Birds are known for their mastery of the skies, but a unique subset of avian species excels in both aerial and aquatic environments. This dual capability, navigating seamlessly through air and water, represents a remarkable evolutionary achievement. The ability to swim and fly showcases how diverse adaptations enable survival across different fluid mediums.
Masters of Two Realms
Many bird groups can both swim and fly, though their proficiency varies. Ducks, geese, and swans (Anatidae) are well-known examples, using water for feeding and safety, and flying efficiently for migration. Cormorants are recognized for deep-diving to pursue fish, with strong flight covering significant distances between foraging grounds and roosts.
Loons and grebes are highly specialized aquatic birds that are also capable fliers, despite appearing awkward on land. Loons, with dense bones, are skilled divers, while grebes are known for rapid underwater hunting.
Seabirds like auks, puffins, and murres also demonstrate this dual locomotion. Puffins are expert aquatic birds that use their wings to “fly” underwater, yet maintain strong flight for traversing ocean expanses. Gulls are versatile, gliding over water, diving for prey, and adept at sustained flight.
Specialized Adaptations for Dual Locomotion
Birds capable of both swimming and flying possess physical adaptations for two very different fluid environments. For aquatic propulsion, many feature webbed feet, acting like paddles for efficient movement. Their bodies are often streamlined to reduce drag while swimming and diving.
Waterproof plumage, from tightly packed feathers and specialized oils, is essential for insulation and buoyancy, preventing water from reaching skin and maintaining body temperature. Some diving birds, like cormorants, have less waterproof feathers, allowing their plumage to become waterlogged, reducing buoyancy and facilitating deeper dives.
For flight, these birds exhibit adaptations typical of aerial species, including strong pectoral muscles. While many flying birds have hollow bones to reduce weight, diving birds often have denser bones to aid submersion and counteract buoyancy. This represents a compromise, as heavier bones make flight more energetically demanding.
Birds like auks and puffins, which use their wings for underwater propulsion, have shorter, stiffer wings optimized for moving through water. This comes at a higher energy cost for aerial flight. This dual functionality means their wing morphology balances the demands of both aerial lift and underwater thrust.
Ecological Roles and Habitats
The ability to both swim and fly provides evolutionary advantages, enabling these birds to exploit diverse ecological niches and survive across varied landscapes. This dual locomotion aids foraging, as many species dive to catch fish, crustaceans, or aquatic vegetation. Pelicans, for example, use large pouches to scoop fish, while murres dive to considerable depths. These birds escape predators by diving or taking flight, offering multiple defense strategies.
Their capacity for both aerial and aquatic travel aids migration, allowing them to traverse vast distances over land and water for breeding grounds, feeding areas, or warmer climates. Many species access nesting sites on remote islands or cliffs, requiring strong flight, yet rely on nearby water for food. These birds thrive in coastal areas, large lakes, and open ocean environments, accessing abundant food and safe havens. Their presence often indicates healthy aquatic ecosystems, as they play roles in nutrient cycling and seed dispersal.