Exactly...Reds dont always get along with other colours of chickens. Red birds are more aggressive.Mine that was crazy aggressive was a red sex link and an ancona. I have read that red sex links can be like that. I also have been told by many that rhode island reds don't mix well with really docile breeds like buffs, and ameraucanas. My grampa had rhode islands and they were aggressive.
I sold all my red hens.