"Granny, what great big ears you've got." Most of you will recognize the line from one of the versions of "Little Red Riding Hood". In that case, "Granny" was a wolf in disguise, but the line could be used for some of our Chihuahuan Desert animals. We've all seen jackrabbits, and certainly one of their outstanding attributes are their handsome—but huge—ears. The normal response to seeing these might be another line from the old tale, "The better to hear with, my child". But many a desert animal has keen hearing with far smaller ears—so what's up? The temperature, that's what's up.
Unlike many arid-land mammals, jackrabbits normally don't retreat
to burrows in the heat of the day. As the air temperature climbs to body temperature
and above, it becomes harder and harder to rid the body of excess heat. What you need
is a radiator—or, sometimes, two of them! The line, "I'm all ears", may
not be literally true for jack rabbits, but it sure takes the heat off them.
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.