I'm in the process of bringing home 2 sub adult redfoots. They are 5 and 5.5 inches. My small back yard is tortoise proof, and I would like to let the tortoises outdoors during the day and inside at night. My only concern is over predators. I'm in an urban part of San Diego but I occasionally see crows, hawks and herrings. How big do you think the tortoises should be before I let them run around unattended? I mostly see crows does anyone have any info about them?