Is it legal to keep it as a pet?

I saved a baby Mohave Ground Squirrel from my cat. I've been feeding him with a dropper and he's doing fine. Is it legal for me to keep him as a pet? Do I have to get any kind of special permit? If I release him now, there's no way he would survive and if I let him go after he's weaned, he won't know how to live in the wild. He's listed as a protected species, not endangered.