The economic word that reflects the observation of there being too few of anything, is scarcity. The way that we typically deal with the quantity of most goods in the marketplace like shoes or services in the marketplace like massages, is to have a market determined price and quantity. If and when shoes were to become scarce, the price would rise significantly and shoe manufacturers would have an added incentive to produce more shoes. We don't need an agency to make this happen. We do however need shoes to be an exchangeable commodity with a price.
Animals and plants that are considered endangered, on the other hand, are not treated like normal goods and services. The purported methodology for dealing with this problem is entirely different. Wikipedia tells us the following:
"Another way to help preserve endangered species is to create a new professional society dedicated to ecological ethics... One final way in which one can conserve endangered species is through federal agency investments and protection enacted by the federal government."Could you imagine having an ethics course explaining why we need to have a sufficient quantity of shoes in the economy? Or what about having a federal agency invest and protect the quantity of shoes? These ideas are preposterous because we recognize that the best way to have any object remain in society is to make it privately owned, put a price on it, and let it trade in the market. The above-quoted solutions are no more viable for animals than they are for anything else.
Now that we know endangered species should be treated like any other good or service, the next question is how to make it happen. There is something specific to endangered species that requires one more step in the analysis. Where are the endangered species located? Since the endangered species are likely to be located in the wild, that is, land either vaguely owned publicly or specifically owned by the government, it isn't enough to just say "privatize the species" when their area of habitation is entirely unprivatized. In fact, that these species are living on public land and disappearing should be no surprise in the first place; that is what we would expect to happen.
If we value endangered species enough, we should not only encourage them to be traded like any other good or service, but we should also privatize all the land upon which they might currently reside. The best way, after all, to get an individual to maintain and protect an animal so that it (and its progeny) never disappears from the earth, is to have him know that it is his animal, on his land, and worth a lot of money. In contrast, what would you expect to happen if an animal is scarce and located on land that nobody owns?