Hunt for Hidden Red Lists Uncovers Thousands of Lost Threat Assessments

A quiet revolution in conservation science is underway, and it began not in a laboratory or a rainforest, but in search engines, libraries and forgotten government websites. An international team of researchers has announced the creation of RegRed, an ambitious project to catalog every regional Red List of threatened species on Earth. In a paper published in the journal Nature Conservation, the team unveiled the first harvest of that effort: a metadata collection spanning 2,090 unique sources from 219 countries and territories, documenting the threat assessments of species at national and regional levels across the past fifty years. The scale of the find is staggering, and so is the message behind it: much of the world’s most intimate knowledge about species decline is scattered, buried, and at real risk of being lost.

The IUCN Red List is the gold standard for extinction risk. Since 1964 it has grown into the most comprehensive global database of species threats, evaluating more than 160,000 species by 2025 against standardised criteria based on population size, distribution range and rate of decline. But the global list has a blind spot that conservationists have long recognised: a species can be classified as of least concern worldwide while sliding toward local extirpation in a particular country or region. A migratory bird that thrives across two continents may have vanished from half of its range. The global picture, however rigorous, simply cannot capture the complicated local realities of decline, fragmentation and loss.

To fill that gap, many nations have produced their own Red Lists, following IUCN categories and criteria or their own governmental decrees of threatened species. These documents are often the backbone of national conservation policy, guiding protected area designation, species recovery programs and environmental impact assessment. Yet until now there has been no comprehensive, openly available index of where these lists exist, what they cover, or how to find them. Earlier attempts, most notably the National Red List project hosted by the Zoological Society of London in collaboration with the IUCN National Red List Working Group, made important strides, but that database covered only 101 sources from 73 countries and has undergone a significant hiatus while its website and infrastructure were restructured to empower national focal points in managing their own data.

The RegRed team took a deliberately broader approach. Rather than relying solely on submissions from official national representatives, they systematically combed through search engines including Google Search, Google Scholar and ResearchGate, worked through national and university libraries, and drew heavily on the IUCN’s own library for official Red Lists. They worked continent by continent and country by country, using adaptable search phrases such as “red list of,” “endangered fauna of” and “list of endangered species of.” When a source could not be assigned to a standard administrative boundary, they created custom regions covering territories like the Arabian Peninsula, the Carpathians or the Dutch Caribbean. Each document was geolocated to the most precise administrative level possible and classified according to its lowest common taxonomic unit.

The result is a dataset of 3,184 records derived from 2,090 sources, with each record representing one source for one taxonomic group. A single national list of reptiles and amphibians thus generates two records, a structure designed to help researchers filtering by group. Every record carries metadata on title, URL, file format, language and publication year, alongside taxonomic classifications normalised against GBIF’s taxonomic backbone. The coverage spans 483 distinct taxa and stretches from 1975 to 2024, with nearly half of the sources published within the last decade alone. The database is freely available through GitHub and Zenodo, and the team plans regular updates as corrections and additions arrive.

The patterns hidden in the metadata tell their own story. Europe dominates the collection with 2,182 records, followed by Asia with 452, reflecting both the intensity of conservation assessment activity in Europe and the fragmentary, group-by-group way its data are published. Germany alone contributed 544 insect group assessments, each covering relatively few species, while the United States tends to publish broader single documents spanning entire faunas. The peaks in publication around 2003, 2010 and 2020 track closely with major international milestones: the establishment of IUCN’s regional Red List guidelines in 2003, the Aichi Biodiversity Targets in 2010, and the Post-2020 Global Biodiversity Framework in 2020. Policy, it turns out, leaves visible fingerprints in the bibliographic record.

The taxonomic breakdown reveals a familiar bias in conservation attention. Animalia accounts for 2,190 records, Plantae 898 and Fungi just 105. Within animals, the phylum Arthropoda leads with 978 sources, though the vast majority of those, 854, concern insects, while arachnids received only 47. Among vertebrates, mammals lead with 202 sources, followed by birds at 185, reptiles at 148, amphibians at 133 and fish at 102. The scarcity of fungal records outside Europe is particularly striking, the authors note, reflecting the historical neglect of a kingdom whose ecological importance is immense. A similar caution applies to vague titles like “Fauna” or “Flora,” which may bundle wildly different taxonomic groups together and complicate automated analysis.

The team is candid about the limitations of the collection. Accessibility varies enormously from country to country: some jurisdictions maintain well-organised public databases, while elsewhere lists are scattered across platforms or hosted on defunct websites, which is precisely why the compilation matters. Source quality ranges from peer-reviewed assessments to scanned books with little or no optical character recognition. Not all sources follow the current IUCN Categories and Criteria, version 3.1, which have evolved over time. Links can decay, especially for documents hosted on government servers, and the team has verified URLs only at the time of publication, inviting readers to report dead links by email.

This metadata release is only step one. The second phase of RegRed aims to digitise the actual per-species threat assessments from all compiled sources, beginning with vertebrates, and to build methods for large-scale, accurate data extraction. The final database will be offered through a web interface and as a downloadable dataset under a CC-BY licence, with the team explicitly framing the effort as open, decentralised and collaborative rather than competitive with existing projects like the National Red List initiative or taxon-specific efforts such as the Patterns and Drivers of Regional Plant Extinctions project led by German research institutions. Anyone with knowledge of regional Red Lists the project may have missed, or who spots errors in the data, is invited to contribute.

What makes the RegRed effort resonate far beyond academia is what it says about the state of the world’s conservation knowledge. Scientists estimate that current extinction rates run between 100 and 1,000 times higher than natural background levels, and effective response depends on knowing precisely where species are in trouble. Some of the documents catalogued here, including traditional Red Books complete with photographs, illustrations, maps and locally relevant species accounts, are treasures in their own right, doubling as freely available field guides and handbooks. By dragging thousands of these documents out of obscurity and onto an open, indexed database, RegRed is doing more than organizing metadata. It is assembling a planetary early-warning system, one national Red List at a time, and inviting the world to help finish the job.

Subject of Research: Compilation of a global metadata database of regional and national Red Lists of threatened species

Article Title: Towards a new global database of regional Red Lists (RegRed): metadata

Article References: Kadlec, I., Uličný, A., Keil, P., & Grattarola, F. (2025). Towards a new global database of regional Red Lists (RegRed): metadata. Nature Conservation, 60, 39-47. https://doi.org/10.3897/natureconservation.60.158981

Image Credits: AI Generated

DOI: 10.3897/natureconservation.60.158981

Keywords: Red Lists, IUCN, biodiversity, conservation, RegRed, species extinction, threatened species, metadata database, national Red Lists, open science, GBIF, extinction risk