Data processing to obtain the most frequent amplitude in overnight recordings.

(A) A typical vibrational spectrum averaged over 3 minutes from an accelerometer in the hive. Note the pronounced peaks at 125 Hz and 250 Hz, a feature common to all honeybee vibrational spectra collected from the comb. (B) A histogram of amplitude values from the same data shown in panel A. The majority of amplitudes are found between 1x10-6 m/s-2 and 5x10-6 m/s-2, as clearly seen in (A). Note that the information regarding frequency is lost. (C) Vibrational spectra (averaged over 3 minutes) collected from midnight to 7 a.m shown as a spectrogram. Each vertical line is the equivalent of the spectrum in (A) but with the amplitude now colour coded (blue = 0 ms-2, red = 3x10-5 ms-2). The large number of spectra available each night results in the histogram shown in (D) which is much smoother. In subsequent figures all histograms shown have been further normalised to their maximum value, this would be approximately 340 in the case of panel D.