The impact of heatwaves is two-fold for bumblebees.
UK species are adapted to our historically cooler climate – with fat, furry bodies that help them retain heat and powerful flight muscles that warm them as they fly.
But in a heatwave their muscles generate more heat, while their thick coats and round bodies make it harder to cool down.
Dr Richard Comont, the Trust’s science manager, says that once air temperatures reach around 28C to 32C, UK bumblebees can start to struggle to fly without overheating. If they cannot fly, they cannot forage.
“They actually cook themselves from the inside out,” says Comont. “Once their internal body temperature is much above 40C, they literally start dying, they start keeling over.”
The BeeWalk data shows in 2022, when the UK had three official summer heatwaves and temperatures reached 40.3C, population numbers dropped significantly.
Red-tailed, buff-tailed and common carder bumblebees – three of the country’s most common species – peaked well below normal levels – down 20%, 25% and 35% respectively – before dropping further into autumn as colonies struggled.
The effects appeared to last beyond that summer. BeeWalk data showed overall queen numbers were below average in March, April and May 2023.
Source:
www.bbc.co.uk
