As yesterday was sunny and fairly warm quite a few of our bees were flying.
Honey bees don't hibernate but huddle together in a cluster for warmth. As they are awake and active, moving their wings constantly to create warmth, they need to eat, and you know what you need to do after you have eaten.
Bees probably don't eat so much in the Winter as they do in Summer, but they do eat and so they do need to get rid of waste matter, something they can't do when the weather is too cold. They need to get out to 'void' at least once every ten days otherwise the inside of the hive gets messy and the risk of disease and infection increases.