Fresh Deer Hide are acquired by harvesting a Deer Carcass. They can be cured by leaving them indoors for 5 days (in-game). Fresh Deer Hide Decay at a rate of 3.333 Condition a day (Stalker difficulty) and will decay into Ruined status if not left to cure indoors. The current curing status can be checked by hovering your reticle over the item, where it will display a "X% Cured" progress. This increases until the item is 100% cured, where the item will automatically become fully cured, will change to a darker texture, and is ready for crafting use. Completely cured items never decay.
Deer are quite common and can often be found in pairs of 2 or 3. Occasionally, a Deer Carcass can be found in several places across Great Bear Island. Multiple Carcasses can be found within a region, and can be harvested for their pelts even when a survivor lacks weapons to hunt Deer.