On not having enough to do:
The author of the most famous invented words (eg 'chortle') in our language also had not enough to do, and he came up with two immortal works of literature, the Alice books.

Is not 'outgrabe' a past participle, so the mom raths have finished 'outgrabing' or whatever? Incidentally 'rath' is irish for an old fort, perhaps where these beasts live.

TomH