A team of researchers in the US have tested ‘laser scarecrows’ that use light to deter birds from crops.
Researchers from the University of Florida and the University of Rhode Island investigated the effectiveness of these laser devices in deterring birds, publishing their findings in the journal Pest Management Science.
The research involved captive flocks of European starlings, which were presented with fresh sweetcorn.
The research demonstrated that the devices, which emit a moving laser beam, can “significantly mitigate” crop damage up to a distance of 20m from the laser device.
Kathryn Sieving, professor of wildlife ecology and conservation at the University of Florida, said that growers are increasingly seeking portable laser unites similar to the ones tested in the research.
She said: “Lasers are being explored widely for crops with short vulnerability windows, like sweetcorn. They seem to be performing very well, especially when different non lethal deterrents are combined (such as lasers combined with loud noises).
“Birds only attack sweetcorn during the brief ripening phase and it lasts for only 5-10 days. So as soon as it ripens, harvest begins,” Sieving added.
“Therefore, in sweetcorn, 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%.”
The study involved two types of trials. In stick trials, fresh sweetcorn was mounted on sticks at varying distances from laser units, and in natural trials, birds foraged on ripe corn grown from seed in a flight pen.
Laser and control treatments were alternated each day over five days, allowing the researchers to assess the birds’ response to repeated laser exposure.
The results indicated that lasers reduced sweetcorn damage marginally in stick trials and dramatically in natural trials, the researchers said.
Sieving said: “The sticks we presented corn on were sturdy and the birds likely could perch and feed on corn while avoiding the laser. Natural corn stalks are flimsy though, and birds would be bouncing in and out… Thus, just as in larger fields, it seems that natural corn makes lasers quite effective.”
Despite the benefits of using lasers to deter birds at a distance up to 20m from the laser device, the effect of the laser seemed to drop off beyond that distance, with little or no deterrence beyond 30m.
However, Sieving said that, in true field settings (i.e. not an enclosed environment like a flight pen) this would be unimportant, as birds would simply fly away and leave a field altogether if lasers were present.
She added: “Lasers are silent, unlike acoustic deterrents…which can be very disturbing to neighbours and workers. Lethal deterrents require permits and time and labour to apply, and the potentially toxic secondary effects on wildlife, soil and water are often unacceptable.”