Wait, there’s such a thing as whitetail-mule deer hybrids? Believe it or not, this is one animal that is not just an urban legend, although your chances for seeing a wild one are probably lower than being struck by lightning. A number of reasons keep whitetails and mule deer from breeding with each other, including geography and their own biology. The two species generally don’t live in the same area, and when they do, they usually don’t associate with each other. Their rut peaks at different times and they have different mating rituals, so the animals don’t usually cross over to see if the grass is greener on the other side unless something very strange happens. Occasionally it does.
Unfortunately, their offspring may not live all that long. Besides looking different, there are a number of anatomical differences that make hybrid deer less likely to survive. The first and possibly most important is that hybrids can’t even run properly. This is because both species run differently. Whitetail deer depend on sheer speed to outrun their predators while mule deer have a slower, but reliable method called “stotting.” Hybrid deer, even though they try their best, run like they’re inebriated.
They also have high fawn mortality and difficulties breeding. This doesn’t mean hybrids can’t breed at all. Scientists are currently studying generations of hybrid deer in captivity, and their DNA can do some really weird things.
But short of a DNA test, how can you tell if you harvested one of the rarest deer in North America? Thanks to some fairly extensive research by experts, such as Arizona Game and Fish biologist Jim Heffelfinger and US Forest Service biologist Roy Lopez, there is a definitive guide to identifying hybrid deer. Here are five places to begin.
1. The metatarsal gland
This is the easiest—and some say only—way to positively identify a whitetail-mule deer hybrid. Located towards the bottom of the animal’s rear legs, the metatarsal gland should be four to six inches on mule deer and covered with brown fur. On whitetails, the gland is much smaller, just about an inch, and higher up than a mule deer’s. It is also marked by white fur.
Like most of their features, hybrid deer fall somewhere in the middle. They have a metatarsal gland between two to four inches long and sometimes surrounded by just a little patch of white hair.
Experts agree that antlers are just about the worst way to differentiate hybrids from their parent species, but that doesn’t mean people will stop trying. Whitetail antlers are marked by a number of tines splitting off a main beam whereas mule deer antlers are generally taller and broader, but bifurcated with very small tines. Since there is so much variation in antler shape, with whitetails sometimes resembling mule deer and vice versa, it is very hard to identify a hybrid just by their rack. They usually veer closer to having whitetail-esque antlers, so if you see what appears to be a muley with a whitetail rack, there may be a chance that it is a hybrid.
One of the most distinguishing features on both species, you can tell either deer apart instantly by their tails. Whitetails, like their name suggests, have tails with white undersides that they flare when threatened. Generally their tails are a bit longer and are wider at the base than the tip. Mule deer have white tails with black tips and it is generally more uniform in size all the way around. Hybrid deer usually have a dark brown tail similar to whitetails, but much darker.
Mule deer have absolutely giant ears while whitetails have something a little bit more modest. Mule deer can sport ears over 10 inches long, while whitetails only measure about 7 inches, maybe 8 if they’re really pushing it. Hybrid deer measure somewhere in the middle.
5. Preorbital glands
The little slit in the corner of the animal’s eye, judging preorbital glands is another way to identify hybrids, if somewhat difficult. Whitetail preorbitals are tiny slits that are also relatively shallow. Mule deer on the other hand, have comparatively wider and deeper preorbitals, with some going as deep as an inch compared to the whitetail’s half-inch. Hybrids have something in between their parent species.
So that’s about it. The differences between hybrids and their parent species are minute, but visible. The two species do interact in many other ways, such as occasionally fighting between bucks. We can assume that the males of either species aren’t too happy by outsiders making the moves on their ladies—it’s hard enough to compete with bucks of your own species.
You can watch a rare whitetail-muley fight below: