Bringing The Heat
Welcome to the FRB blog, where every month we explore the world of honeybees! Today we are going to discuss how bees overwinter: How bees stay warm in cold times and how warm winters do more harm than good.
Winter is a difficult time for most insects, who are ectothermic (cold blooded) and have no means to keep themselves warm. During the freezing months insects are in significant
danger of freezing to death themselves, and so often enter a state of dormancy similar to hibernation in mammals. In this hibernate state insects increase their cold tolerance by decreasing the freezing point of their bodies, either with bodily chemicals, waxy coatings or shifts in internal physicality. Honeybees, however, have a very different strategy.
When the cold begins to set in and the surrounding vegetation begins to die, bees begin preparations for winter. This involves two major things; laying winter bees and ensuring the proper storage of honey. For reasons as of yet not fully understood by researchers, honeybees in the active season live for 6 weeks, but bees born into the winter months live for 6 months. This extended lifespan is necessary for the survival of the hive, but it is unknown exactly what gives the winter bees their longevity.
The other task, that of ensuring proper honey storage, is so that the bees have a source of food during the winter. If you’ve ever wondered why bees make honey, this is exactly the reason. The nutrient rich and unspoiling food is perfect for the bees to eat as they make their way through the long, cold nights.
But what are the bees doing during the winter if they aren’t hibernating or out foraging? They’re heating the hive! Honeybees work tirelessly throughout the winter to maintain an internal hive temperature of 95° fahrenheit. They do this by grouping together into a large, football sized cluster inside the hive, formed around the queen, and then sticking their heads into empty honeycomb cells and vibrating their wing muscles.
The vibration generates heat, which then radiates throughout the honeycomb, and heats the hive like a radiator. Thousands of bees do this all day, every day, rotating in and out of the job as necessary to stay alive.
While it costs less energy for the bees than actively foraging flowers, this state of “dormancy” is still quite arduous, hence the need for large amounts of honey. At the end of the winter, however, the bees will emerge from the hive and begin foraging once again in preparation for the next year’s winter.
In Colorado, especially in the last two years, we have had unseasonably warm winters. There has been little to no snow, and temperatures frequently stay well above 60° fahrenheit. At first glance it is logical to think that this would be beneficial for the honeybees, since it is warmer and the whole point of this exercise is to avoid the cold. This is not the case, however. Warm winters are, in fact, incredibly dangerous for the bees. Honeybees determine many of their behaviors based on external temperature, and so when it gets to 50° outside of the hive the bees will spring into action and begin flying and foraging for food from flowers. In the winter months, however, no matter how warm it gets, all the flowers are still dead. Thus the bees are expending great amounts of energy looking for food that isn't there. When they come back they must eat from their honey stores to stay alive, and eat significantly more than they would have if they had simply stayed inside the hive, since flight and foraging is more energetically expensive. This effect compounds with every winter day that reaches 50°, to the point where the bees will eat through their winter stores long before any flowers bloom and so starve to death. This has been occurring for several years now, but most severely in 2020, where 40% of Colorado’s beehives were lost, and this year is looking to be even worse.
FRB works to ensure the survival of our hives through supplementary feedings during these difficult times for the bees, but we do so only when absolutely necessary to ensure the natural quality of the honey. We hope in the future to see a shift back to normal weather patterns or adaptive behaviors in the bees, but work tirelessly in the meantime to guarantee the dwindling population of pollinators in Colorado stays healthy.
To learn more about honeybees and how they overwinter check out the Free Range Beehives home page or reach out to us using the links at the bottom of the page.