i use black and white newspaper mine nibble it, they don't actually eat it though they make little spit balls out of it, i had some ad's sitting on the floor one day and nibbles and baby was on the floor playing - I'd just swept my carpets and cleaned my living room and my bf called me in from the other room and said i was going to be upset , i looked down and they were nibbling away on the paper i lifted a corner up and there was tons of tiney pieces of paper all over my clean carpet but they had a ball nibbling on the paper
now all my tiels do it at some point of time through out the day