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Biodegradable Blackbird Remedy?

Saturday, September 1, 2001
filed under: Birds

Blackbird Remedy in Sunflower?

A new biodegradable product called Bird Shield holds promise as a blackbird repellent

A new biodegradable product—with an active ingredient, methyl anthranilate, that is derived from grapes—holds promise as a blackbird repellent in sunflower and other crops, such as sweet corn.

Leonard Askham has secured state and federal label approval for his new bird repellent, called Bird Shield. Askham, whose Bird Shield Repellent Corporation is based in Pullman, Wash., says his product was one of the first biochemicals to be entered into the label approval process at the Environmental Protection Agency.

How did Askham discover that a chemical component in grapes repels birds? Askham explains that he spent 25 years researching animal damage control as associate scientist at Washington State University. One day, he learned from a wine grape producer in Washington state that while birds were causing problems in the producer’s wine grapes, the birds were leaving the concord grapes alone. Askham began researching why. He isolated about a half dozen chemicals present in concord grapes that were not present in wine grapes, and further testing led to methyl anthranilate as the key chemical that repels birds.

He began experimenting with the chemical on corn in 1995, and in 1998 and 1999 conducted field trials on sunflower in Forman, N.D. and sweet corn, in Olathe, Colo., applying the product by air.

In 1998, trials were conducted on six sunflower fields near Forman, four of which were treated. The trials were repeated the next year with ten fields, six of which were treated. The remaining plots, two in 1998 and four in 1999, were left untreated to compare with treated plot results.

All of the fields were similar in topography and contained cattail marshes where the birds roosted and drank. The fields, including marshes, were treated twice, at seven day intervals starting when the birds began to feed on the ripening ‘flowers. Twelve sunflower heads were randomly harvested from the center of each plot at the end of the trials. Each head was weighed, measured, the area of damage recorded, and the seed removed.

Two applications of the repellent were sufficient to move the resident population of blackbirds out of the sunflower fields with no substantial damage to the crop (2.6% to 3.4%) compared to damage in untreated sunflower that ranged from 78% to 90% (Figure 1). Harvest weight of sunflower in untreated plots ranged from 133 to 700 lbs/A (344 lb/A average) while yield of treated plots ranged from 1,430 to 1,909 lbs./ac (1,890 lb/A average).

The corn plot data indicated similar success: when the crop was treated with the repellent ten days prior to harvest, during both trial years, less than 1% of the crop was lost from bird damage. Askham says the data indicates that the use of the repellent, when applied when the birds begin to feed on these crops, can be effective in reducing red-winged bird damage to both commodities.

The product is also environmentally safe, he says. The field trials indicate no adverse effects on fish or resident populations of ducks when the product is used as directed. And once applied to a crop, it won’t leach or translocate. “These are all arguments we had to prove to the EPA,” says Askham, including the fact that crops treated with the product aren’t harmful to humans or livestock. “You would have to feed an animal seven tons of treated product a day to see any effect,” he says.

Bird Shield is also labeled for use to repel birds from buildings and residential areas. Askham notes that the product is not effective on nesting birds, however. And since the product is biodegradable, it must be used by a certain date.

The product contains 2.29 lbs. of active ingredient per gallon. It should be applied on corn and sunflower at a rate of one pint of concentrate (0.28 lbs ai) per acre by air. For corn, the product should be applied 10 days before harvest, when the crop begins to ripen, or when birds begin feeding, and reapplied at five-day intervals until harvest, which should be five days after the last treatment.

For sunflower, application should begin when birds begin feeding on the crop, and repeated as necessary to maintain repellency, with a seven-day preharvest interval from the last treatment. Product cost is around $50 a gallon or between $6 and $7 per acre, not including application.

Rick Hoistad farms near Forman, and it was his fields where the sunflower trials were conducted. “We farm near the Tewaukon Wildlife Refuge, and the blackbird activity that carried over proceeded to nearly wipe us out,” he says. Hoistad tried virtually every blackbird control product on the market, and says this is the best treatment control option he’s found yet. “We’re able to raise ‘flowers again with this product.” One key aspect of treatment is that if resident birds can be kept away early, then that will help prevent migrating birds from coming in too. “I’ve seen them wipe out a quarter of land in a matter of a few days,” says Hoistad, who has become a product distributor.

Wildlife Official: Independent Analysis Needed

Officials with the Wildlife Services Division of the USDA Animal and Plant Health Inspection Service in Bismarck, N.D., say they have seen commercial bird control products come and go from the marketplace. Although the effectiveness of this product appears promising, independent analysis of it is needed. “To be fair to growers, we want to give it a good look,” says George Linz, USDA-APHIS Wildlife Services project leader, Bismarck, N.D.

To confirm the product’s effectiveness, USDA-APHIS is evaluating Bird Shield in an independent field analysis during the 2001 growing season. Since total treatment costs could run about $25-$35 acre—$10 to $12 for a treatment with application cost included, repeated two or three times—more analysis is also needed on how the product may be used most cost-effectively by producers in need of blackbird control. “Maybe you don’t have to treat the whole field. There’s still much we don’t know about this product,” says Linz.

Askham agrees that growers will experiment themselves, particularly to save costs. “After all my years of R&D with the product, I have learned that after it is released the growers are the ones who develop the best way to use it,” he says. —Tracy Sayler

Distributors, contacts for more information about Bird Shield:

Rick Hoistad, Northern Plains Ag, Forman, ND, ph. 701-724-3068,

Leonard Felix, Olathe Spray Service Inc, Olathe, CO ph. 970-323-5580,

Bird Shield Repellent Corporation, ph. 1-800-359-1594

Study Looks at Economic Impact of Blackbird Damage in Sunflower

Researchers at North Dakota State University in Fargo teamed with officials at the USDA’s National Wildlife Research Center/Great Plains Field Station in Bismarck to assess the economic impact on sunflower production from a regional population of blackbirds consisting of three species: red-winged blackbirds, common grackles and yellow-headed blackbirds.

The study analyzed blackbird feeding and the percentage of sunflower consumption for male and female birds. The estimates of annual sunflower consumption:

 Red-winged blackbird  9.3 oz male, 5.6 oz female.

 Common grackle 9.1 oz male, 7.8 oz female.

 Yellow-headed blackbird 8.4 oz male, 4.6 oz female.

Based on the average price of sunflower from 1993-1997, each male red-winged blackbird caused 9 cents in damage annually. Females caused 5 cents in damage annually.

Each male common grackle caused 8 cents in damage annually and damage by each female was 7 cents.

Each male yellow-headed blackbird caused 8 cents in damage annually and damage by each female yellow-headed blackbird was 4 cents.

The population of all three species combined impacted production by $5.2 million annually.

Even though the male causes more damage, it’s more beneficial to keep blackbird pest populations in check by controlling the female, according to George Linz, USDA-APHIS, Bismarck.

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