I like this site. It has good info. I would put an apron around the perimeter. Grass will grow up through the wire so it will be mow-able.
http://www.poultrydvm.com/featured-infographic/tips-for-protecting-poultry-from-predators
http://www.poultrydvm.com/featured-infographic/tips-for-protecting-poultry-from-predators