Bald Eagle Showing The Alula In Action
First, for those of you that are asking the question, "What is the Alula?", here is an explanation from Wikipedia: "The alula, or bastard wing, (plural alulae) is a small projection on the anterior edge of the wing of modern birds and a few non-avian dinosaurs. 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 typically bears three to five small flight feathers, with the exact number depending on the species. There also are minor covert feathers overlying the flight feathers. 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. Function: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. The tip of the alula forms a tiny vortex that forces the airflow over the wing to better bind to it. During stretching of the wing down toward the ground, the alula is abducted from the wing and can be clearly viewed."
So that is what the alula is and what it does. Fascinating, isn't it? Call me crazy, but I find behavioral actions and functions very interesting.
This Bald Eagle (I believe a 4 year old) was coming in for a fish at the Strait of Canso, Nova Scotia, Canada and had the alula up when swooping in, even though he didn't actually get the fish. He only leveled it off again once he was flying away as you can see in the following photos :)
I hope you enjoy this series of images showing the use of the 'alula' and learning about it for those that didn't know. For those that already knew about this function, I still hope you enjoyed the images. All the best :)
Canon 7D Mk ll & Canon EF 100-400mm f/4.5-5.6L IS II USM + Canon 1.4x lll teleconverter – @560mm, 1/2500, f8, ISO 640, 0 exposure compensation.
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