Godsbane777: The island grouping just west of Widow's Grotto on the west coast. Widow's Grotto is southwest from Novigrad. In the island grouping, the Cockatrice loctated at the northernmost tip of the largest island.
Another tip is to go through your monster items in the Dismantle screen at a blacksmith or armorer. Often, specific crafting items relating to monsters are already in your inventory and all you need to get them is dismantle the correct loot.
Note: There is only one Cockatrice at the location I mentioned above so if it doesn't drop what you need then see what you can dismantle from it's loot. If nothing, then check your loot from the Griffin, Shrieker, Basilisk, and Wyvern (all the Draconoids/Hybrids I've come across and killed so far.)
Edit: I believe it is a Basilisk there, not a Cockatrice. But, it may drop what you need or you may be able to dismantle it's drop for what you need.
Edit: Griffins spawn on the large southwestern island in Velen. They are around level 15 though, so be prepared.
Dismantling any monster body parts just gives me generic "Monster *insert body part*" like "Monster Eye", "Monster Bone", "Monster Claw", "Monster Heart" etc.
(For example trying to dismantle a Basilisk hide gives me Monster Carapace)
The location on the islands southwest of Novigrad does not have respawning monsters of any kind besides Drowners.
So unless ya find a place where Cockatrice's respawn none of that information was helpful sorry :(
Oh I'm also looking for a place where Ekkimara respawn cause I need some Ekkimara hides as well.
