Australorps are supposedly one of the "less vocal" breeds. I bought 8 chicks a few months back, of which 7 turned out to be roos. The biggest of the youngsters started learning to crow a month ago but I think only because I have an elder roo that the young one was trying to mimic. (Bricktop would crow, then Big Baby would - and that's how it still is, he only crows if the grown-up crows.) The rest of them don't make a sound. I acquired a bunch of white phoenixes yesterday (traded 3 boy aussies for 11 phoenixes) of which one is a roo; he is also silent. Now, whether that's a breed trait, a personality thing or a "location in the hierarchy" thing I can't tell you. If there are other roos in your neighbourhood, even a "less vocal" breed may find himself more inclined to crow; where I am, the neighbourhood roos like to chat in the mid-afternoon on clear, quiet days when they can hear each other!