Only if there farm reared animals,or estate born and reared,otherwise there wild,how can anyone claim a wild deer belongs to them if they did not actually rear the animal in the 1st place,just because it happens to be on a shoot you stalk or farmland you do the stalking on,does not give anyone the right to say its there's.If cattle broke from 1 farm on to a neighbours,could he claim them as his own,no he could not,but in saying that leaving carcasas behind or killing for the fun of it is imo a disgrace.
In the eyes of the law if a wild animal is on your land then it is your property,