Why do some birds fly away with their parents, and others separately?

This is due to the fact that different birds have different lifestyles. Some leave the parental nest as soon as they can. This happens most of the time. But sometimes birds during the flight unite in large flocks. Therefore, some fly with their parents. But the feeling of caring for parents, the elderly and the sick is found only in some species of animals. For example, in most primates, dogs, humans. Birds, like most species, care primarily about their offspring. It is only on rare occasions that feelings of caring for their parents are manifested.