Heidi: I respectfully
disagree with your argument that because wild horse populations increase to the
point that they damage their habitats is proof they are not native, but
"feral". Perhaps you'll consider another explanation. When the horse
disappeared from the New World so too did many
other species: camelids, mastodons, giant slots as well as a whole menu of
predators. In particular, dire wolves, the saber-tooth cats and the
North American lion (similar but larger than the African variety). Every
prey species has a "shaping predator", i.e., a predator that
"shapes' the numbers as well as the physical and social evolution of the
prey species. The mountain lion, for example, "shapes" the
behavior and physical evolution of the mule and white-tail deer; the timber
wolf shapes the elk, the coyote the rabbit, etc. In the case of the
horse, the shaping predator (I believe it was the saber tooth cat) disappeared
at the same time as the horse. When the horse returned to its rightful birth
place -thanks to the Conquistadors - the shaping predator was long gone.
Only the mountain lion remains to predate on the horse - and more than 90
percent of that predation is on foals. The mountain lion simply is not
big enough to shape the population of full grown horses. I certainly don't
disagree with you that unchecked horse populations damage their habitats And I
agree it is self-evident that the Bureau of Land Management (BLM) and the U.S.
Forest Service must find ways to keep their numbers down. These agencies are
working on contraception as one alternative, and of course, there is the much
celebrated mustang adoption program. I don't know whether this is the
ultimate answer or not. But none of this, in my humble opinion, means that
horses should be kept out of areas in which they evolved due to them being
"feral". About your other points. True, North
America - as well as all other continents - has seen significant
climatic change over the eons. For example, the polar regions, at one
time, were balmy enough to support dinosaurs. But to say climatic change in the
relatively short span of time since the end of the last ice age was the reason
for the great die-off of wildlife (including the native horse) requires a
change much more significant than the geologic record supports. Indeed,
between each of the major ice ages that held the northern regions of planet
enthralled more than a dozen times, there were "interstitial"
periods of climate not unlike that which we enjoy today. Indeed, many
geologists theorize we simply inhabit the latest interstitial period and that
another ice age is overdue. I would go even further and suggest to you that as
the great ice sheets retreated back toward the pole the left the great
grasslands in their wake -- horse habitat. Thus, the one major
change in the North American climate caused by the melting of the ice that we
know occurred, actually FAVORED horses. As to your contention that the number
of humans who came to the New World following the end of the last Ice Age were
too few to account for the mass extinctions of the North American fauna, I
believe is, at least, debatable. First, these Neolithic hunters were the
most deadly hunters the human species ever produced. By the time they
arrived, the humanity had successfully clawed its way to the top of the food
chain. Again the record shows that no animal - mammoth or whale - was too
big, too ferocious to escape human predation. The spear, the throwing
stick and soon, the bow and arrow, were superb killing tools in the hands of
these people. And remember, none of the American fauna had ever seen
humans before. The Do-Do Bird is just one example of a wild animal that showed
no fear of humans until it was rendered extinct. I don't find it that difficult
to believe that humans caused mass extinction. It was once said that the
numbers of passenger pigeons and buffalo were just too numerous ever to worry
about their future. One final point is that the geologic record is not yet
clear on how long it took to eliminate these animals from the New
World. It could have ranged from a few centuries to several
millennia. The one geologic point that seems to be clear, is that there was no
great climate change that, by itself, would explain why the horse and so many
other animals disappeared from the continent. I believe the only explanation is
that they were killed by humans. And chief among them was the horse.
