all chicken wire will do is prevent the snake from leaving the pen with a belly full of chicks! I know it is alot more expensive but it will last forever and will save you a lot of trouble. You don't have to make your entire coop and runs snake proof. Snakes generally don't mess with adult birds, just chicks and eggs. Make a seperate pen for the babies! Just a simple 8X8 will be fine and not too costly.