Ultimately, the catastrophic loss of wildlife in Australia is due to human behaviour in one way or another. Land clearance is the primary cause of wildlife losses. Invasive species are another cause but there are many invasive species in Australia one of which is the feral cat. But everything points back to human behaviour as humans introduced all these invasive species in the first place. A study found that 39 mammal species have become extinct since colonisation in 1788 which is equivalent to 38% of the world’s loss mammals and that another 17 are now either endangered or critically endangered. Seven of those could be gone within 20 years.