Endangered Species Day is celebrated annually every third Friday of May. Thousands of people around the world participate by taking action to protect threatened and endangered species. While we are very used to hearing these concepts, we rarely know what they actually mean. So, what do they mean, who defines the criteria for a species to be «threatened» or «endangered» and who monitors it?

This post has been written by Silvia G. Suárez, PhD from Escuela de Ciencia del Mar de la Pontificia Universidad Católica de Valparaíso (Chile).

You can read the spanish version here and the catalan version here.

The Red List of the International Union for Conservation of Nature (IUCN)

The assessment of species’ extinction risk is based on the methodology of the Red List of the International Union for Conservation of Nature (IUCN). The IUCN is the world’s oldest and largest environmental protection organization, founded in 1948, and is currently present in more than 160 countries around the world.

The IUCN Red List of Threatened Species is a comprehensive and objective tool for measuring the state of biodiversity on the planet. It defines the conservation status of species according to their relative risk of extinction (i.e., indicating whether the species still exists and how likely is to become extinct in the near future) in order to define necessary conservation actions, projects and political decisions.

To determine whether priority conservation activities are needed to improve a species’ status, the following factors are also taken into account: the economic viability and probability of success of conservation actions, the existence of international agreements, the effects that the disappearance of the species would have on the world’s population and its ecological, phylogenetic, historical and cultural importance.

What species are being evaluated?

It is estimated that there are 8-15 million species on the planet, but we only know about 2 million! It is therefore not possible to study and categorize the totality of taxa and species existing in the world. In fact, even many of the known species have not yet been evaluated due to a lack of information. For this reason, the Red List is based on the status of higher vertebrates (mammals, birds and amphibians) following the concept of «barometer of life«. This idea concludes that by assessing and monitoring the conservation status of some 160,000 species, we can determine the overall state of biodiversity on the planet over time.

To date, more than 150,000 species have been assessed for the IUCN Red List. While this is an incredible achievement, there are still 10,000 more to go to reach this target.

This brings us to the question of what can (and what can’t) actually be evaluated and included on the Red List:

– All described taxa (species, subspecies, varieties) can be evaluated.

– Undescribed species can be evaluated only if there is an ongoing scientific description, there is information on their geographic range and their evaluation would be beneficial to their conservation status. 

– Introduced species: only wild populations introduced with conservation purposes are included in the Red List. Fig. 1 & 2 show two examples of successful  translocations (movements and releases of species with a clear conservation objective). Species introduced outside their natural range for purposes other than environmental conservation cannot be evaluated.

– Microorganisms cannot be evaluated.

– Captive populations are not evaluated.

Species assessments can be conducted with a global or regional approach. The main idea of the Red List is to assess the largest possible area and number of species throughout the world, but sometimes the study of smaller populations is vital as well. For example, monitoring the conservation status of endemic species (living in a defined geographic location) is fundamental to ensure the good health of the planet’s biodiversity.

Species classification

The first step is to collect and analyse as much information as possible about the particular species, such as its biology, ecology, taxonomy, etc. The next step is the analysis of the collected information, which involves the assessment of the conservation status of species. This process is carried out by scientists, evaluators and reviewers. Sometimes, other collaborators, authorities and research project managers around the world are also involved.

In this process, data are measured against the IUCN’s criteria for the inclusion on the endangered species list which – inter alia – mainly consists of the following six key indicators: its population trends (the overall increase or decrease in the population over time), population size (number of individuals remaining), population structure (number of individuals by age), geographic distribution area, availability of necessary habitats and their actual and potential threats. The study of how these factors change or have changed over time, taking into account the biological characteristics of the species and the threats to which they are subjected, is what determines their classification.

After the evaluation, the species are classified into 9 categories, depending on their relative risk of extinction (Fig. 3). The species classification categories are:

• Extinct (EX): No reasonable doubt that the last individual has died.
• Extinct in the Wild (EW): Known only to survive in captivity, cultivation or well outside its natural range.
• Critically Endangered (CR): Facing extremely high risk of extinction in the wild.
• Endangered (EN): Facing a very high risk of extinction in the wild.
• Vulnerable (VU): Facing a high risk of extinction in the wild.
• Near threatened (NT): Close to qualifying for a threatened category in the near future.
• Least Concern (LC): Population is stable enough that it is unlikely to face extinction in the near future.
• Data Deficient (DD): Not enough information on abundance or distribution to estimate its risk of extinction.
• Not evaluated (NE): Most of the species are still not evaluated. 

Of the species evaluated in the Red List, more than 42,100 are threatened with extinction. When we look at different groups across the living world, amphibians are the most endangered group (41% of the species are classified in the threatened categories). Also, 37% of sharks and rays, 34% of conifers (pine trees), 36% of coral reefs, 28% of crustaceans, 27% of mammals, 21% of reptiles and 13% of birds are currently in threatened groups. Considering the high number of species that are not yet known or assessed, it is estimated that about 1 million species are currently on the brink of extinction.

Over time, species may move within the categories on the Red List. To check their conservation status, re-evaluations are recommended at least every 10 years. These studies can be done by species or by groups of species, for which the Red List Index was developed. The most vital to re-evaluate periodically are the threatened categories (CR, EN, VU) to assess if their status has improved or declined.

The Red List acts as a detector of urgent cases. It identifies species on the brink of extinction to prioritize conservation actions and prevent their total disappearance. The ultimate goal is to get as many species out of the threatened categories as possible to ensure the health of the planet’s biodiversity.

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Extinct species

Unfortunately, conservation measures are not always implemented in time. This results in the extinction of species of incalculable value for biodiversity and ecological balance. 

The Chinese paddlefish (Psephurus gladius), one of the largest freshwater fish in the world, was documented as extinct in 2022. This piscivorous fish lived in the Yangtze River (China) and could measure up to 7 meters and weigh 300 kg. It was an anadromous species, migrating upstream to reproduce. The main reasons for its population decline were overfishing and habitat degradation. The construction of a dam in the middle reaches of the Yangtze River in the 1980s blocked the reproductive route, preventing adult fish moving upstream to spawn. It had been classified in the IUCN threatened categories since 1990. The last specimen was sighted in 2003. 

The Auckland merganser (Mergus australis) inhabited wetlands and marine areas of New Zealand. Its decline was caused by a combination of hunting and predation by introduced species (dogs, cats, pigs, rats). It was flightless, which made it more vulnerable. It was discovered in 1840. The last specimen was seen in 1902.

The great auk (Pinguinus impennis) was a flightless bird measuring about 80 cm in height and weighing 5 kg. It was formerly distributed across the North Atlantic, until its disappearance in the mid-19th century. It was common to see groups of this species in Canada, Greenland and the European coasts (Ireland, United Kingdom, Iceland, Faroe Islands). Its extinction was caused by hunting pressure especially for its feathers, which were used to make pillows. Also, its eggs, meat, fat and oil were highly valued products. Between the 16th and 18th centuries, several countries established strict laws for the protection of the great auk, and its killing was totally banned. Even so, its population had already decreased enormously, and illegal hunting continued. The last colony of great auks lived in Iceland, on a volcanic rock surrounded by cliffs that made it inaccessible to humans. After a volcanic eruption in 1830, the birds moved to another location where a few years later they were discovered and disappeared completely.

The Canarian oystercatcher (Haematopus meadewaldoi) was a bird endemic to Fuerteventura, Lanzarote and its coastal islets in the Canary Islands, Spain. It is believed to be extinct since the 1940s. Its decline was probably due to overexploitation of intertidal invertebrates (its main food source), human disturbance and predation by domestic animals. It was characterized by the intense red colour of its legs.

The state of the oceans

The world’s oceans have faced important threats over several decades. Some of the most impactful are overfishing, habitat degradation, sewage and plastic discharge, industrial development and carbon dioxide pollution. These phenomena have degraded marine life, impacting the health of ecosystems and their biodiversity. Currently, rising temperatures caused by climate change have been categorized as the main threat to ocean life. The impact of climate change is expected to severely affect 60% of marine biodiversity by 2050.

Marine ecosystems are very poorly covered in the IUCN Red List, less than 15% of species have been assessed. Marine taxonomic groups of fish, invertebrates, plants (mangroves and seagrasses) and algae have been identified as priorities in order to have a more global idea of the state of the planet’s oceans. 

By 2023, almost 18,000 marine species have been assessed using the IUCN Red List (Fig. 10). Of these, 1,555 species are in the threatened categories. No less than 276 species (1,5%) have been classified as Critically Endangered (CR), 395 (2,2%) as Endangered (EN) and 884 (4,9%) as Vulnerable (VU). It is important to remember that these are only the species for which sufficient information is available for their evaluation, probably a small number compared to those that actually exist in the world’s oceans.

Some species are running out of time. The noble pen shell or fan mussel (Pinna nobilis) is currently under serious threat, listed as critically endangered by IUCN. It’s one of the world’s biggest living bivalves, an endemic and emblematic species of the Mediterranean Sea. It plays a key ecological role by filtering water and retaining large amounts of detritus (suspended organic matter) contributing to water clarity. Since 2016 it has suffered massive mortality outbreaks due to a pathogen (Haplosporidium pinnae), a protozoan that attacks its digestive system causing its death. This pathogen spread rapidly throughout the Mediterranean causing mortality rates of 80-100% in many regions. Currently, only a few populations are known to remain free of its presence. These are geographically isolated and located in places with very specific environmental conditions. Pinna nobilis has been classified as a species of Community Interest in need of strict protection by the European Habitats Directive (92/43/EEC).

It is therefore urgent and necessary to take conservation measures to protect marine life, to ensure the good health of the oceans and the rest of the planet. To that end, the scientific community recommends the following measures: 

– The establishment of more efficient Marine Protected Areas.

– The elimination of illegal and unregulated fisheries and markets for aquatic species.

– A significant reduction in carbon dioxide emissions.

Successful examples of endangered species conservation

There is also good news! Some species that were previously on the brink of extinction have significantly improved their conservation status thanks to successful implementation of restoration projects and measures. Improving their habitats, eliminating threats and invasive species or reintroducing specimens have allowed for an increase of their population size and reducing their risk of extinction. The following are some encouraging examples that conservation actually works, if done correctly.

• Barndoor skate (Dipturus laevis): A marine ray native to the eastern coasts of the United States and Canada. Due to the incidental catch by groundfish fisheries, its conservation status was defined as Vulnerable (VU) in 2000 and Endangered (EN) in 2003. However, the number of individuals has increased due to the monitoring and reduction of this type of fishing. Currently, it is classified as Least Concern (LC).

• Giant panda (Ailuropoda melanoleuca): This mammal native to the Asian continent has recently been classified as Vulnerable (VU). This may sound like bad news, and in some way, it is, but in fact its conservation status has improved considerably. The giant panda was listed as Endangered (EN) for more than 20 years, facing a very high risk of extinction. Today, there are about 500-1000 mature individuals and its population size is increasing. This has been made possible through the efficient protection and reforestation programs conducted in China. However, it is essential to sustain these conservation measures, as climate change is expected to have a strong influence on the destruction of its natural habitat. It is not yet known how this will affect the current population.

• Juan Fernández Fur Seal (Arctocephalus philippii): This marine mammal is endemic to the western coasts of South America. Almost its entire population inhabits three islands of the Juan Fernández archipelago (Chile), hence its name.
  
  Until the end of the 19th century, it was hunted to the brink of extinction for its pelts. In 1891, its population was estimated at 300-400 individuals. Because no individuals were observed, the species was considered extinct until the middle of the 20th century. However, years later new specimens began to be sighted.
  
  In 1965, hunting was officially banned. Also, in 1978, it was granted full protection status in Chile, which allowed its incredible recovery. Today, it is no longer considered an endangered species, being classified as Least Concern (LC). There is an estimated total of 16,000 mature individuals, with an increasing population trend. Also, some studies indicate that the current geographic distribution area of the Juan Fernández fur seal is already similar to that prior to its exploitation.

• Humpback whale (Megaptera novaeangliae): Who doesn’t know this magnificent whale that lives in almost all of the world’s oceans. Its large-scale exploitation led to a rapid decline in its population size, putting it in the threatened categories for many decades. Its hunting was banned in 1968, with the adoption of important international protection measures. Despite having been severely reduced to a world population in the low thousands at that time, humpbacks have recovered strongly to an estimated 84,000 mature animals which is increasing. Humpback whales enjoy additional protective measures, such as sanctuaries, in several countries. The species is also listed in global conservation agreements. Its latest assessment (2018) classified it as Least Concern (LC).

Today, these species are out of danger of extinction thanks to the applied conservation measures. However, we must be prudent, because their situation could change again in the future. This is why re-evaluations are so important. They can detect new threats, analyze the long-term effects of the conservation measures applied, natural phenomena that could have occurred during that period or any other factor that could have changed their situation.

There is still a long way to go… the example of the pudú

The pudú (Pudu puda) is a deer endemic to South America, inhabiting mainly Chile and Argentina. It’s the world’s smallest deer, reaching a maximum height of 40 cm. Until 1996, there were insufficient data for its evaluation, but it’s probable that it has experienced important declines over time.

Almost half of the native forests of the Valdivia eco-region (Chile) were lost between 1550 and 2007. This area includes most of the pudú’s distribution. Since its first assessment, it has been positioned as a threatened species for 20 years.

The main reason for the current population decline is attacks by domestic animals (mainly dogs) and, to a lesser extent, by its natural predator, the puma. In addition, pudú illegal hunting still exists in some areas. It is currently catalogued as Near Threatened (NT), reducing its danger of extinction in the near future.

The creation of extensive public and private protected areas has helped the pudú to recover its population. It’s considered a «species of special value» in Argentina, where hunting has also been totally banned. In Chile, the pudú is a priority conservation target in the Valdivian Coastal Reserve, where individuals are monitored, and better care of domestic animals, livestock management and forest restoration are promoted.

In addition, society is increasingly aware of the need to protect this emblematic species. Even so, much remains to be done. It’s still not known with certainty how many organisms exist in each of the regions, and what number conforms the total pudú population. More research is needed to better understand and protect this and other species worldwide.

What can you do to help?

To help threatened and endangered species to recover is a collective effort and responsibility. Therefore, you can make a difference. Here are some ways you can help:

• Learn about threatened species in your area and the threats they face. Try not to contribute to them.
• Also about threatened species in the rest of the world. The planet is a huge ecosystem where everything is connected, the ecological balance depends on it.
• Observe wildlife in a non-harmful and responsible way. 
• Make informed consumer decisions about wildlife watching activities (safaris, marine mammal watching, etc.). Participate only in activities that guarantee respect for animals.
• View marine life from a safe distance.
• Find a habitat and species conservation project in your area and participate in restoration projects. A safe and healthy habitat is the most important thing for the protection and conservation of species.
• When you go into nature, don’t leave garbage. Deposit it in places designated for that.
• Don’t buy objects made from a threatened or endangered species (crafts, shells, decorative objects, jewels etc.).
• If you see invasive species in your area, inform any authority, such as municipalities, NGOs or universities.
• Don’t use products tested on animals.
• Reduce the amount of pollution you generate and participate in coastal clean-up events.
• Plant trees native to your area.
• Use water and electricity responsibly.
• Refuse, reduce, reuse and recycle.
• Stay informed and spread the word. Endangered Species Day is a great opportunity to get the message out and take action.

Resources:

1. International Union for Conservation of Nature (IUCN) (https://www.iucnredlist.org/). 
2. IUCN, S. S. C. (2001). IUCN Red List categories and criteria: version 3.1. Prepared by the IUCN Species Survival Commission. Available at: https://portals.iucn.org/library/node/7977. 
3. Guidelines for Using the IUCN Red List Categories and Criteria. (2022). Version 15.1. Prepared by the IUCN Standards and Petitions Committee. Downloadable from: https://www.iucnredlist.org/resources/redlistguidelines. 
4. Endangered Species Coalition (https://www.endangered.org/campaigns/endangered-species-day/).
5. Swan, K. D., McPherson, J. M., Seddon, P. J., & Moehrenschlager, A. (2016). Managing marine biodiversity: the rising diversity and prevalence of marine conservation translocations. Conservation Letters, 9(4), 239-251.
6. Vught, I., De Charleroy, D., Van Liefferinge, C., Coenen, E., & Coeck, J. (2011). Conservation of bullhead Cottus perifretum in the Demer River (Belgium) basin using re‐introduction. Journal of Applied Ichthyology, 27, 60-65.
7. Cheung, W. W., Lam, V. W., Sarmiento, J. L., Kearney, K., Watson, R., & Pauly, D. (2009). Projecting global marine biodiversity impacts under climate change scenarios. Fish and fisheries, 10(3), 235-251.

Cover photo: African penguin (Spheniscus demersus), currently endangered. Photo: peakpx.