Birds are able to fly after diving into water due to their unique anatomy and physiology that allows them to repel water from their wings and body. When a bird dives into water, special oils produced by the uropygial gland near the base of the tail coat the feathers with a waxy, water-repellant layer. Additionally, most aquatic birds have less porous feathers that are more tightly interlocked to trap air and keep the bird dry. The air trapped within the feathers provides buoyancy to bring the bird back to the surface after diving. Once at the surface, birds are able to take flight again by flapping their wings vigorously to shed any remaining water droplets while also relying on the water-repellent properties of their plumage.
How do birds waterproof their feathers?
All birds have a small gland near the base of their tail called the uropygial gland or preen gland. This gland produces an oily secretion made up of wax esters and fatty acids. Birds spread this oil onto their feathers during preening, coating the entire plumage with a hydrophobic, water-repellent layer. The oil smooths out the microscopic barbicels and barbules that make up each feather to help align them and maintain flexibility. It also prevents the feathers from becoming waterlogged, which would make the bird too heavy to fly.
In addition to waterproofing preen oil, most aquatic birds have feathers specially adapted to shed water. Their feathers tend to be stiffer and less porous than those of land birds. The feather barbs may also be more tightly interlocked to reduce the space where water can penetrate. Species that dive underwater, like penguins and puffins, often have shorter feathers to reduce surface area. The overall effect is a dense, overlapping coat of feathers that traps air close to the bird’s body to help keep it warm and buoyant in cold water.
How does trapped air help aquatic birds float and fly?
Thanks to their waterproofing adaptations, a layer of air becomes trapped within a bird’s plumage when it dives underwater. This layer of air forms an insulating barrier that retains body heat and prevents direct contact with the skin. More importantly, the trapped air provides essential buoyancy to help the bird float back up to the surface.
When a bird dives, its feathers are pressed close to the body, forcing out some of the trapped air. But the waterproofing prevents the feathers and skin from getting soaked. This allows enough air to remain caught within the plumage to provide lift. Penguins and other foot-propelled divers utilize their wings for underwater swimming while their feathers hold enough air to make them neutrally buoyant.
The trapped air layer also gives birds crucial lift for taking flight again after surfacing from a dive. As soon as the bird breaks the surface, it can start flapping its wings. The motion works to shed any water droplets clinging to the feathers. The waterproofing causes the droplets to slide off the feather shafts so they take to the air once again. Within a few powerful beats, the wings generate enough lift through the trapped air to become airborne.
Examples of aquatic birds that rely on trapped air
- Penguins – short, stiff, overlapping feathers trap air for warmth and buoyancy while diving
- Puffins – dense plumage resists water penetration and provides lift
- Ducks and geese – oily feathers retain air to help float and stay dry
- Pelicans – pouched feathers that trap air even when diving for fish
- Cormorants – wettable feathers provide less buoyancy but air still aids surface return
How do different types of aquatic birds fly after diving?
The various species of diving birds rely on their unique feather adaptations and trapped air in slightly different ways when taking flight again after being underwater:
Penguins
Penguins porpoise out of the water before flight, leaping partially out to shed water then diving back in to gain momentum for launch. Their small wings provide lift once airborne. Stiff wing feathers prevent soak-through that would add excess weight.
Cormorants
Cormorants, with more wettable plumage, need to fully leave the water before taking flight again. They will often perch or stand with wings outstretched to dry feathers before flying off.
Ducks and Geese
Ducks take running starts across the water, flapping vigorously to lift off. Their oily coat sheds water well. Geese do the same, and may need longer runways to become airborne due to their larger size.
Gannets and Boobies
These powerful divers hurtle out of the water and direct their momentum upwards to launch themselves skyward. Air trapped in their dense plumage gives added lift.
Puffins, Loons, Grebes
All strong divers and swimmers, these birds need space to get airborne. They will flap across the surface while kicking to take off. Their short wings provide lift once in the air.
Pelicans
Pelicans’ huge pouched bills can hold fish-filled water after a plunge dive. But their water-resistant feathers provide buoyancy and lift to fly again after draining the pouch with a jerk of the head.
What are some key adaptations that allow different waterbirds to fly again after diving?
Bird Group | Key Adaptations |
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Penguins |
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Cormorants |
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Ducks and Geese |
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Gannets and Boobies |
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Puffins, Loons, Grebes |
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Pelicans |
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As the table summarizes, different waterbirds have evolved special adaptations like water-repellent feathers, air trapping plumage, and anatomical features to help them regain flight after diving below the surface. While specifics vary by species, all rely on trapping enough air within their feathers to provide sufficient lift and buoyancy to return to the air.
What problems or risks do aquatic birds face when diving and resurfacing?
Despite their adaptations for an aquatic lifestyle, diving birds face some key challenges and dangers when plunging below the water’s surface:
Loss of trapped air
If a bird’s feather coating becomes compromised from oil contamination or damage, it can lose its water-repelling properties. This allows water to penetrate into the plumage, displacing the trapped air layer so crucial for flotation and flight.
Inability to shed water
Birds rely on preening to maintain their feather coating. If the preen gland malfunctions or the bird cannot preen effectively, water can adhere to feathers and make it challenging to takeoff after diving.
Excess time underwater
Most diving birds have adaptations to hold their breath for minutes at a time. But staying underwater too long can lead to oxygen deprivation if the bird cannot surface. This may happen when chasing prey or escaping predators.
Predation
Birds are vulnerable when diving as predators may strike them underwater or attack them as they surface. Species like penguins rely on large numbers and defensive maneuvering when porpoising to avoid predators.
Exhaustion
Repeated diving and flying requires immense energy expenditure. Aquatic birds must balance their need to feed underwater with time spent resting on the surface to avoid depletion and exhaustion.
Conclusion
In summary, birds that pursue prey or feed underwater face the constant challenge of shedding water from their feathers and becoming airborne again. Evolution has shaped specialized feather structure and preening oil in species like penguins, puffins, and pelicans to waterproof their plumage. This traps a layer of air needed for insulation, flotation, and flight. All diving birds rely in some way on this feather-bound air bubble to propel them upward through thrust of their wings or feet. Their unique adaptations allow them to survive and thrive in the aquatic environment despite the difficulties of repeatedly flying after diving into water.