Can Birds Fly Without Feathers?

Birds are known for their colorful plumage and ability to soar through the skies. But what enables them to fly in the first place? If you’re short on time, here’s a quick answer to your question: While most birds need feathers for flight, there are some exceptions.

Feathers provide the lift, thrust, and control birds need to get airborne.

In this article, we’ll take a close look at how bird feathers allow flight, exceptions to the rule, and the impacts of losing feathers on a bird’s ability to fly. We’ll also explore some interesting examples of featherless bird species and how they manage to stay aloft without the help of feathers.

How Feathers Enable Bird Flight

Feathers Provide Lift

The shape and structure of feathers allow birds to generate the lift force required to become airborne. Feathers have an asymmetry that causes air to flow faster over the top, creating an area of lower pressure.

This pressure difference with the higher pressure under the wing produces an upward lift force when the bird flaps its wings (Bernoulli’s principle). The barbs on feathers also help maximize surface area to trap more air.

The wing feathers’ flexibility further aids lift production. As the wing pushes down on the air, the feathers open up slightly, then rebound on the upstroke. This forms a larger wing surface throughout the entire flapping circle to maintain lift.

Tail feathers provide stability and help counteract undesirable airflow to enable smooth soaring.

Feathers Provide Thrust

In addition to lift, flapping wings also generate a rearward push known as thrust that propels the bird through the air. The angle or pitch of the wings can be adjusted to maximize thrust production with each wingbeat cycle.

Most thrust is produced during the downstroke as the wings push down and back on the air to generate momentum.

The rachis (quill) of larger wing feathers contains less material to allow bending and twisting. This flexibility permits better control over wing pitch and shaping to optimize orientation for forward thrust.

Tail feathers act as rudders to counteract drag and yaw rotation, helping streamline motion so more muscle effort goes into forward flight.

Feathers Allow Control and Maneuverability

Feathers covering the wing enable precision adjustments to direction, speed, and attitude. Special maneuvering feathers along the wing’s leading edge alter airflow to facilitate turning, braking, hovering, takeoff, and landing.

The tail feathers act as a stabilizer and rudder to assist with maneuvers.

The relative number and layered construction of feathers provide control over small and large changes to wing shape. This allows fine manipulation over minute shifts to angle of attack and camber during slow, gliding flight as well as more extreme morphing needed for sudden stops, zigzag escapes, or v-shaped dives exceeding 60 mph!

Exceptions: Birds That Can Fly Without Feathers

Featherless Chicks

Newly hatched chicks do not have feathers for the first few days of their lives. Their feathers begin to emerge around 3-5 days after hatching. So technically, chicks are able to fly short distances without having fully developed feathers.

Their wings still allow them to flutter a few feet off the ground, aided by the lightness of their bones and partially developed wing muscles.

One study observed that one-day old chicks of ground-nesting bird species were able to fly up to 13 cm off the ground (source). Their fuzzy down feathers likely provide some lift, but their flight ability mostly comes from the aerodynamics of their wings.

So birds can fly to a limited extent without a full set of flight feathers.

Vultures and Condors

Most vulture and condor species have featherless heads and necks. This allows them to reach deep inside carcasses and clean themselves off easily after meals. Their powerful wings provide enough lift to fly even without feathers covering their entire bodies.

In fact, the Andean condor has a wingspan up to 10.5 feet, making it one of the largest flying birds in the world.

Their enormous, mostly feathered wings generate sufficient lift for flight. So while most birds could not fly without feathers, vultures and condors can easily soar on air currents thanks to their partial baldness.

Pelicans and Cormorants

Like vultures and condors, pelicans and cormorants also have featherless areas on their bodies. Most pelican species have bare patches on their faces and pouches. Cormorants lack feathers on parts of their wings and areas around their eyes.

These bare regions help them plunge dive for fish without getting waterlogged feathers.

Despite missing feathers on certain body parts, pelicans and cormorants can still fly perfectly fine. Their powerful wings have enough feathers and surface area to generate aerodynamic lift. In fact, the great white pelican has a wingspan reaching 11 feet wide.

So similar to condors, pelicans can fly effortlessly with the help of their expansive wings.

Impacts of Losing Feathers on Flight

Difficulty Generating Lift and Thrust

Feathers play a critical role in enabling birds to fly. They help birds generate the lift and thrust required to get airborne and stay aloft. Feathers function similarly to an airplane wing – as air flows over the surface, the shape causes air pressure to be lower above the wing and higher below it.

This differential in air pressure creates upward lift. For birds, their feathers and wing shape create this lift effect. Without feathers, birds would be unable to generate enough lift to overcome gravity and take flight.

In addition, feathers enable thrust via the flapping of wings. As wings flap downward, they push air backward, propelling the bird forward. On the upstroke, feathers maintain airflow over the wing to provide continued lift. Without feathers, flapping would not create meaningful thrust.

Birds rely entirely on their feathered wings and tail to provide the lift and thrust required for powered and gliding flight.

Reduced Maneuverability and Control

Feathers also enable birds to maneuver and control their flight. The asymmetric shape of flight feathers allows birds to alter the lift produced by each wing independently. By changing the angle of attack and shape of their wings, birds can execute banking turns, quickly change direction, or maneuver in confined spaces.

The tail feathers act as flight control surfaces as well – by fanning or closing the tail, birds can pitch their body up or down. Without feathers, birds would be unable to perform controlled turns or adjust their orientation, greatly reducing aerial maneuverability.

In addition, feathers increase the surface area of wings without adding prohibitive weight. This expanded surface area increases lift production and control authority. Without feathers, wings would be truncated stubs – able to produce only minimal lift and control forces.

Simply put, feathers provide birds with responsive, aerodynamically effective control surfaces that enable precision aerial maneuvers.

Increased Energy Expenditure

Feathers also play an important role in minimizing drag and energy expenditure during flight. The smooth, aerodynamic shape of feathers allows air to flow over the wing with minimal turbulence. In addition, feathers can be pressed tight against the body to reduce drag and energy usage during gliding or descending flight.

Without feathers, the stubby wings of birds would generate significantly more drag, especially during the upstroke. This would force birds to work harder to stay aloft, rapidly expending energy stores. The metabolic costs of unfeathered flight would likely outweigh any energetic benefits.

Examples of Featherless Bird Species

Ostriches

Ostriches are well known for being the largest living birds and flightless despite having wings. An average ostrich is about 2.7 meters tall and can weigh up to 156 kilograms. Though flightless, ostriches still retain their large wings that exceed 1.8 meters in both male and female adults.

Their wings are lined with soft plumage but lack the long flight feathers of other flying birds.

Ostriches reside in the savannas and deserts of Africa where they adapted to life without flight. Their powerful legs allow them to sprint at speeds over 70 km/hr, outrunning many predators. Their wings serve very different purposes compared to flying birds like protecting chicks or helping with balance when running.

Cassowaries

Cassowaries are large flightless birds most closely related to emus that inhabit the dense rainforests of New Guinea and northeastern Australia. They stand up to 1.5 to 1.8 meters tall and weigh between 60 to 80 kilograms.

Cassowaries have small vestigial wings with coarse hair-like feathers, but these wings are far too small to allow them to fly. Their black feathers help camouflage them in the low light conditions of the rainforest floor.

However, cassowaries can easily traverse the dense forest and scrub thanks to their powerful legs.

Interestingly, the skeletons of cassowaries reveal that they once used to be able to fly but later lost that ability as they adapted to life on the ground. The rainforest environment provided abundant food sources, shelter from predators and decreased the need for flight.

Kiwis

Kiwis are small flightless birds native to New Zealand approximately the size of a domestic chicken. They average around 25 to 50 centimeters tall but weigh between 1 to 3 kilograms on average.

Kiwis lack an external tail or visible wings, appearing more like mammals. They have extremely small vestigial wings hidden beneath brown, hair-like feathers that serve them no purpose in flight. Instead, kiwis utilize their strong legs and long beaks to forage by probing underground for food.

Interestingly, kiwi chicks hatch with full feathers, allowing them to leave the nest within days to feed themselves, which likely allowed their wings to gradually become more and more vestigial over evolutionary history.

How Flightless Birds Stay Grounded

Anatomical Adaptations

Flightless birds have evolved remarkable anatomical adaptations that allow them to thrive on land instead of in the air. Many species have smaller or non-existent keels on their sternum, which in flying birds serve as an anchor for large, powerful flight muscles.

Without developed flight muscles and breastbones, flightless birds redirect crucial resources to legs and feet optimized for running, swimming, or digging.

For example, ostriches have long, strong legs for sprinting across African savannas at up to 43 mph. Their small wings provide balance and steering while running. Penguins use their flipper-like wings underwater to “fly”, reaching speeds of 15 mph.

Their streamlined bodies and webbed feet make them agile swimmers. Cassowaries have sharp claws for scratching forest floors in search of fruit, and powerful kicks that can disembowel predators.

Some flightless birds also sport specialized feathers. Cassowaries, emus, and kiwis lack barbicels that interlock feathers for airfoil wings. Their soft “hair-like” plumage serves instead as insulation and camouflage.

Many also have distinctive bare patches of skin for display or regulating body heat, like the brilliant red neck-wattle of cassowaries.

Behavioral Adaptations

In addition to anatomy, behavior is key for flightless bird survival. Instead of seasonal migration undertaken by some flying birds, flightless species adapt daily routines, group dynamics, and parenting behaviors to grounded life.

Ostriches, rheas, and emus are fleet-footed sprinters that escape threats by running. By contrast, kiwis’ nocturnal habits and camouflage allow them to hide from predators rather than flee. Penguins form large colonies and take turns watching for dangers while others hunt fish.

Cassowaries are solitary but aggressively protect large home ranges encompassing fruit trees and hatchlings.

Some flightless birds exhibit intriguing and unusual reproductive behaviors as well. Male emperor penguins keep eggs warm by balancing them on their feet and sheltering them beneath a flap of abdominal skin and feathers.

Following hatching, they survive brutal Antarctic winter storms by huddling tightly with chicks. Cassowaries, meanwhile, are among the minority of birds where fathers (not mothers) raise hatchlings, teaching young how to find forest fruits for up to 9 months after hatching.

In short, anatomical and behavioral adaptations allow flightless birds not just to cope but thrive in terrestrial and aquatic habitats. While giving up flight seems risky, evolution has allowed ratites and penguins to redirect precious resources towards the remarkable adaptations that enable their survival.

Conclusion

While most birds rely on their feathers for flight, there are some unique exceptions. Featherless chicks, vultures, pelicans and other birds have adapted to generate lift and thrust without feathers for short periods.

However, most birds suffer significantly if they lose too many feathers, as feathers provide critical lift, thrust and control.

Flightless birds like ostriches and kiwis have evolved grounded anatomies and behaviors to survive without flight. So while feathers enable most birds to master the skies, they aren’t strictly necessary thanks to adaptations in specialized species.