Cock and peacock represent nada and bindu. The peacock displays the divine shape of Omkara when it spreads its magnificent plumes into a full-blown circular form, while the cock proclaims loudly the Pranava sound OM. Muruga shines as the very essence of the Vedas and mantras. Cited from Website: Muruga.
In Nepal Muruga is called Karttikeya who also has a peacock. With Skanda:
the peacock, represents the Vedas; The Vedas being the sabda or sound form of the universe, the peacock symbolizes the universe or the evolutionary trend of Maya. http://www.murugan.org/research/venkataraman.htm
Nada - Bindu
OM - Omkara