Can Forgotten Beasts be killed by Waves of Reclaiming Dwarves?

I had a nice fortress going, when a forgotten beast turned up. I ignored it, safely walled up out of the caverns. Then I decided I wanted to go into the cavern.

So I prepped my fledgeling military, and opened the drawbridge. Unfortunately they were not up to the task. It slaughtered them, and in a 30 more seconds, the rest of the fortress.

So I thought, "No worries, I'll reclaim with some guys with actual military skill." They did not go so well, nor did the next lot. nor did the 60 war dogs after them. Rinse and repeat that several more times.

I notice it is showing dents and scars being preserved between "Reclaiming Waves".

• Does this mean I am slowly wearing down its health?
• Or is it in fact getting tougher and "levelling up", as it kills all the dwarves.
• Is scar tissue tougher than normal body parts?