I have been interested in building a chicken tractor but have a simple question that anyone with one should be able to answer. Does the bottom of your chicken tractor run have wire mesh or is it open to the ground? The reason I ask is, when you lift the tractor wouldn't the chickens (1) escape, (2) have to scoot along with you, or (3) get caught as you move it around? I am just curious because I need to make something for my almost 6 week old chicks so they have some outdoor time and thought a tractor would be ideal. Thanks in advance for your inputs.