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Soaring Flight. Soaring Flight. Andean Condor soaring http://www.youtube.com/watch?v=4j6qDJWiwbA. downstroke : the wing beats down and forwards, producing lift and propulsion.
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Andean Condorsoaring http://www.youtube.com/watch?v=4j6qDJWiwbA
downstroke: the wing beats down and forwards, producing lift and propulsion. upstroke: the wing flexes in towards the body (largely due to a rotation of the humerus about its long axis) and then rises and extends ready for the next downstroke. Passive aerodynamic lift provides the restoring force for the upstroke under most cruising conditions, although during takeoff the upstroke is powered.
There are two main flight muscles attaching to each wing. The pectoralis muscle powers the downstroke and is proportionately very large in birds (up to 35% of body weight). The supracoracoideus is much smaller and has a tendon which curves around to attach to the top of the humerus.
Diagram showing the large fan-shaped pectoralis muscle converging to an attachment on the humerus, and the smaller supracoracoideus deep to it at the front, attaching to the top of the humerus via a tendon passing through the foramen triosseum.
The supracoracoideus can provide power to the upstroke if required but more usually produces a rapid rotation of the humerus at the top of the upstroke. In addition there are 48 other muscles within the wing and around the shoulder which produce the wide range of movements of the wing and its feathers.
Short, rounded wings: fast takeoffs and rapid maneuvers - Grouse Long, narrow wings: high speed gliding in high wind - Albatross Slim, unslotted wings permit fast, efficient flight in open habitat - Falcon Slots in wings of intermediate dimensions increase lift and gliding ability – Buteo hawks
Assuming birds of same weight: Wing Loading: weight / wing area Aspect Ratio: wing length / wing breadth
Hummingbird Videos http://www7.nationalgeographic.com/ngm/0701/feature4/multimedia.html Especially NotePurple-crowned Woodnymph and Marvelous Spatuletail
Kestrel Flight – hovering http://www.youtube.com/watch?v=31Xw75hAwIc
Wing beats vary by type of bird as well as the speed and weight. Robert Burton in the book Bird Flight estimates this range: