Definitions by Jill Gibb
tayra
A South American tree-dwelling member of the weasel family, related to ferrets, martens, and fishers. Like most weasels, they are great fighters, but also easy to tame if raised from infancy.
marten
Imagine a chocolate brown mink (or ferret). Now make the snout and ears a little longer and pointier. Lengthen the legs and tail too. It looks a little foxy. Now, imagine it running through tree branches like a squirrel -- only faster. This is the squirrel munching marten. It is in the same family as the mink and the ferret, it is not a "fox cat".
fitch
Commonly called a "polecat", but, the fitch is not a cat, and neither is it a skunk (which is also called a "polecat"). The fitch is the wild ancestor of the (domesticated) ferret.