A heath hen.
A few days ago, I wrote about the northern white rhinoceros, which is probably extinct in the wild. Only a few captive individuals exist, and I suggested that the only way this subspecies will remain viable is if these animals are crossbred with the southern white rhinoceros. Such suggestions are not given lightly, because in wildlife conservation, sometimes the subspecies has to be exactly right.
The best example I can think of is the attempt to return the now extinct heath hen to the East Coast. It is now accepted that the heath hen was a subspecies of greater prairie chicken that lived on the East Coast from coastal New Hampshire to Northern Virginia. It was heavily hunted on the mainland, and by 1870, the only extant population was on Martha’s Vineyard. This population then became extinct in 1932. The birds were very, very common during the early days of colonization. Laborers had to make deals with their employers that they would be fed heath hen no more than two or three days a week. It was obviously an cheap source of protein that existed as what appeared to be an unlimited resource.
By the end of the eighteenth century, this bird was in trouble. In 1791, the New York legislature considered a law to protect the heath hen and other game species– the first wildlife conservation law in the country’s history.
Now, in the early nineteenth century, the young American republic had expanded into the prairies. In those prairies, the more common subspecies of greater prairie chicken was discovered. Some of these animals were taken east in attempts to augment the heath hen population.
The prairie chickens from the plains never were able to thrive on the East Coast. They probably lacked some sort of morphological or behavioral adaptations to handle the climate of the East Coast. No one has ever figured out exactly what the problem was, but we do know that greater prairie chickens do not nest near improved roads or power lines. They also do not like to nest in areas where fields are cultivated. It is also very likely that these western prairie chickens were unable to feel comfortable enough in East to ever nest.
The story of the failure of the western subspecies of prairie chicken to replace the heath hen is a cautionary note about using a different subspecies to augment or replace an extinct or endangered one.
Such successes with these “replacements” and “augmentations” do exist. The most notable example is the introduction of the Texas cougar to Florida to augment the Florida panther’s genetic diversity. (However, this introductions may be for nought, for there is likely not enough habitat to support this population of Puma concolor.)
However, it is also likely that one might have a case in which the subpecies is entirely unsuitable for reintroduction, as was the case with the greater prairie chicken on the East Coast.
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A feral horse in Nevada.
Now, I’m going to get a little more controversial.
I have read in more than one place that the fully modern horse evolved in North America, and thus, we should consider the feral horse populations on public lands native species. Federal law actually recognizes these population as integral to the Western fauna. However, I don’t think such recognition is warranted. I just don’t think a place exists for feral horses and donkeys on public land. I had a pony growing up, which I liked to ride, and my grandpa had a horse that he rode every day as he tended natural gas wells. Horses have been important to my family, and I think they are very important to our history and heritage. However, that doesn’t mean that we should sacrifice the biodiversity of our public lands just to protect herds of feral horses.
Now, to some of you, what I just said is a heresy. Some are going to say that I hate horses. The truth is I love horses. On my family’s farm, a small herd of pleasure horses is pastured there during the summer. I have always liked having them there. I bring the horses apples. I pet them. I even help socialize foals. I can’t think of a more interesting large animal to get to know.
However, they are very hard on the desert ranges in the West. They defoliate forage and ground cover, which encourages erosion. If a bad drought is in the offing, the situation becomes even worse.
Now, it would be one thing if we could prove that modern horses were the same animal as the horses that went extinct. The most common example that wild horse advocates use is the case of the Yukon wild horse, Equus lambei. The Yukon wild horse lived on the Beringian steppe ecosystem over 10,000 years ago. Historically, it was considered to be a wild ass, and some earlier texts even refer to it as the same species as the modern domestic ass, Equus asinus.
However, all of that changed when a construction project dug up a horse in the Alaskan permafrost. It turned out that this horse, though it looked very similar to a modern horse, actually was the ancient species called Equus lambei. When its MtDNA was analyzed and compared to modern horses, it was very closely related to Equus ferus caballus, the modern horse. Close enough that it may have been the same species. Its MtDNA sequence differed from the modern horse by 1.2 %, which was well within the variance of modern horses.
Now, I’m willing to accept this evidence that Equus lambei was the ancient North American ancestor Equus ferus. But that does not logically folllow that because these two horses are very similar in terms of genetics that the domestic horse should be considered a native species.
The ecosystem for which Equus lambei was adapted no longer exists. It lived on the Beringian steppe, which disappeared as the climate warmed at the end of the Pleistocene. It is very likely that Equus lambei was adapted to this environment in ways that Equus ferus caballus most likely is not.
If releasing modern domestic horses to the West is restoring a native species, then I have a modest proposal to develop a wolf reintroduction program. I say that we should go to every pound in America and adopt every big strong dog. Then we should take them out into wooded areas and turn them loose.
And if we called that wolf reintroduction, I’m sure that every wolf expert in the world would be livid. But we would have a valid argument. Aren’t wolves and domestic dogs the same species? Analysis of their MtDNA proved that they were even more closely related than Equus lambei is to the domestic horse– differing at most by 0.2%. Wouldn’t that be a valid reintroduction?
Of course, it wouldn’t be. Dogs and wolves may be the same species, but they behave very differently. Feral dogs don’t normally form the same sort of packs that wolves, and if dogs can find garbage to scavenge, they aren’t going hunt large ungulates, unless livestock is available. Wolves do form a certain type of pack to hunt large ungulates, and they generally avoid people. A few wolves populations (especially in Italy) do scavenge on garbage, simply because unugulate species are scarce.
So if wolves and dogs have such different behavior, why is it that we assume that the Yukon wild horse could ever be replaced by the domestic horse?
After all, we know that domestic horses don’t do well in arctic or subarctic climates, with the notable exceptions of the Icelandic horse and a few Russian and Scandinavian breeds. Every arctic and antarctic expedition that has used horses has failed. The horses simply couldn’t find enough forage to survive or they suffered greatly in the elements. I have also read accounts of early settlers to northern Labrador who had a very hard time keeping horses in such an environment.
Yet the Yukon wild horse was able to survive in the Beringian steppe environment during the last Ice Age.
That should tell us that the Yukon wild horse had behavioral and morphological adaptations that make it distinctly different from the modern horse. And thus, it cannot be replaced with the haphazard “introductions” of domestic horses to the American West.
Horses did evolve in North America, but they had their chance. The climate changed as the last Ice Age ended. It is also possible that the arrival of human hunters may have had some effect upon their populations. Humans hunted mammoths almost exclusively, but we all know that savanna elephants in Africa play a major role in keeping their ecosystem from returning to forest. It is likely that mammoths kept the ecosystem a certain way, and when humans started killing them, the ecosystem suffered. This problem was further excerbated by climate change and the arrival of new pathogens from Eurasia. It is very likely that because of all of these factors, North American megafauna became extinct, including our native horses.
Equus lambei represented a horse that died out over 10,000 years ago. It may have been very closely related to the modern horse, but the modern horse cannot be considered its replacement. The ecosystem to which it adapted no longer exists, and to claim that the prior existence of that ancient horse justifies keeping feral horse populations on our public lands is simply laughable. I certainly don’t like that the native North American horses are extinct, but it is an unfortunate reality.
And I’m not willing to sacrifice the biodiversity and the integrity of North America’s native ecosystems just to preserve a possible descendant of a species that went extinct over 10,000 years ago.
Sometimes you have the right subspecies, and species and subspecies exist only within their time and place. In the case of the North American horse, the time and place have long since passed. The right subspecies or species no longer exists. And we simply can’t replace it with a domestic animal that has gone feral.
