Humans, like other organisms, have evolved features that help them to survive. This is great for keeping our species going, but often leaves us in the dark when it comes to studying certain aspects of our environment. It wasn't until nearly the middle of the last century that we came to realize that bats navigated in the dark by high-frequency sounds far above our ability to hear. We've slowly learned that some insects, as well as other animals, are able to detect ultra-violet light—light invisible to us, but crucial in guiding pollinators to flowers.
Now comes word that a ground squirrel warns her compatriots of
potential danger by a silent warning call. Silent to us, that is. For the first time,
we've learned that ultrasonic sound is used as a warning call. A researcher, noting
that a squirrel's open mouth and whisper of escaping air elicited an alarm response
in nearby squirrels, brought in sound-detecting equipment used for bats. Sure enough,
the faint whisper was loaded with high frequency elements—a shrill warning undetectable
to an approaching predator.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.