Chicken still in nest alone

I have a baby blackbird ( I think) left alone in a nest in a hedge. It seems too big and fully fledged although a wing looks either damaged or the flight feathers haven't developed properly. 

We monitored for 24hrs , no sign of parents responding to frantic calls. By this time the baby looked weak and was shaking. I fed it worms. By evening to day it was still in the hedge . 

Is it normal for such a large baby to still be in a nest alone with no siblings?