Butterflies are rapidly changing where they live as climate changes
Baku, August 6, AZERTAC
Butterflies are redrawing the map of where they live. A global review of butterfly range shifts finds movement on every continent where they occur, at a scale no earlier survey captured, according to Earth.com.
The stakes reach past the insects. Butterflies pollinate plants, feed birds, and act as an early alarm. When their ranges move this fast, whole food webs are shifting underneath them.
Researchers compiled 6,182 range shift records for 1,758 species across 105 countries. That is roughly one in ten of the butterfly species known to science.
Butterfly ranges shift worldwide
The work was led by Dr. Shawan Chowdhury, head of the Global Change Ecology Lab at Monash University, with 68 butterfly experts from 49 countries as co-authors.
“We found butterfly species shifting their ranges on every continent where they occur. The scale is astonishing, and it’s happening far beyond the well-studied regions of Europe and North America,” says Chowdhury.
In the dataset, 80% of species expanded their ranges. Another 27% contracted, and 22% moved up or down mountain slopes. A single species can fall into more than one group.
Climate change and severe weather were linked to 79% of the documented shifts. Agriculture and human disturbance came next, and they dominated where ranges shrank.
Range expansion sounds like a win. Chowdhury says it should not be read that way, at least not by default.
Speaking to Earth.com, Chowdhury said, “Range expansion should not be treated as good news by default. A species may expand in one region while declining in another, and movement can signal that former habitats are becoming unsuitable.”
The distinction matters for planning. A map showing a species arriving somewhere new says nothing about what it lost at the other end of its range.
There is also a traffic problem behind the numbers, and it explains why so much movement fails.
“In many cases, climate change may push species to move, while land-use change blocks the route,” says Chowdhury.
The paper makes the same point. Even where the climate turns suitable, colonization fails if host plants, microclimates, or connected habitat are missing.
Coverage is wildly uneven. Five European countries – the Czech Republic, Finland, Luxembourg, Spain, and Sweden – have records for more than half of their butterfly species.
Most other countries have documented shifts for under 10% of their national species pool. Central Africa, Southeast Asia, New Guinea, and the Amazon Basin are thinnest of all.
Those are the places where the risk runs highest. Tropical butterflies already sit near their upper heat limits, with narrow ranges and few cool refuges within reach.
“The tropics surprised me most. By including non-English studies and expert knowledge, we found more tropical evidence than would usually appear in global reviews,” says Chowdhury.
Elevational movement is the clearest gap. It was rarely documented in tropical countries, even though roughly two-thirds of butterfly species live mainly on mountain slopes.
The team sorted reported causes into threat categories set by the IUCN. Nine came up, and climate change and severe weather led, linked to 278 of the 352 species with threat data.
Different pressures leave different marks. Climate topped the list for expansions and elevational moves, while farming and human intrusion dominated range contractions.
Examples run across continents. Bog drainage in Germany cost Boloria aquilonaris much of its habitat in that country.
In the United States, the arrival of Pieris rapae pushed Pieris oleracea into a sharp retreat.
Regional patterns vary as well. Development and invasive species topped the list in Oceania, while human intrusion and disturbance dominated in South America.
Long-running counts in Britain show what those pressures add up to. Even a hot summer no longer lifts numbers the way it once did.
The evidence base itself turned out to be part of the finding. English-language papers alone skewed the picture toward expansions and played down contractions.
Adding studies in 15 languages and 68 expert assessments changed the shape of the result.
“When we included non-English studies and expert knowledge, a completely different global picture emerged,” says Chowdhury.
“We need long-term, locally led monitoring supported by proper funding. That means working with local researchers, natural history societies, museums, citizen scientists and conservation groups,” says Chowdhury.
He adds that the fix is not simply more records. “The key is not only collecting more data, but supporting the people and institutions already working in these regions,” says Chowdhury.
The authors are careful about what the percentages mean. They show how well butterfly range shifts are documented, not how often they happen, and bias may inflate the expansion share.
Protected areas were drawn for a stiller world. About 76% of insect species are poorly represented in the current network, and the figure rises to 85% for migratory butterflies.
“Conservation planning needs to move beyond static maps and consider where species are moving, where they are being lost, and whether landscapes allow them to move safely,” says Chowdhury.
In practice that means corridors, host plants, cooler refuges, and restored habitat, plus the nectar quality that warming is quietly eroding.
National plans under the Kunming-Montreal Global Biodiversity Framework will need butterfly range shift data built into spatial planning and reporting.
“Butterflies are early-warning indicators. If their ranges are shifting this dramatically, it signals profound changes across ecosystems,” says Chowdhury.
The study is published in the journal Nature Ecology & Evolution.
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