Butterflies Find New Homes

Scientists studying butterflies around the world have found that climate change and human activity are forcing these insects to move to new places. A large global study looked at 1,758 butterfly species across 105 countries and territories. Researchers say about 80% of those species have expanded the areas where they live, while 27% have seen their living space shrink. The findings show that butterflies are some of the best animals to watch when tracking the effects of a warming planet.

Butterflies are small, cold-blooded insects, which means they rely on their surroundings to control their body temperature. When the environment gets warmer, it changes when butterflies grow, how they behave, and where they can survive. That is why scientists say butterflies are especially sensitive to climate change. Earlier studies mostly tracked how birds and fish have moved, so this new research on butterflies fills an important gap.

The study was led by researcher Shawan Chowdhury at Monash University in Australia. His team found that butterflies are shifting in three main ways: spreading out horizontally into new regions, shrinking back from areas they used to live in, or moving up and down mountain slopes. About 22% of species moved to higher elevations — farther up mountainsides — likely to find cooler temperatures. Some species did both, expanding in one area while disappearing from another.

Real-world examples show how different the changes can be from place to place. In Romania, a butterfly called Colias myrmidone lost a large part of its habitat because farmers changed how they used the land. Meanwhile, in Brazil, a species called Godartiana byses actually spread from one region into new areas as temperatures warmed. In places like Oceania and South America, development and farming pushed butterflies out of their natural homes.

The researchers also noticed something interesting about how butterflies move. More species spread out sideways into new areas than moved up or down mountains. However, the team warns that this may be because it is simply easier for scientists to spot horizontal movement. Tracking shifts up and down a mountain requires many careful surveys over time, which are harder to carry out.

Some parts of the world are much better studied than others. Europe and North America had many reports of butterfly range changes, while Central Africa, Southeast Asia, and the Amazon Basin were far less represented in the data. This means scientists may be missing big changes happening in those regions. Researchers say more study is needed in tropical areas to get a complete picture.

The study raises a big question for conservation: are butterflies that can use many different plants able to expand more easily, while those that depend on just one or two plants face a greater risk of dying out? Expert Priyadarsanan Dharma Rajan says this is a key issue to investigate. Lead researcher Chowdhury adds that scientists and nature managers can no longer treat where species live as fixed and unchanging. 'Protected areas and conservation planning need to account for where species are moving,' he said.