An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild.
[2] The IUCN Red List provides the public with information regarding the conservation status of animal, fungi, and plant species.
This is along with natural forces that may create stress on the species or cause an animal population to become extinct.
[7] Currently the biggest reason for species extinction is human interaction resulting in habitat loss.
Another reason for plants and animals to become endangered is due to the introduction of invasive species.