A roll of white craft paper from Dollar Tree would be a good option as well.
FaeryBee... See how I keep learning here? I didn't even think about craft paper from Dollar Tree!!
I now use newpaper and put what I call paper towel (Is that blotting paper?) on top. I pull the paper towel off the next morning and most times, the newspaper is just fine to use for the day. I was also told the dye now used in newspaper is non toxic to birds. Not so, huh?