Global Warming and Waterfowl

Mallards on beach

Global warming is impacting waterfowl around the world, changing their habitats, food sources and migration cycles.

One of the most important waterfowl breeding areas in North America is the Prairie Pothole Region on both sides of the U.S./Canadian border in the northern Great Plains. Models of future drought conditions in the region due to global warming project significant declines in Prairie Pothole wetlands--up to 91 percent.

This could lead to a 9-69 percent reduction in the abundance of ducks breeding in the region, affecting populations of mallards, gadwall, blue-winged teal, northern pintails, canvasbacks, redheads and ruddy ducks throughout North America's flyways.

This is just one of the areas of waterfowl habitat seeing changes, as detailed in the National Wildlife Federation report, The Waterfowler's Guide to Global Warming.

Impacts to Waterfowl by Flyway

Waterfowler's Guide to Global Warming - Flyways Map

1 - Pacific Flyway

Critical waterfowl habitat of coastal marshes and estuaries along the Pacific Coast could be affected by sea-level rise, changes in inland precipitation patterns and a significant decline in average mountain snowpack.

2 - Central Flyway

The Prairie Pothole Region contains millions of shallow depressions that fill with water in spring. These ponds provide breeding habitat for millions of ducks and other migratory birds and many species of resident wildlife. As climate warms, many ponds could dry up or be wet for shorter periods, making them less suitable for breeding.

In the Great Plains and Rocky Mountains, drought and decreased snowpack could reduce water flow in the Platte River and associated streams. Sandhill and endangered whooping cranes use these water sources as they migrate.

3 - Mississippi Flyway

Shoreline wetlands of the Great Lakes provide critical habitat for breeding and migrating waterfowl, especially diving and sea ducks. Global warming is projected to contribute to cause a 19-39 percent decline in ducks here by 2030.

As climate warms, a possible 3 to 34-inch rise in average sea level by 2100 could eliminate up to 45 percent of coastal wetlands in the contiguous United States. The shallow wetlands of the Gulf coast are particularly vulnerable.

4 - Atlantic Flyway

Global warming is expected to affect the timing and distance of waterfowl migration. Warmer fall and winter temperatures in northern regions would make it unnecessary for waterfowl to fly as far south to find ice-free water and suitable food. For example, the unusually warm, late-arriving winter of 2001 increased hunting opportunities for waterfowl hunters in the Midwest and New England and reduced hunting opportunities in the Mid-Atlantic and South.

Global warming is also expected to affect shoreline wetlands of the St. Lawrence River in the United States and Canada, which provides critical habitat for breeding and migrating waterfowl.

Four Duck Species That May be Affected by Global Warming

Canvasback Duck 

Inhabitants of large prairie marshes during the summer, canvasbacks are wary birds that usually spend the winter on large lakes, bays, and estuaries. A major part of their diet is wild celery, which gives their flesh a rich taste. Canvasbacks are generally regarded as the best-tasting of North American waterfowl. Canvasback habitat is threatened by the draining of the large marshes they require to breed. Their long, V-shaped flocks are a striking sight as they move from one feeding ground to another.

Blue-winged Teal

Fast and wary, blue-winged teals fly in small groups or flocks, turning in unison and flashing the blue area of the wing. They arrive latest of all ducks at their breeding grounds and leave early in the fall. On low, marshy prairies in the central part of the continent, where this duck is most numerous, virtually every pond and pothole has a breeding pair. The male commonly "stands guard" on the pond while the female is incubating.



The mallard is undoubtedly the most abundant duck in North America, approaching nearly 10 million birds after breeding. Mallard courtship actually starts in the fall, and by midwinter pairs have formed. Mated pairs migrate northward together, heading for the female's place of origin. The male stays with the female until incubation is well underway, then leaves to join a flock of other males to begin the annual molt.

Northern Pintail

Once as common as the mallard at nearly 10 million birds, the northern pintail population has declined over the past 50 years to only about 3 million birds. Male pintails are unmistakable with their chocolate brown heads with a white stripe up the side of the neck, and long central tail feathers for which it is named. Winter flocks can be very large, numbering in the thousands. Some individuals winter as far south as Cuba, Mexico or even Central America. Seeds of aquatic plants are the pintail's main food, but in winter it also eats small aquatic animals; when freshwater habitats freeze over, it resorts to tidal flats, where it feeds on snails and small crabs. Male Northern pintails are aggressive, often forcing their attentions on females of other species.

Related Link:

Silent Spring: A Sequel? - Climate change already is affecting the range and behavior of many North American birds; some scientists fear these shifts are just a hint of what's to come.

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