Nate's idea is sound - the mouse will run for cover so you need to provide something portable for him to run into.
A few years ago in a hard fought intellectual battle between man and mouse, I managed to herd a heavily pregnant ladymouse into an empty cornflakes packet on my kitchen side by a cunning arrangement of utensils and crockery. I picked the cornflakes packet up and the mouse slid to the bottom and then popped her back outside in the garden.
Hightower you're lucky about the droppings; before we realised what was happening I just removed them from the sugar bowl thinking "I wonder what these black bits are" before sprinkling the sugar on my cereal