“There were hallmarks of a serial predator in everything he said to me in captivity,” Huskins said.

Bathing elephants is a popular activity among tourists in Thailand, which is home to more than 4,000 wild animals and has a similar number kept in captivity, according to the Department of National Parks.

By 2005, Portugal had no lynxes left, but it was also the year that Spain saw the first litter born in captivity.

Most experts agree that releasing the two whales, which are Icelandic orcas specifically, into the wild would not be suitable as both were born in captivity and would not have the skills to survive.

It's estimated there are now about 150,000 crocodiles in captivity in the NT.