Funny about the Australorp. I have one and they constantly do battle for flock supremacy. Definitely think as you said for a home flock, Sex Links and the like really need more space and to be kept constantly busy with themselves or issues arise.I found my Red Sexlinks to be quite aggressive as juveniles. The Blue Kote seemed to help stop the feather pulling. I had a bunch of purple butts running around at one point. Once one of my Black Australorps became head hen, the Red Sex Links chilled out. It probably helps that they have a large area to free range & a lot to keep them busy.