spiny-rhiny,
It would appear that the turtle in question is actually an eastern box turtle as opposed to a three toed. I say this because, the three toeds rarely have any coloring at all on their carapace. The one in the picture has yellow markings, which points towards an eastern boxie. However, one could easily tell by counting its toes.
There are no species of box turtles native to California, the one in the picture is almost certainly an escaped pet. As far a feeding it goes, a wide variety of fruits and vegetables, as well as worms, snails, crickets (these will need to be hand fed to the turtle), and mealworms can be employed as foodstuff and will be sufficient to meet its dietary needs. It should be fed about 2-3 times a week.
As far as hibernation goes, if the animals is eating, seems healthy, and is robust and active, I would reccommend hibernating it. You mentioned wounds on the shell and head, if these are healed and appear old, there should be no problems. To hibernate the animal, it should placed in a shoebox, or comparable item, with dry soil, leaves and moss, deep enough for the turtle to bury itself. She should then place the box it the garage where it will be safe from maurading outdoor animals. She should check it once or twice a week, look it over for signs of a respiratory problems. After the first several days, this should not be a problem. I only say this because I tried to prevent one of my boxies from hibrenating, he stopped eating and lost a lot of weight. He was okay in the end, but still.
If you need anything else, please post! Good luck!
Regards, EMWhite
