Next to a mother, siblings are the most important relationships young chickens have. When you go shopping for chicken and eggs, the fact that chickens develop such relationships probably doesn’t cross your mind. But chicks which are raised by their mother, develop strong attachment to their brothers and sisters. So, when their mother leaves them on their own, the siblings stick together. They roost together and roam together.
As they age, their sibling relationships get more complicated. The males and female chicks start to separate, with the males hanging out together, and the females sticking together. It’s only possible for chickens to have these sibling attachments where they are raised by their mothers and have plenty of space to be themselves.