That's what I read about them. He's my only Sumatra cockerel right now, so I'll see if it's true, or not. But there's been other people who've had experienced the Breeding Season agression. I don't know the people though.Have you ever experienced that, or it is only what you’ve read? I wouldn’t expect all Sumatra roos to have the same personality at breeding season. Then again, I’ve never had one.