Birds have an incredible ability to fly through the air with grace and speed. But can they also dive underwater like other animals? The answer is yes – some bird species are excellent divers capable of plunging deep below the surface to catch fish or escape predators.
What allows birds to dive?
Certain anatomical and physiological adaptations enable some birds to dive efficiently:
- Streamlined bodies to reduce drag and allow them to slice through the water.
- Wings designed for propulsion underwater via swimming motions.
- Feather coats with waterproofing oils that resist water absorption.
- Powerful leg muscles to propel their swimming strokes.
- High myoglobin levels in their muscle tissue to store oxygen for longer dives.
- Slowed heart rate to conserve oxygen usage while submerged.
- Special membranes to protect their eyes and ear canals at depth.
With these adaptations, birds like penguins, cormorants, gannets, and puffins can plunge into the oceans, lakes, and rivers in pursuit of food. Their streamlined bodies and propulsive wings allow them to swim effectively while their oxygen storing abilities let them stay under for minutes at a time. Their waterproof feathers and protective membranes allow them to dive deep without injury. Together these features make many birds champion divers.
Bird diving techniques
Different species have evolved specialized diving strategies and techniques:
The Plunge Dive
Gannets, terns, boobies and other coastal species perform dramatic plunge dives from heights of 30-100 ft. They barrel into the water, piercing the surface at up to 60 mph. The force drives them underwater while their streamlined bodies and wings transform into aquatic propulsion systems. They chase down fish before using their wings to paddle back up to the surface.
The Pursuit Dive
Cormorants and grebes do pursuit dives, swimming on the surface then diving and chasing prey underwater using their feet and wings for propulsion. They can dive to depths over 30 m and stay submerged for several minutes thanks to high myoglobin levels that allow them to hold their breath for a long time.
The Preening Dive
Diving birds like penguins will do gentle preening dives to clean and waterproof their feathers while escaping predators. They slip gracefully into the water then swim around near the surface grooming their feathers before popping back out.
The Escape Dive
Many diving birds plunge into the water as an escape tactic. Smaller birds like auks can quickly paddle underwater out of the reach of predators. Larger birds crash dive to escape aerial predators, relying on their underwater agility to outswim danger.
Maximum diving depths and times
The maximum diving depths and times recorded for different bird groups include:
Bird Group | Max Depth | Max Time Underwater |
---|---|---|
Penguins | 265 m – 535 m | 18 min |
Auks | 76 m | 4.5 min |
Cormorants | 40 m | 6.5 min |
Gannets | 24 m | 3.6 min |
These depths and times are quite incredible, far exceeding human free diving abilities. Penguins are the champions, with the emperor penguin capable of diving nearly 550 meters deep and staying submerged for up to 18 minutes. Even smaller auks can reach depths over 75 m and hold their breath for several minutes. This demonstrates the superb adaptations these birds have for plunging deep into their watery environment.
Why do birds dive?
Birds rely on diving for several key reasons:
Catching prey
The number one reason diving birds plunge into the water is to catch fish, aquatic invertebrates and other prey. Their underwater agility allows them to swiftly pursue quarry like sardines, anchovies or squid. Penguins can reach swift burst speeds underwater to snag darting fish. Auks paddle quickly in pursuit of small crustaceans. Cormorants use their great eyesight to target bottom-dwelling fish. Diving allows these birds to access food resources unavailable to most other bird groups.
Predator avoidance
On the surface birds are vulnerable to predation from above by falcons, eagles and other raptors. By diving into the water, many species can escape aerial predators that won’t follow them into the aquatic realm. Penguins porpoising into the water become safe from skua attacks. Smaller birds like guillemots quickly paddle underwater away from danger.
Self maintenance
Diving serves important non-feeding functions too. Many birds will do mini-dives to preen their feathers and spread waterproofing oils. Diving helps remove external parasites and maintains feather integrity. Birds like puffins and murres are able to escape to the relative safety of the water to groom themselves.
Notable diving bird species
Some of the most impressive diving birds include:
Emperor Penguins
The largest penguin species, emperor penguins breed on the Antarctic ice and make incredibly deep dives of over 500 meters when hunting. Their extreme adaptations allow them to hunt deep dwelling fish and krill in the cold southern oceans. Strong leg muscles and dense bones help counteract pressures at great depths.
Puffins
Puffins are small attractive auks noted for carrying fish crosswise in their beaks. They dive down using their wings to pursue small fish and can swim to depths of 60 meters. Puffins have excellent underwater vision to spot prey and paddle swiftly with their wings.
Gannets
These large coastal seabirds perform dramatic plunge dives from great heights to catch fish. Their streamlined bodies, expansive wings, and waterproof feathers allow them to hit the water at high speeds and pursue prey deep below the surface. Gannets may dive to over 20 meters depths.
Cormorants
Expert fishers, cormorants dive and swim using their big webbed feet to chase down small fish. They propel through the water with powerful kicks and have special feathers that reduce buoyancy. Cormorants can reach depths over 30 meters.
Murres
Also known as guillemots, murres plunge into frigid arctic waters in pursuit of fish and invertebrates. Their compact bodies allow rapid acceleration underwater and specially adapted wings provide propulsion. Murres can spend several minutes submerged diving to depths of 200 meters.
Ocean diving vs. freshwater diving birds
Both ocean and freshwater habitats have diving bird specialists with adaptations for those conditions:
Ocean divers
- Penguins – dense bones for pressure resistance.
- Shearwaters – salt glands to excrete excess salts.
- Gannets – waterproofing oils for buoyancy control.
- Auks – compact rigid bodies and short wings for propulsion.
Freshwater divers
- Cormorants – wettable feathers to reduce buoyancy.
- Grebes – lobed toes for fast swimming.
- Herons – long necks and spear-like bills to snatch fish.
- Kingfishers – streamlined heads to pierce the water.
Oceanic divers tend to have more robust adaptations to handle deep diving pressures, while freshwater divers emphasize greater maneuverability and speed to catch prey in smaller water bodies.
Bird diving hazards and air sacs
Bird lungs do not inflate and deflate like mammalian lungs. Instead they have a system of air sacs used to ventilate their respiratory system during diving. This offers several key advantages:
- Prevents water pressure building up in lungs during deep dives.
- Maintains bouyancy during extended dives.
- Enables unidirectional airflow for efficient gas exchange.
However, there are still hazards to diving birds including:
- Oxygen toxicity at extreme depths.
- Decompression sickness during fast ascents.
- Waterlogging of plumage making buoyancy control and flight difficult.
- Predation from aquatic mammals like leopard seals.
Birds have adaptations to moderate these dangers including special membranes over their nostrils and slow ascent rates following deep plunges. But diving remains an energetic and hazardous activity for birds. Their anatomy allows them to access aquatic food resources, but still poses challenges compared to those faced by specialized divers like whales.
Can all birds dive?
While many birds dive effectively, some groups cannot dive or swim at all. Birds that are unable to plunge underwater include:
- Ostriches and emus – their size prevents diving and swimming.
- Songbirds – lack waterproofing and aquatic adaptations.
- Raptors – feathers not suited for underwater propulsion.
- Cranes – specialized for wading, not diving.
- Pigeons and doves – limited leg and wing propulsion.
However, most waterbirds have some diving ability based on leg kicks alone. Groups like ducks and geese can submerge and swim short distances. But specialized diving requires anatomical adaptations like waterproofing, dense bones, breath control and underwater propulsion. Birds without those specializations are very limited in their ability to plunge below the surface.
Conclusion
Many birds are talented divers, using their underwater agility to catch prey and escape predators. Penguins, cormorants, auks, gannets, and other species have evolved adaptations that allow them to plunge into the depths and swim effectively. They have mastered the art of diving, opening up aquatic food resources and refuges unavailable to other bird groups. So while not all birds can dive, many species have perfected the ability – granting them access to a whole underwater world that remains mysterious to most other animals stuck on land or confined to the surface.