i recently observed 2 pigeons on a rafter outside some stores in a shopping mall. one pigeon seemed to be sitting on the other pigeon's head. The pigeon that was apparently being sat on was making a very strange noise and its wings were moving almost like it was having a seizure. it was clear that they were obviously not mating and the bird on the 'bottom' was not being deprived of air. Has anyone else ever seen this display? Any idea what they were doing?