Collecting Deer Heads is one of the additional activities available in Alan Wake 2 which will allow you to unlock a room located at the end of the corridor in the Elderwood Palace Lodge in Bright Falls, where you will find a lot of supplies. There are 12 of Deer Head Locations in total.
When you interact with all 12 Deer Heads then return to the head hanging on the wall in the Elderwood Palace Lodge. Then head to the corridor. You should then see the deer entering the room making the door to the room unlock.
How many deer heads you are still missing can be checked by interacting with the deer head hanging in the Mind Place.
