Ducks, Geese, Swans

Anatidae, the family of water birds that includes ducks, geese, and swans, is found globally except for Antarctica and comprises about 174 species in 43 genera. These birds are adapted to an aquatic lifestyle, most having webbed feet, and are equipped for swimming, floating, and sometimes diving. They range greatly in size, from the tiny cotton pygmy goose to the large trumpeter swan, have strong wing muscles for flight, and mostly possess flattened, serrated bills for filter feeding, although some are piscivorous like the mergansers. Anatids often showcase differences between males and females in coloration, and they are vocal with a range of sounds. While they are largely herbivorous, feeding on water plants, their diet can diversify to include fish, molluscs, or aquatic arthropods. These birds are seasonal, monogamous breeders, with some species forming lifelong pairs. They lay simple nests lined with down, and the precocial young are self-sufficient immediately after hatching. Certain species have been domesticated for their feathers, meat, and other uses, yet at least five species have gone extinct since 1600 due to human impacts, with others currently threatened. Duck species have also been important cultural icons and economic assets for humans. The classification of Anatidae is complex, with relationships between groups not completely resolved and subject to change as new genetic studies provide further insights. Fossil records indicate that Anatidae are an ancient group with a lineage that stretches back to the time of dinosaurs.