be very disturbing to neighbors and workers. Lethal deterrents require permits and time and labor to apply and the potentially toxic secondary effects on wildlife, soil and water are often unacceptable.”

The study is published in the journal Pest Management Science

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