Explaining endangerment levels: From Least Concern to Critically Endangered

When scientists assess the survival prospects of a species, they don’t simply label it as “safe” or “in danger.” Instead, they use a globally recognised system to describe the level of threat a species faces. The IUCN Red List of Threatened Species, maintained by the International Union for Conservation of Nature, is the most widely used tool for this purpose.

For anyone working in wildlife conservation, from policymakers to citizen scientists, understanding these categories is key to recognising the urgency of action.

What Is the IUCN Red List?

The IUCN Red List evaluates species based on specific criteria, including population size, rate of decline, geographic range, and degree of habitat fragmentation. Each species is assigned a category that reflects its risk of extinction in the wild.

These categories are not just scientific labels, they guide conservation priorities, research funding, and legal protections worldwide.

The Main Categories Explained

Below are the core IUCN categories, arranged from lowest to highest risk of extinction:

Least Concern (LC)

Species in this category are widespread and abundant, facing no immediate threat of significant decline.

Example: The Lesser Hedgehog Tenrec (Echinops telfairi) is currently listed as Least Concern due to its stable population.

Near Threatened (NT)

These species are not yet endangered, but they are close to qualifying for a threatened category in the near future.

Example: The European Hedgehog (Erinaceus europaeus) is Near Threatened in many countries due to population declines from habitat loss and road mortality.

Vulnerable (VU)

Species at high risk of extinction in the medium term. They may have experienced significant population declines or have very limited ranges.

Example: The Dryad Shrew Tenrec (Microgale dryas) is Vulnerable due to ongoing deforestation in Madagascar.

Endangered (EN)

Species facing a very high risk of extinction in the near future. Populations are often small, fragmented, and declining rapidly.

Critically Endangered (CR)

Species facing an extremely high risk of extinction in the immediate future. Even small changes in their environment can push them over the edge.

Extinct in the Wild (EW)

Species that no longer exist in their natural habitat but survive in captivity or in managed populations outside their historic range.

Extinct (EX)

Species for which there is no reasonable doubt that the last individual has died.

Additional Categories

Data Deficient (DD)

There isn’t enough information to make a direct assessment. This does not mean the species is safe — it may be at serious risk but lacks sufficient study.

Not Evaluated (NE)

Species that have not yet been assessed by the IUCN.

How Assessments Are Made

The IUCN uses quantitative criteria such as:

• Population trend: Is the population increasing, stable, or decreasing?
• Geographic range: How widely is the species distributed?
• Degree of fragmentation: Are populations isolated?
• Threats: What pressures are they facing (habitat loss, hunting, climate change, etc.)?

Assessments are carried out by species experts and are regularly updated as new data becomes available.

Why This Matters for Hedgehogs and Tenrecs

Many hedgehog species are listed as Near Threatened or Vulnerable, reflecting declines from road deaths, habitat loss, and reduced insect prey. In Madagascar, several tenrec species are in higher threat categories due to deforestation and hunting pressure, while others remain in Least Concern, for now.

Understanding these categories helps conservationists prioritise efforts, whether that means urgent intervention for Critically Endangered species or preventative action for those still in Least Concern.

In Summary

The IUCN Red List is more than just a checklist, it is a living record of our planet’s biodiversity and the pressures it faces. From Least Concern to Critically Endangered, each category tells a story about how close a species is to disappearing from the wild. Recognising these levels is an essential step toward effective conservation.