Sure you aren't seeing buck w/out antlers?? The way I always tell is obviously body size, but if you look closely, bucks will hold their ears down a little more than a doe. This, I'm guessing is from the antler being there. I have studied this, and maybe I'm nuts, but I'm a believer in that.
...and on that day when my strength is failing, the end draws near and my times has come, still my soul will sing Your praise unending, ten thousand years and then forevermore!