Seagulls dancing on the roof

Have you ever seen birds 'dancing' on grass?  The idea is that the vibrations they cause on the grass are transmitted through the soil to worms.  The worms think that there is heavy rain and come to the surface in an effort not to drown.  At this point the gulls eat the worms.

My office has a green roof.  Gulls come and tap dance on it, making a great deal of noise.  I can honestly say it doesn't sound much like rain to me.  But it amuses me to think of Fred and Ginger on to roof, dancing for their lunch (or not).