Posted: 29/07/2013 at 14:32
Simple answer is - you probably can't I'm afraid! You can put chicken wire over the area but of course that makes it hard to put plants in so it would only work if you intend to sow seed which you could do through the mesh. Aternatively you could make a 'cage' type cover with mesh to prevent them getting in to start with - mainly during the late Autumn when they start building up a store - which you can lift off when you want to plant.
Re the waterlogged bit -you could build another raised bed there and put some good drainage at the bottom of it before putting your topsoil/compost in. A piece of membrane or similar over the rubble/gravel will stop all the soil getting washed through.