Music to My Ears

Winter Aviary - January 2011

It’s easy to figure out how a hive is doing in the middle of winter. You just open up the hive and pull out frames until you find the cluster of bees. The challenge is doing this without killing every last bee. Opening the hive exposes the hive to deathly chilling temperatures:

• at 50 degrees F, brood rearing stops and workers cannot fly
• at 42 degrees F, bees cannot move because their muscles are not warm enough
• at 40 degrees F, bees die

However, if bees are able to form a tight winter cluster that is protected from the elements, they can generate their own heat from their honey stores and a colony can withstand outside temperatures to minus 40 degrees F! So unless it is sunny and mild with no wind and temperatures above 50 degree F, you should not risk killing hive by opening it.

I recently snooped on one hive – with six inches of snow on it – without opening it up.

Hive body frame with embedded microphone

I hooked my Zoom H1 field recorder up to a microphone embedded in the middle of a hive body brood frame (shown to the right. Click on it for an enlarged view). A couple taps on the side of the hive and I had a recording of some buzzing bees.

Click here to hear the Winter bees of the blue hive. Is it me or do you hear the girls playing bongos? There are some other weird sounds in there. Any ideas?

Buzzing bees are like crying babies. They are both irritating to single males and non-beekeepers. But once you become a father or a beekeeper, these sounds become evidence of life. That 18 month son of mine, screaming it’s head off, is breathing just fine, thank you very much. And the sound of grumpy bees means that I probably won’t have to replace a deadout with a nuc, which – this late in the Winter – wouldn’t arrive until after our largest nectar flow of the year – the flowering of Tulip Poplars. It is all music to my ears.

I was surprised that these bees were not as loud as summer bees. There could be a couple reasons for this:

• There are more bees to buzz in the summer. All the drones and summer bees are gone.
• There is little reason for bees to move their wings. Heater bees generate heat without moving their wings. They do this by dislocating their wings from their wing muscles.
• The bees on the outside of the cluster are colder – and so may move slower – than inner bees.
• The cluster may have moved away from the microphone.

Well, I’m not likely to figure all this out this year but I thought I would take a look to see what the dominant frequency of bee sounds looked like. I used Audacity to redact a 30 second snippet and to amplify the signal. That is the snippet you just played. Then I imported the snippet into Sonic Visualiser, a program for viewing and analyzing audio data. Both programs are open source and totally free.

The image you see below shows the sonogram of 10 seconds of grumpy bees. The horizontal axis is time and the vertical axis is frequency. It shows a dominant frequency around 210 bps. This is a frequency you might expect from an adult worker fanning. The wings of younger bees (<= 9 days) are less stiff and vibrate faster.

We will compare this to sonograms to sonograms taken later in the Winter and early Spring when brood rearing has started and there are more young bees.