How we can know the blackberry secret in Pigeon room

When in Rusty Lake Hotel we make attempt for Pigeon, we must to find black berry inside the prisoner small bird by TORTURE him!!! I did think this very unpleasant.. How we can know it must be to hurt this bird Six time to get to win?? Is hint given before in some where, of count to pull lever? Or must only cruel person know what way to win..

I have missed some where the hint from Mr owl and I wish knowing its place..