Spanish butterflies regulate their body temperature more effectively when sunbathing than their British counterparts. Yet they face greater exposure to rising heat due to climate change, putting them at higher risk of extinction.
An international team of researchers led by scientists from the University of Cambridge in the United Kingdom and the Barcelona Institute for Evolutionary Biology, a joint center of the Consejo Superior de Investigaciones Científicas and Pompeu Fabra University, reached this conclusion after studying butterfly populations in the United Kingdom and Catalonia.
The study, published in the Journal of Animal Ecology, shows that as temperatures rise, these insects change their behavior to avoid heat. Spaniards tend to orient their wings toward the sun to warm themselves in cooler moments, while British populations rely more on seeking warm microclimates.
Global warming threatens butterflies across regions. While Britain may experience short term gains from warmer conditions, the Spanish population could struggle to adapt quickly enough to the faster pace of change.
habitat loss
In the United Kingdom habitat loss remains a major threat to these insects. Researchers emphasize pragmatic measures such as May Without Mowing, which allows wildflowers to grow along roadsides and supports tree planting, could help counter habitat destruction.
Butterflies, like all insects, are cold-blooded and rely on their environment to regulate body temperature. Understanding these regulatory patterns is crucial for predicting which species are most at risk from climate shifts.
The UK portion of the study, focusing on a cooler climate, found that butterflies are capable of regulating body temperature well there, but the researchers also examined whether populations in warmer climates, such as Spain, behave differently. Lead author Eric Toro-Delgado of IBE noted these questions.
optimum temperature
In Spain, butterflies spend more time near their optimum working temperature. As weather becomes warmer, the risk of overheating increases, explained Andrew Bladon of the Department of Zoology at the University of Cambridge, a co author of the study.
By measuring body temperature and air temperature in around 800 specimens from Spain, scientists confirmed that Spanish populations regulate heat more effectively than the British, and both national groups tend to avoid heat when air temperature reaches about 22 degrees.
Bladon added that nature reserves in the UK feel like islands with limited diversity and suggested that creating biodiverse field edges, roadside wildflowers, and taller grasses would help butterflies move and find preferred temperatures, enabling them to thrive even as conditions change.
Big risk in Spain
Despite current resilience, Spanish butterfly populations face rising risk as global temperatures climb. The UK climate is shifting toward Spain’s warmer profile, which could alter long term outcomes for both groups.
Bladon noted that while climate change might offer some short term benefits to British butterflies, both countries show signs of heat avoidance. Catalan butterflies are especially at risk because they already live near their thermal optimum.
Researchers warn that butterflies face a dual threat from rising temperatures and climate impacts such as droughts or heat waves. Extreme weather not only pushes butterflies beyond their thermal limits but can also impact the plants their caterpillars depend on.
Toro Delgado stressed that climate change and biodiversity loss go hand in hand, urging urgent action to protect key species like butterflies.
Reference: DOI 10.1111/1365-2656.14039.
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