Birds in Field and Fruit Crops
Birds in Field and Fruit Crops
Exclusion
Exclusion techniques are rarely practical in commercial operations, but are very effective and very practical for backyard gardens, orchards or fruit trees. Many net and twine companies make a netting which prevents bird damage to backyard gardens and fruit trees.
Netting can be used to enclose the entire garden, vine or tree to exclude birds from crops, installation is sometimes difficult because the netting must be supported by a frame to prevent the netting from damaging the plant involved. In addition, some nets may prevent adequate sunlight from reaching the foliage or restrict pollination. However, the netting will provide a 100% protection and may be used year after year if it is durable net.
A commercially available, inexpensive acrylic webbing prevents bird damage to gardens, vines and fruit trees. It is light-weight, spiderweb-like material this is draped directly over the plants. It does not require support in most cases and does not interfere with water, sunlight, pollination or plant growth. When correctly applied, it is 100% effective. However, some people may object to its appearance or its spiderweb-like feel. Post harvest removal is usually desirable, although the material may retain its effectiveness for more than one year.
Repulsion
Visual repellents, such as whirlers, streamers, spinners, reflectors, plastic hawks and owls, etc., are rarely practical in commercial application. These methods may be satisfactory for backyard crops. Regardless of the situation it is important to vary the techniques at least every other day. Otherwise, the birds soon learn that such devices are harmless and ignore them. If locations are altered, colors varied, and positions changed, the effectiveness of these repellents is enhanced. Furthermore, it is extremely important to apply these techniques before damage begins or as soon as possible after it is noticed.
Auditory repellents are among the most effective frightening devices but certain principles must be adhered to or they become ineffective.
1. Apply these techniques before damage beings or as soon as possible after damage is detected
2. Alter the application every two or three days to prevent the birds from becoming used to one technique.
3. Apply these techniques persistently, especially during peak damage periods of early morning and late afternoon.
4. A combination of two or more techniques is the most effective.
5. Frightening devices are most effective against starlings, blackbirds and waterfowl, and are least effective against robins, waxwings, thrashers and orioles. A permit from the U.S. Fish and Wildlife Service is required to frighten waterfowl and other migratory birds such as sandhill cranes, robins, waxwing, etc. A permit is not required for blackbirds when doing damage.
22 Caliber Rifle Fire
The whizzing sound made by a .22 cal., hollow point rifle bullet is extremely effective in frightening birds from field and orchard crops, with the added advantage that birds can be frightened from a long distance. Caution must be used to ensure that the rifle fire is not hazardous to human beings and livestock. Rifle fire applied judiciously for a few minutes during the peak morning and afternoon feed times can reduce damage significantly in conjunction with other frightening techniques.
Double-Shot Shotgun Shells and Pistol Bombs
Several companies manufacture special shotgun shells or pistol bombs that fire charges into the air that explode above the damaging birds. These aerial bombs are extremely effective in crops and orchards. If applied in combination with other frightening techniques, such techniques can reduce damage significantly.
Automatic Exploders
Automatic exploders or bird-scaring cannons automatically detonate a gas to produce an extremely loud explosion. These devices range from simple mechanisms which generate and detonate acetylene gas to devices which have photoelectric regulators and electronic detonation of bottled gas. These automatic exploders are very effective when supplemented with other frightening devices, providing their application is altered at least every other day. Most farmers who have used these guns are fully aware that if the exploder is permitted to operate in the same place day after day at the same interval, it soon becomes ineffective. Change location and firing interval every other day. One exploder effectively protects about 10 acres.
Recorded Alarm and Distress Cries and Electronic Frightening Devices
These bird-scaring mechanisms are very effective, but their application is somewhat limited because of high cost and limited range. Furthermore, because they make extensive use of batteries and loudspeakers, they are subject to vandalism. However, these devices are worthwhile in high- value crops where damage is severe. Again, they are far more effective if used in conjunction with other frightening techniques.
Psychochemical
Amino-4-pyridine (Avitrol) is available to pest control operators and government agencies for use on field and sweet corn. The chemical is applied to a grain bait which is then diluted 100 to 1 so that only one kernel out of one hundred is treated. This material is then broadcast in fields receiving bird damaged. When a few of the birds ingest treated kernels, they exhibit extremely wild and erratic behavior. This reaction then frightens the rest of the birds from the field. This method is very effective, but is usually not economical unless damage exceeds 5% of the total production of the field. A permit is required from the Law Enforcement Division, Michigan DNR.
Seed Coatings
You can apply several commercial chemicals to seed coatings to prevent sprout pulling by many kinds of birds. Consult your county extension agent for the most recent information. Mix thoroughly 1 pt. of 94-98% coal tar with 2-3 bushes of seed corn and plant immediately to repel crows.
Population Reduction - Trapping of starlings and blackbirds
When used before the fruit crop ripens, decoy traps in fruit orchards can substantially reduce damaging populations and thus reduce damage. Some traps are portable, others are large and permanent. Bait traps with bread, corn and water. Also keep a few live birds in the trap at all times as decoys and thus increase the trap's effectiveness. The trap is designed so that trapped birds can easily be herded to a small corner where they are forced into a holding cage. The holding cage can then be covered with plastic and fumigated with automobile exhaust.
Such traps also permit the release of desirable protected birds. Initial construction cost can be high, and the daily maintenance required may make them impractical under certain conditions. Blueprints for traps are available from your county extension agent or from the U.S. Fish and Wildlife Service. A permit is required from the U.S. Fish and Wildlife Service.
