The Saltwater Crocodile may not be the a vulnerable crocodile species, but it is symbolic for the many Crocodile species that are vulnerable or threatened on the IUCN Red List. On the opposite end of the spectrum are the Chinese and Philippine crocodiles. With less than 100 adults in the wild, the most endangered crocodile in the world is the Philippine crocodile, Crocodylus mindorensis. The most endangered alligator is the Chinese alligator, Alligator sinensis having less than 150 adults.
Just like with many endangered species, there is no one direct cause for the decline of crocodilian populations around the world. Depending on the species, there are some common factors that have had an effect on wild populations.