Native honey bees in your forest

When we think of honey bees, we usually think of them as living in human-managed beehives and with honey production for humans as their purpose. Paul Butler, Forestry Liaison Officer, Teagasc Athenry, explains more in this article.

For a number of years, it was considered that there were no wild honey bees left in Ireland and that the only bees were the ones being kept by beekeepers.

However, there was no real evidence for this and in about 2015 Grace McCormack from NUIG decided to begin a survey of wild or free-living colonies of bees. The survey uncovered not only the existence of a population of wild honey bees in Ireland, but that population was healthy and relatively disease free. This is good news. In general the population of honey bees in Europe has declined due to habitat destruction, pesticide use, disease and even the killing of wild nests to favour kept colonies. Ireland, in fact, is a stronghold of the native Northern European Black Bee, Apis mellifera mellifera. This bee may even be genetically different from the main European Black Bee population and especially well adapted to the particularly wet and windy conditions found on our little island.

Looking after this unique population

The natural home for these bees is in woodland. Of course in Ireland we have a very small amount of forest cover (approximately 12% as opposed to the European average of about 38%). And this forest estate is relatively young. That means that the old, hollow trees that bees favour as their nest sites are few and far between. Bees are amazingly adaptable and, in the absence of hollow trees, have made their homes in roof spaces, stone walls, and old ruins. They do prefer trees, however. When artificial hollow trees are made available to bees in an area, these are colonised first and quickly over all other options. Why? Well a hollow tree provides just the array of conditions that the bees like.

They like a high up entrance to their nest. A tree hollow can be many meters up on the tree. This is in contrast to a conventional beehive, which is basically at ground level or a few feet up at best.

They love a well insulated nest. A tree trunk surrounding a hollow provides just that and protects the nest from rain, but also from extremes of temperature - both in summer and in winter. A tree hollow can be surrounded by many inches of insulating wood. In contrast, the walls of a human-made hive are regularly as thin as half an inch. This well insulated hollow means that the bees don’t need to use as much energy to stay warm in the winter (and so they also need to store a smaller amount of honey) and so the colony winter survival odds are improved.

Hollow trees tend to be scattered here and there. That means that the colonies are dispersed far apart in the forest (the average distance in one study was about 800m distance between colonies). This again is in contrast to the situation in a human-managed apiary, where many colonies are kept close together, literally inches apart in many cases. The greater distances between colonies seems to reduce disease, there is less incidence of robbing of stores by other colonies and foragers have less trouble finding their own colony when they come home. It basically seems to be less stressful for the bees.

Tree hollows also tend to be small and the bees can occupy and use them efficiently. They can cover the rough surfaces with propolis, which is essential to bee health. Human-made hives tend to be a lot bigger to maximise honey production for human harvest and are usually made from smooth timber, which is difficult for the bees to propolise.

Creating spaces in your woodland for bees to nest in is a great way of helping this native bee to continue to thrive. Having bees in your woodland also means that your trees, your garden plants and your field crops will benefit from the pollination services of this little insect.

Encouraging bees

So how to encourage bees in your woodland? One way is simply allowing some old trees to remain standing and hope that natural hollows will occur and be colonised by bees.

Another more direct approach is to buy or create artificial hollows or conservation log hives. These are sections of tree trunk hollowed out using a chainsaw and long-handled chisels. Once the hollow is made, a roof and a floor are added to complete the space and an entrance made to allow the bees access. It is surprising how quickly a well positioned log hive is colonised by bees, who seem to relish the chance to have a home in the next best thing to a hollow tree.

Figure 1: A log hive in a high tree

Because these hives are not for honey production, there is no need to open them as conventional beekeepers do with conventional honey-producing hives. This is a benefit to the bees because opening the hive is a source of stress to the bees and a disruption of hive functioning.

Figure 2: Various types of log hive

A further advantage of these logs is that the bees have free rein to construct their comb as they see fit. In a conventional hive, there are usually wooden frames guiding the bees where to build. In addition, the frames are usually filled with stamped sheets of wax that encourages the queen to lay only worker bee eggs. When left to their own devices, the queen chooses naturally to lay mostly worker bees, but also approximately 20% drone eggs. These drones are the male bees and that 20% from each hive provides enough genetic diversity for the bees in the local area to be able to adapt and evolve to changing environmental circumstances. Bees should of course never be imported from other countries, as this dilutes the genetic integrity of the unique Irish population.

It is also, of course, possible to operate more conventional-style bee hives in your forest and harvest some honey from these. This usually will involve a hive that has frames and that can be opened to access the honey on those frames. This can be done in such a way that a small amount of honey can be harvested with minimal disturbance to the bees. It does require more hands-on intervention of course and so a greater degree of knowledge and skill is required in order to carry out those tasks.

And, of course, it is also true that there are many other bees in Ireland apart from the honey bee. In fact a total of 98 bees live here. The populations of some of these insects are critically low and all the measures we use to encourage wild honey bees will also benefit them, for example, using less herbicides and leaving areas of un-cut grass. Click here for more on these bees and how to help them.