Q: I planted a Japanese maple in late winter. It was doing great until recently when two squirrels wreaked havoc. My husband witnessed the hooligans and ran out to shoo them away, but this is what was left .
A: From my observations, every squirrel carries a little bit of craziness in its brain.
My local squirrels have chewed on my gasoline can, chewed my tomato plants at the base, chewed on wooden siding, and chewed on aluminum wire. I have not noticed them chewing on rocks but they do lick the mortar between bricks on my front steps.
I have no explanation of why they attacked your maple tree except temporary insanity. You can make a cage out of chicken wire to go over it to protect what is left.