White-tailed deer are ubiquitous in the Eastern and Midwestern states. They are like pigeons or raccoons or brown rats, suddenly making appearances in the most human-dominated environments, and if you’re from this part of the country, you won’t bat an eyelash. The deer are here, just as the sun shines or the rain falls.
But the odd thing about white-tailed is the species is unusually old. Kurten and Anderson claim that oldest remains of the species have been dated to 3.5 million years old. The deer has done well in all those years, and it is often said that the white-tailed deer is the ancestor of both the black-tailed deer and the mule deer. The black-tail evolved when an offshoot of the white-tail became isolated along the Pacific Coast some 2 million years ago when the glaciers advanced through to mid-continent.
As those glaciers retreated, the white-tail expanded west once again, and the black-tails that had colonized the arid and montane parts of the interior West apparently crossed with them. Valerius Geist made much hay about the white-tail mitochondrial DNA that is now found in mule deer, as did I. Using Geist’s ideas, I even posited that the mule deer was a species younger than the domestic dog, because it is a true hybrid species that only evolved within the past 10,000 years.
Since Geist wrote his book on deer biology and taxonomy, most researchers have generally not followed his lead. Most experts consider the black-tail and the mule deer to be the same species, and the best analogy to think of these two forms is they mirror our classification of brown bears on this continent. If it is a large brown bear from Pacific Coast, it’s called a brown bear. If it is a small brown or “grizzled” bear from the interior West or interior Alaska, it is called a grizzly. The only exception to this rule is all brown bears in California were called grizzlies, even though California did have large coastal brown bears.
This is pretty much the geographic distinction that is applied to black-tailed deer versus mule deer. Black-tails live along the coast, while mule deer live in the interior.
Most authorities generally don’t pay much attention to the odd similarity between mule deer and white-tail mitochondrial DNA. Mitochondrial DNA is inherited from the mother, and it is possible that there really was a female white-tail that bred with a male ancestral mule deer some 10,000 years ago. For whatever reason, virtually all mule deer descend from this female white tail, even though the bulk of their ancestry is that arid-land black-tail stock.
This suggestion has been pooh-poohed because modern white-tail/mule hybrids have a low survival rate in the wild. They inherit a mixture of the mule deer’s evasive stotting behavior and the white-tail’s evasive bounding behavior, and deer with such mixed behavior more easily fall to predators.
But it is possible that a hopeful monster sort of appeared from this ancient hybridization, a hybrid that had a good enough evasive behavior to avoid predation and pass on her genes.
White-tailed deer are among the most studied of all wildlife, but the literature on their DNA is rather sparse. We know from their recent history that white-tailed deer were very close to extinction by the turn of the twentieth century. Industrial-level slaughter for their much coveted hides, which were in great demand for work clothes, had reduced their numbers throughout their range in the United States. Packs of free-roaming dogs killed fawns and ran down the adults, and market hunters sold the venison to restaurants as exotic fare.
State after state passed conservation laws on white-tailed deer. States began to transport deer into deer sparse regions, and by the middle part of the twentieth century, deer numbers had recovered to allow some hunting. By the time I was born in the 1980s, there were more white-tailed deer in North America than there were in 1492.
Such a boom and bust history surely has left a legacy in white-tail DNA. As the older species, I would expect white-tails to have greater genetic diversity than the mule and black-tail species.
But maybe not. The white-tail likely underwent a severe genetic bottleneck as a result of all that unregulated hunting and dogging. Maybe they really are really quite inbred after all.
Of course, that diversity could have been somewhat captured if deer from Mexico and Central and South America would be included in the studies. Yes, white-tailed deer, unlike Mule deer and black-tails do range south of Mexico.
One of my most prized possessions is a shed antler from a Columbian black-tail that was given to me by a friend who came to visit us from Oregon this summer. (Check out her blog here).
It wasn’t the biggest shed I’d ever seen, but it looked like a sort of hybrid between the mule deer and the white-tail. It was of a creature from a different forest, where the evergreens dominate and the rain falls all through winter. Our white-tails are creatures of the oak woods and the cornfields, where the snow falls in the winter and air gets so cold it cuts you like a knife.
But they are kin, connected by that common ancestor in that primal white-tail of 3.5 million years ago. Their kind were here long before humans ever stepped foot on this continent, and the thrived through the long days of the fellest predation from bone-crushing dogs, running hyenas, and saber-toothed cats.
Our humanity can cause their destruction, but at the same time, we’ve created a true deer utopia of sorts, as we’ve killed off all the wolves and cougars and most of us don’t even bother to carry a gun in the woods anymore.
But just as glaciers advance and retreat and the fortunes of predators wax and wane, so too will this utopia. Climate change and development are already taking a toll on mule deer numbers, as are the growing populations of traditional predators.
Evolution has set these deer on a course with our own kind’s meteoric rise. We have conjured and conjoined and manufactured and manipulated until we now exist as near deities on our own planet. Near deities, maybe, but we are also surely aliens.
So from our deer parks of suburbia we will watch them with benign curiosity, and maybe we’ll take time to know them, to ask about them, to consider them more closely.
And do not for a second consider them or us fixed in our places in the grand scheme of the cosmos.
It took many biologist quite a long time to admit that coyotes do indeed interbreed with dogs as well. People can be hard-headed.