Does anyone on Fluther know anything about parrot behaviour?

I used to feed seed to about a dozen wild cockatoos from my windowsill. Unfortunately, I had to stop feeding the cockatoos because they became destructive at the times I was not there and a neighbour complained. Anyway, all of the cockatoos except for one stopped coming to my window. The one that did still turn up only came at dusk so I started feeding just this one. He turned up every day by himself. Today I was sitting at my computer and I heard this really horrible sounding noise, like a groaning. I looked out the window and there was “my” cockatoo sitting on my windowsill but he was covered in mud, his crest was down and he was shaking. He looked like he had something wrong with his tongue and he kept opening and closing his mouth. He was very, and I mean very distressed. He was also not in his usual place. I tried to feed him but he wouldn’t take the seed. Then I noticed five other cockatoos sitting in the trees just looking at us. It was quite creepy. My cockatoo looked terrible. My heart went out to him and I was afraid that maybe he was unable to fly. I tried to reach him but was unable to. The other cockatoos then flew down to the windowsill wanting food. I waved my hands and they left – along with “my” cockatoos. It is past dusk now and “my” cockatoo has not come back as he usually does. My question is this: Is it possible that the other cockatoos could have attacked him because I was feeding him and not them? Will they kick him out of the flock or worse, kill him? If this is so I feel dreadful. If you genuinely know about their behaviour please help me understand.