The UK's beloved bumblebees are facing an unprecedented threat from increasingly frequent and intense heatwaves, with new analysis revealing a worrying decline in populations following the record-breaking temperatures of 2022. Data from the Bumblebee Conservation Trust shows that three of the country's most common species – red-tailed, buff-tailed, and common carder bumblebees – suffered declines of up to 35%.
Dr Richard Comont, science manager at the Trust, explains that UK bumblebees are uniquely adapted to cooler climates, but their thick coats and round bodies become a disadvantage in high temperatures. 'When air temperatures reach approximately 28C to 32C, our bumblebees can struggle to fly without overheating,' he warns.
The impact of extreme heat was starkly evident in 2022, with three official summer heatwaves and temperatures soaring to 40.3C. Monitoring data showed significant population drops, particularly in the autumn and spring of 2023, when overall queen numbers remained below average. The struggles of bumblebees are compounded by dwindling food supplies during heatwaves, as prolonged periods of extreme heat and drought cause flowering plants to dry up.
Dr Paul Williams, a bumblebee expert at the Natural History Museum, highlights that foraging becomes an energy calculation for bumblebees; if the energy expenditure outweighs the nectar return from dried-up flowers, they cannot afford to waste energy searching. Insufficient food leads to slower larval development, weaker colonies, and ultimately, fewer new queens being produced.
Conservationists are urging the public to take action, with creating more flower-rich habitats identified as the most effective way to help bumblebees find essential food sources. Dr Sarah Beynon, an insect expert, has transformed her west Wales farm into a nature reserve through the planting of meadows, willows, hedgerows, and late-flowering crops.
Even small efforts can make a difference, such as planting native wildflowers on doorsteps or windowsills to provide a vital 'service station' for foraging insects. As global temperatures continue to rise and heatwaves become more frequent, it's crucial that we act now to support the UK's struggling bumblebee populations.