I don't know about Intelligent but I had a cat that was bringing me mice every so often in the morning and was knocking the door for like 10 minutes with her back leg!

The first time I got scared cause I didn't want the mouse to get in the house and I didn't know who was knocking on the door but I think it was half-dead...oh yeah I forgot to mention that all the mice were still alive.

I'll never understand that behavior..she was well fed.