The eMarketer report found that out of Facebook's 1.11 billion monthly active users, 889.3 million of those were not human.
Apparently Facebook is aware of the issue and knows that some of their user estimates may be inaccurate.
In a report filed in June 2012, shortly after the company's initial public offering, Facebook wrote: "We estimate that 'duplicate' accounts (an account that a user maintains in addition to his or her principal account) may have represented about 4.8 per cent of our worldwide MAUs (monthly active users) as of June 30, 2012."
Facebook claims that eMarketer may be counting those numbers differently, or the number of fake accounts may have gone up in the past year.
Last year, Facebook estimated that 1.5 per cent of Facebook accounts were "undesirable" or spam accounts.
A lot are just accounts for users' pets. People have been making Facebook pages for animals for years. In 2010, it was estimated that there were at least a few thousand profile pages for dogs and cats along with less common pets such as birds, hamsters, ferrets, turtles, fish and rabbits. I don't know about you but sometimes updating my own Facebook can be a chore, let alone updating a Facebook page for my dog or cat.