In my brother's case, he's already identified the animal as a deer or elk, but wants to make certain it is a legal animal (as in some seasons it is not legal to kill a female of the species.)

Texas used to make that a little easier by referring to deer as "antlered" and "antlerless" rather than male or female.

In Montana deer must have at least one antler 4 inches long and antelope must have a "horn or horns" 4 inches long for either to be considered an antlered buck. An antelope with both horns less than 4 inches long is considered a doe or fawn and a deer with both horns less than 4 inches long is considered "antlerless".

By the time you get into identifying antlered, antlerless, brow-tined and spike bull elk you really need good optics!