Why Do Female Deer Sometimes Grow Antlers?

It became pretty obvious that my dad and I weren’t going to notch our antlerless tags that night. The sun continued to drop, shooting light ran out, and we started making our way back to the truck. But as we stumbled down the mountain, our friend Richard made a quiet comment under his breath that stopped my dad and me in our tracks.

“I think that spike buck was actually a doe.”

As we recalled the image of the three whitetails, my dad and I agreed that the spike did have a particularly skinny neck for a buck, even a young one. The one measly antler lacked any branches and only measured four or five inches. And it would be slightly unusual for a buck to travel with a doe and a yearling so casually, especially on the verge of the pre-rut. We immediately jumped to the conclusion that the animal was simply an underdeveloped buck who would be unrecognizable the following year. The idea that the deer might be female seemed impossible. How wrong we were.

Testing Theories According to Kip Adams, chief conservation officer for the National Deer Association, in extreme instances female deer can end up with high testosterone levels.

“It doesn’t happen very often in the wild because it takes some type of hormonal imbalance or injury to the deer to cause that hormonal imbalance, so it’s rare in nature,” Adams told MeatEater.

When this does occur, the antlers are usually small, skinny, unbranched, or barely discernible from the crown of the head. Some stay either partially or fully in velvet. It would be practically impossible for doe antlers to fully develop and resemble a normal set of buck antlers, Adams said.

“During the spring and summer, testosterone levels rise slowly, which causes antler growth. In bucks, a steep increase in testosterone, usually in the late summer, causes those antlers to harden,” Adams said. “In does that have antlers, the antlers typically aren’t that large, and they almost always stay in velvet or only partially harden, because it takes quite an imbalance to grow them in the first place. They almost never get that surge of testosterone that’s required to actually harden them off.”

Hunters Who Cry ‘Doe’ Despite the unlikely nature of harvesting a doe with high T, many hunters have bagged fully antlered deer without male sex organs and instantly assumed they’d found a once-in-a-lifetime animal. But this often isn’t the case.

“You’ll see reports each year where hunters will kill this deer with big antlers and numerous tines, and they’ll go to field dress it, and it won’t have testicles. And they’ll think it’s a doe with this big set of antlers, but in most cases that’s not true," Adams said. "It’s likely a buck that’s injured itself and lost its testicles, or it’s a cryptorchid or hermaphrodite.”

In bucks with cryptorchidism, their testicles never fully descend from their abdominal cavity. In addition to stunted antler growth, this can create other antler-related phenomena like nontypical formation and “cactus buck” syndrome, in which bucks don’t have enough testosterone to shed their velvet properly and the annual growth builds on top of itself.

Hermaphrodidic deer are a bit more complicated. They have both male and female sex organs and can present as either bucks or does, with antlers or without. A simple Google image search of “hermaphrodite deer” yields a few confused hunters yanking their deer into unnatural positions to get the antlered head next to the bare spot where male sex organs would be for photo evidence of the cervid sorcery. Some hunters look ecstatic to come across the rarity, while other images are more “grip 'n' grimace” than “grip 'n' grin.”

To Shoot or Not to Shoot Adams pointed out that these unique deer are one of the reasons why states might choose to label their tags as “antlered” and “antlerless” instead of “buck” or “doe/fawn."

“You can have bucks that don’t have antlers long enough to be classified as antlered deer, and you can shoot a doe that has antlers long enough to classify the deer as antlered, which you can then put your antlered tag on,” Adams said. “As far as I’m aware, there aren’t legal ramifications there.”

He also pointed out that female deer with high testosterone can also successfully and healthily reproduce. It isn’t unheard of to see an antlered deer nursing a fawn, a dead giveaway that the deer is definitely a doe. Cow caribou and other female ungulates of other species frequently grow antlers.

There are countless exceptions to the rule that bucks are the only deer to boast antlers, all of which are proof of how important properly identifying your target really is. Ultimately, we’ll never know for sure if the single-spiked whitetail we saw was female or not. But one thing’s certain: It’s way more fun to reminisce about an unsolved mystery of nature than a phone call to the game warden for accidentally shooting an antlered deer with an antlerless tag.