I think it is based on several factors. I have small children so I cannot have a rooster that even considers spurring or jumping. I also free-range quite often so I need a roo that is protective and alert. As has been stated before I don't think anyone wants to weed out any type of normal rooster behavior, but aggression towards people cannot be tolerated.
Ideally you would have an attacker and a non attacker for comparison. Former will give all sorts of signals that unpleasant thoughts are going through his mind long before he attack. Look at the video posted earlier in thread and pay particular attention to the roosters vocalizations and the way he holds his body. He is sending all sorts of signals he is aggressive. Look at how he orients towards guy with foot. Look at how his tail is held. These signals doing not even involve cutting the wing. Listen to tembor of notes in his cals and id possible compare them to the notes of a rooster just talking / making contact calls. Hens do same when being aggressive to each other. Such signals can be used as a more sensitive indicator of aggression than outright attacks.
The trilling usually happens as they are settling down. We've been cage training and they usually trill after they sit down comfortably and preen. They will also trill when you pet them and they are happy. Here is a video...please ignore the T.V. in the backgroundBoth of my roosters make lots of different noises, I'm not sure if they do that one. Could you describe it a little bit for me? I love all of their vocalizations, they're so complex (some people laugh at me when I say that about chickens, but it's true!
