Green laser
lights may be the answer
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| Professor Rebecca Brown poses in the URI agronomy fields where she is testing various strategies for keeping birds from feeding on sweet corn. (Photo by Nora Lewis) |
Large flocks of starlings and blackbirds are voracious
consumers of sweet corn, costing local farmers as much as $800 per acre in lost
product. And this year is turning out to be a particularly bad year for bird
damage.
But
the most effective and economical strategy farmers have used to scare the birds
away – propane-powered cannons that make a loud booming sound at random
intervals – are not especially popular with neighbors, many of whom complain
about the noise.
So the Rhode Island Department of Environmental Management
asked a University of Rhode Island researcher to investigate alternatives.
Rebecca
Brown, a URI professor of plant sciences and an expert on growing vegetables,
said the problem of bird damage in commercial corn fields is a serious one.
“Flocking
birds can cause an enormous amount of damage to sweet corn,” she said. “They
get in there and shred the husks and eat the kernels, and then the farmers
can’t sell it. Some birds have even figured out that if they follow the picking
crews, they’ll get the best corn at the best time.”
In
addition to propane cannons, some farmers have tried tying reflective tape or
balloons throughout their fields to frighten the birds or used spray-on bird
repellents. But neither is cost effective.
So Brown began by investigating a practice called topping, which some advocates claim is effective. The practice involves cutting off the top of the plant after it sheds its pollen.
“The
idea is that it stops the birds from damaging the corn because it significantly
reduces the amount of cover they have in the fields,” Brown explained. “So
instead of having five or six leaves over the bird while it’s sitting on an ear
and eating, there’s only one. It supposedly makes the birds more vulnerable to
hawks and other predators, reducing damage to the corn.”
But
it doesn’t appear to be the answer farmers were hoping. While Brown has little
data suggesting that the practice is effective at reducing damage, her studies
found that it reduces the yield of corn from each acre while requiring a great
deal of labor – or a very expensive and specialized tractor – to implement.
“That
added cost and reduced yield, which also means a reduced income, means it’s not
worthwhile,” Brown said.
Next
Brown turned to the use of green lasers in place of cannons to scare the birds.
She built a prototype using a commercial laser pointer for less than $200 that
she hooked to a digital module and programmed to shine the light beam across
the field in different patterns.
So far, it seems to be working, and it doesn’t
harm the birds.
“Birds
are much more sensitive to green light than we are,” she said. “So even if you
can’t see the light beam, the birds can. And birds are particularly sensitive
to moving light. Their chief predator comes after them from above. So when they
see that flash of light, the birds wonder whether it’s just a flash of light or
a hawk. They don’t want to stick around to find out, so they clear out.”
Some
commercial growers of sweet corn in Rhode Island have purchased high-powered
laser systems for as much as $2,600 that can cover an area of 15 acres, and
Brown said they are happy with the results.
“I’m
still trying to get data on how effectively it keeps the birds away, but it
looks promising,” Brown said. “One of the hard parts of getting data is that
the growers want to protect all of their corn, so getting them to do a control
plot with no protection is difficult.”
She
plans to conduct one more year of tests using a green laser to confirm the
results of this year’s preliminary study.
“I
had never heard of anyone using a laser before late last summer, so this has
been our first preliminary study,” Brown said. “Hopefully next year we’ll be able
to say that we’ve solved the problem.”