A global study finds nearly 10% of butterfly species have shifted where they live, but poor monitoring in the tropics could be hiding much larger changes.
Butterflies around the globe are changing where they live, with some species moving to new areas and others disappearing from their homes, in response to climate change, habitat loss and agriculture, a new study found.
In what is possibly the most exhaustive assessment of how butterflies are doing worldwide, the researchers found that nearly 10% of butterfly species have adjusted their ranges. But with a lack of monitoring in the tropics, where around 80% of insects live, many more species could be on the move, with important repercussions for conservation.
“We found range shift evidence for 1,758 butterfly species, which is roughly 10% of the known butterfly fauna,” Shawan Chowdhury, the study’s lead author and head of the Global Change Ecology Lab at Australia’s Monash University, told me. Around 19,000 butterfly species occur worldwide.
Most of the butterflies that moved – 1,427 species, more than three-quarters – expanded to new areas. About one-quarter – 480 species – contracted their ranges, meaning they disappeared from parts of their range, and about one-fifth – 381 species – moved to a different elevation.
Around 400 species, nearly one-quarter of the species that shifted their range, moved in more than one way. “Some species are documented as expanding in one part of the world, contracting in another and maybe [experiencing an] elevational shift in another part of the world,” Chowdhury explained.
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Regional differences in butterfly movements
The type of range shift varied by region: Range gains dominated in the tropics, at 80% of the species that moved, while in Europe, range expansions and losses were roughly the same (41% and 37% of affected species, respectively).
While the worldwide average of butterfly species that shifted their range was 10%, in ten countries more than half of butterfly species moved, and in 32 countries on all six continents at least one-quarter of butterflies did so.
In five European countries – the Czech Republic, Finland, Luxembourg, Spain and Sweden – more than half of butterflies changed their ranges.
What caused butterflies to move
Climate change and severe weather drove most range shifts, particularly movements into new areas, as butterflies sought cooler areas to escape rising temperatures.
“In the northern hemisphere, they’re actually moving towards the north, and in the southern hemisphere they’re moving towards the south,” Chowdhury said. “In Europe, for example, there are many species which are migrating from the Mediterranean to northern Europe. There are many new species in Finland.”
But butterflies in Scandinavia don’t have much room to move north if the temperature becomes too hot for them.
Range contractions, on the other hand, were mostly caused by land-use changes, including habitat loss and agriculture, especially in temperate areas like North America and Europe.
Information gaps in the tropics
Butterflies in more than 100 countries were affected by the range shifts, Chowdhury said. But the amount of available information on range movements differed strongly between temperate zones and the much less-studied tropics, which also harbor most insect diversity.
To assemble the most comprehensive dataset of butterflies possible, the study team reviewed more than 500 scientific papers in 15 languages, studied so-called “gray literature,” such as technical reports or conference papers, and reached out directly to dozens of other researchers.
Completing an ambitious project like this takes time. “I started planning this project in August 2022,” Chowdhury said. Four years later, the study was published.
Still, he acknowledged that significant data gaps remain despite the study’s thoroughness.
Countries in temperate areas often have long-term monitoring studies. “They know what’s happening to the species [in Europe], and even in the U.S. But for the rest of the world, we don’t really know what is happening,” he said.
More species could be moving without scientists’ knowledge
That means that while the researchers observed range changes in only around 10% of butterflies, the other 90% of butterfly species aren’t necessarily all staying put. Scientists have just not observed any changes in their ranges.
“I’m confident that there are maybe hundreds of other species, or maybe thousands, which are also experiencing a similar kind of range shift,” Chowdhury said. “We don’t really have adequate data to actually be confident about their range trends.”
And though more than three-quarters of documented range shifts involved expansions into new areas, Chowdhury said he suspects more species are losing ground than scientists have documented.
“It’s easier to identify new locations,” Chowdhury explained. “If you think about citizen science observations or monitoring, for example, people are more interested in recording new species, but people are not really providing evidence for the absence of the species.”
Range expansions can be a mixed blessing
Moving into new areas can be a double-edged sword because of habitat loss and how other species respond to climate change.
“If there is no suitable habitat in that particular area, like because of the habitat loss or agricultural intensification, then the species cannot really survive in those areas,” Chowdhury said.
A mismatch can also occur when a butterfly moves but the host plant it depends on does not. “Entire plant-pollinator dynamics could actually change because of this,” he said.
Protecting butterflies in the face of climate change, habitat loss and pesticides
Nick Haddad, a professor of integrative biology at Michigan State University who was not involved with the study, said butterflies in North America and Europe “are expanding at an incredible rate northward.”
But, he cautioned, “Whereas expansion can happen quickly into new places that are climatically suitable and, for butterflies, have the food plants that they need, there can be a long path to extinction or loss in places that are less suitable.”
Haddad said he works with butterflies in decline. “What we know is that we’ve lost a quarter of all butterflies in the last two decades in the United States, and the pattern is consistent with what we found in Europe.”
Locally, expanding butterfly ranges can benefit biodiversity and provide an initial boost in numbers, he said.
“But now imagine species that live in natural areas that are cut up by agriculture or urbanization or roads,” he said. “Then there has to be some pathway to allow range shifts to happen poleward or up elevation.”
That’s why conservationists have proposed so-called “landscape corridors” to help facilitate range expansions and provide refugia for species to escape to cooler areas with suitable habitat.
Species that can’t move on their own might need help through assisted migration, where biologists help move species to new, suitable habitats. But, Haddad said, “The problem with assisted migration is we couldn’t do it for enough species.”
Many rare butterflies, like the once-common Poweshiek skipperling that now occurs in only a handful of places, are stuck where they are, however.
“If those places become too hot – well, their range is not going to expand,” he said. “They’re just going to get toasted in place.”
What you can do
Everyone can help support local butterflies and insects in general by contributing to citizen science.
“If we have a clear idea about the species distribution because of the citizen science and long-term monitoring, then we’d be able to do more on insect conservation,” Chowdhury said.
Experts also recommend planting native flowers to provide food and habitat for butterflies and other insects and minimizing the use of insecticides.
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Links to resources:
- Chowdhury et al., 2026: Extensive climate-induced range shifts in butterflies across the globe. Nature Ecology & Evolution, 2026.
- Chowdhury et al., 2026: A framework for the strategic conservation of tropical insects. BioScience, 2026: biag136.
- Edwards et al., 2025: Rapid butterfly declines across the United States during the 21st century. Science, 387(6738): 1090-1094.
- Pinkert et al., 2022: Global geographical and latitudinal variation in butterfly species richness captured through a comprehensive country-level occurrence database. Global Ecology and Biogeography, 31:830-839.
- Citizen science: iNaturalist
