QUESTION: Bob, I found this photo on my trail camera. Is this a doe with a penis or a buck with no antlers? - Joseph C.
ANSWER: At first, I was a little suspicious the photo might've been altered, but that doesn't appear to be the case.
Upon confirming to the best of my ability that it's legit, I then forwarded it to several colleagues. Those who didn't think I was pulling their leg also believe the photo is unaltered, and they agree with my supposition as well.
At some point in our lives we are taught the basic differences between boys and girls. This starts at the chromosomal level and extends through the secondary sex characteristics (body parts).
We're also taught that an individual (of any species) is either one or the other. The truth is not so black and white.
One common example among deer is antlered does. If for some reason a doe experiences unusually high testosterone levels, she might grow antlers, usually spikes, that remain covered with velvet.
Does with larger, polished antlers are much rarer, and often turn out to be something different from what they seem.
Occasionally, a buck's reproductive organs (testes) fail to descend, and will remain inside the body cavity. He'll have a penis but will appear not to have testes. He might or might not grow antlers, which might or might not shed velvet.
It is also possible for deer to have reproductive organs and other features of both sexes. Such animals are called hermaphrodites. Because it has both a penis and an udder (look closely), that appears to be the case with the deer in your photograph.