A cockatrice head is a very rare drop from Cockatrices, which requires 25 Slayer to kill. It can be mounted in Player-owned house in the Skill Hall at 38 Construction.
If players wish to have the cockatrice head mounted, it must be taken to the Taxidermist in Canifis. She will charge 2,000 coins and turn it into a stuffed cockatrice head. They can then mount it in their player-owned house using 2 Teak planks. If you remove this from your trophy hall or remove your trophy hall overall, you will lose it.