These birds, also long part of the museum collection, have taken pride of place in a large "change-over" display case near the museum's Search Centre.
The museum has about two million artefacts.
This "change-over" display case enables museum visitors to view interesting items, many of which have been in storage for some years.
The helmets, several from the 16th or 17th centuries, have been displayed for about a year.
An exhibition label explains all chickens belong to the same species, Gallus gallus, although selective breeding has resulted in about 60 breeds, ranging greatly in appearance and nature.
Among birds on display is an Australorp hen, of an Australian breed which holds the world record for egg production, at 364 eggs a year.
People first started keeping chickens to use in cockfighting, and for religious purposes, including sacrifice.
Since chickens were first domesticated at least 8000 years ago, they had become more commonly raised for their meat and eggs.
Originally the word "chicken" referred only to juveniles (chicks), with adult birds termed "fowl".
Today, however, the word "chicken" was often used to refer to the species more generally, including both young and adult birds, organisers said.
