|Copyright: Tom Conzemius (pirate)
|Date Taken: 2013-01-15|
|Camera: Canon 7D, 100-400L is|
|More Photo Info: [view]|
|Photo Version: Original Version|
|Date Submitted: 2013-01-26 9:53|
|[Note Guidelines] Photographer's Note|
|White tailed Tropicbird|
In landing birds one can easily see the alula
The alula is a small projection on the anterior edge of the wing of modern (and some ancient) birds. The word is Latin and means "winglet"; it is the diminutive of ala, meaning "wing". The alula is the freely moving first digit, a bird's "thumb," and is typically covered with three to five small feathers, with the exact number depending on the species. Like the larger flight feathers found on the wing's trailing edge, these alula feathers are asymmetrical, with the shaft running closer to anterior edge.
In most situations, the alula is held flush against the wing; however, it can be manipulated. When flying at slow speeds or landing, the bird moves its alula slightly upwards and forward, which creates a small slot on the wing's leading edge. This functions in the same way as the slats on the wing of an aircraft, allowing the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall. During stretching of the wing down toward the ground, the alula is abducted from the wing and can be clearly viewed.
Alula in ancient birds
The presence of an alula has been confirmed in several now-extinct ancient relatives of modern birds, including Eoalulavis hoyasi (an enantiornithine from the mid-Cretaceous, 115 mya) and the earlier Protopteryx fengningensis. Since these species are not closely related to modern birds, either the alula evolved twice, or it did so more than 130 million years ago.
devildoc, CeltickRanger has marked this note useful
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An elegant photo of a likewise bird!
Nicely chosen moment, perfectly still, good focus, excellent detail and exposure.
A fine photo.
very nice capture of this inflight bird with good detail and colour.
great tonal range and the back ground.
OMG. What a stunning capture of a flying bird. Never seen anything like this before. Natural colors and fine details...... Nitin
Its landing flight pose with the long tail
with the POV and framing, it gives
dynamism to the image, TFS