For years, arguments about pollinator declines on Scotland's heather moorlands have centred on a familiar suspect: the honey bee. Commercial hives are trucked onto the hills each summer for the ling heather bloom, and critics have long worried that these introduced colonies outcompete native bumblebees, butterflies, moths and beetles for a limited supply of nectar. A new University of Bristol-led study suggests that this framing may have pointed conservationists in the wrong direction.
Published in the Journal of Applied Ecology, the research found that spring grazing by sheep removed almost two-thirds of the nectar available to emerging bumblebees, while the arrival of commercial honey bee hives produced only a modest shift in the foraging behaviour of wild pollinators. In other words, how moorland is managed for livestock appears to shape pollinator fortunes far more than how many hives are parked among the heather.
A Season-Long Survey Across 20 Moorland Sites
To identify the most effective way to protect wild pollinators, researchers from Bristol's School of Biological Sciences surveyed plant and pollinator communities at 20 moorland sites across Scotland, tracking the full flowering season from May to September. The design allowed them to compare plots with and without introduced honey bee apiaries, and to set actively grazed and burned land — managed under 'muirburn' practices — against areas left to regenerate naturally.
The scale of the fieldwork was substantial. Over the season, the team recorded more than 1.6 million individual flowers and more than 5,000 plant-pollinator interactions, spanning 58 plant species and 405 pollinator species. Ten of the sites hosted commercial apiaries during the heather bloom, with an average of 34 hives at each location.
What the Data Showed
Two findings stand out from the analysis, and they point in the same direction. First, spring grazing by sheep was linked to 63% less spring nectar than was available at ungrazed sites — a loss that lands precisely when bumblebees need it most. Second, the introduction of honey bee hives had only a small effect on how wild pollinators foraged, caused only a minor change to the structure of plant-pollinator networks, and produced no measurable difference in the quantity or quality of pollen that bumblebees collected.
- 20 moorland sites surveyed across Scotland from May to September.
- More than 1.6 million flowers and over 5,000 plant-pollinator interactions recorded.
- 58 plant species and 405 pollinator species documented.
- 10 sites hosted commercial apiaries during the heather bloom, averaging 34 hives each.
- Spring grazing by sheep was associated with 63% less spring nectar than ungrazed plots.
- Honey bee hives showed no measurable effect on the quantity or quality of pollen collected by bumblebees.
The Honey Bee Effect Was Smaller Than Expected
The results push back against a widely held assumption. Because commercial beekeepers across Europe regularly relocate hives onto heather moorland during the summer flowering of ling heather, concerns about competition between managed honey bees and wild pollinators have driven much of the debate about heathland conservation.
Dr. Maisie Brett, the study's lead author, was direct about how surprising the findings were. "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," she said. "Managing livestock with pollinators in mind could be more impactful than restricting beekeeping."
That is a meaningful reframing. Restricting beekeeping is a relatively narrow policy lever, and one that pits conservationists against an established rural industry. Livestock management, by contrast, touches on grazing calendars, stocking densities and burning regimes — decisions that already sit with landowners and land managers.
Why Spring Nectar Matters So Much
Timing appears to be the crux of the problem. The nectar that sheep remove in spring is the nectar that newly emerged bumblebees depend on early in the season, before the summer heather bloom arrives. When that resource is stripped away, the insects are entering their active season with a depleted larder.
The summer months tell a different story. During the heather flowering period, when hive densities on the moor are at their highest, the study detected only modest changes in the behaviour of wild pollinators. The bees were sharing a landscape, but the data did not show the kind of competitive squeeze that many observers had predicted.
Grazing, Muirburn and Natural Regeneration
The study deliberately set land that was actively grazed and burned against land allowed to regenerate on its own, treating habitat management as the central variable rather than a background detail. That choice places the research in the middle of a long-running conversation about how Scotland's uplands are managed — and it suggests that pollinator conservation and agricultural practice are not separate agendas.
Heathland habitats are shaped by grazing and burning, and those practices have ecological consequences that extend well beyond vegetation structure. The Bristol team's results indicate that the pollinator consequences are large enough to warrant explicit consideration, particularly where spring grazing coincides with the emergence of bumblebees and other early-season insects.
What the Findings Mean for Policy
The practical takeaway is a shift in emphasis. Rather than focusing narrowly on the number of honey bee colonies present on the moor, the study points to the timing and intensity of livestock grazing as the more consequential variable for wild pollinator populations. Sites left ungrazed in spring retained substantially more of the nectar that supports bumblebees, butterflies, moths and beetles through the season.
Because commercial apiaries are a fixture of the summer heather economy — and because honey bees remain a valued part of rural livelihoods — a framework that targets grazing management may prove both more effective and easier to implement than one built around restricting beekeeping. That does not mean hives are harmless, only that the measurable competition they generate in this system appears considerably smaller than the resource loss caused by sheep in spring.
Open Questions and Next Steps
The study covers a single flowering season across one set of Scottish moorland sites, which makes it a strong snapshot rather than a long-term verdict. Whether the patterns observed hold across multiple years, different grazing intensities and other upland regions is a natural next line of inquiry. What the work does establish is a clear ordering of effects: in this landscape, habitat management outweighed the presence of managed honey bee colonies as a driver of wild pollinator foraging conditions.
For conservationists, land managers and beekeepers alike, the message is that the argument over honey bees may have been the easier conversation to have — and not necessarily the most important one.
This article is based on reporting by Phys.org. Read the original article.
Originally published on phys.org
