Blackbirds are certainly not a shy bird, they rush around like they are telling all the other birds to go to bed and then wake them all in the morning. I can't make out that when they have a nest they make loads of noise to advertise where it is especially if a magpie is about, it does get me looking for the nest raider though and I will scare them off
When we had the snow last week I had about a dozen blackbirds all in my garden which is very small, which shows they can share if they have to