Telltale have said [quote]A new threat emerges: an eerie, nocturnal predator stalking the group, hunting them relentlessly across the island.[/quote]
They can also be seen in the trailer. (About 35 seconds in.)
At first I thought they were Compys. They're small, numerous and nocturnal (the book reveals they are nocturnal) which all fits however the way Telltale are building it up it's probably something more dangerous.
So what do people think? Any ideas? Let the speculation (and the inevitable thread derailment) commence!