Century of Records Shows Europe's Wild Bees Losing Ground

Most of Europe's wild bee species, and about half of its hoverfly species, have retreated from parts of the continent where they used to be reliably found, according to a century-spanning analysis of more than four million wildlife records published this week in the Proceedings of the National Academy of Sciences. The study, led by ecologist Carlos Martínez-Núñez at the Doñana Biological Station, part of Spain's National Research Council, is among the largest attempts yet to track how individual pollinator species have fared across an entire continent rather than in the handful of well-studied countries that have dominated previous research.

The research team compiled 4.3 million occurrence records stretching from 1921 to 2020, covering roughly 88 percent of Europe's known bee and hoverfly species. At the continental scale, the picture looked relatively stable: overall species counts in most regions changed only modestly over the century, and 87 percent of bee species and 89 percent of hoverfly species recorded in the historical data were still being detected somewhere in Europe between 2001 and 2020. But that aggregate stability masked a sharper trend underneath it. Looking at individual species rather than totals, the researchers found that most bee species and close to half of hoverfly species had become less likely to turn up at any given site, a pattern the authors describe as a gradual narrowing of range rather than outright disappearance.

Where the losses are concentrated

The declines were not evenly spread. Richness fell in both the Atlantic region, which includes Britain, Ireland and parts of France, and the Continental region covering much of Central Europe, for both bees and hoverflies. The Alpine region stood out as an exception, recording a recent uptick in bee richness that the authors attribute, tentatively, to species shifting to higher elevations as temperatures rise. Species traits such as body size or diet explained little of the overall variation, though cold-adapted bees tended to decline more steeply than warm-adapted ones, and some of the steepest losses turned up among parasitic bee genera and dietary specialists, groups that depend on narrow ranges of host species or flowers.

The study's authors are careful to distinguish their findings from a collapse already under way. Roughly 9 to 13 percent of historically recorded species went undetected in the most recent two decades of data, but the paper notes many of those were already rare before 1990, and the team stops short of declaring mass extinctions. The more immediate warning, they write, is that species richness counts alone can look deceptively steady even as individual populations quietly thin out and contract, a distinction that has implications for how conservation agencies track biodiversity loss in the first place.

The paper lands alongside an already strained picture for European pollinators. An assessment released last October by the International Union for Conservation of Nature found that roughly 10 percent of the continent's 1,928 assessed wild bee species, more than 170 in total, are now at risk of extinction, up from 77 species a decade earlier, with bumblebees and cellophane bees facing even steeper risk. That assessment, like the new PNAS paper, pointed to agricultural intensification, pesticide exposure and the loss of flower-rich habitat as the main pressures, with climate change identified as a growing threat on top of those older drivers.

Why the trend matters beyond the hive

Wild bees and hoverflies pollinate the large majority of the world's flowering plants and contribute to the yield or quality of most major food crops, work that managed honeybees alone cannot replace. A sustained, species-by-species erosion of range is harder for policymakers to notice than a dramatic die-off, but ecologists say it carries similar long-term consequences for crop pollination, wild plant reproduction and the broader food webs that depend on insects. Because the new database draws heavily on historical records concentrated in northwestern Europe, the authors also caution that trends in southern and eastern parts of the continent remain comparatively uncertain, a gap that limits how confidently the findings can be extended to the whole of Europe.

Researchers call for swift, targeted action

Ignasi Bartomeus, a co-author on the study at the Doñana Biological Station, framed the findings as grounds for urgency rather than alarm.

"It is not too late to reverse the declining trends we have observed."

Martínez-Núñez struck a similar note, saying the data point to "a crucial window to act before further declines occur" and that the quiet erosion of range for many species "shows many are becoming less widespread across Europe" even where overall counts look unchanged. Ainhoa Magrach, a researcher at the Basque Centre for Climate Change who was not involved in the study, told Spain's Science Media Centre that the pattern extends across the continent in ways earlier research, concentrated in Britain and the Netherlands, had not been able to show, and warned that continued declines could weaken both wild plant reproduction and crop pollination more broadly.

The study's publication, first reported by Phys.org and since picked up by outlets including EconoTimes, coincides with the 17th Conference of the Parties to the UN Convention on Biological Diversity, under way in Yerevan, Armenia, through October 30, where governments are conducting the first global review of progress under the Kunming-Montreal Global Biodiversity Framework adopted in 2022. Pollinator decline is expected to feature in discussions of that framework's targets on species protection and sustainable agriculture.

The authors say their dataset could help refine future IUCN Red List assessments by flagging species whose range contraction has gone unnoticed in simple richness counts, and they recommend a familiar set of remedies: preserving remaining natural habitat, diversifying agricultural landscapes, maintaining flowers through more of the growing season and cutting pesticide use. They add that smaller-scale efforts, including planting native flowers and leaving pollinator refuges in gardens, parks and urban green space, can complement larger policy changes. Whether the Yerevan talks translate any of that into binding commitments remains to be seen; for now, the study stands as one of the clearest continent-wide signals yet that Europe's pollinators are losing ground gradually, even where the numbers on paper still look largely intact.