Bulwark Wings. Instead of for flying, the auger's wings are used for protecting itself from falling rocks and high falls. The auger has resistance to bludgeoning and ranged attacks, and when it would take damage from a falling it treats the fall as if it were half the distance.

Auger Beak. As it's name suggests, the auger's beak allows it to drill into almost any material. Used for making their caves high in the canyons and cliff faces, it's beak gives it a burrow speed of 20 ft through earth, and 10 ft through solid stone.

Camouflage. The auger's wings also serve to conceal them from the many predators of the mountains. While an auger is standing still they are almost unrecognizable from the various stones that line the cliffs. A DC 16 Wisdom (Perception) check will allow them to be picked out from among the rocks that surround them.

Dive-bomb. If an auger falls at least 10 feet, it can perform a dive-bomb. By hiding itself inside it's hard wings, the auger is able to strike the ground with enough force to shatter boulders. Any creature adjacent to the auger upon landing must make a DC 15 Dexterity saving throw. On a failed save, the creatures suffer 2d6+2 damage for every 10 feet the auger falls, and are stunned until the end of their next turn. Any unattended, non-magical items in the area are destroyed.

Sunder. The auger uses it's drill-like beak to crack open the hard shells of it's prey. As part of a beak attack, the auger can also damage shields and armor. Each hit from the augers beak permanently and cumulatively applies a -1 penalty to the AC it provides. Armor reduced to an AC of 10 or a shield that drops to +0 is destroyed. 

Beak. Melee Weapon Attack: +4 to hit, reach 10 ft., 1 target. Hit:  9 (2d6 + 2) piercing damage. 

Wing bash. Melee Weapon Attack: +4 to hit, reach 5 ft.,  3 targets in front of the auger. Hit: 6 (1d6 +2) bludgeoning damage. DC 12 Strength save or be pushed away 5 ft.