Fig. 1. Geese, ducks, and
other waterfowl may damage crops by feeding in fields.
The term waterfowl is
properly applied only to ducks, geese, and swans (Fig.
1). Space does not permit full species descriptions
here. A bird identification guide should be consulted
for exact species descriptions.
Many of the control
techniques are equally applicable to damage situations
involving coots, rails, and cranes, which are not
discussed in this publication.
In North America, most
waterfowl are migratory, flying long distances in the
spring and fall between the summer breeding grounds and
wintering areas. Some species or geographic populations
of some species, however, never leave the breeding
areas. The Florida and mottled ducks, southern
populations of wood ducks and hooded mergansers, and
some populations of Canada geese are nonmigratory.
Ducks and geese breed
throughout North America. The primary goose production
areas for Central, Mississippi, and Atlantic Flyway
geese are Banks Island, Baffin Island, and the greater
Hudson Bay area. Most of these birds winter in the
southern Great Plains, Texas, Louisiana, and Mississippi
coastal marshes, or the Chesapeake Bay and mid-Atlantic
states’ coastal marshes and barrier islands.
The primary breeding
grounds for geese using the Pacific Flyway are the
Yukon, Kuskokwin, and Copper River deltas and the north
and west coasts of Alaska. These birds typically winter
in Washington, Oregon, and California (especially Baja
California, the Baja California Sur coastal marshes, and
the central valley of California).
The primary North American
breeding grounds for ducks are the prairie pothole
region of Alberta, Saskatchewan, Manitoba, Montana,
North and South Dakota, and Minnesota. Historically,
this area probably produced more ducks than the rest of
the continent combined. Other important breeding areas
include coastal and interior Alaska, and the Mackenzie
River Delta. Primary duck wintering grounds include the
central valley of California, the southern Great Plains,
Gulf Coast marshes, Caribbean Islands, and Central and
Many of the historical
North American waterfowl breeding, migrating, and
wintering areas are changing because of agricultural and
land-clearing practices, northern prairie pothole
drainage, and development of the US Fish and Wildlife
Service’s National Wildlife Refuge system. Worldwide,
waterfowl occur on every major land mass except
Waterfowl, as their name
implies, are most often found near water. They can,
however, fly long distances to and from favorite feeding
grounds, which may include agricultural or upland sites.
Some species, such as the mallard and certain subspecies
of Canada geese, are extremely adaptable. They are
equally at home in rural and urban environments, on a
pond in a city park, or on a marsh in Alaska.
The food of individual
waterfowl species ranges from fish to insects to plants
in various combinations, depending on availability.
Waterfowl bills have evolved to allow the exploitation
of a wide variety of food sources and associated
habitats. Even though many species are adapted to
feeding in the water, most will readily come on land to
take advantage of available food. Since space does not
permit a species-by-species description of food habits,
a few general comments will suffice.
During the prefledging
period, young waterfowl feed primarily on aquatic
insects and other invertebrates. As adults, waterfowl
have an omnivorous diet. Dabbling ducks, whistling
ducks, and shovelers are primarily filter feeders and
will consume almost anything edible. Torrent ducks, blue
ducks, and scaups feed heavily on aquatic insect larvae,
snails, and other invertebrates found on and under rocks
in streams and ponds. Large eiders, scoters, and steamer
ducks feed heavily on mollusks and shellfish. Steller’s
eider feeds more on soft-shelled invertebrates. Fish are
the main food of mergansers. Swans are aquatic grazers
and geese are terrestrial grazers.
General Biology, Reproduction, and Behavior
Waterfowl are normally
monogamous and solitary nesters. The size of the nesting
territory is determined by the aggressiveness of the
particular pair of birds. Pair formation in geese and
swans tends to be permanent until one of the pair dies;
the remaining bird will often remate. Ducks seek a new
mate each year.
Ducks and the Ross’s goose
generally lay one egg each day until the clutch is
complete. Most other geese and probably all swans lay an
egg every other day until the clutch is complete.
Incubation is not started until the last or
next-to-the-last egg is laid, thus all the eggs hatch at
about the same time. There is a slight correlation
between the length of incubation and the size of the
adult bird. Incubation periods range from about 23 days
for cackling Canada geese, 28 days for giant Canada
geese and mallards, to 38 days for trumpeter swans.
Young waterfowl are precocial and begin foraging shortly
after hatching. The nest site is abandoned 1 to 2 days
Studies indicate many
species have a first-year mortality rate of 60% to 70%
and a 35% to 40% mortality rate in subsequent years.
Life spans of 10 to 20 years for captive ducks and 20 to
30 for captive geese and swans are not uncommon.
Damage and Damage Identification
Goose problems in urban
and suburban areas are primarily caused by giant Canada
geese, which are probably the most adaptable of all
waterfowl. If left undisturbed, these geese will readily
establish nesting territories on ponds in residential
yards, golf courses, condominium complexes, city parks,
or on farms. Most people will readily welcome a pair of
geese on a pond. They can soon turn from pet to pest,
however. A pair of geese can, in 5 to 7 years, easily
become 50 to 100 birds that are fouling ponds and
surrounding yards and damaging landscaping, gardens, and
golf courses. Defense of nests or young by geese and
swans can result in injuries to people who come too
Migrant waterfowl damage
agricultural crops in northern and central North
American. In the spring, waterfowl graze and trample
crops such as soybeans, sunflowers, and cereal grains.
In autumn, swathed grains are vulnerable to damage by
ducks, coots, geese, and cranes through feeding,
trampling, and fouling. Young alfalfa is susceptible to
damage by grazing waterfowl. Geese sometimes damage
standing crops such as corn, soybeans, and wheat. In
southern agricultural areas, overwintering waterfowl can
cause problems in rice, lettuce, and winter wheat.
Mergansers, mallards, and
black ducks cause problems at some aquaculture
facilities by feeding on fish fry and fingerlings.
Common eiders and black and surf scoters cause problems
when they feed in commercial blue mussel and razor clam
beds. For more information, see Bird Damage at
In the United States,
migratory birds, including most waterfowl, as well as
their nests and eggs, are federally protected (50 CFR
10.12) by the Migratory Bird Treaty Act (MBTA) (16 USC.
703711). A complete list of all migratory birds
protected by the MBTA can be found in 50 CFR 10.13.
Also, all states protect most waterfowl. Exotic and
feral waterfowl species including mute swans, greylag
geese, muscovy ducks, and Pekin ducks are not protected
by the MBTA, but may be protected by state law or local
ordinance. Persons wishing to take any migratory bird
outside of the legal hunting season must first secure a
federal permit from the US Fish and Wildlife Service (USFWS),
and in some cases a state permit. “Take” means to
pursue, hunt, shoot, wound, kill, trap, capture, or
collect, or attempt to pursue, hunt, shoot, wound, kill,
trap, capture, or collect (50 CFR 10.12). “A federal
permit is not required to merely scare or herd
depredating migratory birds other than endangered or
threatened species or bald or golden eagles” (50 CFR
21.43a). Three species and one subspecies of waterfowl
that occur in the United States are listed as endangered
in 50 CFR 17.11, October 1, 1992 edition (Table 1). In
addition, five subspecies of rails, and one species and
one subspecies of crane are listed.
Contact personnel from
your local USDA-APHIS-ADC office for information on
obtaining a federal permit to take migratory birds.
“Landowners, sharecroppers, tenants, or their employees
or agents actually engaged in the production of rice in
Louisiana may, without a permit, shoot purple gallinules
(Ionornis martinica) when found committing or about to
commit serious depredations to growing rice crops on the
premises owned or occupied by such persons . . . between
May 1 and August 15 in any year.” (50 CFR 21.45).
Table 1. Members of the
families Anatidae (ducks, geese, and swans), Rallidae
(coots and rails), and Gruidae (cranes) occurring in the
United States listed as endangered in the Code of
Federal Regulations, Title 50, Sec. 17.11, 10-1-92
Laysan duck (Anas laysanensis)
Hawaiian duck (Anas wyvilliana)
Aleutian Canada goose (Branta canadensis leucopareia)
Hawaiian goose (Nesochen sandvicensis)
Hawaiian coot (Fulica Americana alai)
California clapper rail (Rallus longirostris obsoletus)
Light-footed clapper rail (Rallus longirostris levipes)
Yuma clapper rail (Rallus longirostris yumanensis)
Hawaiian moorhen (Galinula chloropus sanduicensisie)
Mississippi sandhill crane (Grus canadensis pulla)
Whooping crane (Grus americana)
Damage Prevention and Control Methods
Waterfowl can be difficult
to disperse once they become established on a pond or
feeding site. Promptness and persistence are the keys to
success when attempting to repel nuisance or depredating
waterfowl. Frightening devices and repellents should be
in place before the damage starts to prevent the birds
from becoming acclimated to the site.
Discourage geese and other waterfowl from using a
pond by making it and the surrounding area unattractive
to them. Reduce nesting, loafing, and escape cover by
mowing to the edge of the pond, and by using herbicides
to eliminate emergent aquatic vegetation. Contact your
local Cooperative Extension office for specific
recommendations for vegetation management in ponds.
Reduce or eliminate fertilizer applications to the
surrounding grass area to make the grass less
nutritionally attractive to grazing waterfowl. Feeding
of waterfowl around the pond site should be prohibited.
In cold climates, shut off pond aerators in the winter
and allow the pond to freeze.
Giant Canada geese
generally will not establish nesting territories in
areas where they cannot easily walk in and out of the
local pond. Construct new ponds so there is an 18-to
24-inch (45to 60-cm) vertical bank at the water’s edge.
Discourage Canada geese from using existing ponds by
vertically straightening the banks or by erecting a 30-
to 36-inch (75-to 90-cm) high poultry-wire fence around
the pond at the water’s edge. Use large boulder rip-rap,
which geese cannot easily climb over, in locations such
as levees or banks around airport runways. Caution:
Large boulder rip-rap may provide nesting or loafing
habitat for some species of gulls.
Construct overhead grids of 0.015-to 0.030-inch
(0.4-to 0.8-mm) stainless steel spring wire, or
0.071-inch (1.8-mm) and heavier ultraviolet-protected
monofilament line to stop waterfowl from using
reservoirs, lakes, ponds, and fish-rearing facilities.
Several hundred feet (m) of monofilament line or
stainless steel wire can be supported between two
standard, 5-foot (1.5-m), steel fence posts, because
these materials are extremely light. The 0.072-inch
(0.18-cm) polyester line weighs about 12.1 pounds per
mile (3.4 kg/km); 0.016-inch (0.041-cm) stainless steel
wire weighs about 4 pounds per mile (1.14 kg/km).
Construct grids on 20-foot
(6-m) centers to stop geese; grids with 10-foot (3-m)
centers will stop most ducks. Grid wire spacing may need
to be reduced to 5 feet (1.5 m) or less to stop all
waterfowl. In most instances, grid lines should be
installed high enough to allow people and equipment to
move beneath them. Tie the grid wires together wherever
two lines cross to prevent rubbing. Excessive rubbing
will result in line breakage. Independently attach lines
to each post and not in a constant run. This will
prevent having to rebuild the entire grid when one line
Where aesthetics or other
factors preclude overhead grids, grids can be installed
at the water surface, or no more than 1 inch (2.5 cm)
below. In these installations, grid wire spacing should
be no more than 5 feet (1.5 m).
Use 1- to 1.5-inch (2.5-
to 3.75-cm) mesh polypropylene UV-protected netting when
total exclusion is needed, as in contaminated oil
containment basins. Support the netting with at least
0.19-inch (0.46-cm), 7 x 19-strand galvanized coated
cable on 20-foot centers. The support cables must be
well-anchored to carry the weight of the netting and to
allow the cable to be stretched tight to reduce sag as
much as possible. High winds are the greatest hazard to
this type of netting installation. Attach the netting to
the support cables to prevent wind-caused abrasion.
Abrasion can be more damaging than UV radiation.
poultry-wire fences around gardens or yards will help
keep geese out of such places, as adult geese with young
will not cross a fence and leave their young behind.
Good results have also been reported using 20-pound test
(9-kg), or heavier, monofilament line to make a 2-to
3-strand fence in situations where aesthetics preclude
the use of woven-wire fencing. String the first line 6
inches (15 cm) off the ground, with each additional line
spaced 6 inches (15 cm) above the preceding line.
Suspend thin strips of aluminum foil at 3-to 6-foot
(1-to 2-m) intervals along the lines to increase
visibility of the barrier. Best results are obtained
when the monofilament line fence is in place before
geese start grazing.
Half-inch (11-mm) mylar
tape can also be used to construct 2- to 3-strand
vertical goose-resistant fencing around lawns, gardens,
and crop areas. Place the first strand 1 foot (0.3 m)
above the ground, with each succeeding strand 1.5 feet
(0.5 m) above the previous strand.
Commercial clam growers
have been able to protect their clam beds from common
eiders by covering them with heavy 0.5-inch (1.27-cm)
mesh nylon netting. Mussel ropes can be protected from
scoters and eiders by suspending them in cages made of
0.25-inch (0.64-cm) mesh plastic coated wire fencing.
Caution: Birds may become entangled in the netting or
wire and drown. This could expose the owner to
prosecution under the Migratory Bird Treaty Act.
Agricultural Crops. Agricultural damage caused by
waterfowl can be reduced by timing crop planting or
harvest periods so they do not coincide with periods of
migration. For example, teal may damage early-planted
rice in some southern states. Rice that is planted in
April, however, after the birds have migrated north, is
relatively safe from damage by waterfowl.
Spring grains are
vulnerable to waterfowl damage in some northern regions
because of the agricultural practices required for their
production. Many spring grains are swathed at harvest
time, allowed to dry in the field, and then combined.
The short growing season, possible early frost, uneven
soil types, and topography sometimes prevent the even
ripening needed for straight combining. In areas of
severe waterfowl damage, farmers should consider the use
of on-farm or commercial grain dryers so that high-mois-ture
grain can be combined early. Early harvest and forced
drying of high-moisture grain, however, is expensive,
and can result in shrinkage and reduction of grain
Where conditions permit,
the production of winter grains instead of spring grains
may help eliminate waterfowl damage. Winter grains can
normally be straight combined in July and August, long
before migrating waterfowl arrive in the area.
Admittedly, a winter grain’s rosette of leaves is
vulnerable to grazing and puddling damage by waterfowl
in both the fall and spring. Research, however, has
shown that light grazing of the winter rosette can
actually increase stooling and grain yield.
Conduct spring planting in
as short a time as possible. This may reduce the length
of time that area crops are vulnerable in the fall and
allow harvesting in the shortest time possible. Delay
fall plowing as long as possible in areas where
waterfowl damage standing or swathed grains. Waterfowl
can be encouraged to feed in the stubble, away from
unharvested crops, by using harvested fields as
field-baiting sites (see Alternate Food Sources below).
Recent research indicates
that geese prefer certain grass species over others for
food. Bluegrass (Poa spp.) is one of the most preferred,
and tall fescue (Festuca arundinaceae) is one of the
least preferred. Plant tall fescue instead of bluegrass
to reduce goose grazing in golf courses, parks, or
cemeteries. Plant trees to interfere with the birds’
flight paths and plant shrubs to reduce the birds’
Alternate Food Sources.
Waterfowl damage to crops can be reduced by providing
alternate food sources in the form of lure crops or
direct feeding. For maximum benefit, an established and
well-organized program should be in place.
Lure crops are typically
grains that are used to attract and hold waterfowl,
thereby protecting other crop areas. Two general
strategies are used in establishing lure crop areas: (1)
seeding selected areas known to have a high incidence of
waterfowl damage with the specific intent of allowing
the birds to utilize the lure crop; (2) allowing the
birds to select a lure crop field and then paying the
landowner for the resulting loss.
Plant lure crops using
local crop(s) most subject to waterfowl damage. Plant at
the normal rate when using good quality seed. Increase
the normal planting rate by a factor of 1.5 to 2 when
using commodity grain or out-of-date seed to offset
reduced germination rates. Do not allow any hunting or
harassment of waterfowl in the lure crop area until all
crops are harvested and the damage season is over.
Field baiting involves
scattering grain in previously harvested fields or at
natural waterfowl feeding and/or loafing areas to
attract and hold waterfowl away from unharvested fields.
Studies in North Dakota indicate that the most effective
diversion of waterfowl occurs when the bait is made
available within 2 to 3 days of the birds’ first feeding
in an area. There are no set rules about the amount or
type of bait to use. Make enough bait available to
ensure that none of the birds go away hungry. If the
birds cannot get enough to eat at the baiting site, they
will go elsewhere. The bait grain should be something
the birds are familiar with and prefer. The same
material that is grown in the field should work well. Do
not allow any harassment of waterfowl in the area of the
baited field until all crops are harvested and the
damage season is over.
Surplus grain to conduct
these feeding programs can be obtained from the
Commodity Credit Corporation (CCC). People interested in
obtaining CCC grain for use in waterfowl damage
abatement programs should contact personnel from their
local US Fish and Wildlife Service regional office. CCC
surplus grain may only be used for the direct feeding of
depredating waterfowl or for seeding waterfowl feeding
areas. It may not be used to replace grain lost to
Regardless of the method
used (lure crop or field baiting), it may be necessary
to initially scare or herd the waterfowl away from the
surrounding fields. Once the birds have habituated to
the feeding site, and damage has stopped, repelling
efforts can be reduced.
Federal law requires that
all artificial feeding be stopped and all grain be
removed at least 10 days before hunting waterfowl within
the zone of influence of the baited area (50 CFR
Waterfowl may be repelled by almost any large
foreign object or mechanical noise-making device placed
in a field. The length of time frightening devices are
effective depends on the nature, number, and variety of
devices used. Move frightening devices every 2 to 3 days
and use them in varying combinations to improve efficacy
and prevent habituation. Repellents should be in place
before the start of the damage season to prevent
waterfowl from establishing a use pattern.
Visual repellents such as
flags, balloons, and scarecrows are normally used at one
per 3 to 5 acres (1.2 to 2 ha) before waterfowl become
accustomed to loafing or feeding in the area. After the
birds become accustomed to using an area, one or more
per acre (0.4 ha) may be necessary. Visual repellents
should be reinforced with audio repellents such as
automatic exploders, pyrotechnics, or distress calls for
All applicable state and
local laws must be observed when using frightening
devices. Pay particular attention to laws governing the
making of loud noises, discharging of firearms, use of
pyrotechnics, and use of free-running dogs. Also
consider the possible reaction of neighbors.
Flags for repelling
waterfowl can be made with 4-foot (1.2-m) laths and 6 x
30-inch (15 x 76-cm) strips of 3-mil safety orange
plastic or red and silver mylar ribbon (Fig. 2). Tests
conducted at Audubon National Wildlife Refuge indicate
that black flags are not effective. Place flags so they
are visible by waterfowl from all points in a field.
Waterfowl will land in an area where flags are not
visible. Once the birds land in a field with flags and
begin feeding, the flags’ effectiveness may be lost.
filled with helium, staked in open fields or over water,
have proven to be effective waterfowl repellents. Tether
the balloons with enough 75-pound (34-kg) test
monofilament line to allow them to rise at least 10 feet
(3 m) into the air. The use of balloons larger than 2
feet (0.6 m) in diameter is not recommended due to their
increased wind resistance. Balloons with large
contrasting eye spots seem more effective than balloons
without eye spots.
Scarecrows can be made out
of almost any material available. Three concepts should
be incorporated into any scarecrow design: movement,
bright colors, and large eyes. For maximum effect, the
arms and legs should readily move in the wind.
Construction materials should be of bright colors such
as red, blaze orange, or safety yellow. Research
indicates that scarecrows with large eyes are more
effective than scarecrows with small eyes.
Mylar tape, 1/2 inch (11
mm) wide, has been used successfully to protect lawns,
crops, and other areas from bird damage. When properly
installed, mylar tape combines three control strategies
in one — overhead grids, sound repellents, and visual
repellents. Wind blowing over the tape will produce a
roaring sound as the tape twists and flashes, reflecting
the sunlight. Install the tape 1 to 3 feet (0.3 to 1 m)
above the area to be protected on 6-to 30-foot (2- to
10-m) centers. For a 100foot (30-m) span, the tape
should be twisted no more than 4 or 5 times before tying
it off. Over-twisting will reduce the flashing and
roaring effect. Mylar tape has a tendency to break at
the knot. This can be overcome by covering the last foot
(0.3 m) of the mylar with nylon strapping tape before
tying it off.
Water spray devices, using
high pressure, rotating, clapper-type sprinkler heads
have been used to repel other bird species from
reservoirs and fish raceways. Gulls have been repelled
from drinking water reservoirs by covering 50% of the
total water surface with the sprinklers and cycling them
on and off (5 minutes on and 35 to 45 minutes off)
during the daylight hours. Similar methodology may be
effective against waterfowl.
Automatic exploders, also
known as propane cannons, make a loud noise without
discharging a projectile. One exploder may protect up to
25 acres (10 ha) under ideal conditions. The rate of
firing is manually adjustable; exploders should be set
to fire about every 5 to 10 minutes. Reduce waterfowl
habituation and increase the effectiveness of exploders
by mounting them on turntables so the cannon rotates a
few degrees with each firing. Turn exploders off after
dusk and on at dawn to reduce neighbor complaints, bird
habituation, and save on fuel. Clock timers or
photocells are available for this purpose. Waterfowl may
use fields on bright moonlit nights. When they do, it
may be desirable to run exploders all night.
Pyrotechnics such as
shellcrackers, whistle bombs, screamer/banger rockets,
and noise bombs can be used to repel depredating
waterfowl. These devices should be fired to explode in
the air just over the birds to produce the greatest
scaring effect and reduce the fire hazard. Allowing
pyrotechnics to explode on the ground could ignite dry
grass or weeds. Refer to Bird Dispersal Techniques for
Recorded distress calls
have been used to repel several species of nuisance
birds. Canada goose distress call tapes are not
commercially available as of this writing. Individuals
have made their own Canada goose distress call
recordings and have successfully repelled nuisance
Dogs trained to chase
waterfowl have been used to protect golf courses and
grain fields. Depending on the location and situation,
dogs can be free running, on slip-wires, tethered, or
under the control of a handler.
Fig. 3. Layout for walk-in
funnel trap to capture flightless geese. Canada geese
can be herded into a walk-in funnel trap during the
flightless Funnel opening 75' to 100' period for capture
Local concentrations of
problem waterfowl can be reduced by live trapping. The
final disposition of trapped birds should be agreed upon
in advance by all relevant state and federal agencies.
The trapping method to use will depend on the type of
birds and the location of the problem. Secure a federal
permit before carrying out live capture activity (50 CFR
Walk-in funnel traps (Fig.
3) are the most effective traps for capturing Canada
geese in late June or early July, when the adult birds
are molting and have lost the ability to fly, and the
goslings have not yet fledged. The traps also work well
for feral ducks and geese in parks and similar
Set up the trap next to a
lake or pond being frequented by the birds. When
possible, place the trap in the area where the geese
normally walk in and out of the water. In situations
where there is no lake or pond, place the trap in a
large open area.
Construct a walk-in funnel
trap using the following, or similar materials:
100 to 200 feet (30 to
60 m) of 3-foot (1-m) poultry wire (for the trap
60 to 80 feet (18 to
24 m) of 5-foot (1.5-m) woven-wire fencing (for the
21, 5-foot (1.5-m)
steel fence posts to support the fencing.
Netting to cover the
top of the holding pen if the geese are to be held
several hours or overnight.
Once the trap is
constructed, herd the geese into it using boats, and/or
people walking on land. The exact number of boats and
people needed depends on the size of the area and the
number of geese. Gasoline-powered boats are not
recommended because they are too noisy. Canoes,
rowboats, or boats with electric trolling motors work
best. Surround the geese on three sides, leaving the
only avenue of escape towards and into the trap. Once in
position, slowly and quietly drive the geese into the
trap opening (Fig. 4) and into the holding pen. From
there, load the birds into suitable transport equipment
(such as turkey crates and covered pickup trucks) for
final disposition. When handling birds, wear eye
protection and long-sleeved shirts to avoid getting hit,
scratched, or pecked.
Fig. 4. Herding geese into
a walk-in funnel trap.
Rocket or cannon nets,
typically 25 x 50 feet (8 x 24 m) can be used to capture
waterfowl. Nets with 1-to 1.5-inch (2.5-to 3.8-cm) mesh
work well for ducks; 2- to 2.5-inch (5- to 6.3-cm) mesh
is best for large geese. Place the net at a baiting site
located close to water and bait the site with corn or
other suitable bait until the bait is well accepted.
Once the target birds are trained to feed at the bait
site, capturing them is merely a matter of re-baiting
the area, allowing the birds to concentrate on the bait,
then firing the rockets or cannons that carry the net
over the birds. Remove the trapped birds from the net as
quickly as possible. Place the birds in suitable
transport equipment (chicken crates, turkey crates) and
take them to the predetermined location.
Spring-powered nets, about
half the size of a standard rocket or cannon net (16 x
25 feet or 4.9 x 7.6 m), are available. They can be
triggered manually or electronically. One manufacturer
claims a closure time of less than 0.75 seconds using
No. 3 mesh netting, and 1.5 seconds using No. 6 mesh
quiet operation and the absence of explosive and flying
projectiles may, in some situations, be an advantage
even with the net’s small area.
Net launchers use a single
large rifle blank cartridge to propel the net. They are
fired from the shoulder much like a shotgun or rifle.
Net launchers are available in two styles: wide angle
for launching a 20 x 20-foot (6 x 6-m) net, designed for
air-to-ground helicopter capture, and narrow angle for
launching a 12 x 12-foot (3.6 x 3.6-m) net, designed for
ground-to-ground capture. The smaller net launchers are
well suited for capturing individual or small groups of
Alpha-chloralose is an
immobilizing agent that depresses the cortical centers
of the brain. Waterfowl fed about 30 mg of alpha-chloralose
per kg of body weight become comatose in 20 to 90
minutes. Full recovery occurs 4 to 24 hours later.
Alpha-chloralose is best suited for capturing individual
or small groups of problem waterfowl in situations or at
times when other methods are not safe or practical.
The US Food and Drug
Administration (FDA) has approved alpha-chloralose as an
immobilizing agent for the USDA-APHIS-ADC program to use
in the capture of waterfowl, coots, and pigeons. This
use is granted exclusively to ADC under a continuing
Investigational New Animal Drug (INAD) application.
Alpha-chloralose may only be obtained from the Pocatello
Supply Depot for use as an avian wildlife immobilizing
agent. Alpha-chloralose may only be used by ADC
employees or biologists of other state or Federal
wildlife management agencies that have been certified in
its use, or persons under their direct supervision.
There are no chemical repellents currently
registered with the US Environmental Protection Agency
(EPA) for controlling waterfowl. Several chemicals that
have shown taste or olfactory repellent properties,
including methyl anthranilate, are currently being
studied by USDA-APHIS-ADC Denver Wildlife Research
Center and other agencies.
There are no toxicants currently registered with EPA
for controlling waterfowl.
Hunting, where safe and legal, is the preferred
method of reducing local populations of problem
waterfowl. Hunting has a strong repellent effect as
well. State wildlife management agencies can provide
information on current waterfowl hunting regulations.
In situations involving
real and direct threats to human health and safety, such
as geese around an airport, it may be possible to obtain
a permit from the US Fish and Wildlife Service to kill
migratory game birds. “Such birds may only by killed by
shooting with a shotgun not larger than No. 10 gauge
fired from the shoulder, and only on or over the
threatened area or areas” (50 CFR 21.42a). Such permits
are generally issued only when the use of nonlethal
control methods is not practical or possible. A solid
rationale as to why nonlethal methods will not work and
why the birds must be removed is generally required
before a permit to kill migratory game birds is issued.
The growth of local waterfowl populations can be
effectively slowed by destroying nests and eggs. This
method is especially effective with nuisance Canada
geese. Secure a federal permit before carrying out this
activity (50 CFR 21.41a).
Render eggs nonproductive
by vigorously shaking them as soon as possible after the
full clutch is laid and incubation begins. The longer
incubation continues, the more difficult it becomes to
destroy the embryo by shaking. It is safe to assume that
the clutch is complete and incubation has started if the
eggs feel warm. In situations where the start of
incubation is unknown, eggs can be aged using the
flotation method (Fig. 5).
Eggs in flotation stage 6
may be on the verge of hatching. If pipping has started,
the eggs should not be shaken, as shaking will probably
only accelerate hatching. Also, the US Fish and Wildlife
Service, Region 3 Law Enforcement, has taken the
position that a pipped egg contains a live bird, not an
embryo. Live birds may not be killed under authority of
an egg destruction permit.
After shaking the eggs,
return them to the nest, and allow the birds to incubate
for at least 3 weeks. The eggs and nest should not be
destroyed immediately after shaking. Doing so may cause
the geese to renest. Usually geese will not attempt to
renest if they have been incubating eggs for more than 3
weeks. Remove all nest materials and eggs from the area
after the appropriate waiting period. The nest and eggs
must be removed to discourage continuation of the
nesting effort and defense of the nest territory.
Most nest/egg destruction
permits do not authorize possession of waterfowl nests
or eggs. Therefore, all eggs and nest materials
collected under authority of such a permit must be
disposed of immediately.
Fig. 5. Age embryos by
placing 3 or 4 eggs in a pail of water and determining
Economics of Damage and Control
significant losses to agricultural and aquacultural
crops, damage golf courses, cemeteries, lawns, and
gardens, and contaminate reservoirs. Their activities
can cause real economic hardship, aggravate nuisance
situations, or create human health hazards. A reliable
figure for the total national economic loss caused by
waterfowl does not exist. The following examples serve
to illustrate the magnitude of the problem, however.
In 1960, waterfowl caused
an estimated $12.6 million worth of damage to ripening
small grains on the Canadian prairies. In 1980,
waterfowl were credited with causing $454,000 worth of
damage to small grains in North Dakota, South Dakota,
and Minnesota combined.
The 1989 appraised crop
losses due to goose damage totaled $105,000 in the four
Wisconsin counties surrounding Horicon Marsh National
Wildlife Refuge (NWR). It is estimated that in the
autumn of 1989 over 1 million interior Canada geese
passed through Horicon Marsh NWR. This area has one of
the largest and most active goose damage abatement
programs in the country, with an annual budget of more
Goose damage to golf
courses is difficult to quantify. A survey in 1982 of
219 golf courses in the eastern United States, however,
indicated that 26% had nuisance Canada goose problems.
It is not uncommon for geese to cause $2,000 to $3,000
damage per year to a golf course. Two golf course
superintendents in the greater Cleveland, Ohio, area
estimated that Canada geese caused between $2,000 and
$2,500 worth of property damage to each of their courses
in 1989. Three other golf course superintendents, in the
same geographic area, estimated that they spend $1,000 a
year just cleaning up Canada goose droppings, exclusive
of any direct property damage.
I wish to thank Richard A.
Dolbeer and Paul P. Woronecki of the USDA-APHIS-ADC
Denver Wildlife Research Center, and Douglas A. Andrews,
Ohio USDA-APHIS-ADC, for their editorial assistance in
the preparation of this manuscript.
Figure 2 adapted from
Figure 4 photo by T. W.
Figure 5 adapted from
For Additional Information
Bellrose, F. C. 1980. Ducks, geese, and swans of North
America, 3d ed. Stackpole Books, Harrisburg,
Pennsylvania. 540 pp.
Conover, M. R. 1991.
Reducing nuisance Canada goose problems through habitat
manipulation. Proc. Great Plains Wildl. Damage Conf.
Conover, M. R., and G. C.
Chasko. 1985. Nuisance Canada goose problems in the
eastern United States. Wildl. Soc. Bull. 13:228-233.
Cross, D. H.. 1987.
Deterring waterfowl from contaminated areas. US Dep.
Inter. Fish Wildl. Serv. Office of Information Transfer,
Region 8. 19 pp.
Duncan, M. J. 1980. The
use of plastic flags for controlling waterfowl damage in
small grains. US Dep. Inter. Fish Wildl. Serv. Leaflet.
Bismarck, North Dakota. 1 pp.
Emigh, F. D. 1962. Open
reservoir bird protection. J. Amer. Water Works Assoc.
Johnsgard, P. A. 1968.
Waterfowl: their biology and natural history. Univ.
Nebraska Press. Lincoln, 138 pp.
Knittle, C. E., and R. D.
Porter, 1988. Waterfowl damage and control methods in
ripening grain: an overview, US Dep. Inter. Fish Wildl.
Serv. Fish Wildl. Tech. Rep. 14. 17 pp.
National Archives and
Records Administration. 1992. Code of Federal
Regulations, Title 50, Parts 1 to 199, Wildl. Fish.,
Washington, DC. 615 pp.
Terry, L. E. 1984. A wire
grid system to deter waterfowl from using ponds on
airports. in Bird hazards at airports, prepared for the
Fed. Aviation Admin. by the US Dep. Inter. Fish Wildl.
Serv., Denver Wildl. Res. Center, Task H -DWRC Work Unit
904.33. 19 pp.
Westerkov, K. 1950.
Methods for determining the age of game bird eggs. J.
Wildl. Manage., 14:56-67.
Scott E. Hygnstrom; Robert
M. Timm; Gary E. Larson
PREVENTION AND CONTROL OF
WILDLIFE DAMAGE — 1994
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