>There seem only two ways bees in the mantel can refuel: 1) by food sharing bee to bee from the inside to the outside of the cluster - unlikely as the bees are too tightly packed to align head to head; or the outer bees work their way to the hollow centre and are then fed by the active house bees or fill themselves from the open food cells in the hollow core.

Please correct me if I am wrong, but my observations
on wintering clusters is that there never seems to be
open food cells with reserves in the center,  it appears 
to be consumed or distributed within a few inches of 
the leading edge of the cluster prior to the core.  So 
might this suggest that the sharing of food within the 
cluster is distributed bee to bee throughout the entire 
cluster, and not at refueling stations at the core?

I can understand a slow rotation of bees throughout
the cluster as being essential as a rotation of the 
workforce to give occasional rest,  but the theory
of migrating to the core to feed does not seen to fit 
actual configuration of the winter cluster with stores 
being situated at the leading edge of the core outwards.

Joe 

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