Wildlife : Birdwatching - 680

The great tit (Parus major)

Around the end of March, these birds finally begin to leave the city and move into the forests. But some remain in the cities. According to my calculations, about 1-3 birds can be found in every yard. It is as if they are taking a duty before the autumn arrival, and their relatives will fly.
I’ve been studying this event for the second year in a row and I can’t understand what kind of tits remain, their age, place in the hierarchy. I thought that those whom I tamed would remain, but no, they all flew away, and now there are completely unfamiliar to me birds that are afraid of me.