The Anas genus of ducks are known as dabbling ducks. Dabbling ducks are birds who feed near the surface of lakes, rivers and ponds. Ducks in the Anas genus feed primarily on vegetation, small insects and fish. The northern pintail, garganey, cinnamon teal, mallard, mottled duck and the American wigeon are some of Illinois' dabbling ducks. According to the University of Illinois, the mallard duck, or Anas platyrhynchos, is the most widespread duck in Illinois and North America. Dabbling ducks are medium-sized ducks with most species ranging from 13 to 15 inches in length.
Diving ducks are ducks under the Aythya genus of birds. These ducks are birds who dive under the water's surface to hunt for food. Diving ducks are omnivorous and their diet includes invertebrates, fish and aquatic plants. Illinois' list of Aythya ducks includes lesser scaups, ring-necked duck, canvasback duck and redhead duck. Aythya ducks are approximately 12 to 15 inches long; the largest diving duck in Illinois is the canvasback duck, or Aythya valisineria, at 15 inches. Many diving ducks in Illinois live in the Illinois River Valley, reports the Illinois State Museum website.
Two of Illinois' merganser ducks -- common merganser and red-breasted merganser -- belong to the Mergus genus. Mergansers are ducks who are able to live in freshwater and saltwater environments; however, most mergansers live in freshwater habitats. Mergansers have more slender beaks than dabbling and diving ducks. Also, these ducks are among the longest Anatidae species; male common mergansers grow up to 25.5 inches as adults. Mergansers are carnivorous and they eat fish, invertebrates and amphibians. Another merganser in Illinois, the hooded merganser, is in the Lophodytes genus.
Illinois is home to three swans -- tundra, trumpeter and mute. All three swan species belong to the Cygnus genus. Swans are the largest Anatidae birds in Illinois. The largest swan is the Mute swan, or Cygnus olor, which reaches over five feet. Cygnus birds have elongated necks and eat on land and in water. In the water, swans only reach for food near the water's surface; the diet of swans consist primarily of plants, but they also eat small invertebrates. Migration habits vary among the swans. Tundra swans migrate regularly, while trumpeter and mute swans are partially migrant -- which means not all populations within a species migrate.