The best way to avoid shooting a buck fawn is to just totally avoid shooting fawns altogether if possible. This info below will repeat some points already mentioned above, but here are a few hints on how to do that:

First, avoid harvesting an antlerless deer that is traveling alone. For one thing, there are no other deer to compare body size with and that makes an estimate of age tough. Also, a mature doe tends to travel in a family unit or with other deer most of the time. A lone, antlerless deer is likely to be an orphaned fawn that has temporarily been abandoned by its mother due to the activities of the rut. It is not uncommon to see groups of 3 or 4 abandoned fawns banding together during the rut while they wait for the dams to return.

Secondly, while a mature doe is obviously larger than a fawn, it is not a good idea to just go by the size difference. A buck fawn will usually be bigger than a doe fawn, so you can probably imagine what happens. Every year buck fawns are shot by mistake because they are standing next to a doe fawn and the hunter assumes the bigger animal of the two must be the adult doe. A better idea is to go by body size and facial features together. A mature doe will have a longer and more pointed nose and ears. The face and ears of a fawn will look round and stubby. A good comparison would be the way a puppy looks as compared to an adult dog. Using both criteria for comparisons will decrease your chances of harvesting a buck fawn by mistake.

Third, if you like to hunt fields, it is usually not a good idea to shoot the first antlerless deer that feeds its way out into the field. The first deer to enter fields are normally fawns. The very first deer out is likely to be a buck fawn. Buck fawns tend to be more bold and curious than doe fawns and that trait has a tendency to put them on a hunter’s meat pole.

Forth, when deer are traveling single file in the woods between bedding and feeding areas, the first deer in line is normally the dominant, mature doe (just the opposite of deer entering a field). When deer are traveling in this manner, the first deer is directing traffic and is probably the mother or grandmother of the family unit (the alpha female). Examine the first deer closely though, to make sure you are not looking at a small band of abandoned fawns (as discussed earlier).