Thursday, September 15, 2011
For hummingbirds, the tails have it
It began with a blur, a moving blur over flowers in a pot on a neighbor’s deck railing. When the blur moved to a flowering bush closer to my window view, I realized it was a hummingbird. Amazing: in September, with fewer flowers out there and the weather likely to change at any time.
Next time I looked out, the bird was gone – but I was curious. The Birds of New Jersey Field Guide, by Stan Tekiela, lists only the Ruby-Throated Hummingbird (Archilochus colubris), indicating it migrates to southern states, Mexico and Central America. But how could it possibly cover such distance while also seeking nectar and insects? Without food, what powers it?
And how could such a tiny thing make it to the next town over, let alone a southern state, or beyond? (“Stan’s Notes” say this bird “weighs only two to three grams” and “it takes about five average-sized hummingbirds to equal the weight of a single chickadee.”)
Coincidentally, a NYTimes story about hummingbird romance disclosed that the humming of their wings is what gives the birds their names. However, it’s the male hummingbirds’ high frequency tail feather vibrations produced during dives in front of females that may be what female birds use to choose mates.
Each of 14 species makes fairly unique and distinctive sounds, scientists reported, also mentioning that a single tail feather may vibrate (“the sound of one feather vibrating”?), or two, or all of them.
(http://www.nytimes.com/2011/09/13/science/13feather.html . . . photo by Chris Clark)