Willow tits (Poecile montanus) generally reside in one territorial area throughout their adult lives. But brutal winters in the north kill off many of them. They aren’t able to manage well on their own, and storing seeds in the autumn is not always enough. For the young of the year, it is absolutely vital to find a flock to spend the winter with. Juvenile birds also have to try to become high-ranking members within the flock.