Although most people find a few birds acceptable, problems quickly develop as bird numbers increase. These problems include overgrazing of grass and ornamental plants; accumulation of droppings and feathers; attacks on humans by aggressive birds; and the fouling of reservoirs, swimming areas, beaches, docks, lawns, and golf courses. Flocks of geese and other waterfowl also feed on a variety of crops, including corn, soybeans, rice, lettuce, winter wheat, barley, and rye.
Damage to Property
Canada goose nests occur near sidewalks and entryways of homes and other buildings, adjacent to paths and roadways, and on rooftops and porches. They are also found in more traditional areas, including parks and other open space. Flocks can leave behind a large amount of fecal material, especially if they routinely use the same sites. The feces can reduce the water quality of ponds and spoil the lawns of parks, golf courses, apartment complexes, and business parks. Mallards, wigeons, and coots also flock in parks and residential developments and cause similar problems.
Damage to Agriculture
Migratory waterfowl cause damage to agricultural crops in many parts of the United States. Crops are vulnerable to damage by ducks, coots, and geese through direct consumption of crops as well as trampling and fouling. Some waterfowl also cause problems at aquaculture facilities by feeding on fish fry and fingerlings.
Health and Safety Concerns
Defense of nests and young by geese and swans can result in injuries to people who approach too closely. Populations of waterfowl may contaminate recreational areas with pathogenic bacteria that may pose human-health risks. Waterfowl on or near airports affect public safety due to the possibility of bird-aircraft collisions.
Damage to Natural Resources
Canada goose and mute swans may impact native wild rice, restored wetlands, and tidal marshes when large flocks graze on vegetation and trample plantings.Resident Canada goose and non-native Mute Swans may out-compete native waterbirds and waterfowl for habitat and food. Resident Canada goose and non-native Mute Swans may out-compete native waterbirds and waterfowl for habitat and food. Additionally, overabundance of ducks, geese and swans in natural areas may cause erosion and reduce water quality due to feces and runoff.