There are several types of birds that are able to swim and dive underwater in search of food. The most common groups of swimming and diving birds include seabirds, waterfowl, and some shorebirds. Within these groups, some specific examples of birds that regularly swim and dive underwater include penguins, puffins, murres, loons, grebes, cormorants, and ducks.
Seabirds that Swim Underwater
Many seabirds have evolved excellent swimming and diving abilities to help them catch fish, squid, and other marine prey. Some of the most impressive underwater swimmers among seabirds include:
- Penguins – All species of penguins are excellent swimmers and can dive to impressive depths in search of food. Emperor penguins can reach depths of nearly 500 meters when hunting.
- Puffins – These colorful seabirds use their short wings to essentially “fly” underwater as they pursue small fish and invertebrates. Atlantic puffins can dive to 60+ meters deep.
- Murres – Also known as guillemots, these football-shaped seabirds dive down and use their wings to pursue schooling fish. Thick-billed murres can reach depths over 200 meters.
Other seabirds with excellent diving skills include cormorants, gannets, boobies, auks, and some species of tern.
Waterfowl that Dive Underwater
Many species of waterfowl frequent both freshwater and marine habitats and will dive underwater to find food. Some of the most prolific diving ducks include:
- Long-tailed ducks – These agile divers can plunge up to 60 meters deep to catch mollusks, crustaceans, and other invertebrates.
- Canvasbacks – Preferred foods like aquatic plants and roots require diving abilities, with dives reaching 15+ meters deep.
- Redheads – These omnivorous diving ducks will submerge and stick their tails up vertically while feeding on aquatic insects, mollusks, and plant material.
Other diving duck species include scaup, pochards, mergansers, goldeneyes, buffleheads, and ruddy ducks. Swans and geese within the waterfowl family do not typically dive.
Shorebirds that Dive for Food
Many wading shorebirds plunge into the water or undermine rocks to catch invertebrates and other prey. Some shorebirds with diving skills include:
- Loons – Excellent swimmers and divers, with some species like the common loon able to go as deep as 60 meters underwater.
- Grebes – Able to dive and swim underwater using their feet for propulsion. Horned and red-necked grebes can go deeper than 30 meters.
- Phalaropes – These slender sandpipers spin and stir up prey from muddy bottoms in shallow water.
Additional shorebirds that will dive or swim underwater to feed include avocets, stilts, and dippers.
Diving Adaptations in Swimming Birds
Birds that regularly dive and swim underwater have evolved a number of anatomical and physiological adaptations to help them thrive in an aquatic environment. Some of the key adaptations include:
- Streamlined bodies to reduce drag and allow efficient swimming
- Webbed feet or lobes on the toes to provide propulsion under water
- Legs placed further back on the body to be more effective for swimming
- Wings modified for providing underwater propulsion
- Extra covers over nostrils and ears to keep water out
- Exceptional ability to hold breath for extended dives
- Increased myoglobin in muscles to store oxygen for prolonged dives
- Plumage adapted to shed water and provide insulation
These adaptations allow strong swimmers like penguins, puffins, loons, and sea ducks to thrive and fill ecological niches based around underwater diving and swimming.
Hunting and Feeding Behaviors
Birds that are adept at swimming and diving use their skills in various ways to catch prey and find food underwater. Some behaviors and strategies include:
- Pursuit diving – Swimming rapidly after fish, squid, or other mobile prey
- Plunge diving – Propelling the body vertically down into the water to capture prey
- Pursuing schools of fish – Tracking and catching fish concentrated in large groups
- Undermining rocks or mud – Dislodging invertebrates from the seafloor or pond bottom
- Grabbing food from the surface – Lunging out of the water to catch prey
- Filter feeding – Straining tiny plankton and particles from mouthfuls of water
Different species use specialized techniques based on the type of food they pursue. For example, gannets plummet from high up to snatch fish near the surface, while penguins porpoise in and out of the water to catch krill.
Depth and Duration of Dives
The depth and duration that diving birds can reach on their underwater excursions depends on the species. Some examples include:
Bird Species | Maximum Depth | Average Dive Duration |
---|---|---|
Emperor penguin | 265 to 535 m | 4 to 5 minutes |
Long-tailed duck | 60 m | 30 to 60 seconds |
Thick-billed murre | 200 m | 2 to 4 minutes |
Western grebe | 30 m | 30 to 90 seconds |
The physiology of these birds allows them to exploit underwater food resources at depths and durations that would not be possible for terrestrial species. Their adaptations allow them to find prey even in dark, oxygen-deprived waters.
Underwater Vision
To successfully hunt and capture prey under the sea, diving birds have excellent underwater vision. Features that help them see well include:
- Flattened, streamlined eye shape
- Ability to adjust lens and corneal focus underwater
- Increased number of rod photoreceptors for low-light vision
- Special ultraviolet filters in the eyes
- Nictitating membranes that act like built-in goggles
These adaptations allow clear underwater sight even at murky depths. Some species also have specialized retina structures to help them see well both in water and in air.
Swimming Bird Species
Here is a summary table of some of the major groups of birds with specialized adaptations for swimming and diving underwater:
Bird Group | Example Species | Key Adaptations |
---|---|---|
Penguins | Emperor penguin, little penguin | Wings modified into flippers, dense bones, streamlined shape |
Puffins | Atlantic puffin, horned puffin | Flattened bill for catching fish, short stiff wings provide thrust |
Auks | Murres, auklets, guillemots | Compact shape, scaled skin for streamlining, heavy bones |
Seaducks | Long-tailed duck, scoters | Lobes on feet, salt glands for ocean water, waterproofing |
Cormorants | Double-crested cormorant | Hooked bill grabs slippery prey, wettable feathers |
Loons | Common loon, red-throated loon | Solid bones for diving, legs far back for propulsion |
Grebes | Pied-billed grebe, eared grebe | Lobed toes, heavy plumage, dense bones |
Conclusion
Many unique species of swimming and diving birds have evolved to take advantage of ecological niches based around water habitats and underwater food sources. Their adaptations allow them to plunge into oceans, lakes, rivers and other waters to find fish, invertebrates, plants and other prey. Groups such as penguins, loons, and puffins demonstrate how birds can develop excellent abilities for diving and swimming under the sea.