One in Ten Butterfly Species Has Shifted Range as Climate Warms

The study examined 6,182 range-shift records covering 1,758 species in 105 countries, drawing on both English and non-English scientific literature as well as 68 expert assessments. It was published in Nature Ecology & Evolution.

Lead author Dr Shawan Chowdhury, who heads the Global Change Ecology Lab at Monash University's School of Biological Sciences, said the results reveal a rapidly changing natural world and significant blind spots in the way biodiversity change is tracked. He noted that butterfly species were found to be shifting their ranges on every continent where they are present, and that this was occurring well beyond the closely studied regions of Europe and North America.

Dr Chowdhury described climate change as now a dominant force reshaping where species can survive, saying that for many butterflies the only option is to move — often quickly — in order to track suitable conditions.

Expansions, contractions and elevational shifts

The research shows that 80 per cent of affected species expanded their ranges, frequently moving into areas that have become newly suitable as temperatures rise. At the same time, 27 per cent experienced range contractions, and 22 per cent shifted along elevational gradients. Elevational shifts were rarely documented in tropical regions, which the authors flag as a major concern given the narrow thermal limits of tropical species.

When the researchers assessed how many species in each country had documented range shifts, five European countries stood out — the Czech Republic, Finland, Luxembourg, Spain and Sweden — each holding records for more than half of their butterfly species. Across all countries, 32 had documented shifts for at least a quarter of their known butterfly species, and 10 had records for more than half.

Missing data and geographic gaps

Dr Chowdhury said one of the most striking findings was how much evidence had previously been missing. Including non-English studies and expert knowledge produced a substantially different global picture, and without those sources the scale of range shifts — particularly in the tropics, where 80 per cent of insect species live — would have been dramatically underestimated.

The study identifies critical geographic gaps in the data: Central Africa, Southeast Asia, New Guinea and the Amazon Basin remain severely under-represented despite being major global biodiversity hotspots. Dr Chowdhury noted that tropical butterflies already live close to their upper thermal limits, meaning even small temperature increases can push them beyond tolerable conditions, particularly when land-use change is fragmenting the habitats they depend on to move and track suitable climates.

The authors caution that without equitable, standardised and multilingual biodiversity monitoring, conservation efforts risk being shaped by an incomplete and biased body of evidence. Dr Chowdhury said butterflies function as early-warning indicators and are currently signalling change across the entire planet, and that dramatic range shifts point to profound transformations in ecosystems more broadly.

The researchers call for coordinated global monitoring, particularly in the tropics, to establish where species are moving and how they can be protected — including in the context of meeting the Kunming-Montreal Global Biodiversity Framework targets. The study concludes that climate-driven redistribution of species is not a future scenario but an ongoing and accelerating reality that requires conservation strategies capable of responding to species in motion.