Airdate: Apr 24, 2000
Scientist: Doug Altshuler
Hummingbirds are the only birds capable of sustained hovering, a form of flight they need to get nectar from flowers that don't provide perches.
We're listening to the sounds of a ruby-throated hummingbird, flapping its wings up to sixty times per second, as it hovers in place. Well, this unusual form of flight is just one way that hummingbirds are unique in the world of birds. I'm Jim Metzner, and this is the Pulse of the Planet, presented by DuPont.
"I think hummingbirds are one of nature's most beautiful creatures, they're extremely colorful, and they are extremely specialized in their physiology."
And that makes hummingbirds especially interesting to Doug Altshuler, a biologist who specializes in physiology at the University of Texas at Austin.
"Hummingbirds are the only birds that are capable of what we call sustained hovering, which is that they can actually fly in place for long periods of time. All of their power is directed directly below them, to try and compensate for the effect of gravity. And they can't glide, and just outstretch their wings. So its a very, very expensive form of flight and their adaptation for overcoming this is to beat their wings very, very fast, in a hover."
Altshuler says that hummingbirds are a wonderful example of evolution matching form to function. Rather than perching to feed, like most other birds, they hover and drink flower nectar. And for this, they've developed the perfect physique.
"So hummingbirds have a very specialized form of eating, and to accomplish this they also have a very specialized form of flight, and that's hovering flight and they also have very specialized body types. These body types consist of wings which have several bones fused, so that they have a very stiff wing during flight, and one that won't bend so much and therefore lose energy as it's beating back and forth at a very high rate."
Of course, all this wing flapping can make a bird pretty hungry. Hummingbirds eat several times an hour and consume twice their weight in flower nectar every day. Pulse of the Planet is presented by DuPont, bringing you the miracles of science, with additional support provided by the National Science Foundation. I'm Jim Metzner.