What links the London Stock Exchange, posh grocer Fortnum & Mason and the Scottish parliament building in Edinburgh? All great institutions, of course, but they have also proudly introduced beehives to their rooftops.
In the midst of worrying stories about declining bee populations, it has become a popular pursuit. Businesses and government install the hives with great fanfare to signal their green credentials, but is this actually a good thing for honey bees, beekeepers and the public?
For beekeepers it is clearly more convenient to keep hives at ground level. The bees do fine, and level locations are plentiful in most areas. Both ground and roof locations require beekeepers to carry out routine and seasonal management, such as hive inspections and honey harvesting. However, hive equipment is bulky and heavy. Steve Benbow, a commercial beekeeper in London, has described the effort of carrying hives to the roof of the Tate Modern art gallery via chambers, lifts, corridors, and a final ascent up four flights of stairs. Moving stuff is a lot easier at ground level.
Swarm behaviour
Then there are the swarms. Each spring, beekeepers have to manage this natural part of the life cycle in which a colony divides – swarming is how honey bee colonies reproduce. The swarm, when it leaves the colony, can contain 10,000 bees. Beekeepers manage their hives to prevent swarming. However, prevention is never 100%. If swarming does occur, the swarm usually settles near the parent hive and can then be put into an empty hive and moved to a more convenient location.
Swarming from a rooftop probably makes little difference from a bees’ perspective. But the swarm is liable to be more of a public nuisance. Mark Patterson of the London Beekeepers Association told us that swarms from high-rise hives often settle high. He recounted episodes of abseiling down buildings, calling in the fire brigade and using window-washing platforms to collect central London swarms originating from high-rise hives.
So much for our convenience, what about the bees? Well it is true that honey bees actually prefer to nest above ground level. Tom Seeley, a honey bee biologist at Cornell University, has shown that swarms are picky when selecting a nest site. By attaching plywood bait hives to trees he found that swarms prefer five metres above ground to one metre.
When Seeley located wild honey bee colonies in hollow trees in a nearby forest he found the average height was 9.7 metres (in a range of between 5.3 and 17.3 metres). That’s about three storeys high.
This shows that honey bees do not mind being quite high up, at least when nesting in a forest. We don’t actually know why honey bees in the wild prefer not to nest at ground level. It may provide protection against predators such as bears. Urban hives at ground level are unlikely to be predated, other than by humans, of course.
Altitude attitudes
In the UK, hives on iconic buildings such as St Paul’s Cathedral in London, can be very high up, 52 metres in that case. This is higher than bee colonies live in trees. Is this good for the bees? As far as the risks to a successful colony go, James Fischer, a New York rooftop beekeeper, told us that hives above ten storeys are “speculative ventures”; those above 15 stories are on “life support”.
Research has yet to establish if height itself is an issue for honey bee colonies. Honey bees routinely forage several kilometres from their hive. To a bee, flying level or flying vertically should make little difference as air resistance, not gravity, is the main challenge. Flying vertically to a hive at 50 metres would be negligible extra distance.
More obvious is the fact that apiary sites should not be too exposed. Beekeepers know that good locations should be sheltered from the wind and this may be harder to achieve on roofs. Tall buildings often cause the wind to form unusual draughts and eddies.
Sweet reward
What is the real motivation for keeping rooftop hives? With trendy London honey retailing at up to four times the price of a similar Leicestershire honey, financial reward is one incentive. A somewhat different motivation is the desire of businesses and government bodies to showcase environmental credentials, by helping to save the “endangered” honey bee.
However, this may not actually be helpful, particularly when it adds more hives into an area where there are already many, as seems to be the case in London. More hives increase the risk of spreading bee diseases and annoying neighbours. Overstocking can also increase competition for nectar and pollen which is not good for honey bees or beekeepers, or other pollinator species. Many towns, and especially central London, probably already have as many hives as the available flowers can support. Most people will have no clue that each new hive will consume the floral resources produced by the equivalent of eight hectares of lavender.
Keeping bees can be a fascinating hobby. And with the surge of interest in urban farming, sustainability, food security, and the environment – as well as intense media focus on bees – it is not surprising that beekeeping is becoming increasingly popular. People who take up beekeeping or staff who join corporate beekeeping projects often report genuine benefits such as more contact time with nature.
But beekeeping isn’t easy. For a novice, the reality can easily be dead colonies and no honey, rather than the hoped for abundant harvest. Once people start to question the motivation for installing yet another rooftop hive, they may find that more benefit could be gained, for bees, humans and other flower visiting insects, by growing flowers that provide nectar and pollen for all pollinators.