Experts have said that privacy concerns, "fatigue", general boredom and the rapid rise of alternatives are to be blamed for a global exodus from Facebook.
There are signs that its impressive growth rate - an average of more than 100 million new users a year - may be slowing down.
Queensland University of Technology social media expert Peter Black said Australians were likely to start deleting or deactivating their profiles in growing numbers.
"If Facebook hasn't already peaked in Australia, it will soon," News.com.au quoted him as saying.
"That term 'Facebook fatigue' is right."
Around the world, Facebook's ability to attract new users has noticeably declined.
In the UK, more than 100,000 people reportedly deactivated their account in May, with an estimated six million users pulling the plug in the US.
University of Queensland digital communications expert Dr Sean Rintel also pointed to interest in Google+, which has attracted some 25 million users within the space of less than two months, many of whom were poached from Facebook.