I think you're more likely to get more knowledgeable responses than I can give if you post on the Trees forum. [There's a link there to the Maples forum -- but the Trees forum is much busier.]

I had some gnawing damage on my bloodgood similar to yours and the bark is closing up pretty nicely, took a few months, thoguh.

You don't say where you live..It looks to me like a winter bark cracking if you are from a colder area or the spring freeze..but that is a bit unusual for an older tree ..I have had younger hard maples and fruit trees do this..it usually heals over time ..but it could be vermin or something else I would have your local extension service or a licenced arbourist look at it ..without on the spot inspection we might do more harm than good with arm chair diagnosis..I think it could be serious and my instinct it is a bark defoliating thing that could be a symptom of something much more dangerous..I personally don't agree with Matt on this or your statement of storm damage ..i have seen this before and it looks like a bark related thing to me NOT storm stress...but as i said your best bet is to get a pro analysis.David

Chicken wire loosely crumpled around the trunk is very effective as well. Allows the bark to breathe properly and almost disappears from sight!! Too bad it doesn't keep the deer away as well! The squirrel damage is usually something an otherwise healthy tree can handle pretty well. Unless they manage to strip all the bark off the circumference of the trunk.