Some, like the Swamp Sparrow and Marsh Wren, nest there almost exclusively. Many millions of ducks, geese, gulls, and other waterfowl also nest, breed, and feed there along with numerous waders and shorebirds-herons, bitterns, rails, and sandpipers. Kingfishers, owls, Ospreys, and other predators feed in wetlands. Birds such as Mallards and teals use wetlands while moulting because marshy areas provide excellent escape cover. Sandhill Cranes, geese, and Tundra Swans stop over in marshes during migration, to rest and feed and to regain their strength.
Wetlands are rich in nutrients and teem with more life than most people suspect.
Billions of microscopic algae and larger plants grow and flourish in the shallow waters, using the sun's energy to produce and reproduce their substance. They serve as food for countless forms of animal life, and these in turn are often consumed by birds and other animals. Bacteria and fungi are at work everywhere, breaking down dead plant and animal tissues and releasing nutrients for further use. But in marshes, sloughs, and other wetlands, nutrients tend to remain and accumulate. This is one of the reasons why wetlands in southern regions are so productive and why they attract so many forms of wildlife.