Mule Deer doe, late spring

On a recent visit back to the mid-west of my childhood, a walk through the leafless hardwood forest brought me back to watch the eastern White-tailed Deer (Odocoileus virginianus). If you live anywhere east of the Mississippi, then you’ve undoubtably seen them yourself. And once again I was impressed at how well this large animal could blend in with the brown, early spring woods unless the wide, white “flag” of its tail was raised in alarm.

Here in New Mexico, we have no Whitetails. But we have a relative, the western Mule Deer (Odocoileus hemionus) so named because its ears are as much as 25% larger than those of a comparably-sized Whitetail.

Although both species are similarly-sized deer and under special circumstances may hybridize, they are really quite different animals in appearance and behavior. Without turning this into a lengthy treatise, I’ll try to describe a few of the key differences.

Mule Deer buck in velvet, late Summer. Photo courtesy of Outspire guest Jim Mackenbrock

(1) Ears : Mule deer have big ones.

(2) Tail : The tail of the Whitetail is wide and fluffy, brown on the upper side and crisp, bright white on the underside. When the deer is alarmed, the tail is raised to show the white “flag” to its companions as a danger signal. The Mule deer tail is more like a short length of black-tipped rope. In flight, the tail is not raised.

(3) Antlers : Male deer of both species–the bucks–grow antlers each year. After the second year, the antlers are branched. Typically, the branches on Whitetail antlers all occur as forks off the main beam, while Mule deer have antlers which are a series of “Y”s. Individual variations occur, though, so this is not positive proof of species.

Whitetail bucks in velvet.
Photo copyright Coy Hill, used by permission. http://countrycaptures.blogspot.com/

(4) Color : Both deer species have white bellies. But Whitetails are a nice, soft brown with that white tail. Mule deer are a gray-brown with a prominent darker forehead. The Mule deer butt looks different, too, since the skinny tail doesn’t cover the lighter buff-colored rear end.

(5) Mating behavior : Even where the two species’ ranges overlap, hybrids in the wild are very rare. It’s thought that the body cues, pheromones, and courtship behavior as well as timing of the rut may be different enough to prevent hybrid production. For instance, Whitetail bucks relentlessly pursue the doe, sometimes at a run, until she permits mating. Mule deer courtship is slower and subtler with lots of body cues.

(6) Gait : Here’s where it gets interesting! Whitetails are indigenous to eastern forests and grasslands. When frightened, their escape strategy is blinding speed. They bound and run through the brush, tail up, leaping over small obstacles and running around larger ones. Mule deer are adapted to live in the rougher, rockier country of the west. When they flee, they use a stiff, four-footed springing gait called the “stott”. If you remember old Warner Brothers cartoons of the skunk “Pepe Le Pew” you should get the idea. (Check out Pepe for a trip down Memory Lane, stotting around 4:05min. http://www.youtube.com/watch?v=uuWZdzNzji0 ) With these high bounces, Mule deer can go over obstacles and up rocky slopes that pursuers cannot follow so quickly.

Illustration of some differences.
Oates, David W., “DIFFERENTIATION OF MULE DEER AND WHITE-TAILED DEER” (1989). Nebraska Game and Parks Commission Publications. Paper 16.

There are other differences as well in external glands, feet and teeth, but they would be identifiable only on close inspection.

So look closely when you visit New Mexico or other parts of the Rocky Mountain west to appreciate that even the deer are special!