from Google (define:feral)
wild and menacing; "a pack of feral dogs"
and from Wiktionary
feral (comparative more feral, superlative most feral)
wild, untamed, especially of domesticated animals having returned to the wild http://en.wiktionary.org/wiki/feral
also....all animals once lived in the Garden of Eden and were tame so even by the "gone feral" definition they are feral.....and no I do not have a reference from the Pali Canon for this.....Moses predates the Pali Canon I think.....
If cat's gone feral are not a part of a natural ecosystem are they then part of a supernatural ecosystem?