In Zoroastrianism, Ahura Mazda (the supreme god) was sometimes depicted as a man with the head of a rooster. Perhaps your bead is based upon this idea.

However, I am not confident this is an ancient bead.

This link presents some interesting ideas related to Persian animal symbols, and demonstrates the importance of roosters in symbology:
https://zoroastriansnet.files.wordpress.com/2008/11/birds-animals-and-symbols-in-zoroastrianism.pdf

JDA.