Biology Reference
In-Depth Information
Scientists describe bird songs using sound spectrogram, or a sonogram — a graph
showing each tone's frequency and duration. Some practice or training are necessary to
interpret them.
Rather than describe a song at all, people now often email me recordings. They don't
need a fancy microphone — many just point a digital camera toward a singing bird and
use the video function. Whether or not we can see the bird, this lets us hear it!
Q My wife and I moved to Dallas in January. As the weather has warmed, we've
come to expect a high-pitched twirp in the twilight at dusk and dawn. It sounds like
some swallow, and I assume that it's feeding on insects, though I don't know how it
sees them in the darkness. I don't think this is bats — there are too many. How can
I figure out what bird this is?
A It's very tricky to describe sounds in a way that someone else can “hear.” But I would
bet your birds are either Common Nighthawks or Chimney Swifts. Nighthawks make
a funny beep! or peent! in the twilight sky as they catch insects. Chimney Swifts also
feed in low light, and you're apt to hear them because they gather in large congrega-
tions to roost. How can you tell which one this is unless you get a good look? Go to
www.allaboutbirds.org and type in just about any North American species name and you
can listen to its sounds.
The number of different songs that a bird sings varies depending on the species and
theindividualbird.ChippingSparrowsrepeatthesamesinglesongoverandover.North-
ern Cardinals sing 8 to 10 songs, American Robins 70, and Northern Mockingbirds 200.
Brown Thrashers are the record-breakers, however; they are mentioned in Ripley's Be-
lieve It or Not! for their amazingly huge repertoire of 2,000 songs.
FEMALES WHO SING
When I took an ornithology class back in the 1970s, we learned that male birds do the
singing and females do the listening. This seems obvious intuitively: males are the ones
with conspicuous plumage and the job of defending the territory while females incubate
eggs, usually trying to be as inconspicuous as possible. And it's true that many or even
most songs we hear from familiar backyard birds, from mockingbirds to Chipping Spar-
rows, are sung by males.
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