Wrangler has recently started biting/nibbling the top of my ear when he gets on my shoulder. I have tried and tried to admonish him "no bite!", remove him back onto his cage, or onto my arm if we are out, as a way of showing him that ear biting loses shoulder priveledges....but he persists. It's just a quick one/two nibble, but it hurts, and my ear is sore now! He also marches across my keyboard. I put up a hand to block him and tell him "no keyboard" or push him aside with my hand...but he just doesnt seem to get it. He is a smart boy, he picks up on things quickly. He is potty trained, knows not to go on furniture, etc...but these two issues he seems to just not get it, or be determined to ignore me. Suggestions?