Friday, October 21, 2016

Wintering Bees Cluster: What's going on?

A common question that non beekeepers constantly ask is how bees survive through cold winter temperatures. “They create a cluster and use vibration to keep the cluster warm” is the typical response that usually concludes “they do not hibernate”. As beekeepers, do we truly understand what is happening within that cluster? We understand that the bees generate metabolic heat, but how?

Honey bees would not have a chance if they did not function as a highly organized superorganism that worked efficiently. Each bee fills a need within the colony and this assigned division of labor allows honey bees to be successful.

To maintain heat within the cluster the colony mush be able to produce heat and use bees to insulate and reduce heat loss. The bees on the outer edges of the cluster act as insulators and will rotate into the center where the temperature is warmest. The “heater bees”, as discovered by Professor Jurgen Tautz at the Wurzburg University, in Germany, are responsible for maintaining the temperature of the brood nest.
Thermal imaging has revealed that heater bees will decouple their wings so the muscles can move at full speed without moving their wings. This movement will increase their body temperature to the point where they should cook themselves, up to 111 Fahrenheit, but are able to withstand. Further investigation revealed that the heater bees would position themselves in empty cells amongst the brood in order to sustain temperature in the surrounding cells. These bees will even place their thorax on cells to increase the temperature within by a few degrees.

The point to be mindful of is that the cluster stays warm, the hive does not. Bees make no attempt to maintain heat throughout the entire hive. A hive that is uniformly warm would not require a cluster to form around the brood. Warmth is essential for maintaining brood health and bee movement.

How can beekeepers help?
  •  Beekeepers are able to help the colony maintain cluster temperature by removing unnecessary dead air space. Condense the hive down to manageable setup and reposition the food stores for easy access.
  • Insulators are great to trap heat but will also trap in moisture. Choose a material that is absorbent or allows for moisture to escape.
  •  Use windbreaks to prevent gusts of wind penetrating the hive.
Some great resources for assisting with the cluster include: