WATERFOWL (Ducks, Geese, Swans, etc.)

Waterfowl or (especially in North America) wildfowl, also waterbirds, is the collective term for the approximately 147 species of swans, geese and ducks. Wildfowl usually live on wetlands. Many species are hunted, and some are kept for ornamental purposes.

Identification
The term waterfowl is properly applied only to ducks, geese, and swans. 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.

Range
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 non-migratory.

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 South America.

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 Antarctica.

Habitat
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.

Food Habits
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 re-mate. 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 after hatching.

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 close.

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, over-wintering 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.

Economics of Damage and Control
Waterfowl cause 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 than $135,000.

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.

Legal Status
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. 703. 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 FR 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).

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 edition.

ANATIDAE:
Laysan duck (Anas laysanensis)
Hawaiian duck (Anas wyvilliana)
Aleutian Canada goose (Branta canadensis leucopareia)
Hawaiian goose (Nesochen sandvicensis)

RALLIDAE:
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)

GRUIDAE:
Mississippi sandhill crane (Grus canadensis pulla)
Whooping crane (Grus americana)


Damage Prevention and Control Methods

Exclusion
Install fence around ponds, gardens, and yards. Install overhead grids or netting on ponds, reservoirs, and fish raceways.

Habitat Modification
Vertically straighten pond banks. Allow ponds to freeze in winter. Eliminate vegetation (nesting/escape cover) in and around ponds. Reduce or eliminate fertilizer use around ponds.

Cultural Methods
Change the timing of planting and harvesting of vulnerable crops. Produce winter grains instead of spring grains. Use grain dryers to allow earlier harvest of high-moisture grain. Plant crops uniformly in spring. Delay fall plowing as long as possible. Use less-preferred plant species in parks, cemeteries, and lawns. Plant trees and shrubs to block flight path. Provide lure crops. Field baiting.

Frightening
Flags. Mylar tape. Balloons. Scarecrows. Water spray devices. Automatic exploders. Pyrotechnics. Recorded distress calls. Dogs.

Live Capture
Walk-in funnel trap. Rocket/cannon nets. Spring-powered nets. Net launchers. Alpha-chloralose.

Repellents
None are currently registered.

Toxicants
None are currently registered.

Shooting
Hunting is the preferred method of reducing localized populations, where safe and legal. Hunting has a strong repellent effect. Killing under special permit is advised only in extreme situations.

Other Methods
Destruction of nests and eggs helps to slow down local population growth.




ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (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).