Butterfly Population at Risk Due to Climate Change, Experts Claim

Numerous studies have focused on the implications of climate change using the mean observations on existing ecosystems, but not on short-term weather disruptions such as heavy rainfall, heatwaves, or droughts. In line with the wide spectrum of the climate change concept, extreme climatic events (ECEs), which do not show any normal pattern, were one of the factors included by a research team from the University of East Anglia to understand the impact of climate change on United Kingdom's butterfly population. 

"This is the first study to examine the effects of extreme climate events across all life stages of the UK butterflies from egg to adult butterfly. We wanted to identify sensitive life stages and unravel the role that life history traits play in species sensitivity to ECEs," PhD student Osgur McDermott-Long from the School of Environmental Science, University of East Anglia said in a press release.

The team utilized the UK Butterfly Monitoring Scheme (UKBMS) data which is known to have high-quality and long-term datasets. It included around 1,800 sites in the United Kingdom where butterfly sampling and population monitoring has been done for the past 37 years. Since UKBMS can provide information within the past decades, an analysis was done incorporating weather data to compare the possible effects of the ECEs.

To further explain the impact of extreme climatic events, McDermott-Long's team noted the population changes of the resident butterfly species, butterflies which only breed once in a year, and those that observe multiple breeding seasons. According to their findings, those that breed more than once a year are more susceptible to the detrimental effects of ECEs on the population. Precipitation, or occurrence of heavy rain during the cocoon stage, was also crucial, accounting up to 25 percent of their observed species.

Meanwhile, the extreme heat was also found to be the culprit behind the potential population decline of around half of UK's butterfly species if it occurs during the "overwintering" stage of the developing butterfly. But even if ECEs pose risks, the team said that they may also have beneficial effects on the butterfly population. For instance, warmer climate during the adult stage of butterflies could help provide a more comfortable environment since they are naturally "warm-lovers," and within the UK species, one species was found to have a higher population during this time.