Geronimo!

Once again River proves that she's a kitten trapped in a bunny's body due to her love of leaping off high places.
If you look closely, you'll see Simon attempting to scale the back of the couch.  The operative word here is attempting.  It's just as well that he didn't make it because he'd be up there all by himself.

Looks can be deceiving.

River isn't really a bunny...
She's a kitten in disguise!
That's all I can conclude after seeing her perpetual love of high places and jumping down from them.  Seriously, what other animal does this?