Nutty Saddler congrats on your chicks! I WISH mine had been at least 10 weeks when I got them. Really wasn't counting on babies. Ah well, they are doing good at least, and aren't in my bedroom keeping me awake anymore.
Thankfully, in my part of the country fox are extremely rare. Our biggest threat to the chickens is raccoons, but so far I haven't had any problems, my henhouse is secure, and once the babies DO get outside, they are only out during the day and supervised. Plus, I have 6 dogs - 4 of which are farm bred old time collies, who take their jobs as livestock guardians very seriously! I have not seen a single possum, raccoon, or skunk on the property since the first few days I moved in.