First, thanks to all for the feedback and comments. There is one point of misunderstanding that I must address, however.
The argument has been made that the extinction of species is "just evolution", thereby implying that since these animals couldn't compete with man, it was inevitable and natural that they die out. This is fallacious.
First, to define the debate - evolution is genetic changes in a population over time. That's it. "Survival of the fittest" has nothing to do with it, other than the fact that an animal that survives long enough to procreate as much as possible, and thereby pass its genes on, is "fitter" than an animal which does not. To quote R. C. Lewontin in Human Diversity: "In evolutionary terms, an Olympic athlete who never has any children has a fitness of zero whereas J.S. Bach, who was sedentary and very much overweight, had an unusually high Darwinian fitness by virtue of his having been the father of twenty children."
Second, evolution is both blind and amoral. The process of evolution does not say what is "right", "wrong", or even "natural" - that is a value judgment that only a sentient being can make. Shrugging off the extinction of species by saying "it's alright, it's just evolution" is a misuse of science - a kind of naturalistic appeal to authority. (This was particularly well-addressed in this post
Third, the extinction events I've mentioned were not natural. Evolution "works" over timescales of thousands of years, and it does so best in large, diverse, and isolated populations. When your predators are armed only with tooth and claw and depend on your kind for their sustenance, it works out very well. Take a look at the boom-bust cycles in the population of wolves in Yellowstone, for example. If the wolf packs are very successful - or if there are simply too many wolves - their food source dwindles. In response, a number of wolves will die, and fewer pups will be born. The food source recovers, and the circle of life continues (cue Disney theme tune).
There is no evidence I've seen of a species being completely wiped out through predation in the animal kingdom other than at the hand of, or through the assistance of, man. (I'd be interested in seeing any cited reference to the contrary). Why not?
Because man has two things going for him: he is omnivorous, and he uses tools. How is the Thompson's gazelle meant to evolve against the spear, atalal, or long-range rifle? When the population of gazelles drops, does mankind immediately suffer? And if Thompson's gazelle is completely wiped out, does mankind starve to death? Of course not - we move on to slaughter something else, pick berries, or grow crops. The feedback mechanism stuttered when we developed molars and incisors in the same jaw, and stopped completely when we fashioned flint into spearheads. (Alternatively, nature's big payback may just be waiting a hundred years down the track).
I do side with the statement of Jeff Goldblum's character in Jurassic Park about the dinosaurs - "Nature selected them for extinction." But I was at pains to present species that were wiped out not by some cataclysmic event that we were and are powerless to prevent, but creatures that we, as human beings, wiped out through conscious action. When a Mauritian stole the last Elephant bird egg, she or he must have had some awareness of what he was doing - yet they took it anyway. It was conscious action, not "natural evolution" that caused these species to disappear from the Earth. I am presenting the possibility of conscious action bringing them back.
And as for those of you who argue that "I am only responsible for myself, and no-one else", I would make the case that you live in a rather insular and theoretical world. Most people not living in a log cabin in Montana recognize that they have some degree of responsibility to their family, community, and/or country, regarding its health, security, and prosperity. So - if you were that Mauritian, would you take the same action? And if it was in your power to do so, would you undo its consequences?
It is not my intention to indulge in some Homo sapiens guilt-trip. I am only asking if we, as human beings, completely extinguish other species, is it responsible or even reasonable to bring them back, assuming we have the power to do so?
-- "Don't criticise. Create a better alternative."