An endangered species is one that is classified as in danger of extinction. Extinction may be caused by loss of habitat and loss of genetic variation. Loss of habitat can be caused by natural means or by human activity. In animal species, inbreeding, humans overhunting or overfishing can lead to the loss of genetic variation.
The International Union for Conservation of Nature (IUCN), the oldest and largest global environment organization, developed the world’s most inclusive list of the global conservation status of biological species in 1964. This list is called “The Red List”, and it outlines the risks of extinction. This list is separated into seven levels of conservation, and those are: Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, and Extinct.
Conservation efforts are put into place in hopes of increasing the population of a species. These efforts include: preventing poaching or illegal hunting, thwarting the destruction of habitats, and adding breeding programs. Poaching happens worldwide, and poachers make money by selling horns, ivory, and fur, among other items. Not keeping exotic pets, not buying anything made from ivory, even legally gained, and spreading the word can help with the stop of poaching. Humans are largely responsible for the destruction of habitats that can cause a species to inch toward extinction. The Association of Zoos and Aquariums (AZA) adopted a Species Survival Plan® (SSP), which is a captive breeding program which manages threatened or endangered species, and aids in the perpetuation of the population of a species.
Sources:
http://www.iucnredlist.org/about/overview
http://education.nationalgeographic.com/education/encyclopedia/endangered-species/?ar_a=1
http://www.exploringnature.org/db/detail.php?dbID=115&detID=2742
http://en.wikipedia.org/wiki/IUCN_Red_List
https://www.aza.org/species-survival-plan-program/
http://en.wikipedia.org/wiki/Endangered_species