The research, published in the British Ecological Society’s Journal of Applied Ecology, has found that grazing in spring can remove much of the nectar emerging bumblebees need, while commercial honey bee hives introduced during the summer heather flowering period have a much smaller impact.
Commercial beekeepers across Europe regularly move hives onto heather moorland during the summer flowering of ling heather. This has raised concerns about competition between honey bees and wild pollinators, including bumblebees, butterflies, moths and beetles.
To find out the best way to protect them, researchers from Bristol’s School of Biological Sciences surveyed plant and pollinator communities at 20 moorland sites across Scotland over a full flowering season (May to September), comparing plots with and without introduced honey bee apiaries, and comparing land that was actively grazed and burned using ‘muirburn’ practices against land left to regenerate naturally.
The team recorded over 1.6 million individual flowers and more than 5,000 plant-pollinator interactions across 58 plant species and 405 pollinator species. A total of 10 sites hosted commercial apiaries (an average of 34 hives each) were also studied during the heather bloom.
The team found that spring grazing by sheep removed almost two-thirds (63%) of vital spring nectar for bumblebees than ungrazed sites, while the introduction of honey bee hives only made a modest effect on the foraging behaviour of wild pollinators. Their presence caused only a small change to the structure of plant-pollinator networks and had no measurable effect on the quantity or quality of pollen collected by bumblebees.
Dr Maisie Brett, the study’s lead author, said: "We expected honey bees to be the main threat to wild bees and other heathland pollinators, but it turns out how we manage these habitats may matter far more. Managing livestock with pollinators in mind could be more impactful than restricting beekeeping."
The researchers recommend carefully managing or avoiding sheep grazing on heathland in spring to protect the blaeberry flowers, only introducing honey bee hives during peak heather flowering, and maintaining a patchwork of habitat types (which careful grazing can facilitate) to support wild pollinator communities.
Dr Brett added: “The findings are particularly timely given the recent Scottish Wildlife Management and Muirburn Act (2024), which now restricts heather burning, and the current Scottish Pollinator Strategy, which does not currently address the potential impact of managed honey bees on wild pollinators.”
The research was funded by the UKRI and BBSRC, and in collaboration with landowners and beekeepers across east Scotland.
Paper
‘Heathland pollinator communities are more strongly influenced by land management than by honey bee competition’, by M. Brett et al, in the Journal of Applied Ecology