Thurman W. Booth
Little Rock, Arkansas 72201
Additional Bird Control Information
Birds, especially migratory birds, provide enjoyment and recreation for many and greatly enhance the quality of our lives. These colorful components of natural ecosystems are often studied, viewed, photographed, hunted, and otherwise enjoyed.
Unfortunately, bird activities sometimes conflict with human interests. Birds may depredate agricultural crops, create health hazards, and compete for limited resources with other more favorable wildlife species. The management of bird populations or the manipulation of bird habitats to minimize such conflicts is an important aspect of wildlife management. Problems associated with large concentrations of birds can often be reduced through techniques of dispersal or relocation of such concentrations.
Two general approaches to dispersing bird concentrations will be discussed in this chapter: (1) environmental or habitat modifications that either exclude or repel birds or make an area less attractive, and (2) the use of frightening devices. The following chapters in this publication also discuss bird dispersal techniques in detail: Bird Damage at Aquaculture Facilities, Birds at Airports, Waterfowl,and Blackbirds.
Habitat modifications include a myriad of activities that can make habitats less attractive to birds. Thinning or pruning of vegetation to remove protective cover can discourage birds from roosting (Fig. 1). Most deciduous trees can withstand removal of up to one-third of their limbs and leaf surface without causing problems. Adverse effects are minimized during the dormant season. Thinning often enhances commercial timber production. Dramatic changes are not always necessary, however. Sometimes subtle changes are effective in making an area unattractive to birds and causing bird concentrations to disperse or relocate to a place where they will not cause problems. Bird dispersal resulting from habitat modifications usually produces a more lasting effect than other methods and is less expensive in the long run.
Fig. 1. Before and after pruning trees to reduce attractiveness as a bird roost.
The use of frightening devices can be extremely effective in manipulating bird concentrations. The keys to a successful operation are timing, persistence, organization,and diversity. Useful frightening devices include broadcasted alarm and distress calls, pyrotechnics, exploders, and other miscellaneous auditory and visual frightening devices (see Supplies and Materials for information on commercial products). No single technique can be depended upon to solve the problem. Numerous techniques must be integrated into a frightening program.
Electronic Devices. Recorded alarm and distress calls of birds are very effective in frightening many species of birds and are useful in both rural and urban situations. The calls are amplified and broadcasted (Fig. 2a). Periodically move the broadcast units to enhance the effectiveness of such calls. If stationary units must be used, increase the volume to achieve greater responses. Electronically produced sounds such as Bird-X , AV-ALARM , or other sound generators (Fig. 2b), will frighten birds, but are usually not as effective as amplified recorded bird calls. This should not discourage their use, however. The greater the variety and disruptiveness of sounds, the more effective the method will be as a repellent.
Fig. 2. (a) Recorded bird alarm or distress calls can be effective in frightening birds. (b) Electronically produced sounds also will frighten birds away from an area.
Pyrotechnics. Pyrotechnic devices have long been employed in bird frightening programs. Safe and cautious use of these devices should be emphasized. The 12-gauge exploding shells (shell crackers) are very effective (Fig. 3). They are useful in a variety of situations because of their long range. Fire shell crackers from the hip (to protect eyes) from single-barrel, open-bore shotguns and check the barrel after each round to be sure no obstruction remains. Some types of 12-gauge exploding shells are corrosive, requiring that the gun be cleaned after each use to prevent rusting. Though more expensive, smokeless powder shells will reduce maintenance.
Pyrotechnics should be stored, transported, and used in conformance with laws, regulations, and ordinances.
Several devices that are fired from 15mm or 17-mm pistols are used to frighten birds. For the most part, they cover a shorter range than the 12gauge devices. They are known by many brand names but are usually called â€œbangersâ€ if they explode, and â€œscreamersâ€ if they do not. Both types should be used together for optimal results. Noises up in the air near the birds are much more effective than those on the ground. The use of a shotgun with live ammunition is one of the most available but least effective means of frightening birds. Shotgun fire, however, may increase the effectiveness of other frightening devices. Live shotgun shells should not be included in a frightening program unless there is certainty that no birds will be crippled and later serve as live decoys. Also, live ammunition creates safety problems in urban areas and is often illegal. Rifles (.22 caliber) fired from elevated locations are effective where they can be used safely.
Rope firecrackers are an inexpensive way to create unattended sound (Fig. 4). The fuses of large firecrackers (known as fuse-rope salutes or agricultural explosive devices) are inserted through 5/16- or 3/8-inch (8- or 9.5-mm) cotton rope. As the rope burns, the fuses are ignited. The time between explosions can be regulated by the spacing of the firecrackers in the rope. The ability to vary the intervals is an asset since birds can become accustomed to explosions at regular intervals. Burning speed of the rope can be increased by soaking it overnight in a saltpeter solution of 3 ounces per quart (85 g/l) of water and allowing it to dry. Since the burning speed of the rope is also affected by humidity and wind speed, it is wise to time the burning of a test section of the rope beforehand. Because of the fire hazard associated with this device, it is a good idea to suspend it over a barrel, or make other fire prevention provisions.
Exploders. Automatic LP gas exploders are another source of unattended sound (Fig. 5). It is important to elevate these devices above the level of the surrounding vegetation. Mobility is an asset and will increase their effectiveness, as will changing the interval between explosions.
|Fig. 3. Shell crackers are fired from a 12-gauge shotgun. They produce an aerial explosion and can be useful in frightening birds out of fields or away from roosts.
||Fig. 4. Rope firecrackers are relatively inexpensive tools that are useful in frightening birds.
Fig. 5. Automatic LP gas exploders make loud sounds that frighten birds. Controlled by a timer, they can be left unattended.
Other Frightening Materials.
Other frightening devices include chemicals such as AvitrolÂ®sup> and a great variety of whirling novelties and flashing lights, as well as innovative techniques such as smoke, water sprays, devices to shake roosting vegetation, tethered balloons, hawk silhouettes, and others. While all of these, even the traditionally used scarecrow (human effigies), can be useful in specific situations, they are only supplementary to a basic, well-organized bird frightening program. Combining different devices such as human effigies (visual) and exploders (auditory) produce better results than either device used separately.
Scott E. Hygnstrom;
Robert M. Timm; Gary E. Larson
PREVENTION AND CONTROL OF WILDLIFE DAMAGE â€” 1994
Cooperative Extension Division Institute of Agriculture and Natural Resources University of Nebraska -Lincoln
United States Department of Agriculture Animal and Plant Health Inspection Service Animal Damage Control
Great Plains Agricultural Council Wildlife Committee