A group of chickens is called a flock, kinda like other birds. :)
A system
A flotilla.
colony
A school of fish.
A group of lions is called a pride.
If you mean "group", it is a covey.
A band.
A group of horses can either be called a band or a herd.
A group of whales are commonly called a pod, or a school.
genuinely a cluster, but some have developed their own names for it.
Chickens are not all female. There are both male and female chickens. Male chickens are called roosters, while female chickens are called hens.
Domestic Chickens