Ducks are various species of waterfowl in the family Anatidae. They are generally smaller and shorter-necked than swans and geese, which are also part of this family. Ducks are classified into several subfamilies but do not form a monophyletic group, as swans and geese are not considered ducks. They are mostly aquatic birds found in both freshwater and saltwater.
Ducks have a cosmopolitan distribution, found on every continent except Antarctica. Some species inhabit isolated oceanic islands and are often vagrants in places like the Hawaiian and Galápagos Islands.
Many duck species from the temperate and Arctic regions are migratory, while those in the tropics are generally not. In Australia, some ducks are nomadic, following temporary water sources after rainfall. Their diet includes grasses, aquatic plants, fish, insects, and small animals.
Dabbling ducks feed at the surface or on land, using a comb-like structure called a pecten along their bill to strain food, while diving ducks forage underwater and are typically heavier, which makes taking off harder. Some, like mergansers, are adapted for catching larger fish.
Ducks usually form monogamous pairs for a single breeding season, though larger and more sedentary species may bond longer. They typically breed once a year, nesting before laying eggs. Mother ducks care for their ducklings but may abandon them under certain circumstances, such as nest abandonment or poor health.
Ducklings are vulnerable to predators, including birds, large fish, and land mammals. While adult ducks can fly quickly, they may still be preyed upon while on water by larger predators like pike.
