![]() The alula is commonly referred to as the “bastard wing” – one of several definitions of the word bastard is “of abnormal shape or irregular size “. It is the birds “thumb” and is covered by three to five small flight feathers. The alula is the freely moving first digit on the leading edge of the wing of modern birds. The alula (plural alulae) is clearly visible. I’ve previously posted a different but similar photo of this bird in flight but back then I hadn’t noticed something else interesting about these images. The photographers best chance to get one in full flight (as opposed to at take-off) is to catch it hovering – which they’re prone to do, especially if there’s a bit of a breeze.ġ/2000, f/6.3, ISO 500, 500 f/4, 1.4 tc, natural light, not baited, set up or called inĪnd hovering is exactly what this bird was doing. These raptors are small, fast and usually fly erratically which makes them very difficult to track with a large lens. Kestrels in flight have largely eluded me for eight years now. ![]() I was happy to get this image and a few of the others for two reasons. Maybe you can appreciate just a little more the wonderful adaptations of these amazing creatures.Earlier this winter I was able to get some shots of a male American Kestrel in flight. See if you can spot the alulas on a stilling Red-tailed Hawk. For a great look at stilling Redtails, come visit the windier spots of the Golden Gate National Parks: the Marin Headlands, Lands End, and Mori Point. Although migration distances vary by species and even within species, migration is still a physically demanding process that these animals undertake each year.Īlthough much of the GGRO’s focus is on the hawks’ autumn migration, March and April are also great raptor migration months. Raptors on migration need all of their energy-saving tricks. This redirects airflow and adds a bit more surface area, contributing to increased lift and fine-tuned control, much like the flaps on an aircraft. However, while a bird is stilling or landing, the alula protrudes from the rest of the wing. All birds have one on each wing, and they can be thought of as the bird’s thumbs, homologous to the thumb structures of humans.ĭuring normal flight, the alula is hidden, pressed against the rest of the wing. The alula is a mobile digit on the anterior-or forward-portion of the wing with a few feathers attached directly to it. It is during this stilling behavior that the alula, or “bastard wing” of the Red-tailed Hawk, comes in handy. The airfoil shape of the wing causes air to move faster over the top of the wing than below, resulting in an upward lift from the slower moving air beneath the wing. The hawk faces into the wind so that air moves from the front of the bird to the rear. It is an energy-saving behavior that allows the bird to remain airborne with minimal flapping and only slight adjustments of the wings and tail. Stilling is a behavior most notably employed by Red-tailed Hawks. The group of students stared in wonder at the bird as I explained some of the basic biology of the raptors that migrate through the Headlands every year. ![]() I explained that the Red-tailed Hawk in question was not, in fact, tethered to the hill, but was practicing what is known as “stilling”. ![]() The innocence and excitement of the young boy asking the question made me smile. ![]() Where do the raptors come from? Where are they going? Why do they migrate? How far do they go? Rarely was I inclined to laugh out loud at a visitor’s queries. As an intern and new docent with the Golden Gate Raptor Observatory, I had heard many of the same questions over and over again. “Is that hawk on a leash?!” The absurdity of the question nearly stopped me in my tracks last fall. ![]()
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