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  • Review Article
  • Published:

The status, threats and conservation of Critically Endangered species

Nature Reviews Biodiversity volume 1, pages 421–438 (2025)Cite this article

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Abstract

Over 47,000 species on the Red List of the International Union for Conservation of Nature are assessed as being at risk of extinction, including more than 10,000 Critically Endangered (CR) species. In this Review, we focus on the status, geographical and taxonomic patterns, and threats to CR species, and the actions needed for their conservation and restoration. Just 16 countries host more than half of all CR species. Although many CR species benefit from protected areas, two-fifths require targeted species-based interventions, such as ex situ actions and conservation translocations. Further, although conservation actions are associated with improved outcomes for CR species, including reduced extinction risk, actions in place have been documented for fewer than half of these species. In addition, the assessment of conservation status is incomplete for many species and subject to taxonomic and geographical bias; as more species are assessed the number of CR species is expected to increase. To address these challenges, the conservation community has improved approaches to planning and prioritization, developed tools and metrics, and enhanced capacity to deliver conservation actions. Nevertheless, greater political ambition and substantial financial investments are needed to resource the work of governments, institutions, communities and Indigenous peoples if we are to save and recover CR species.

Key points

  • Critically Endangered (CR) species are those closest to extinction and represent a potential single point of failure for achieving the Kunming–Montreal Global Biodiversity Framework, because many CR species require urgent management actions to ensure their recovery.

  • The protection and cost-effective conservation of Key Biodiversity Areas, including Alliance for Zero Extinction sites, has benefited the species for which these areas have been identified, including CR species of birds, mammals and amphibians.

  • Expanded use of the International Union for Conservation of Nature’s Green Status of Species and emphasis on functional recovery will renew the focus on both the recovery of species and their contribution to ecosystem function and services, while providing a robust method of tracking the progress of recovering species’ populations towards ‘healthy and resilient levels’, as enshrined in Goal A of the Global Biodiversity Framework.

  • Uptake of conservation metrics and tools by government and the private sector would enable the identification of areas where investments in threat abatement or restoration activities could yield the greatest positive impact on species conservation.

  • Updating estimates of costs and shortfalls for effectively conserving CR species and the sites they depend upon is urgently required but should not preclude or delay efforts to scale up resources aimed at the conservation of CR species.

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Fig. 1: Classifying Critically Endangered species.
Fig. 2: Distribution of Critically Endangered species.
Fig. 3: Changes in Red List category over time.
Fig. 4: Threats to Critically Endangered species.
Fig. 5: Conservation actions for Critically Endangered species.

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Acknowledgements

A.T.S. is supported through the Natural Environment Research Council’s C-CLEAR Doctoral Training Partnership (grant NE/S007164/1).

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Authors and Affiliations

  1. Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX, USA

    Thomas E. Lacher Jr

  2. Re:wild, Austin, TX, USA

    Thomas E. Lacher Jr & Barney Long

  3. BirdLife International, Cambridge, UK

    Stuart H. M. Butchart

  4. Department of Zoology, University of Cambridge, Cambridge, UK

    Stuart H. M. Butchart & Ashley T. Simkins

  5. IUCN Species Survival Commission, IUCN, Gland, Switzerland

    Stuart H. M. Butchart, Rikki Gumbs, Barney Long, Cristina Lopez-Gallego & Michael Hoffmann

  6. Institute of Zoology, Zoological Society of London, London, UK

    Rikki Gumbs

  7. IUCN Colombia Species Specialist Group, Medellin, Colombia

    Cristina Lopez-Gallego

  8. Instituto de Biología, Universidad de Antioquia, Medellín, Colombia

    Cristina Lopez-Gallego

  9. Threatened Species Unit, Biodiversity Assessment and Monitoring Directorate of the South African National Biodiversity Institute, Pretoria, South Africa

    Domitilla Raimondo

  10. IUCN IdSSG, CTSS-IPB University, Kota Bogor, Indonesia

    Sunarto Sunarto

  11. Zoological Society of London, London, UK

    Michael Hoffmann

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Contributions

T.E.L., S.H.M.B., R.G., B.L., A.T.S. and M.H. wrote the manuscript. T.E.L., S.H.M.B., R.G., B.L., C.L.-G., D.R., S.S., A.T.S. and M.H. reviewed and/or edited the manuscript before submission, and all authors researched data for the article and made a substantial contribution to discussion of content.

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Correspondence to Thomas E. Lacher Jr.

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Related links

Agreement on the Conservation of African-Eurasian Migratory Waterbirds: https://www.cms.int/en/legalinstrument/aewa

Alliance for Zero Extinction: https://zeroextinction.org

Amphibian coordinating and fundraising group: www.amphibians.org

Conservation Evidence: www.conservationevidence.com

Conservation Leadership Programme: https://www.conservationleadershipprogramme.org/

Durrell Conservation Academy: https://training.durrell.org/

EDGE Fellowship Programme: https://www.edgeofexistence.org/edge-fellows/

Equator Principles: https://equator-principles.com/resources

Evolutionarily Distinct and Globally Endangered species: https://www.edgeofexistence.org

Fonseca Leadership Fund: https://www.thegef.org/fonseca-leadership-program

GBF Targets: https://www.cbd.int/gbf/targets

Global Species Action Plan: https://iucn.org/resources/grey-literature/global-species-action-plan

Green Status: www.iucnredlist.org/about/green-status-species

Harlequin toads: www.atelopus.org

Indigenous and local knowledge: https://www.iucnredlist.org/resources/ilk

Integrated Biodiversity Assessment Tool: https://ibat-alliance.org

International Finance Corporation’s Performance Standard: https://www.ifc.org/en/insights-reports/2012/ifc-performance-standard-6

IUCN Conservation Actions In-Place Classification Scheme: https://nc.iucnredlist.org/redlist/content/attachment_files/dec_2012_guidance_conservation_actions_in_place_classification_scheme.pdf

IUCN Conservation Actions Needed Classification Scheme: https://www.iucnredlist.org/resources/conservation-actions-classification-scheme

IUCN Threats Classification Scheme: https://www.iucnredlist.org/resources/threat-classification-scheme

Kunming–Montreal Global Biodiversity Framework: https://www.cbd.int/gbf

Red colobus monkeys: www.redcolobusnetwork.org

Red List Categories: https://www.iucnredlist.org/about/regional

Red List Criteria: https://www.iucnredlist.org/resources/summary-sheet

Reverse the Red: https://www.reversethered.org/

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Lacher, T.E., Butchart, S.H.M., Gumbs, R. et al. The status, threats and conservation of Critically Endangered species. Nat. Rev. Biodivers. 1, 421–438 (2025). https://doi.org/10.1038/s44358-025-00059-4

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