Chicken Griefing

My brother has just about crossed the line on griefing. Today, on my soon-to-be server, I was working on the upstairs of my house. When I came down to check how it looked from outside, crowding EVERY SINGLE BLOCK, were chickens. My brother had thrown eggs all over my downstairs. (I had my sound off so i didnt hear the clucking from upstairs). I went outside to kill him a couple of times but instead of seeing the usual town square, I saw nothing but chickens, surrounding the ENTIRE SERVER. no joke. Every square inch of the civilized area was filled to the brim with the bloody cluckers. I'm not sure if I should de op him (since he is my brother and all) Or what. Would that ACTUALLY count as griefing? If yes, what should his punishment be? (he has no buildings of his own yet so I cant fill his property with chickens) If no, What SHOULD I do??? comment on what you think, and diamond and favorite please! Thanks!