How is a species added to the endangered species list

When there is a huge influence of factor (or more factors) that affect the survival of the species.

Explanation:

List of Endangered and Threatened species is a list of living organisms that need protection.

endangered means it the species is in danger of extinction threatened means that the species is in the stadium before becoming endangered

Factors that affect the survival of the species are:

destruction or modification of their habitat (usually under the influence of human activity) disease high predation influence overutilization of an animal or plant (for comercial, educational or other purposes) natural disasters etc.