User blog comment:BlackTempest/Defense methods against the creatures of the Grim./@comment-24.158.202.97-20130817012945

I'd say the first line of defense is that sheer cliff they toss the froshes off of. Notice the vertical rock is well above treetop level? That negates going from the forest to the cliff top. Only flying Grim are not stopped by this. And if the flying Grim are carrion eaters or scavengers, they may have no urge whatsoever to fly away from their food supply.

No doubt there are active defenses of some kind, but they already have one hellacious passive defense.....