Lift in relation to drag.

In order to achieve elevation and forward motion, or flight, birds are able to manipulate air pressure to utilize a force known as lift while mitigating the opposing force to lift, known as drag. Lift is generated by the redirection of air to the ventral side of the wing. This occurs due to the streamlined and asymmetric structure of the wing. The accumulation of this pressure creates a natural gradient, which then pushes against the wing in an effort to restore equilibrium. This movement of fluid generates lift and the amount of lift generated is secondary to the SA of the wing as well as the speed of the air passing through the feather. In addition, lift can be artificially enhanced in slower wind speeds by increasing the angle of attack or the angle of the wing. By doing this, the SA of the wing is increased, which directly increases lift, however, this also increases drag and after a certain angle the drag will overwhelm the total lift, causing the bird to stall. This phenomenon is also utilized and is commonly used for precision landing that does not require a gradual decline in speed.