microphone is heavy

Today I have been editing recordings taken from a formica rufa (wood ant) nest.  Within seconds of placing the microphone on the nest the ants were all over it, and so it was easy to record the ants moving and doing what they do.  I also experimented with miking up a dried leaf and recording the ants walking over that.

These particular ants are quite small (I have recorded heavier) and so I wasn’t able to record each ant’s individual steps as I had hoped.  I could however get a workable recording level when many ants were walking, although I had to keep remembering to keep my distance as these ants are very inquisitive, and they bite.  (They use formic acid – the same as stinging nettles).

Interestingly when I was doing my editing I noticed a (very) occasional ultrasonic signal at about 31kHz, the main part of which was a six-note phrase, all on the same note, and with the rhythm of “microphone is heavy”.  The strange thing is that from reading the literature on this ant (and ants in general) I have not been able to find any references to ultrasound transmission, and so I don’t know….. was it from the ants, and if not where did my ultrasonic signal come from?  Listen to a recording of it (at roughly a fortieth of the speed and pitch) here.