A Peacock butterfly photographed in Germany.

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Boris Roessler / dpa / AFP

The resistance of butterflies to climate change could be linked to their ability to regulate their body temperature well, which depends on the size and color of their wings, according to a study released on Thursday.

Ectotherms, butterflies do not produce internal heat: their body temperature depends solely on heat exchanges with the environment.

However, their regulatory capacity varies significantly depending on the species, notes this study published in the

Journal of Animal Ecology

.

Some species are particularly obliged to take shade to protect themselves from the sun and manage to moderate their internal temperature.

4,000 wild specimens analyzed

They are "likely to suffer more from climate change and destruction of natural habitats," which sees small islands of freshness diminish, says lead author of the study, Andrew Bladon, of the university's zoology department. British Cambridge.

To measure how butterflies cope with climatic variations, the researchers captured 4,000 wild specimens from 29 species across Britain, over several months in 2009, then in 2018.

They were able to take their temperature using a tiny thermometer.

Diagnosis: larger specimens, with pale colors, such as the white butterfly or the "lemon" butterfly, have better thermoregulation because they can tilt their wings to direct sunlight.

These populations, according to the researchers, are stable or even increasing.

We must diversify the landscapes

Conversely, species with smaller and more colorful wings, such as the small copper butterfly, regulate their temperature less well, and depend on shade for cooling.

They have seen their populations decline over the past 40 years.

In Britain, butterfly populations are declining in two thirds of species.

According to Andrew Bladon, landscapes must be diversified to protect these insects essential for pollination.

By leaving, for example, taller patches of grass on lawns - to give them shade - or by "breaking the monotony of agricultural landscapes, with natural hedges, ditches and wooded plots", explains the researcher in a statement.

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