Gland, Switzerland (IUCN) –Experts from the International Union for Conservation of Nature (IUCN) have analysed how targeted management of invasive alien species (IAS) can reduce extinction risks for threatened species across the European Union (EU), in line with the EU Biodiversity Strategy for 2030.
Published in the open-access journal NeoBiota, and funded by the European Commission, a new study identifies where and how targeted action against IAS (species that have been introduced to areas outside their natural range, either intentionally or unintentionally by human activities, and cause negative impacts) can have the highest conservation impact.
The authors applied the IUCN Species Threat Abatement and Restoration (STAR) metric to measure opportunities for species threat abatement caused by IAS. The research estimates that fully removing threats from IAS could reduce extinction risk for EU species by up to 16%.
The Macaronesian Islands, namely the Canary Islands (Spain), Madeira (Portugal), and the Azores (Portugal), present the largest opportunities for reducing species extinction risk. The research calculates this at an over 40% reduction in extinction risk if IAS were eliminated, illustrating how IAS pose a significantly higher threat to islands compared to mainland ecosystems. Islands are particularly vulnerable due to their unique biodiversity, high levels of endemism, and often fragile ecosystems.
"Given the alarming impact that invasive alien species have on native biodiversity and the economy, it is essential to identify where action can have the greatest effect. In this context, our work presents the first regional application of the Species Threat Abatement and Restoration (STAR) metric, a science-based method that links conservation actions to the reduction of species extinction risk. By applying STAR with data from the EU Red List of threatened species, we highlight opportunities for addressing invasive alien species across national and subnational levels in the EU," said Randall Jiménez Q., Senior Conservation Scientist, Science team, IUCN (first author of the research).
“Mitigating the impacts of invasive alien species offers some of the greatest potential gains for conserving native biodiversity, while also delivering benefits for ecosystem services and local economies,” Boris Erg, IUCN European Regional Director, said. “This analysis provides decision-makers with guidance on where efforts can achieve the most significant results, supporting progress toward the EU Biodiversity Strategy target of reducing impacts on threatened species from invasive alien species by 50%.”
For specific IAS, the greatest opportunities to reduce regional species extinction risk by mitigating threats from IAS come from managing feral goats (12.4%), mouflons (8.1%), rabbits (5.3%) and rats (4.6%).
Invasive alien species are a major threat to global biodiversity and the total cost of biological invasions across all European Union member states has been estimated at 129.9 billion US dollars between 1960 and 2020. In Europe, measures for IAS management are mainly established through the European Union Biodiversity Strategy 2030, which aims to halve the number of IUCN Red List of Threatened Species at risk from IAS by 2030.
Across the EU, 3,759 species (excluding marine animals) have been assessed as Near Threatened or Threatened with extinction, of which 579 (15%) are documented to be threatened by IAS (IUCN 2024).
A 2023 report from the Intergovernmental Panel on Biodiversity and Ecosystem Services (IPBES) found that IAS have been a significant driver in 60% of documented plant and animal extinctions. The report, informed by experts from the IUCN Species Survival Commission (SSC) Invasive Species Specialist Group (ISSG), identified 3,500 invasive species that are severely harming biodiversity and human livelihood. These are increasing rapidly, with a forecast increase of 36% by 2050 – posing threats to the realisation of the Global Biodiversity Framework.
Supporting quote:
"This study provides compelling evidence that targeted action against invasive alien species in priority areas can significantly reduce extinction risk for hundreds of species across the EU. It underscores the urgent need for science-based, well-coordinated responses to biological invasions—responses that integrate biosecurity, invasive alien species management, and ecosystem restoration, particularly in biodiversity hotspots such as the Macaronesian Islands."
— Piero Genovesi, Chair, IUCN Invasive Species Specialist Group
Original source:
Jiménez RR, Smith KG, Brooks TM, Scalera R, Mair L, Nunes AL, Costello KE, Macfarlane NBW (2025) Guiding action on invasive alien species towards meeting the EU's Biodiversity Strategy for 2030. NeoBiota 99: 109–129. https://doi.org/10.3897/neobiota.99.148323