Does this kind of behavior mean my Silkie is a rooster?

[lilyashlyn]

I have a 12 week old Silkie who is starting to bully the 2 other chickens and 2 smaller chickens. And he seems like he's generally on the lookout and really skiddish (even though he got handled as much as the others)
Now, my 5 week old chick is starting to defend itself when my 12 week old goes up to it and stands really tall with its chest puffed out. And recently the 5 week old started doing the same thing to the older one like they are establishing dominance. Because the chick that's doing this is so young does it mean it's potentially a rooster? They don't actually touch each other or chest bump but it's more like a "look how big I am, I'm in charge!" And the little one is like "you don't scare me!" Where my other chick the same size just runs away from him lol

 

[Jesusfreak101]

It could be a rooster but i have hens that would stand up and fight with my rooster until he was sexually mature and started mating the hens. Only really way to tell if it has saddle, sickle, or long pointy neck feathers.