Nat wrote:

I'm thinking they're telling each other I'm bigger and badder (is that a
word?) then you, don't mess with me.  Or in the case of toms/female in
heat, she's mine I tell ya, back off, lol.

So that they appear larger?

The truth is, and I hate to be the one to say this, but nobody, except
cats, really know why cats do anything!

But it sure is fun to guess.  ;*)

Minus

It's to make themselves appear bigger to the challenger. If you notice, when
they do the "puffy tail" thing, it's usually in combination with a posture
where they are turned sideways and the back is arched. They also think this
gives the illusion of looking bigger. (Or that's my take on it anyway!)

Sherry