There are no specific stages as such, one flows on from the previous. When the starlings start grouping, the parents no longer feed them and indeed may peck them as they have either lost the breeding urge and are getting ready to molt (requires different hormones to be activated) or getting ready to start another brood. Either way, once the young are self sufficient they are no longer bonded to their parents and are 'encouraged' to leave the parent's breeding territory to prevent them decreasing the available food supply. Molting birds also need a high protein diet.
Some other birds such as the coot have an interesting breeding season; once the first brood is self sufficient they hang around and stay bonded to their parents. They assist with protecting the territory and even help to feed subsequent youngsters.
It is all about propogation of the best genes.
There are about 8600 species of birds and they all have slightly different habits and ways of bringing up the kids.