The effects climate change could have on waterfowl habitat and waterfowlers would likely be different across regions. Following is an overview of potential climate change impacts in some of Ducks Unlimited’s highest priority conservation areas.
Warmer temperatures in the Pacific Flyway would likely cause more precipitation to fall as rain rather than snow, leading to more extreme flood events in the winter, altering the timing, quantity, and quality of water in this region. This may be particularly troublesome in California’s Central Valley, a continentally important waterfowl wintering area where water shortages are already commonplace. Along the coast, sea level rise would particularly impact shallow tidal habitats of vital importance to migrating and wintering Pacific brant and many other waterfowl species.
The Western Boreal Forest, where a high proportion of the ducks that migrate through the Pacific Flyway are produced, is already experiencing significant changes as permafrost thaws, wetlands dry up, and the ranges of plants and animals shift northward.
Northern Central Flyway - Prairie Pothole Region
The Prairie Pothole Region provides breeding habitat for up to 60 percent of North America's ducks. The region is already under severe pressure as millions of acres of grassland have been converted to cropland in recent years. If the climate warms and evaporation and water use by plants increase, many vital pothole wetlands may dry up or be wet for shorter periods of time, making them less productive habitat for waterfowl. More than 80 percent of prairie wetlands are less than 2.5 acres in size, making this highly dynamic ecosystem and the waterfowl that rely on this landscape particularly sensitive to changes in water abundance and availability.
Northern Mississippi Flyway - Great Lakes
The Great Lakes contain 20 percent of the world's fresh water, sustain an economy for 40 million people, and support millions of waterfowl throughout their annual life cycle. Waterfowl managers face challenges of historic wetland losses exceeding 60 percent, reduced water quality, invasive species, and a growing human population in the region.
Mounting scientific evidence suggests that the climate of the Great Lakes region is already changing: annual average temperatures are growing warmer and extreme heat events are occurring more frequently. The duration of lake ice cover is decreasing as air and water temperatures rise. Despite an increase in heavy precipitation events, the climate of the Great Lakes region is projected to grow warmer and likely drier during this century.
Declines in breeding black ducks and migrating scaup and canvasbacks would continue to be issues as climate change further impacts the region. Reduced summer water levels are likely to reduce groundwater supplies, causing small streams to dry up and shrinking the size of wetlands, resulting in poorer water quality and less habitat for breeding waterfowl.
Southern Central and Mississippi Flyways
Coastal land loss is the primary threat to waterfowl habitat in this region, especially in Louisiana. Projected sea level rise would claim even more of this vital coastal waterfowl habitat, presenting significant conservation and policy challenges along the Gulf. A predicted sea-level rise of more than three feet over the next 90 years would result in dramatic losses of waterfowl habitat in coastal Louisiana, threatening resident mottled ducks and a variety of other wildlife.
Farther north, in the Mississippi Alluvial Valley, the climate could become warmer and drier in the future, which would likely affect water availability for agriculture and waterfowl management. A shift to non-irrigated crops would mean a widespread loss of rice agriculture, which currently provides vital food resources for waterfowl and other migratory birds.
Loss of winter and migration habitat in the southern Mississippi Flyway from rising sea levels and reduced precipitation and water availability would diminish the region’s capacity to support wintering waterfowl, threatening cherished hunting traditions.
In the northern reaches of the Atlantic Flyway, the current trend of warmer temperatures, particularly in winter, is expected to continue in the future, potentially impacting nesting black ducks and wood ducks. Flooding is expected to become more common and increase in severity. Sea level rise would alter coastal waterfowl habitat throughout the flyway, as fresh and brackish marsh is replaced by less diverse salt marsh and open water. And loss of sea grass beds would affect black ducks, canvasbacks, and other waterfowl that depend on this food resource while migrating and wintering on coastal waters.