Yesterday a reader wrote to say that all her bees were in the top brood box and she didn’t recall this happening last year. She wanted to know if this was normal.
The fact is that winter bees kept in a vertical hive will move up as they consume their stores. Remember that the bees stored their honey overhead all summer long. First they filled in the area around the brood nest, and next they went into the honey supers and filled them as well. It is only natural that they will search for honey in the place they stored it—which is overhead.
However, if the bees have plenty of honey, this upward migration occurs slowly over the course of the winter. Only when they deplete the honey in their immediate area do they move up to look for more.
If a cluster is large it extends to cover more of the frames. These large clusters may consume all the honey in all the frames because it is right in front of them. Sometimes, however, the cluster is small and occupies only some of the frames. These bees may “miss” the honey that is stored several frames to the left or the right—and move up early instead. You can picture this as a chimney built through the honey. Colonies have been known to starve in this situation—especially in very cold weather when the bees can’t leave the cluster to go in search of food.
In my experience, colonies that have chimneyed through the honey and gathered on top of the frames to starve usually have smaller, less populous clusters. It’s a question of probability. More bees covering more area are more likely to run into the food stores than small, compact clusters.
My recommendation is this: if you find bees clustered on top of the frames, feed them with some type of winter (non-liquid) feed such as candy cakes, fondant, or granulated sugar. Or, if it is warm enough, open the hive and move any remaining honey close to the cluster where they can find it. You may be able to reverse your brood boxes. That is, put the cluster on the bottom and place any frames of honey on either side and directly above the cluster.
Bees kept in a horizontal hive, such as a top-bar hive, are already as high up as they can go. They will move laterally to get the honey, but they usually move in only one direction. Let’s say, for example, that the cluster started in the middle of the hive and moved to the right. Once all the honey in that direction is eaten, they will not normally turn around and traverse the empty space to find the honey at the other end—especially when it is too cold to break cluster.
One trick some top-bar beekeepers use is this: at the beginning of the winter they rearrange the top bars so the cluster it at one end of the hive—not in the middle of the honey. This way, the bees are always moving in the same direction and always finding more honey. No backtracking is required.
In any case, if your bees are all clustered at the top or on one end of your hive this early in the winter, you will almost certainly have to do some intervention to keep them alive until spring.