Why a warm winter is bad news for our butterf lies
EXTREME weather such as heatwaves, cold snaps and floods are threatening future butterfly populations, research suggests.
Increasingly topsy-turvy conditions associated with climate change are worse for the insects than ‘moderate increases in average temperature’, the study warns.
While warm summers can boost numbers, warm winters have the opposite effect as they can make butterflies emerge too early from their pupae.
And this has been a ‘terrible’ year for the insects because of the warm winter in 2015, the report said.
Researchers analysed data from the UK Butterfly Monitoring Scheme, collected from more than 1,800 sites across the country over 37 years.
They found heavy rainfall last winter hit more than a quarter of butterfly species in the UK. But the greatest harm was caused by higher temperatures, which affected more than half the species.
While the hot summer may have boosted populations in more than a third of species, overall the negative effects of the warm winter outweighed the good, the scientists reported.
Study co-author Dr Aldina Franco, from the University of East Anglia, said: ‘Although the summer was warm, the number of butterflies counted was particularly low.
‘For example, recent low counts of gatekeeper, common blue, comma, peacock and small tortoiseshell butterflies could be… due to their negative response to warm winters.’
Lead author and UEA colleague Osgur McDermott-Long, whose findings are published in the Journal Of Animal Ecology, said: ‘The study has demonstrated previously unknown sensitivities of our butterflies to extreme climatic events, which are becoming more frequent with climate change. Some of these effects are undoubtedly putting future populations at risk, such as extremely warm winters.’