Bees use as much energy collecting pollen through “floral buzzing” as they do taking off in flight, a study shows.
Scientists have found the vibrations bumblebees use to shake pollen loose from flowers are among the most exhausting behaviours they perform, forcing bees to “carefully choose” which flowers are worth visiting.
The study, released by the Royal Society, is the first to directly measure the energy cost of floral sonication, or “buzz pollination” – where bees vibrate flowers to extract pollen.
Natacha Rossi, a University of Sussex research fellow who led the study, said: “As nectar availability shifts due to climate change or habitat loss, the energetic demands of pollination could influence bee behaviour and, ultimately, where bees forage and which plants they pollinate.
“These results help us to better understand plant-pollinator relationships and just how hard at work a buzzing bee really is.”
In 2024, the number of bumblebees in the UK declined by almost a quarter compared with the 2010-2023 average, according to the Bumblebee Conservation Trust. The researchers said the drop was probably due to the cold and wet conditions in the UK that spring. Despite a rebound in 2025, numbers for many species are still below average.
Using lasers and respirometry equipment to monitor three colonies of buff-tailed bumblebees, researchers discovered that a single “buzzing event” required about the same amount of energy as a flight take-off. Because buzzing can last longer, the total drain on energy can be even greater.
Dr Beth Nicholls, principal research fellow at the University of Sussex, said: “The findings suggest that floral buzzing could represent a major part of a bee’s daily energy budget, something that has previously been overlooked.
“These bees must carefully choose which flowers they visit to ensure they have enough energy to pollinate.”
The research said that the finding “challenges the common assumption that flight dominates bee energy budgets”.
The metabolic rate of a floral buzzing bee is more than 30 times higher than its resting metabolism, according to the study, making the process among its most energetically demanding behaviours.
The researchers warned that declining nectar supplies caused by climate crisis and habitat destruction could intensify the strain on pollinators.
Prof Mario Vallejo-Marin, at Uppsala University, said: “We long suspected that buzz pollination was an energetically expensive affair. We can now put a number to it and begin making quantitative predictions of how it could affect the ecology and evolution of bees and buzzpollinated flowers.”
The study points out that the energetic drain on the bee does not stop when the pollination stops. According to the paper, after the bee vibrates the pollen loose, it must engage in a “grooming and pollen-packing phase”.
This grooming takes even more energy. The bee then has to force a high-power take-off to carry its new, heavier load away, making the whole process a demanding two-phase sequence.
Find more age of extinction coverage here, and follow the biodiversity reporters Phoebe Weston and Patrick Greenfield in the Guardian app for more nature coverage
