The IUCN Red List: what it is, how it works - and just why it's so important
The IUCN Red List tracks the conservation status of species worldwide, but how are they assessed and does it really help their survival?
Lemurs are in trouble. Of the 113 described species and subspecies of lemur – all of which live exclusively in the forests of Madagascar – 98 per cent are threatened with extinction.
It’s a bleak statistic, but a helpful one. Because it’s only by being armed with this knowledge about the conservation status of lemurs that we can begin to address the challenges they face.
What is the IUCN Red List?
We have this information at our fingertips thanks to the International Union for Conservation of Nature (IUCN), whose Red List of Threatened Species offers the world’s most comprehensive overview of the conservation status of animals, fungi and plants. There are other lists of threatened species out there: national and regional lists used to guide government policy; and lists focusing on particular groups of animals or plants, pulled together by NGOs such as the RSPB.
These play an important role in directing conservation efforts in jurisdictions around the world, but are necessarily limited in their scope. The IUCN Red List, which provides information on 150,388 species worldwide, dwarfs them all.
Contrary to what you might expect, not all the species on the Red List of Threatened Species are actually threatened. While the Red List might be best known for charismatic rarities such as the snow leopard or Komodo dragon, it also includes plenty of mundane, common species: you’ll find the common woodpigeon, grey squirrel and garden snail on the list, too.
What does being on the IUCN Red List mean and what are the different categories?
Being on the Red List just indicates that a species has had its conservation status assessed and categorised as either Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern or Data Deficient.
Only those listed as Critically Endangered, Endangered or Vulnerable – currently 42,108 species or 28 per cent of the total Red List – qualify as ‘threatened with extinction’.
A further 8,816 are Near Threatened and 77,491 are of Least Concern. Over twenty-thousand more are categorised as Data Deficient, meaning there’s not enough known about them to be able to make a judgment.
How many species does the IUCN Red List cover?
These are big numbers, but the IUCN Red List actually covers just 7 per cent of the world’s described species. “We’ve only really touched the tip of the iceberg,” says Craig Hilton-Taylor, head of the IUCN Red List Unit. “To try and assess every single species worldwide would be an impossible task, because species are being discovered and described all the time.”
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The Red List has very good coverage in particular groups of animals – mammals, birds, amphibians and warm-water corals, for example – but there are significant gaps elsewhere. “We don’t have enough fungi on the list, we don’t have enough plants, we don’t have enough invertebrates, and so we have to keep adding to these other groups,” says Hilton-Taylor.
How do species get on the IUCN Red List?
Anyone with sufficient knowledge of a species can submit it to the IUCN for consideration for the Red List. Population size, population decline or increase, geographic range and risk of extinction are taken into account in order to recommend a particular conservation status. It’s a deliberately open process (the IUCN offers free training for assessors), but the vast majority of Red List assessments are completed by the staff and volunteers of the IUCN’s various partner organisations and networks.
How many experts are there working on the IUCN Red List?
It’s tricky to put an exact figure on the number of experts across all these zoos, botanical gardens, universities and NGOs, but Hilton-Craig estimates it’s about 25,000: “We have experts in every country in the world, who are feeding in data on anything, from bees to molluscs to elephants to polar bears to butterflies, plants, fungi - everything!”
Once a Red List assessment – a rigorous scientific paper drawing on the best available data – has been submitted, it’s reviewed by an expert or group of experts and then by staff at the Red List Unit.
It might be just a few weeks before an assessment is published and a species added to the list (as is the case with most of the new plant and fungi additions), or this process might take years.
“Some of the assessments are really contentious,” says Hilton-Taylor. “The more charismatic the species, the more data there is and the more controversial it becomes.” The most recent reassessment of the white rhinoceros, for example, began in 2014 and wasn’t published until 2020: “It took time to get all the data needed from across Africa and to agree the approach to use for the assessments,” he explains.
Does the IUCN Red List offer the species legal protection?
While getting onto a national or regional endangered list might offer a species certain automatic protections when it comes to hunting bans or habitat protection, the IUCN Red List has no legal ramifications. Rather, it’s “a scientific tool” that gathers evidence of the threats to a species, the conservation actions currently in place, and what’s needed to lessen the threat of extinction, says Hilton-Taylor.
“It’s up to other NGOs, conservation bodies, advocacy groups or governments to take that information and use it.”
Listing in a certain Red List category might qualify a species for particular pots of funding. The Mohamed bin Zayed Species Conservation Fund (headed by the President of UAE), for example, which has given out more than $20 million since it was founded in 2009, only awards grants to conservation projects focussing on Endangered species, prioritising those species that face a high threat of extinction.
Listing might also be effective in shining a spotlight on particular species in need of conservation support. “We saw this when dozens of species of lemur were added to the Red List in 2012,” says Remco van Merem, species conservation grants coordinator in the IUCN’s Species Conservation Action Team. Those listings prompted the IUCN to produce a document that called for funding to the tune of $7.6 million for a range of conservation projects in Madagascar.
“That did not immediately lead to funding at the time, but it did enable conversations to be had with interested donors,” says van Merem. The result of
those conversations was a private foundation in Geneva agreeing, in 2016, to fund the IUCN Save Our Species Lemurs Initiative, which distributes cash for lemur conservation. Among the many projects that SOS Lemurs has already supported is one working with locals based close to Madagascar’s largest national park, helping them to set up insect farming as an alternative to hunting lemurs for food.
It’s not just about cash, though. By simply raising the profile of a species, a global listing can very effectively focus the attention of the conservation community. Take Butyriboletus loyo, for example, an edible bolete mushroom known as the ‘porcini of the south’. Found only in small pockets of Chile’s Valdivian rainforest, it was assessed as Endangered in 2019.
“There was recognition that the species was in trouble,” says Gregory M Mueller, chief scientist at the Chicago Botanic Garden and chair of the IUCN’s specialist group on fungal conservation. “There had been uncoordinated activity, but actually getting it globally listed really catalysed a broader collaboration and initiative to do something about it.”
Efforts are now ongoing to work with the local indigenous people, whose economy depends on B. loyo, to develop sustainable harvest techniques and to find ways of inoculating more trees with the fungus to grow its population.
Can species be reassessed or downlisted?
Species are never removed from the Red List (unlike some national or regional lists), but they are sometimes moved down following reassessments, which take place regularly. A species might be ‘downlisted’ in response to successful conservation efforts, as happened in 2021, when four commercially fished species of tuna each moved down a category because their populations had been showing signs of recovery, thanks to better enforcement of international fishing quotas.
Or the IUCN might decide to downlist a species because new information regarding factors such as population size or rate of decline has come to light. Brazil’s Guarajuba tree (Terminalia acuminata) is a case in point: listed as Extinct in the Wild since 1998, several specimens were unexpectedly found by staff of the Rio de Janeiro Botanical Garden in 2015, prompting a relisting as Endangered when the species was reassessed in 2021.
Downlisting isn’t carried out lightly, however, taking place only when experts are confident that doing so will not reverse the progress that prompted the category move in the first place. Not only must a new Red List assessment take place, but there’s a minimum five-year pause built into the downlisting process to ensure that progress is genuine.
For longer-lived species, even more time is allowed: it took humpback whale experts 12 years to decide to move the species from Vulnerable to Least Concern, which took place in 2008. It’s testament to the integrity of the assessment process that, 10 years later, at the humpback’s most recent reassessment in 2018, it was again categorised as Least Concern.
It’s important to note that downlisting is simply an update on the current threat level a species is facing. It’s not necessarily an indication that conservation efforts can be curtailed.
“On the contrary,” says Glenn Plumb, chair of the IUCN’s bison specialist group, referring to the case of the European bison, which was downlisted to Near Threatened in 2020. “I characterise it as a cautionary tale: when a species is recovering, if something were to happen, if protection was withdrawn, it would move back to Vulnerable really quickly.”
Yet at the same time, he says, a downlisting should be regarded as a moment to “celebrate the progress that has been made and the dedication that’s been shown”.
Does moving a species down the list make it harder to safeguard in the future, because conservation funding will be awarded elsewhere? Ian Burfield, global science coordinator for species at Birdlife International, and coordinator of the Red List Authority for Birds, isn’t too worried on this point. He acknowledges that large, flagship species – such as the northern bald ibis, which was downlisted to Endangered in 2018 – have it easier when it comes to conservation funding than smaller, lesser-known ones, but that in general, “once you’re invested as a donor to a particular species, you’re probably really keen to try and see it through all the way down back to Least Concern”.
One way that the IUCN is trying to mitigate the risk of negative impacts from downlisting is through an additional metric that provides information on species recovery and conservation impact. So-called Green Status assessments became an optional part of Red List assessments in 2020, providing a percentage score indicating how well it has recovered. There are only 23 species with Green Status information listed so far; those that were assessed in the process of creating the methodology for the new metric. Hopefully more will be added in due course. Hilton-Taylor’s wish is that Green Status assessments will become standard, naturally increasing in number as species are assessed and reassessed.
“It’s quite exciting because it’s showing the other side of the coin: how dependent a species is on conservation action and whether we can move it back to being fully recovered or not,” he says. “That gives the donors an incentive: if I keep investing in that species, I can move it all that way [to fully recovered]. But if I stop, it might slip back into a more threatened category.”
How does the IUCN Red List help biodiversity?
Ultimately, the Red List isn’t just about individual species. It’s about the state of biodiversity as a whole. By considering the conservation status of whole groups of animals, plants or fungi – mammals, say, or warm-water corals – the IUCN is able to identify wider trends and patterns, which are essential for international policymaking.
As Hilton-Craig puts it, “We have to answer both questions: what’s happening to individual species – so we can inform conservation on the ground – but we also have to keep the big picture in mind. International policy doesn’t look at individual species.”
It would be impossible to calculate the impact of the Red List on global efforts to halt biodiversity loss – the variables are too numerous, the causes and effects too complex. What we can say, without a doubt, is that this act of international collaboration, this coming together of about 25,000 people across the world, represents an extraordinary collective achievement of which we should be immensely proud. It can be easy to lose heart in the face of seemingly endless threats to biodiversity on Earth – the very existence of the Red List gives us hope.
Jo Caird is a freelance journalist who lives in East London and writes for newspapers, magazines and the web. She specialises in citizen science and conservation with a strong community focus. Read more about her work at jocaird.com
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