Endemic species are those that are found in a single defined geographic location, such as an island, state, nation, country, or other defined zone. They are indigenous to a place and are not found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be endemic to that particular part of the world. Endemic species are crucial to the health of our planet because of the enormous variety of living beings they contribute to the environment. They ensure the proper functioning of the ecosystem services of the habitats they occupy. However, they are also the most vulnerable of all species and are therefore in the greatest danger of extinction, which can be due to natural causes or human activity. Endemic species can be classified in two ways, by their geographical distribution or genetics, giving rise to a series of categories:

• By location:
  • Microendemic species: are those established in a limited area.
  • Quasi-endemic: are species that go beyond the limits of their specific zone.
  • Semi-endemic: are species that spend only part of the year in a specific area.
• By genetics:
  • Apo-endemics: these are species that derive from others and which, unlike patro-endemic species, occupy smaller areas than their predecessors.

It is important to note that endemic species are sometimes confused with or incorrectly called native or indigenous species, but the terms differ in meaning. Native or indigenous species evolved in an area and may be found there as well as in surrounding areas. Endemic species, however, are native species that are found only in a specific habitat within a given area.