I also found myself asking if livestock would start disappearing from the McFarlane ranch...
Kidoh here!. In a newspaper there is a post explaining the disapearing of many people and ghosts in the cementery.
No Chupacabras, Yetis, Bigfoots, UFOs or Aliens in this game.
but on the Undead Nightmare DLC there is a Chupacabra, Sasquatches and a Unicorn but still no aliens Yetis or Bigfoots.
Sasquatches ARE Bigfoots...
lots of mythical creatures in RDR DLC's: Chupacabra, Sasquatch, Unicorn, War, Death, Famine, Pestilence, Jackalope and Zebra Donkey