My 5 hives have come out of winter healthy which leads me to the next obvious question: Why did I lose my two hives last year, and, this year, have my 5 hives all survive?
First, I know it isn't due to how much food they stored. This year, I worried going into winter because the hives had little honey in storage. Bee Workers of the World Unite! had very little indeed! Last year in comparison, the two hives were packed with honey going into November and it was all still there when I examined the dead-outs in February.
Survival could be due to two factors beyond either the bees' or my control. First, last January had two weeks of continuous subzero temperatures. The bees probably couldn't move up to the capped honey within inches of the cluster. Second, I still suspect that my bees had a significant virus infection created by an immense varroa mite infestation.
But I did do other things to prepare the bees for winter that I didn't do last year:
1. I moved the hives slightly, so that they would receive plenty of winter sun.
2. Monta and I made quilt boxes for both the top bar hives and langstroths. These boxes absorbed a significant amount of moisture that rose up from the cluster.
3. While I kept the screen bottom boards on the langstroths, I did duct tape the openings, keeping the cold air out.
4. Besides wrapping the hives with black wintering materials, I also placed hay bales around the hive to cut down on strong winds.
5. I tilted boards in front of the bottom entrances. The bees could leave through the bottom entrances but didn't get full exposure to the chilly winds.
While these are the things I did, I can't be assured that these interventions were actually the key to the bees' survival. Honey bee survival/death is the result of a number of apicultural and environmental factors. It probably cannot be reduced in any particular silver bullets.