The Winter cluster
During the Winter, Bees no longer forage for food and instead rely on their stores of Honey they have built up during the Summer. The Bees cluster together in the middle of the Hive and use their combined body heat (generated by rapidly flexing their flight muscles) to survive the cold. By doing this, the Bees can maintain at core temperature of ~35°C.
The Bees wil cluster next to the stores of Honey; as as they consume it the cluster will move upwards, keeping in contact with the stores. Once they reach the top of the frame, they will move to the side, again following the stores. However, if the Bees move to one side of the Hive, they may be at risk of Isolation Starvation.
As a general rule, a full Hive will require ~20kg of Honey to survive the Winter (UK average). As a full frame will contain ~2.5kg of Honey, the Hive needs to contain ~8 full frames of Honey stores at a minimum.
Bees can starve to death in a Hive that still contains Honey stores. This is known as Isolation Starvation and it occurs when the Bees feed to one end of the Box, not realising they have left stores at the other end, and so starve.
The diagram below shows the schematic of a Brood within a Hive:-
A large (strong) overwintering colony (A above) only has to move a short distance to access stores in midwinter. In contrast, a small (weak) overwintering colony has to move much further.
Consequently, small colonies become isolated from their stores during long, cold periods when the colony is clustered. This leads to starvation.
When to feed bees
In order to keep a colony alive, at times it is necessary to feed the Bees directly. This can be for a variety of reasons:-
Removal of Honey Stores - When Bees store Honey it is to be used as a food source over the Winter. If the Beekeeper removes this store then the food must be replaced or the Bees will not survive the Winter.
Splitting a colony - When a colony is split, the resultant sections may not have enough food in the short term. To prevent the loss of the colonies, the Bees should always be fed directly when splitting.
Poor Spring weather - When the colony starts to become more active in the Spring, they will usually be at the end of their Winter stores. If there is a prolonged spell of poor wet weather at this time, the Bees will not be able to forage and are at risk of starving.
Note - if being fed with sugar syrup, the correct strength syrup must be used depending on the time of year. See - Beekeeping Tools for further information.
Water and Bees
Bees like all living things require water to survive. But Bees also require water for use within the colony as well:-
Cooling the Colony - During warm periods, Bees use water to cool the colony through evaporation. They do this by spreading droplets of water on the Comb and then fanning it with their wings to speed up the evaporation process.
Using Honey stores in Winter - Honey tends to crystallise in low temperatures, so in order to consume it the Bees need to dilute it with water to make it liquid again.
Making Royal Jelly - Nurse bees, who feed the developing larvae, also have a high demand for water. The nurses consume large amounts of pollen, nectar, and water so that their hypopharyngeal glands can produce the jelly that is used to feed the larvae.
During the Summer months, foraging Worker Bees will bring water back to the colony as needed. This is why it is important to have a good safe water source close to the colony.
During the Winter months, when foraging stops, the Bees still require water. There is less required than during the Summer months due the lower activity of the colony and the lack of brood to feed, but water is still needed. The Bees will usually collect the condensation that gathers on the inside of the Hive and use this, but if the weather is warm enough they may forage beyond the Hive for water.
This is risky, as if the core temperature of a Bee drops too much, its flight muscles will not work and it will not survive. Due to this, it is good practice to ensure there is an ice-free water source very close to the Hive during the Winter.
Foraging for water is surprisingly dangerous for a Bee. This is because the Bee risks drowning if it accidentally falls into the water. This is because the surface tension of the water stops the Bee being able to fly back out.
If the Bee can reach the side and climb out, they can survive however. Because of this, it is good practice when providing a water to make sure there is enough places that the Bees can land safely and climb back out of the water if needed. This can be done by placing objects such as stones, moss or marbles into the water so stick out.
The images below show examples of Bee Watering Stations:-
Hive lockdown & location
As discussed above, water inside the Hive is vital to the survival of Bees within it, however too much water can be a problem. Water promotes the growth of moulds and other microorganisms as well as chilling the Bees through evaporation. This is why the Hive roof is covered ina waterproof material and why all gaps in the Hive are plugged with Propolis (a waterproof material) by the Bees.
This is also why the Hive should be placed on a strong Hive Stand, so that it is raised off the wet ground and is stable in Winter storms. Some beekeepers bind the Hive parts together with strapping over the Winter (as fewer inspections are taking place) to make it harder to be blown over.
In preparation for Winter, Mouse Guards or entrance reducers should also be added to Hives to prevent the overwintering colony from infestation.
The Hive will get a good proportion of ventilation through the open mesh floor below it, but only if the Hive is sited in such a way that there is good airflow around it. The air should be able to flow around the Hive without exposing it to strongs winds, screening bushes around the Hive are ideal.
By siting the Hive in a location that get exposed to the Sun (even the Winter Sun), the air temperature around the Hive will be 1-2°C warmer than in the shade. This can be the difference between being able to leave the Hive to defecate or not, reducing the risk of Dysentery.
In Winter, the Hive inspections are greatly reduced. This is because opening the Hive can very quickly chill a colony, so the Hive should only be opened if absolutely necessary.
Every 2-3 weeks a very quick check should be done to ensure the Bees have enough food stores remaining. This can be either done "by heft" (lifting the side of the Hive approximately an inch and gauging the weight) or by a very quick peek under the Crown Board.
The steps below show how to interpret the "peek" check:-
If the Bees are not visible in the "peek" check, it means that they are still low down on the comb and nothing further is required at this stage.
If the Bees are visible at the top of the frames, they have used up a lot of their food stores and should be fed as described above.
The start of Spring in Scotland can vary wildly, depending on the weather can start anywhere from the end of March to the middle of May. Due to this, special care must be taken to ensure that the Bees have enough stores to last out a particularly cold or wet period.
If a colony has not been actively flying by about mid-march, a more full check should be done on as warm a day as possible. If the colony is still alive but small and trapped below empty comb (see above) it may be at severe risk of Isolation Starvation and should be fed immediately. This can be done by wedging fondant between the combs in contact with the remaining cluster of Bees.
Once the foraging Bees are seen in large numbers, returning with fresh Pollen, then the weekly inspection schedule can be restarted.