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Researchers Hope to Curb Blackbirds’ Appetites for Corn

Red-winged blackbirds and common grackles are responsible for millions of dollars in damages to agricultural crops each year. For these, and many other bird species, a farmer’s field is one big bird feeder. The development of an effective bird repellent for use on food crops would help alleviate the damage.  In a study with captive red-winged blackbirds, NWRC researchers tested the efficacy of anthraquinone to prevent bird damage to ripening sweet corn. Anthraquinone is a natural substance that not only has a laxative effect, but also absorbs near-ultra violet (UV) light, which is visible to most birds. It is currently marketed and sold as a bird repellent seed treatment called Avipel®.

“When given a choice, red-winged blackbirds were 1.4 times more likely to eat untreated ears of sweet corn compared to treated ears among all six levels of anthraquinone application,” states lead author and NWRC biologist Jim Carlson.  NWRC researchers hypothesize that applying a repellent such as anthraquinone to crops, followed by subsequent application of a color or flavor cue similar to the repellent (such as a near-UV color cue), might help protect newly planted and ripening crops from blackbird damage.

“We’re finding out more and more about the feeding preferences and behaviors of birds and what it takes to make an effective repellent,” notes NWRC research biologist Dr. Scott Werner. “It’s an exciting time to be working on this issue.”

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