Australia is home to a diverse array of bird species, some of which have adapted the ability to swim and dive underwater. This allows them to forage for food in rivers, lakes, and oceans around the country. There are several groups of birds in Australia that exhibit impressive underwater swimming abilities.
Penguins
Penguins are perhaps the most iconic aquatic birds in Australia and around the world. There are three species of penguins that inhabit Australia:
- Little penguin – The little penguin is the smallest penguin species in the world and is found along the southern Australian coastline. They grow up to 33 cm tall and weigh about 1 kg. Little penguins can dive to depths of 20-30 meters to hunt for fish, squid, and crustaceans.
- Fiordland penguin – The Fiordland penguin is a medium-sized penguin species that inhabits southeastern Australia, Tasmania, and New Zealand. They reach 45-60 cm in height and 2-3 kg in weight. Fiordland penguins feed on fish, squid, and krill and can dive up to 120 meters deep.
- King penguin – The king penguin is the second largest penguin species and breeds on islands near Antarctica. They occasionally visit the south coast of Australia during the winter months. King penguins grow up to 90 cm tall and weigh 10-16 kg. They are capable of diving deeper than 300 meters in search of food.
Penguins have evolved a number of adaptations that make them excellent swimmers and divers. Their wing bones are flattened and stiff, acting like flippers to propel them through the water. A layer of fat and dense feathers help insulate them from cold water temperatures. Penguin eyes are adapted to see well underwater by having a flat, thick lens. They can slow their heart rate to conserve oxygen while diving for extended periods.
Cormorants
Cormorants are medium-to-large sized seabirds that inhabit Australia’s coastlines. There are several species of cormorants found across the country:
- Little pied cormorant – Found along the entire Australian coastline and inland waterways.
- Great cormorant – Found along the southern Australian coast.
- Black-faced cormorant – Found along the southern Australian coast.
- Little black cormorant – Widespread in wetlands across Australia.
Cormorants are skilled divers, reaching depths of up to 30 meters in search of fish, eels, crustaceans, and amphibians. They propel themselves underwater with their large webbed feet. Cormorants have waterproof plumage and a reduced oil gland to avoid their feathers becoming waterlogged while diving. They can remain submerged for over a minute during a single dive.
Grebes
Grebes are a family of small to medium-sized diving birds with lobed toes and pointed bills. There are several grebe species native to Australia:
- Australasian grebe – Found across Australia in freshwater lakes and slow-moving rivers.
- Hoary-headed grebe – Inhabits lakes, swamps, and estuaries in southern and western Australia.
- Great crested grebe – Mostly found in eastern Australia and Tasmania.
Grebes dive to catch small fish, crustaceans, tadpoles, and aquatic insects. They use their feet to propel themselves while swimming and diving. Their legs are positioned far back on their bodies, making them less efficient at walking on land but excellent at swimming. Grebes can dive to depths over 30 meters and have adaptations like dense bones and high myoglobin concentration in their muscles to cope with diving for food.
Darters
Darters, also known as snakebirds due to their serpentine neck and habit of swimming with their body submerged, are medium-sized diving birds found across Australia. The most common and widespread species is the Australasian darter.
Darters swim using their large webbed feet and propel themselves underwater with powerful kicks. They spear fish with their long, pointed bill and swallow their prey whole while still submerged. Darters have waterproof plumage and will swim buoyantly with just their neck and bill poking above the waterline. They can stay underwater for extended periods in search of fish and other aquatic prey.
Ducks, Geese, and Swans
There are numerous species of ducks, geese, and swans in the Anatidae family that inhabit Australia and have adaptations allowing them to dive and swim underwater:
- Musk duck – A stiff-tailed diving duck found in eastern Australia. They regularly dive 3-4 meters in search of aquatic plants and small invertebrates.
- Blue-billed duck – A small, stiff-tailed diving duck inhabiting Tasmania and the southwestern mainland. Dives to depths of 20 meters.
- Hardhead – A diving duck widespread across Australia. They forage underwater for aquatic plants and insects.
- Pacific black duck – An omnivorous dabbling duck that will upend and make shallow dives to feed on plants and invertebrates.
- Maned duck – Found across eastern and southeastern Australia. Both males and females make regular dives while foraging.
- Magpie goose – Found across northern Australia. They dive to depths over 4 meters to find aquatic vegetation.
- Black swan – Widespread across Australia. They feed on submerged aquatic plants obtained by diving and dabbling.
Many ducks make use of their oil gland to coat their feathers for waterproofing before diving. Mergansers, a type of diving duck, have serrated edges to their bill which helps them grip slippery fish underwater. The stiff tail feathers of some diving duck species, like the musk duck, are used as rudders to provide agility and steering while submerged.
Loons
Loons are a group of diving birds found in the northern hemisphere. One species, the Arctic loon, is an occasional visitor to the waters off northern Australia during the winter months. The Arctic loon is an excellent swimmer and diver, using its pointed bill to snare small fish and aquatic crustaceans. It propels itself underwater using its feet and can reach depths down to 60 meters.
Shearwaters and Petrels
Shearwaters and petrels are seabirds in the Procellariidae family. While most species are surface feeders, some have adapted to pursue prey underwater:
- Short-tailed shearwater – Makes shallow dives to capture small fish and krill.
- Wedge-tailed shearwater – Catches prey by diving up to several meters below the surface.
- Flesh-footed shearwater – Dives from the surface to pursue schools of fish.
- Common diving petrel – Dives underwater in search of krill, small fish and squid.
These diving seabirds use their wings for propulsion and steering while swimming underwater. They have solid bones and unique nasal anatomy to withstand pressure changes while diving.
Gannets
Gannets are large seabirds that plunge dive from heights of up to 30 meters to catch fish and squid. Two species are found in Australia:
- Australasian gannet – Breeds on islands off southern and western Australia.
- Masked booby – Breeds on offshore islands in northern Australia.
Gannets have air sacs in their face and chest that cushion the impact when they hit the water at high speeds. Their streamlined bodies and pointed wings help them slice cleanly into the water to pursue prey. They use their feet and wings to propel themselves while swimming underwater.
Herons
While primarily wading birds, some herons will submerge their head and neck underwater to ambush fish in shallow waters. Australian heron species known to feed in this manner include:
- White-faced heron
- White-necked heron
- Nankeen night-heron
- Striated heron
These herons typically feed in rivers and wetlands. Their long neck allows them to strike prey while their body remains above the waterline. However, they are capable of briefly diving their entire body when needed.
Pelicans
Pelicans are large waterbirds with a huge throat pouch used for catching fish. Two species found in Australia forage by diving:
- Australian pelican – Widespread in wetlands across Australia. Plunge dives from the surface to depths of up to 3 meters.
- Pink-backed pelican – Found in northern Australia. Dives from heights of up to 12 meters to catch fish.
The impact when pelicans hit the water from plunging dive is cushioned by their air sacs beneath their skin. They scoop fish up in their elastic throat pouch while swimming underwater.
Tropicbirds
Tropicbirds are a family of agile seabirds found in tropical waters. The red-tailed tropicbird and white-tailed tropicbird are summer breeding visitors to islands off northern Australia. They catch fish by plunge diving into the ocean and pursue their prey while swimming underwater using their wings to propel themselves.
Boobies
Boobies are seabirds closely related to gannets. The brown booby and red-footed booby breed on islands off northern Australia. They are spectacular plunge divers, dropping from heights of 20-30 meters to catch fish. Streamlined bodies and spear-like bills help them catch fish while submerged.
Crows
The Australian raven and little crow are known at times to wade into shallow water and briefly submerge their head to catch prey like fish, frogs, and crabs near the shoreline. They do not actively dive underwater, but will immerse their head when the opportunity arises in shallow wetlands or intertidal zones.
Kingfishers
Kingfishers are medium-sized birds specialized for catching fish. They inhabit rivers, lakes, and coastlines across Australia. While most kingfisher species hunt from perches above the water, some are capable of diving down to pursue prey underwater, including:
- Azure kingfisher – Can dive up to 1 meter below the surface.
- Laughing kookaburra – Dives to catch fish, shrimp, and crayfish.
Kingfishers have tough, pointed bills for spearing fish and protective membranes that cover their eyes when diving.
Conclusion
Australia is home to a wide array of aquatic birds with impressive swimming and diving abilities. Penguins, cormorants, grebes, darters, and many types of waterfowl are expert swimmers and divers uniquely adapted for pursuing prey underwater. Even some tropical seabirds, like shearwaters and gannets, are capable divers. Diving allows these birds to access food resources in rivers, lakes, and oceans that are not available to strictly terrestrial species. However, diving underwater puts physiological stresses on birds due to pressure changes and limited oxygen, requiring specialized adaptations to allow different species to thrive in aquatic environments.
