From Creatures Wikia
A feral run is where you hatch a group of norns, teach them words and a few other things (like food and herbs being good and weeds being bad), inject any COBs or Agents into Albia or the Ark, and leave them to grow up for a while, interfering when you like. This means that feral runs are easier than wolfling runs.
The idea being is that the creatures learn how to look after themselves and the offspring learn from the adults.
Also, a "Forum Feral Run" can be run, where entrants and cobs/agents are sought from the collections of the community, often named after their owners, and set loose in a world together, the gamemaster updating the owners of the entrants on a forum thread, often with pictures.