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Damage Control
The type of control you choose will depend on a number of factors. Use your knowledge of damage patterns and species behavior to decide when and where to use control methods and the types of control methods to use.
Netting: For many types of fruit, netting is the most effective way to reduce bird damage. Cover, cage, or surround trees, vines, and bushes with nylon or plastic mesh, closely woven wire, or cheesecloth before the fruit begins to ripen and throughout the harvest period.
In most cases, netting is placed directly over the plants or bushes, but for some fruits such as highbush blueberry, a framework is built and the netting is suspended over the frame. The major disadvantages of netting include the high initial cost, the time necessary to apply it, and the inconvenience of working around it. Although netting is expensive, it can be reused for a number of years if it is removed carefully and stored over winter. When deciding whether to use netting, growers should consider the costs of purchasing and installing it relative to the losses from bird damage. Although netting is the most effective means of bird control for small fruits and isolated trees, other methods are available.
Scare Tactics and Noise Devices: Many growers use visual scare devices and noisemakers to frighten birds away from fruit crops. Visual scare devices include streamers, spinners, aluminum pie tins, plastic owl and snake models, and scare-eyes (large balloons with eyes painted on them). They are most effective when used in conjunction with sound devices. Because birds learn quickly that visual scare devices are harmless, they should be used only during short damage periods and should be changed regularly. Varying locations, colors, and types of scare devices enhances their effectiveness.
A number of noise devices are available. Cannons, exploders, sirens, and other noisemakers work best when the sound is presented at irregular intervals and the sound source is moved frequently. Taped distress calls are more effective, but the calls are usually species specific, so a grower must obtain a tape of the distress calls of the type of bird causing the damage. A problem with both visual and scare tactics is that birds become accustomed to them over time.
Chemical Repellents: One chemical repellent, methyl anthranilate (MA), currently is registered for use on small fruits in Pennsylvania. In the past, the repellent methiocarb (Mesurol) was registered for use on cherries and blueberries; however, this product is no longer registered in Pennsylvania.
Methyl anthranilate is a colorless to pale-yellow liquid with a grape-like odor. It has been used as a food and drug flavoring for humans for years. In preliminary tests, fruit treated with MA were consumed significantly less than untreated fruit. In addition, human consumers could not detect a difference in taste between fruit that had been treated earlier in the season and fruit that had not been treated. MA should not be applied to blueberry plants, however, because it has been known to cause foliar burns in field studies and has not been cost effective. Methyl anthranilate is currently registered for use on fruits and turf.