Chipmunk with balding spots?

[emarie5077]

There’s a wild chipmunk I’ve become friendly with who I’ve noticed seems to be lowing his hair. I tried to get some photos while feeding him a snack this evening; does anyone have any idea what this is? I’m not sure how to tell if it’s ringworm or mange (or just shedding/fur rubbed off from something else), and know that the treatment for the two are very different. I’d like to help him out if at all possible, as he’s an absolute delight.

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Thanks for any help you can provide!