Nature Notes: Deer

Deer were an important source of protein to the Native Americans of the American Southwest. The mining camps, forts, and settlements that came later also depended on the plentiful whitetail and mule deer for sustenance. Today, deer are the most popular game animal in the Southwest. 

The deer family, cervidae, includes all animals that shed their antlers annually. In the United States, this includes moose, elk, caribou and mule and white tail deer. 

Both species of North American deer evolved from a common ancestor that crossed the Bering Strait land bridge from Asia about 5 or 6 million years ago. After migrating to North America, this ancestral species split into eastern and western lineages between 2 and 5 million years ago. The eastern lineage eventually became the whitetail deer and the western lineage became the mule deer. 

As plentiful as deer are now, their population was threatened at one time. Unregulated harvesting, overgrazing of habitat by ranching interests and severe drought led to serious population declines in the latter part of the 1800’s. 

This human-induced population crash eventually led to regulations that today generally ensure a viable, healthy deer population throughout the United States. 
The case is much different in Mexico, where deer populations are threatened by unregulated over-hunting and habit destruction, except where they are protected in parks and private game ranches.

Generally, the two species of deer are associated with different vegetation types. In the southwestern United States, whitetails are more generally found above 4000 feet elevation, and mule deer occupy the lower elevations and foothills. Of course, their ranges often overlap, and mixed herds are sometimes seen, especially at feeders.

But interbreeding is infrequent, and hybrid offspring rarely survive to adulthood.  There are certain characteristics used to differentiate the two species.
Whitetail deer have a long, wide, flattened tail that is broad at the base and narrower at the tip. The dark tail is fringed with white hair that is an extension of the underside. When startled, whitetail deer often raise their tail, displaying the brilliant white underside.

Mule deer have shorter, ropy tails that are usually white on the dorsal side, with a distinctive black tip surrounded by a white rump. They do not flag their tails.

Mule deer usually have dichotomous forking antlers. That is, the antler forks into two branches, then each branch forks again. In contrast, whitetail deer antlers have multiple branches forking off a main line. The branches themselves do not fork.

Adult mule deer are larger, and have longer ears, giving their faces a “mulish” look. 

When startled, whitetails run directly away with great speed. Mule deer bound away in a motion called “stotting,” where all four hooves land and push off the ground at the same time. They are not as fast as whitetails, but their bounding motion can cover rough terrain very quickly.

The next time you find deer eating your roses, watch them run away from your “Shoo,” and you’ll be able to tell by how they run whether they’re white tail or mule deer.


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