April 2020 Natural Mystery Answered

Last month, we tried out an audio mystery for the first time. It proved challenging. Congratulations to Mike Holtz, who was the sole person to send in a correct answer. Like others who submitted answers, Mike began trying to identify this as a bird call. But as he and several others realized, this is not the call of a bird. It is the call from which this animal gets one of its more colorful common names.

This is the call of the largest burrowing squirrel in the east, Marmota monax, know colloquially as a woodchuck, a groundhog, and across Appalachia as a whistle pig for this high-pitched alarm call.

In the Peterson Reference Guide Behavior of North American Mammals, Elbroch and Rinehart note that the repetition rate of the calls expresses the level of danger. A single call notes a minor risk, while frequent repetition indicates high risk.

Kirsten Welge, who correctly guessed that this was the vocalization of some kind of squirrel, identified the following features of the call which she used to essentially rule out birds as possibilities:

• High volume (“robust”), 1 note “cheep” call

• Clear tone -- no “static” or buzzing in the timbre

• Interval of 5-9 seconds silence between notes

• Short duration (<1 sec)

• Pitch rises slightly over the call, less than a half-tone above the starting pitch

Maren Miller noted the similarity between these calls and the calls of Spring Peepers, but noted that:

"Spring Peepers tend to chirp on a slightly lower pitch than the A flat/A natural pitch in this recording and I'm not necessarily hearing obvious pond, lake, or wetland background sounds that I would expected to hear in a Spring Peeper's habitat."

But it was Mike Holtz who pulled this sound out of his memory banks and posted the sole correct answer. Congratulations, Mike!

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