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Frightening Devices

Visual | Auditory | Habituation | Current Research

Animals can be frightened from an area by use of one or more visual or auditory (sound-producing) scaring devices. These tools are most effective when used for short periods of time because animals will habituate to the device once they realize that it won't harm them.

Visual Devices

Helium-filled balloons with and without eyespots and hawk or owl kites, as well as scarecrows (some inflatable or able to move), have been in use as depredation deterrents for a long time. They can successfully, short-term, repel birds from small agricultural fields. Additionally, spotlights, and flashing lights or strobe lights can be used to repel nocturnal (active at night) animals. Because most animals are neophobic or afraid of new objects, moving or reflective stimuli, such as flags and streamers are effective. Mylar ® tape is a shiny tape strung above a field or garden that twists in the breeze causing it to flash in sunlight. This has been used to reduce blackbird numbers in small agricultural fields. Mylar flags are used to keep geese from winter wheat, corn and alfalfa.

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Auditory (Sound) Devices

Bangers.--Things that make a big "bang" are used extensively as frightening devices. For example, cracker shells are fired from a shotgun and explode loudly after traveling 100-150 m providing 2 loud bangs, 1 when the shell is fired and 1 when it explodes. A modified starter pistol can fire bird bombs that travel 20-30 m before exploding. Racket bombs, screamer shells, and whistle bombs make whistling or screaming noises as they travel through the air. Rope firecrackers (long ropes with firecrackers strung along and a slow-burning fuse) ignite individually over a long period of time.

Propane exploders. Exploders are devices in which propane is ignited in a firing chamber by a spark, are probably the most used frightening device for birds and deer. This device produces multiple, loud explosions. Some have automatic timers and rotating barrels. Occasional use of a shotgun to reinforce the exploders is important for frightening birds. Either live ammunition or shell crackers can be used. Shell crackers, fired from a 12-guage shotgun, shoot a projectile that explodes 50-75 m away.

Distress calls and alarm calls.--Distress calls are the sounds a bird makes when it is captured by a predator. This sound is more like a scream than a normal call and its function is to shock a predator into dropping the bird. Alarm calls are much softer calls that are sent out to other birds when a predator is detected. Recordings of both these types of calls, broadcast over a speaker, have proven effective at frightening birds. These calls are commercially available for many species.

Ultrasonics.--Ultrasonic devices emit sounds with frequencies outside of what humans can hear and are sometimes are marketed for bird control. However, objective research has not demonstrated effectiveness of these devices in repelling birds. Most birds detect sounds in about the same range of frequencies as humans. These devices are not proven useful with rodents or other mammals either.

Novel sounds.--Animals are afraid of unfamiliar sounds, so some devices have been commercially marketed for wildlife scaring. Av-Alarm ® is a noise generator designed to keep birds out of fields by producing an irritating (to birds) sound. Alternatively, a warbling siren with strobe lights has been used for scaring coyotes away from sheep. It appears most noise generators are not generally unsuccessful.

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Habituation

Frightening devices often produce immediate results, but animals quickly habituate or get used to the devices and they lose their effectiveness. In fact, habituation is a main-problem with all fear-provoking stimuli. For this reason, these tools are best used in situations where they are only necessary for a few days. For example, when fields are planted in the spring and birds dig up the newly planted seeds (losing interest in sprouted seeds). Scaring devices are most effective when combinations of stimuli are used and random timing patterns are in place. For example, deer habituated in less than 3 days to propane cannons used to protect piles of corn when the cannons were programmed to detonate systematically every 8-10 minutes, however, motion-activated cannons were effective for up to 6 weeks. It's important to note that habituation is affected by both by the type, duration and intensity of the stimulus and the animal's hunger (or lack of alternative food sources).

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Recent Research and Development

Recent studies and methods development have been varied. Lasers, using the red end of the color spectrum look like an affordable visual harassment tool. They have mostly been used with birds such as cormorants, geese, crows and others. Research continues on other colors wavelengths. An additional tool for use in dispersing birds is the the effigy. Dead vultures or taxidermic mounts of recently killed vultures placed in roosts have proved highly effective in dispersing both black and turkey vultures.

Behavior-contingent disruptive stimulus devices, activated by animals entering protected areas, are already being examined as means of protecting pastures from predators. In these devices, movement activates sensors. When a signal is detected a light and sound disruptive stimulus device is activated.

*The above discussion of frightening devices taken primarily from Conover (2002) and Dolbeer (1999).

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References

AVERY, M. L., D. E. DANEKE, D. G. DECKER, P. W. LEFEBVRE, R. E. MATTESON, AND C. O. NELMS. 1988. Flight pen evaluations of eyespot balloons to protect citrus from bird depredations. Proceedings: Vertebrate Pest Conference 13:277-280.

BELANT, J. L., T. W. SEAMANS, AND L. A. TYSON. 1998. Evaluation of electronic frightening devices as white-tailed deer deterrents. Proceedings: Vertebrate Pest Conference 18:107-110.

CONOVER, M. R. 1994. How birds interpret distress calls: implications for applied uses of distress call playbacks. Proceedings: Vertebrate Pest Conference 16:233-234.

CONOVER, M. 2002. Resolving human-wildlife conflicts: the science of wildlife damage management. Lewis Publishers, CRC Press, Boca Raton, Florida, USA.

CUMMINGS, J. L., C. E. KNITTLE, AND J. L. GUARINO. 1986. Evaluating a pop-up scarecrow coupled with a propane exploder for reducing blackbird damage to ripening sunflower. Proceedings: Vertebrate Pest Conference 12:286-291.

DOLBEER, R. A. 1999. Overview and management of vertebrate pests. Pages 663-691 in J. R. Ruberson, editor. Handbook of pest management, Marcel Dekker, New York, USA.

FALL, M. W. 1990. Control of coyote predation on livestock--progress in research and development. Proceedings: Vertebrate Pest Conference 14:245-251.

FRINGS, H. 1964. Sound in vertebrate pest control. Proceedings: Vertebrate Pest Conference 2:50-56.

GLAHN, J. F. 2000. Comparison of pyrotechnics versus shooting for dispersing double-crested cormorants from their night roosts. Proceedings: Vertebrate Pest Conference 19:44-48.

GORENZEL, W. P. AND T. P. SALMON. 1992. Urban crow roosts in California. Proceedings: Vertebrate Pest Conference 15:97-102.

HOTHEM, R. L. AND R. W. DEHAVEN. 1982. Raptor-mimicking kites for reducing bird damage to wine grapes. Proceedings: Vertebrate Pest Conference 10:171-178.

KOEHLER, A. E., R. E. MARSH, AND T. P. SALMON. 1990. Frightening methods and devices/stimuli to prevent mammal damage--a review. Proceedings: Vertebrate Pest Conference 14:168-173.

LINHART, S. B. 1984. Strobe light and siren devices for protecting fenced-pasture and range sheep from coyote predation. Proceedings: Vertebrate Pest Conference 11:154-156.

LINHART, S. B., G. J. DASCH, R. R. JOHNSON, AND J. D. ROBERTS. 1992. Electronic frightening devices for reducing coyote predation on domestic sheep: efficacy under range conditions and operational use. Proceedings: Vertebrate Pest Conference 15:386-392.

MARSH, R. E., W. A. ERICKSON, AND T. P. SALMON. 1992. Scarecrows and predator models for frightening birds from specific areas. Proceedings: Vertebrate Pest Conference 15:112-114.

MARTIN, L. R. AND S. HAGAR. 1990. Bird control on containment pond sites. Proceedings: Vertebrate Pest Conference 14:307-310

MOTT, D. F. AND S. K. TIMBROOK. 1988. Alleviating nuisance Canada goose problems with acoustical stimuli. Proceedings: Vertebrate Pest Conference 13:301-304.

PARKHURST, J. A. 1994. An overview of avian predation and management techniques at fish-rearing facilities. Proceedings: Vertebrate Pest Conference 16:235-242.

PFEIFER, W. K. AND M. W. GOOS. 1982. Guard dogs and gas exploders as coyote depredation control tools in North Dakota. Proceedings: Vertebrate Pest Conference 10:55-61.

SIMPSON, G. 1972. Some approaches to controlling depredations by crows and jays in Tulare County. Proceedings: Vertebrate Pest Conference 5:112-117.

STEWART, J. L. 1974. Experiments with sounds in repelling mammals. Proceedings: Vertebrate Pest Conference 6:222-226.

TOBIN, M. E. 1998. Research and management of bird depredations at catfish farms. Proceedings: Vertebrate Pest Conference 18:67-70.

WERNER, S. J. 2000. Cormorant research and impacts to southern aquaculture. Proceedings: Vertebrate Pest Conference 19:81-81.

WORONECKI, P. P. 1988. Effect of ultrasonic, visual, and sonic devices on pigeon numbers in a vacant building. Proceedings: Vertebrate Pest Conference 13:266-272.