The best time to let your chickens free range is when you can be out there to watch them, but even then that's no guarantee they will be safe. There are many posts on BYC where folks have been less than 10 ft away when a hawk boldly snatched a chicken right in front of them. I've lost a pullet to a hawk at 11am, another pullet was attacked by a hawk sometime between dawn and 3:30p when I got home from work, although I'm thinking it was sometime in the early afternoon because that hawk had the nerve to come back later that afternoon and sit on top of the roof-covered run, terrorizing the already traumatized hens. Another hen was attacked twice and survived, both times were late morning. Today, I lost one of my favorite hens to a fox sometime between 9a - 11a. Owls are also a concern around here at dusk. Free ranging hens is very risky, but it's a risk I'm willing to take. Mine free range from dawn to dusk. I'm in the process of adding a hot wire to my fence and am searching for a livestock guardian dog, but that will take time. Since you live in a wooded area, foxes are a threat and they will attack during the day as well as at night. Good luck with your hens, and