Here is the full list of all 18 Whitetail Challenge achievements.
Harvest the Monster Buck
Access to Alpine Forest level
Access to Winter Woods level
Access to Bushlands level
Access to Cypress Swamp level
successful 2nd Buck Harvest
1st Buck Harvest- rifle
1st Doe Harvest- rifle
1st Coyote Harvest- rifle
1st Buck Harvest- shotgun
1st Doe Harvest- shotgun
1st Coyote Harvest- shotgun
Discover Cave
Buck Tags Found
Ammo Found
Rations Found
Medicine Found
Flashlight Found