I have a small flock of 10, so i just cut up a couple of tin cans (folded the edges) and screw them on the wall.
On the question wether grits are necessary, my understanding is that the grits (crushed granite) have certain abrasiveness that may not exist on the garden variety stones from free ranging.
On the question wether grits are necessary, my understanding is that the grits (crushed granite) have certain abrasiveness that may not exist on the garden variety stones from free ranging.