I often get asked what my honeybees do during the Winter months. The simple answer I give is, they sit there and shiver :) ...but there's more to the story.
First we have to understand the bee's calendar. There are two important dates to keep in mind...June 21st and December 21st. These two dates (or approximate dates) tell the bees what is coming next. June 21st, the first day of Summer, or the Summer solstice, is the longest day of the year. The bees recognize that the daylight hours are waning and signals them to begin prepping for Winter. They begin losing the urge to reproduce (swarm) and focus on food stores for getting through the Winter. Brood production will gradually decline, "winter bees" (for another discussion) are raised, and food stores are gathered and arranged in the hive for easy access. Once the cold arrives, the bees will cluster. The cluster involves the bees going headfirst into the cells and forming somewhat of a ball to keep the inner most portion of the colony (the brood) at around 95 degrees Fahrenheit. The bees consume honey for energy and use their wing muscles to "shiver" and generate heat. The cluster will move together about the hive to remain in contact with honey. As long as one bee has access to the honey, all of the bees have access to the honey. They share the honey with each other through a process called trophallaxis. Typically in European breeds of honeybees, the cluster will move upward "through" the honey as Winter progresses.
All the way up to December 21st, the colony will continue to reduce brood production, and sometimes, but not always, cease rearing all together. When December 21st, the first day of Winter, or the Winter solstice comes, the bees begin recognizing a lengthening of daylight hours. This prompts them to prepare for Spring, reproductions, and big nectar flows. They will begin ramping the brood production up and trying to grow the colony. This process is hard on the colony, as the remaining bees in the colony are old, the environment is still cold, and the resources (food) are being used up. Many colonies will starve in February because of the heavy brood rearing using up all their stores. February typically brings the Maple bloom and colonies, if the weather cooperates, begin to make up for the lost resources.
The colony may get down to as little as a pound of bees (3,000 bees) during the Winter, but hopefully, the colony is 60,000 bees strong by the Tulip Popular nectar flow and will make a bumper crop of honey.