Avian Predators: Frightening Techniques for Reducing Bird ...

SRAC Publication No. 401

Southern
Regional
Aquaculture
Center

November, 1990

Avian Predators

Frightening Techniques for Reducing Bird
Damage at Aquaculture Facilities

Gary Littauer*

Bird predation at aquaculture facilities whistle cartridges are 15mm Shellcrackers produce a noise similar
can often be reduced by use of a cartridges that are fired from handheld to bird bangers but are fired from a 12
variety of frightening techniques. .22 caliber blank pistols (Figure 1). gauge shotgun and travel 50 to 100
These techniques rely on noise and/or All are fired into the air toward the yards before exploding. They have
visual stimuli to convince bird birds to be frightened. Bird bangers greater range than bird bangers and
predators that an area is unsafe. travel 10 to 30 yards and explode in are easier to use, particularly from a
Repeated harassment with frightening force similar to an M-80 firecracker. vehicle, since they do not require the
techniques can sometimes condition Screamer sirens travel about 100 separate step of loading a .22 blank to
local populations of birds to avoid yards emitting aloud screeching propel the device. However, they are
areas where they are unwelcome. noise. Whistle cartridges travel about more expensive and a 12 gauge shot-
100 yards emitting a whistling noise. gun is required. Short barreled single
Success in using frightening techni- It is best to use several kinds of these shot shotguns with open cylinder
ques can vary depending on a number devices so that birds do not acclimate chokes are recommended for using
of factors. These include bird species, to anyone noise. shellcrackers. Barrels should be check-
the mix of techniques used, frequency ed before each shot to assure the wad
and duration of use, availability of Figure 1. Flare pistols are effective when from the previous round did not lodge
other food sources, location of ponds used in conjunction with other scare in the barrel. The powder in some
in relation to roosting and loafing devices. brands of shellcrackers is especially
areas, and whether the birds have es- corrosive and incomplete burning of
tablished regular feeding patterns. To powder is common. Shotguns should
be effective, producers must commit be cleaned after each session of firing.
to using a variety of techniques and
changing them often. The rope firecracker is a noise device
that uses 3/8- or 5/16-inch cotton fuse
Audio frightening rope and large waterproof firecrack-
techniques ers. The fuses are inserted into the
rope at intervals. The rope is lit atone
Pyrotechnics – These include several end and hung from a stake or other ob-
fireworks devices used for scaring ject. The rope burns (smolders) at the
wildlife. Bird bangers (Bird Bombs®), rate of about 1 inch per 10 minutes
screamer sirens (racket bombs), and depending on the weather and ignites
each firecracker which then falls to
* Animal Damage Control, Uvalde, TX the ground and explodes. These can
be hung at strategic locations around

the farm and do not require a constant municate fear or distress by alarm or haps out of curiosity or an instinctive
human presence to function. To mag- distress calls. Broadcasted recordings desire to mob the “predator” that has
nify the sound and reduce fire hazard, of these calls can frighten some “caught” one of their members. Al-
they can be hung inside a suspended species and cause them to avoid areas though this may seem to be an indica-
section of stovepipe with a wire bas- (Figure 2). Distress call tapes are tion that distress calls cause the
ket on the bottom. available for great blue herons, snowy opposite effect of that desired, it may
egrets, gulls and double-crested cor- be a good time to reinforce the birds’
There is some fire hazard in using morants. The response of fish-eating fear by shooting pyrotechnics at the
pyrotechnics. Care should be taken to birds to these noises has been vari- birds.
assure they do not come into contact able, and success probably depends on
with explosive or flammable materials the situation in which they are used. Electronic noise generators (capable
when being used. Also, eye and ear of emitting noises of variable frequen-
protection is strongly recommended. Figure 2. Control box for broadcasting. cy and modulation), loud music and
Local laws and ordinances may bird distress calls from a pickup. timed siren devices have been tried
restrict use of pyrotechnic devices, for scaring fish-eating birds with vary-
and local authorities should be con- Flocks of certain fish-eating bird ing degrees of success.
sulted before using them. species such as cormorants. gulls and
even great blue herons have” oc- Playing distress calls or electronic
Automatic Exploders – These casionally been observed flying noises may not show an obvious
devices utilize propane gas or toward broadcast distress calls, per- direct effect on bird predators. How-
acetylene and an automatic timer to ever, they may reinforce other scaring
emit loud explosions at controllable in- techniques. If a local population of
tervals. Some models emit a variable birds is conditioned to be afraid of dis-
number of blasts (one to three) at each tress calls or electronic noises, broad-
time interval to reduce the predict- casting these sounds may mean fewer
ability of the noises. This is intended rounds of pyrotechnics or live am-
to reduce the chances that birds will munition will have to be used, result-
lose their fear of the noise. Rotating ing in lower overall costs for bird
mounts are available for some models control.
to change the direction of the blasts to
enhance effectiveness. Automatic Live Ammunition – Shotgun and
timers are available for some models rifle fire is effective in scaring bird
to turn them on and off each day. predators from pond complexes.
Using exploders in conjunction with Many farmers use live ammunition be-
scarecrows and other control techni- cause it is less expensive than
ques probably enhances their effec- pyrotechnics.
tiveness. Older automatic exploders
sometimes have a tendency to catch These various noisemakers have all been used successfully in bird control.
on fire. Although the fire is usually
small, producers should avoid locat-
ing these devices on or near equip-
ment.

Birds can become accustomed to the
noise of exploders. The devices
should be moved to new locations at
least every 1 to 3 days and the inter-
val of explosions varied to increase
the time it takes for birds to lose their
fear of the sound. When large num-
bers of birds are ignoring exploders, it
may be a good idea to turn them off
and resort to more aggressive techni-
ques such as patrolling ponds with
pyrotechnics and/or live ammunition.
Continued use in those situations
probably just reinforces the birds’
tolerance of loud noises.

Recorded Distress Calls/Electronic
Noises – Many species of birds com-

Rifle bullets can ricochet off water so walking or a vehicle driving on a shaped bag, a battery powered electric
extreme caution must be exercised. pond levee from long distances (200 fan, a siren-like noise maker, and a
Many agricultural facilities will not be yards or more). They seem to be more system of timers with a photo cell
suitable for using rifles to scare birds effective when used in combination switch. The timers periodically turn
because of safety considerations. with noise producing devices such as on the fan motor inflating the
Cartridges in .22 caliber rimfire are in- propane exploders. Scarecrows appear scarecrow which rises up presenting a
expensive and can be used to frighten less effective against great blue human shape where none was present
bird predators from long distances. herons. Inexpensive silhouette shortly before. The photocell switch
High powered center-fire rifle scarecrows can be jigsawed from 1/2- can be set to start the device at dusk or
cartridges can have a dramatic effect inch plywood and wired to steel fence dawn. An initial field trial of this
on birds when fired in their direction. posts. A realistic human shape and fa- device indicated deterrence of cor-
This is because bullets fired from a cial features enhance its scaring morants from catfish ponds.
high powered rifle often produce a ability, and brightly colored paint
loud cracking noise similar to a adds visibility. Hanging the arms so Scarecrows should be moved often to
bullwhip as they pass by. There is a they sway in the wind adds motion to new locations to reduce bird habitua-
greater risk of inadvertently killing a the scarecrow (Figure 3). tion. When birds show little or no fear
protected bird when using a rifle for Vehicles parked on pond levees are they should be removed and aggres-
frightening purposes than when using sometimes effective scarecrows when sive scaring techniques should be
a shotgun. If high powered rifles are birds are scaring easily from a vehicle used.
used, it is advisable to use smaller driven by a bird control employee.
caliber, high velocity rounds with one They should be moved every few days Radio-Controlled Aircraft – Skilled
of the super explosive brands of bul- to reduce the chance of birds becom- operators of radio-controlled airplanes
lets so that bullets have a greater ing accustomed to them. Intermittent have frightened cormorants and other
chance of breaking up without use of propane exploders and/or fish-eating birds from aquaculture
ricocheting when they impact the human-shaped scarecrows next to ponds. The birds can be hazed with
ground or water. Full-metal jacketed parked vehicles may increase their the airplanes as they attempt to arrive
bullets should be avoided since they effectiveness. at pond complexes. Observations sug-
are prone to ricocheting. gest that one operator and plane may
Figure 3. Using a scarecrow and propane be required to effectively cover 200 to
Many producers use inexpensive exploder is sometimes effective if moved 300 acres of ponds if the ponds are
small game shotgun rounds fried into regularly. blocked into one contiguous unit.
the air to frighten birds. Pyrotechnics, Problems with this technique include
although more expensive, are general- Automatic pop-up scarecrows have weather limitations, having suitable
ly more effective because there is been developed to scare birds. One taking off and landing places, and
greater variety in the types of noises model uses a mannequin head on a refueling. Even skilled operators
they cause and they get the noise steel rod that is propelled 30 inches occasionally crash radio-controlled
closer to the birds. However, when into the air by a propane exploder planes. Costs for using this technique
birds are regularly flushing from adapted for the purpose. Another may be substantially greater than
hundreds of yards away, there is model uses an inflatable human- using unskilled labor with pyrotech-
probably less difference in effective- nics and/or live ammunition.
ness between pyrotechnics and live
shotgun ammunition. In general, it is a Other Frightening Techniques –
good idea to intersperse pyrotechnics Highly reflective mylar ribbon (flash
with shotgun and rifle fire for maxi- tape), hawk silhouette kites, and
mum effectiveness. helium balloons have been shown to
be effective at times in scaring birds
Use of live ammunition can pose a in other damage situations. Their ef-
risk of inadvertently killing an oc- fectiveness in scaring fish-eating birds
casional bird. Producers must have from aquaculture facilities has not
permits before killing fish-eating been determined, however. Limited at-
birds, whether intentional or not (see tempts to use helium balloons on cat-
section on Supplemental Killing). fish ponds identified problems in
keeping the balloons up in winds of as
Visual frightening little as 5 to 10 mph and in keeping
techniques them inflated sufficiently to remain
aloft for more than a day or two.
Scarecrows – Human-shaped effigies Beach ball type balloons with large
or scarecrows have shown some effec- eye spots to mimic the stare of a large
tiveness in deterring cormorant flocks. bird of prey have been positioned
Scarecrows seem to work best when around cattish ponds with no notice-
birds are easily frightened by a person able effect on fish-eating birds.

Water sprays from rotating sprinklers diminished. Be sure you have both q Frequently change locations of
placed around ponds or raceways federal and state permits if required passive frightening devices such
have been found to repel certain birds, in your state before killing any as scarecrows and exploders, and
particularly gulls and herons. Ap- protected species. When using live change the combination of techni-
parently, the sprays reduce the ammunition to frighten birds, ques being used as often as neces-
visibility of the fish in the water. They producers must be careful to avoid
seem to work best when adequate killing any birds unless depredation sary.
water pressure is used combined with permits have been obtained.
an automatic on-off cycle. q Be aggressive.
Control strategies using
Flashing lights have been used with frightening techniques q Pursue limited kill permits
mixed results to frighten night-feeding promptly if frightening techni-
birds such as night herons and great In most situations, larger flocks of ques become inadequately effec-
blue herons. Aircraft-type strobe fish-eating birds will be easier to scare tive.
lights have an apparent blinding ef- from aquaculture ponds than small
fect, confusing the birds and reducing scattered numbers. Producers should SRAC Publication No. 402 provides
their ability to catch fish. Flashing expect a reduction, but not necessari- further information on strategies for
amber barricade lights and revolving ly total elimination of bird use of controlling bird damage at aquacul-
lights have also been tried with some their ponds from the use of frighten- ture facilities.
success. Most birds reportedly be- ing techniques. Key points to remem-
come rapidly accustomed to lights, ber when using these techniques for Technical assistance
however, and other techniques must bird control are:
be employed. The Animal and Plant Health Inspec-
q Begin frightening programs tion Service (APHIS) of USDA can
Supplemental killing before the birds have established provide technical assistance to
regular feeding patterns. The aquacultural producers experiencing
When birds become accustomed to longer they are accustomed to losses to bird predators. On-site
frightening techniques, it is often ad- coming to a facility, the more dif- evaluations of predation problems,
visable to kill a limited number of ficult they will be to frighten recommendations on control techni-
birds to reinforce the others’ fear. Cer- away. ques and strategies, and sources of
tain legal restrictions apply. Consult scaring equipment and supplies are
SRAC Publication No. 404 for infor- q Try to frighten the birds before available from APHIS Animal
mation on the legality of killing fish- they land at the facility. If you Damage Control personnel. To find
eating birds and obtaining necessary can scare them off early in the the nearest Animal Damage Control
permits. In general, it is wise to obtain morning, you can usually move office in your state contact your local
necessary permits and to conduct them to other feeding areas. county Extension agent or call the
limited, supplemental killing as soon USDA, APHIS, ADC Regional Office
as possible after the effectiveness of q Use a variety of techniques; do in Nashville, TN at (615) 736-5095.
frightening techniques has not depend on just one or two
devices or techniques.

This publication was supported in part by grants from the United States Department of Agriculture, Number 89-38500-4516, sponsored jointly
by the Cooperative State Research Service and Extension Service; The United States Fish and Wildlife Service and The United States
Department of Agriculture, Animal and Plant Health Inspection Service-Animal Damage Control.