Water birds, or aquatic birds, encompass a diverse group adapted to living in marine or freshwater environments. These birds exhibit a range of adaptations for swimming, diving, and wading. Common habitats include oceans, lakes, rivers, and wetlands. Their evolutionary paths have equipped them with specialized features like webbed feet, waterproof feathers, and elongated beaks, facilitating their aquatic lifestyle. Examples include ducks, swans, herons, and penguins. Their evolutionary history is marked by adaptations that have allowed them to exploit aquatic food sources effectively, making them integral components of their respective ecosystems and indicators of environmental health.

Water birds possess unique anatomical features suited to aquatic life. Many have waterproof feathers and oil glands for preening, keeping them buoyant and dry. Webbed feet or lobed toes aid in efficient swimming, while varying beak shapes reflect diverse diets, from filter-feeding ducks to fish-catching herons. Their bones are often less dense than terrestrial birds, aiding in flotation. Movement varies: some paddle gracefully, others dive, and many fly, with wings adapted to their lifestyle. Vocalizations range from melodious calls to honks and quacks. Keen vision helps spot prey in water, and some species even have specialized eyesight for underwater clarity.

Humans have long been fascinated by water birds, incorporating them into myths, art, and literature. Swans symbolize grace and fidelity, while ducks feature in children's stories and cartoons, like the famous Donald Duck. Historically, water birds have been hunted for food and feathers, leading to population declines.

Today, many species are protected by laws and conservation initiatives, recognizing their ecological importance and the enjoyment they bring to birdwatchers and nature enthusiasts. Wetland conservation efforts are crucial for their habitats, and citizen science projects often involve monitoring water bird populations to aid in their preservation.