Lots of folks want to know if bees consume more food in warm winters or cold winters. I’ve been searching for scientific data on this for quite a while but I haven’t found any. So, for what it’s worth, I hereby offer my opinion.
Based on hearsay and my own beekeeping experience, I believe that bees expend more energy—and so eat more food—in warm winters than in cold ones. As counter-intuitive as that may seem, I’m convinced it’s a common occurrence.
In very cold winters the cluster remains intact for long periods, brood production is extremely low or non-existent, and all other hive activities come to a standstill. The bees vibrate their wing muscles to create heat and the highest temperatures are found in the center of the cluster, but that temperature can be lower than when brood is present.
In warm winters, however, with occasional balmy days and temperatures that rise into the 40-60°F (4.5-15.5°C) range, the bees begin doing other things. They may take cleansing flights, some search for pollen, the undertaker bees carry dead bodies from the hive, house bees clean debris from the nest and sweep cobwebs from the corners. Brood production may increase, and with increased brood production comes the need for consistently higher temperatures in the nest along with constant feeding and tending of the larvae.
All of these activities require energy even though some of them are not very effective. Foraging for pollen, for example, requires lots of energy and it may or may not produce good results. The higher than normal temperatures seem to “trick” the bees into searching for something that may not be there—or may not be found in sufficient quantities to make the trips worthwhile. We’re talking cost/benefit ratios here, and the benefits will depend on local conditions.
And don’t forget, the nights are still cold. The cluster resumes warming itself during the long winter nights, so it is still expending a lot of “keep warm” energy even though the daylight hours are warmish.
In addition to tricking the bees, I think beekeepers, too, get lulled into thinking that warm weather means the bees will have plenty of food. I, for one, have been seduced into believing that winter stores would last longer during a balmy winter. But experience has shown otherwise, and I now check for honey stores earlier in warm winters than in frigid ones.