Sometimes conservationists kill animals in order to protect another species.
In New Zealand millions of dollars are spent to control rats, possum and other non native species that are a huge threat to our native birds.
In Australia, one of the issues they contend with are feral donkeys who are blamed for destroying ecosystems so they are shot by helicopter or rounded up and killed.
But Dr Arian Wallach from the University of Technology Sydney says conservation killing is not necessary. Her voice is part of a growing chorus calling for "compassionate conservation." She shares her research into alternatives to save native species without killing another.