Winter mortality claims between 25% and 30% of managed honey bee colonies across the United States every year. Sometimes it is the result of high pathogen loads in the winter bee population; sometimes it is due to starvation. The short, mild winters we experience in Mississippi would lend one to believe that starvation is less likely an issue, and yet it does occur; usually during late January and February. Granted, winter mortality is more common among beginner beekeepers, but some years the losses are widespread in the beekeeping community.
The most frustrating discovery during winter colony inspection is a small, dead cluster of bees in the brood box, and a full super of honey above them. The combs surrounding the cluster are probably empty. Especially if the cluster is quite small (i.e. softball size) this could be a case of poor access to food. It is important to note the size and position of the cluster at the beginning and end of the overwintering phase. Bees begin to form a cluster when daytime highs are consistently about 60 F. This happens around mid-November in most of Mississippi. The colony gathers around the remaining capped brood in the brood nest, so it is important to locate this area when preparing hives for winter. You will want to place capped honey comb above and directly beside the cluster, as bees naturally eat their way up through honey comb. A very small cluster may not be able to travel far to reach honey stores, so if you are using a syrup feeder, make sure it is located proximate to the cluster.
Temperatures fluctuate quite drastically between December and March; there are periods of 70 F daytime temps that may last a few days to a week, followed by a sudden drop to sub-freezing night time temperatures. These huge temperature gradients will cause bees to break cluster and feed heavily, then reform a cluster, often somewhere else in the hive. It is very important to perform an inspection mid-winter to ensure bees have not eaten back too much of their stores due to these warm intervals. It is also important to rearrange honeycomb for better access if the cluster has moved away from the honey.
I usually perform our winter inspection during the mid-January warm spell (guess what I’m doing this week), and almost always feed 1:1 sugar syrup to compensate for high bee activity. Once the maples and redbuds start to bloom in late February, I will go back through our hives and feed a thinner syrup to encourage wax production for brood rearing. Bees are bringing in pollen during this time, but I will typically supplement with 1/3 to 1/4 of a pollen patty.
The take-home message here is to be sure to do a January inspection, even if you think your bees had plenty of stores going into winter. Starvation is not just a problem for northern beekeepers!