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Bird wing

life science Maturity 9-11 Next article →

A bird wing is a specialized pair of forelimbs used for movement through the air. These limbs possess unique feathers that generate both lift and thrust. This combination allows many bird species to achieve flight.

Swan.spreads.wings.arp
Swan.spreads.wings.arp

However, not all birds use their wings to fly. Some terrestrial birds, like the extinct moa, have reduced wings or none at all. Other birds, such as penguins, have evolved wings that function as flippers for swimming in aquatic environments.

The internal anatomy of a wing follows the basic structure of most tetrapods. It begins at the shoulder with the humerus bone. This connects to the forearm, which contains the ulna and the radius bones. The bird's hand is a highly transformed structure where many bones have merged or shrunk. Three metacarpal bones and some carpal bones fuse to form the carpometacarpus.

Aile (main)
Aile (main)

Three fingers attach to this fused structure. The most forward finger holds the alula, a group of feathers that functions like the slats on an airplane wing.

Scientists have spent about 150 years debating the identity of these finger bones. There is a discrepancy between different types of scientific data. Anatomical, paleontological, and molecular data suggest these are fingers 1, 2, and 3. In contrast, embryological data suggests they are actually fingers 2, 4, and 4. One likely explanation is that finger buds 2 through 4 follow the genetic program meant for fingers 1 through 3.

Birdwing
Birdwing

Wing morphology, or shape, determines a bird's specific flight capabilities. This shape represents a trade-off between speed, maneuverability, and energy use. Scientists measure this using two main parameters. The first is the aspect ratio, which is the ratio of wingspan to the mean chord. The second is wing loading, which is the ratio of the bird's weight to its wing area.

FlightSilhouettes
FlightSilhouettes

Most wings fall into one of four main categories.

Elliptical wings are short and rounded, which allows for tight maneuvering in dense vegetation. These are common in forest raptors like Accipiter hawks and many non-migratory passerines. Pheasants and partridges also use these for rapid takeoffs to escape predators.

Blue Jay (Jim Ridley 2010.)
Blue Jay (Jim Ridley 2010.)

High-speed wings are short and pointed. These are used by fast-flying birds like ducks. The peregrine falcon reaches a recorded dive speed of 242 mph (389 km/h). The spine-tailed swift holds the record for the fastest straight, powered flight at 105 mph (170 km/h).

High aspect ratio wings are long and narrow, providing high efficiency for long-distance travel. When paired with low wing loading, they allow for slow flight or hovering, seen in kestrels and terns.

RoseateTern23
RoseateTern23

Seabirds use these for dynamic soaring, which uses wind shear above ocean waves to create lift. Finally, large inland birds like eagles and vultures use soaring wings with deep slots. These slots are located between the primary feathers. They reduce induced drag and wingtip vortices by capturing energy from air flowing between the upper and lower wing surfaces.

Black vulture soaring in Lima
Black vulture soaring in Lima

Wing injuries can be devastating for birds that rely on flight. A broken bone or major injury can cause a wing to droop or sit in an unusual position. Such injuries often prevent birds from feeding, socializing, or escaping predators. In some cases, surgical amputations in birds of prey can lead to death. Interestingly, some small birds like the killdeer use injury as a survival tactic. A parent may feign a broken wing to lure a predator away from its nest. This behavior makes the predator focus on the parent rather than the eggs or chicks.

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🖼️ Images & Media (8)
File:Birdwing.svg
Birdwing.svg
File:Swan.spreads.wings.arp.jpg
Swan.spreads.wings.arp.jpg
File:H. albicilla wing.png
H. albicilla wing.png
File:Aile (main).png
Aile (main).png
File:FlightSilhouettes.svg
FlightSilhouettes.svg
File:Blue Jay (Jim Ridley 2010.).jpg
Blue Jay (Jim Ridley 2010.).jpg
File:RoseateTern23.jpg
RoseateTern23.jpg
File:Black vulture soaring in Lima.jpg
Black vulture soaring in Lima.jpg
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