A herd of wild horses racing across the open range is as much a part of the west as cowboys, cattle and pickup trucks—meaning, of course, that they too are an invasive species.

(Arguably the only large grazing animal who actually belongs on the rangelands of the American West is the bison. But that's another story entirely…)

Anyway, thanks to a tight budget and an overflowing number of horses already in captivity, there may be more free mustangs running across the drought-parched high plains and mountains of the west than usual this year—certainly more than a lot of westerners, particularly cattle ranchers, think necessary.

Much of the west's 40,000 or so wild horses live on public land spread across ten states, putting them mostly under the authority of the U.S. Bureau of Land Management—which holds yearly roundups across the region to haul in thousands of wild horses, some of which are adopted off while others spend the rest of their days grazing in government pastures.

But this year the agency plans on rounding up only around 2,400 wild horses and burros, mostly in Wyoming but also in Nevada, Utah, Oregon, California and Idaho. That's over 11,000 short of the number the agency says need to be removed from public lands to keep the overall population of wild horses in check with native wildlife and ranching operations.

In fact, BLM officials say that the wild horse population in Colorado won't be touched at all this year.

Federal officials say that they already have around 49,000 horses and burros being held in government-funded facilities across the midwest.

Some wild horse advocates say that the BLM is doing it all wrong, pointing to a National Academy of Sciences report that recommended the agency invest in widespread fertility control instead of spending millions each year housing wild horses.

That report concludes that the BLM wild horse removal program—which has rounded up nearly 100,000 horses in the past 10 years—is likely having the opposite of its intended effect of mitigating long-term overpopulation and environmental damage.

"(T)he current removal strategy used by BLM perpetuates the overpopulation problem by maintaining the number of animals at levels below the carrying capacity of the land, protecting the rangeland and the horse population in the short term but resulting in continually high population growth and exacerbating the long-term problem."

"The BLM already warehouses more wild horses in holding facilities than remain free in the wild," said Deniz Bolbol of the American Wild Horse Preservation Campaign in a statement released last week. "The agency's plan to remove thousands more mustangs and burros from the range makes no ecological, scientific or fiscal sense."

According to the BLM, the agency spends over $70 million each year on wild horse programs, with over $46 million spent just maintaining the captured horses that aren't adopted out.

Other horse advocates claim that the real culprit in damaging western rangelands is one of the west's other major invasive species—cattle.

"Ranchers continue to scapegoat wild horses for range damage caused by wide-scale livestock grazing on our public lands," said AWHPC director Suzanne Roy to TheHorse.com. "Instead (of) spending tax dollars to round up thousands of wild horses, the government should be reducing livestock grazing on public lands and eliminating the taxpayer subsidies that accompany the unsustainable practice."

Western ranchers—arguably yet another invasive species along with cattle, wild horses and wild horse advocates—disagree, claiming that wild horses are the ones destroying rangelands already damaged by years of continued drought across the west.

Pushed by ranching interests, many western states, including Nevada (home to the largest population of wild horses and burros in the west at over 25,000) and Utah, are pushing for legislation that would shift control of wild horse populations from the federal government to local states and Indian tribes who would then decide exactly what constitutes "overpopulation."

"This really is a political problem," said Iron County, Utah, Commission Chairman David Miller to the Salt Lake City Tribune. "We need Congress to get off their butts."

In addition, BLM officials in Nevada are in the midst of a lawsuit from the Nevada Association of Counties and the Nevada Farm Bureau on behalf of Nevada ranchers alleging that the agency violated the 1971 Wild Free-Roaming Horse and Burro Act by not removing excess horses from public Nevada ranges shared with livestock.

The ranchers claim the the failure to remove the wild horses resulted in damage to the ecological integrity of the land, and harmed their livelihoods. BLM officials have asked that the lawsuit be dismissed, saying that they simply don't have any more room or means to care for more wild horses.

The Wild Free-Roaming Horse and Burro Act (PDF), signed by President Richard Nixon in 1971, was designed to keep wild horse populations at manageable and sustainable levels. It made it a crime to kill or harass wild horses without federal permission, required federal agencies to protect and study the animals and allowed public land to be set aside specifically for wild horse populations.

But the act is vague in how, exactly, those populations are to be managed. A herd of wild horses, which have no living natural predators, can double in size every four years. Agency policy and general public indignation generally forbids the BLM—which is also charged with accommodating the wildly disparate and usually contradictory needs of grazing, wildlife, hunting, soil erosion, mining and other priorities on public land—from selling wild horses for slaughter, even though they are allowed to do so by law.

This leaves few practical, immediate (equine birth control isn't really "immediate," especially in the context of a political timescale) remedies for horse population control beyond adopting out as many horses as possible and leaving the rest to spend their life out to pasture.

Adding to the growing legal and legislative morass is an effort by two wild horse advocacy groups—Friends of Animals and The Cloud Foundation—to have wild horses declared an endangered species alongside grizzly bears, wolves, condors and humpback whales, among others.

They argue that horses are not an invasive species, but rather a species that died out in North America only "temporarily" at the end of the last Ice Age 11-13,000 or so years ago before being reintroduced to the continent by the Spanish about 500 years ago.

"It is native to North America," Jay F. Kirkpatrick, director of ZooMontana's Science and Conservation Center told the Associated Press in June. "The Spanish were just bringing them home."

But the BLM holds the position—shared by The Wildlife Society (PDF) and many experts—that the wild horses living across the American West today are the descendants of domesticated and specifically-bred horses that escaped or were released by Europeans in the 15th and 16th centuries plus others that became feral in modern times, and are not direct genetic links to the ancestral wild horses that evolved in North America and spread to Eurasia via the Bering land bridge during the Pleistocene.

During the time between their post-Ice Age die off and the return of horses to the Western Hemisphere with Christopher Colombus in 1493, all of the animal's natural North American predators—including saber-toothed cats—became extinct.

The idea of listing mustangs as an endangered species is not sitting well with the cattle industry, which dropped not-so-subtle hints that doing so might actually endanger the Endangered Species Act itself.

"Listing wild horses under the ESA — which is meant for wildlife, not domesticated, non-native animals — would only serve as another demonstration of just how damaging that statute is," said Dustin Van Lieu of the Public Lands Council, which is tied to the cattle and sheep industry.

So—all of the shouting and posturing by both parties aside—what should be done with wild horses? And what about cattle?

Well, on the plus side, wild horses are certainly more captivating, while the undeniably more-pragmatic cow has been specifically designed for the great masses to eat and wear. But on the negative side, both cattle and horses can be damaging enough to a nice, normal green pasture—much less an arid rangeland already stressed by a lack of rain and a warming climate.

Here's a thought: Perhaps we should consider cutting our losses by getting rid of both wild horses and cattle and just give the whole damn thing back to the bison.

It's all really their home anyway.

Image via AP