UK Bumblebees Face Population Decline as Extreme Heatwaves Limit Foraging

Bumblebees, long considered a staple of the British summer, are struggling to adapt to an increasingly volatile climate. New analysis, shared exclusively by the BBC, reveals that the record-breaking heatwaves of 2022 had a lasting impact on several of the UK’s most common species. As Britain experiences more frequent heat events, conservationists are warning that the biological limits of these insects are being pushed to a dangerous breaking point.

The Physical Toll of Rising Temperatures

The challenge for UK bumblebees is rooted in their biology. Adapted to a historically cooler climate, these insects possess dense, furry bodies and powerful flight muscles designed to retain heat. While these traits are an advantage in mild weather, they become a liability during extreme heat, as the bees struggle to dissipate the heat generated by their own activity.

“They actually cook themselves from the inside out. Once their internal body temperature is much above 40C, they literally start dying, they start keeling over.”

Dr. Richard Comont, science manager at the Bumblebee Conservation Trust

Dr. Comont notes that once ambient air temperatures hit the 28C to 32C range, bumblebees experience significant difficulty in flying. When they are grounded by the heat, they cannot forage for the nectar and pollen necessary to sustain their colonies.

Population Declines Linked to 2022 Heatwaves

The impact of extreme weather is not merely theoretical. Monitoring data from the Bumblebee Conservation Trust’s “BeeWalk” scheme provides a clear picture of the damage caused by the 2022 summer, when temperatures in the UK reached 40.3C. The populations of three common species—the red-tailed, buff-tailed, and common carder bumblebee—saw sharp declines, with peak numbers dropping by 20%, 25%, and 35% respectively.

The stress on these colonies extended well beyond the summer months. Monitoring in the spring of 2023 showed that the number of queens was consistently below average across March, April, and May, suggesting a weakened reproductive cycle caused by the previous year’s environmental pressures.

Energy Deficits and Foraging Challenges

Heatwaves create a two-fold problem: the physical inability to fly and the loss of food sources. As drought conditions often accompany heatwaves, flowering plants produce less nectar. Dr. Paul Williams, a bumblebee expert at the Natural History Museum, explains that foraging is a delicate energy calculation for the insects.

They need to make a profit, Dr. Williams said, noting that bees cannot afford the energy expenditure of visiting dried-up flowers that provide no reward. When this energy calculation fails, larvae development slows, colonies become less robust, and fewer new queens are produced for the following season.

Strategies for Conservation in Urban Landscapes

While the broader threat of climate change remains, experts emphasize that individual actions can help mitigate the impact on local bee populations. Creating flower-rich habitats is considered the most effective way to provide a safety net for insects during extreme weather.

Dr. Sarah Beynon, an insect expert who manages a farm in west Wales, has successfully transformed her land into a nature reserve by planting diverse hedgerows, meadows, and late-flowering crops.

“Your flowerpot is a service station. It’s somewhere to rest, refuel and carry on.”

Dr. Sarah Beynon, insect expert

Beyond providing flowers, Dr. Comont suggests that adding small ponds and shade to garden spaces can offer vital relief for bumblebees. Water is essential for the quality of nectar produced by plants, and dense shrubs can create cooler microclimates, allowing bees to move between foraging sites without being exposed to the full intensity of the sun.

Sources: ca.news.yahoo.com.