In the video below, we clear the level with two birds for three stars and 154220.
We send Hal long distance – well over the top to arc back and hit the stone truck on the lower level in the middle. The truck rolls down the hill and starts a TNT storm which wipes out the left side. Next, Bomb bird goes straight into the middle structure, resting up agais the pig hiding in the stone block, and BLAM! Stone is thrown everywhere, taking out the left side of the structure below and starting a slow collapse of the upper right, which eventually drops the boulder and more stone onto what remains below.