The IUCN (International Union for Conservation of Nature and Natural Resources) organization cyclically issues a “red list” of the organisms that are threatened by extinction. At present the list includes 12,500 species subdivided into the categories “in critical danger”, “in danger” and “vulnerable”. For example, out of the almost 10,000 species of birds, over 1,000 are classified in one of the three categories indicated above. Which means that more than 10% of the avifauna in the world, has a significant risk of extinction.
