How to know whether a species is endangered or not? In order to answer this question, the International Union for the Conservation of Nature (IUCN) has classified species of living organisms in terms of their risk of extinction. This "Red List" is an useful tool in determining which species are threatened the most by human activity and what kinds of conservation efforts are required to keep the planet's species alive.

IUCN'S CONSERVATION STATUS

Class	Explanation	Example species
Extinct (EX)	The species is extinct: no living individuals exist.	e.g. European mink in Finland
Critically endangered (CR)	The species is in an extremely critical state and will become extinct without succesfull conservation efforts.	greater spotted eagle, wolverine, Arctic fox
Endangered (EN)	The species has a very high risk of becoming extinct in the wild.	wolf, gyrfalcon
Vulnerable (VU)	The species is at risk of becoming extinct because of human activity.	bear, beaver, lynx, flying squirrel, peregrine falcon
Near threatened (NT)	The species' populations are not endangered, but it is close to being at high risk of extinction some time in the future.	mountain hare, roe deer, great horned owl
Least concern (LC)	The species' populations are stable and abundant.	e.g. most rodents

Each category contains species at a specific level of becoming extinct or disappearing from a certain area. The conservation status of a species is calculated by monitoring changes in the species' population size and distribution. Conservation statuses are often estimated within different areas, such as in different nations. This is why one species can be extinct in Finland but still found living in the wild in Sweden.

The IUCN Red List should not be interpreted in a way that suggests that only the species that belong to the most critical categories need to be conserved and protected. In truth, nature conservation should be undertaken in a way that safeguards the survival of all the species of an ecosystem.