Natural History

I make no bones about my view that the horses that roam the American West are feral and should not be regarded as native wildlife. This view shouldn’t controversial, but it is.

Lots of romanticism exist about horses and the West, including that brief time when Native cultures used horses as their greatest asset in hunting bison.

But the truth is that the horses one might see roaming the ranges of the American West are all derived from domestic horses that went wild on the range. The initial ones were all derived from Iberian/North African horses that Spanish colonizers brought into the New World, but these were later augmented with horses brought over from the rest of Europe.

If one were to say that the various forms of freely breeding swine in North America were feral, it would be easy to get agreement. Suids are not native to the Americas, though a sister lineage, the Tayassuidae, are native to North America. The tayassuids, better known as peccaries or javelinas, once ranged as far north as the Yukon, but since the Pleistocene, they have not ranged north of Texas, New Mexico, and Arizona.  Feral swine, though, exist over large sections of the country, and wildlife and agricultural departments spend lots of time, money, and manpower on controlling their numbers.

Feral horses, though, get special privileges, as do feral donkeys.  They receive a certain amount of protection not afforded to other feral livestock in the Wild and Free-Roaming Horses and Burros Act of 1971. The horses and donkeys are not controlled in the same way feral pigs are. There is no continuous open season on them in the way that most states manage feral pigs.  Indeed, it is actually a crime to kill or harass feral horses or burros on federal land.  Excess horses and burros are managed through roundups, where some of them are deemed adoptable and sold to the general public.

For those of us with a modern ecological mindset, which has a deep disdain for making allowances for feral livestock, this law makes little sense.

But there is a sort of argument for this act. It goes something like this:

The modern horse species evolved in its current form in North America. Some taxonomists contend that there was once a Holarctic distribution of this species during the Pleistocene, and with the latest ancient DNA studies, I tend to agree with this assertion.

The North American population of horses became extirpated at the end of the Pleistocene, and when European horses went feral on the Western ranges, this constitutes a rewilding event.

Now, I don’t buy this argument very much, but I can say that there are some things we might consider. North America’s original population of cougars became extinct at the same time. The cougars that live in North America are derived from South American cougars that recolonized the continent about 2,000 years later.

Further, conservationists and sporting groups spend lots of resources on restoring and protecting elk populations. Elk have a much shorter history on this continent than horses ever did. Different experts have estimated when elk have first arrived. 40,000 years ago has been suggested, but more recent data points to them colonizing North America only 15, 200 years ago.

If elk arrived in North America only that recently, their status as native wildlife exists only as a weird  accident of geography. Elk are the on Cervinae or “plesiometacarpal deer” in the Americas. All the other deer in the Americas are Capreolinae or “telemetacarpal deer.”  Sika, axis, red deer, and fallow deer are also Cervinae, but they were introduced after colonization.

Elk don’t live in far northeast of Russia anymore. The elk of North America are the genetic legacy of this ghost population.

So the feral horse advocates could at least through the recent arrival of elk in North America as something to consider when we say their favorite animal is not native. Horses have a long evolutionary history in North America, and we just happen to be at an odd point of the history of horses that no native horses exist here. The earliest horse, Eohippus, first appeared in North America 52 million years ago.

So the feral horse advocates could say that we have a species that derived from a lineage that was here for over 50 million years that has now been restored through feral livestock and thus deserves these protections.  And this animal has at least as much rights to be free and roaming in North America as a large deer that had no connection to this continent until the latest Pleistocene.

However, the extinction of the horse in North America likely stemmed from natural climate change at the end of the Pleistocene.  Horses became extinct because they were poorly adapted to the new ecosystems, and as we have seen, horses really don’t do that well out in the deserts and semi-arid ranges of the West. They require water tanks to get them through long droughts, and they eat lots of forage. Not as much as domestic cattle, of course, but on ranges that are heavily catered toward livestock grazing, the horses are just an extra set of grazers that are taking away forage from native wildlife.

And even if we were to accept that horses were restored native wildlife, why on earth would we ever extend these protections to donkeys? Donkeys, though of ancient North American origin, evolved in their current form in Africa.

So although I do think of horses as no longer being native to North America, I do think questions of them being native or introduced are complicated, much more so than the question of feral pigs or cats. And yes, there is something like an argument that can be made for the native status of horses, even though I think it’s mostly in error.