How do birds fly?

Flight is the form of movement used mainly by birds, which tend to walk clumsily with a few exceptions, for example the ostrich, and also by other animals, such as many insects and a few mammals.

An essential requirement for an object to be able to fly, that is, to move through the atmosphere overcoming the effects of gravity, is combine strength and weight in a proper relationship. The anatomy of birds has evolved from their reptilian ancestors to a strong skeleton of reduced weight, streamlined in shape and capable of supporting powerful muscles, thus achieving mastery of flight.

Basics of bird flight

There are many specific forms of flight among the large number of existing types of birds; For example, the albatross (family Diomedeidae) has long and narrow wings and can stay in flight for a long time without moving them taking advantage of air currents; On the contrary, hummingbirds (family Trochilidae) cannot stop flapping for a second.

But basically, all birds use the same aerodynamic principles. Virtually the entire anatomy of birds is designed and involved in flight, but above all their atand can be explained, among others, by applying Newton's laws of motion.

The Newton's third lawalso known as Law of action-reaction, states that if an object exerts a force on a second object, this second object exerts a force of equal magnitude but in the opposite direction on the first object. The movement of the wings pushing the air down would have this effect; the downward force on the air creates a force on the bird in the opposite direction.

But also, just as it happens in an airplane, the upward force also appears when the bird advances without flapping its wings. This is because the shape of the wings creates a downward flow of air and, responding to Newton's third law, the air creates a force in the opposite direction which, if it overcomes the action of gravity, will make the bird fly.

If the speed and pressure of the air flow around the wings are measured, the flow speed is greater in the air that passes over the top of the wing, thus creating a area of ​​lower pressure on the wing with respect to the bottom where a relatively higher pressure is created, the origin of the upward force.

And all this thanks to the shape of the wings. But this is not enough. For the lifting force to be sufficient, the force of the airflow must be adequate. That is, the bird needs propulsion force. Airplanes use engines that provide them with this force, while birds can use various techniques: the first is the movement of its wingsthanks to powerful muscles, and the second take advantage of air currents.

For example, by moving the wings they can direct the lift force under the wings at different angles, achieving the necessary propulsion.

adaptations for flight

The wings are the key anatomical structure in the flight of birds, since they are the ones involved in generating the lifting force. In some species, the body shape it can also generate a lift force following the same principles, but generally it is the wings that are responsible.

But in addition, birds have developed many other anatomical adaptations for flight, especially to reduce the high energy demand of flying:

  • Body shape designed for reduce resistance with the arie
  • skeleton with hollow bones to reduce body weight.
  • loss of many bones Regarding other animals, for example they have lost the tail bone (it can be observed in fossils of the first birds, for example in Archeopteryx) and they have lost the jaw and teeth (replaced by much lighter and more aerodynamic beaks).
  • Unidirectional pulmonary system to more quickly satisfy the high amounts of oxygen demanded by flight.
  • Antioxidant Cellular Systems enhanced to compensate for the increased formation of free radicals from the increased metabolic rate.
  • Adapted ribcage to anchor the powerful muscles that flap their wings.
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