The Biology and Managment of colonies in Winter
This excellent document from the Canadian Association of Professional Apiculturalists provides a quick and clear overview of honey bee behaviour over the winter months including changes in the hive correlated to specific temperatures.
The graph of colony metabolic rate seems particularly useful for estimating honey consumption over the cool months
After hearing a variety of ideas on how this years mild winter might have affected the bees it was nice to find some quantitative data on the subject.
It also offers some thoughts on dealing with moisture in the hive and comparisons of solar versus insulated hive wraps for winter.