Hi Holly. The stains are calcium build up in hamster urine. Get a bottle of plain white vinegar (just the stuff you buy from supermarkets) and let the vinegar sit on the stains for a while, say half an hour and then use a nail brush or an old tooth brush to scrub it off. Keep applying the vinegar until it has loosened all the white marks. Hope this helps. x
Get A Life, Get A Rodent!