Thinking like a savanna

Reposted from the old TfK.

Asiatic elephants at the Bronx ZooA few years ago, I someone gave a presentation here, arguing that we should reintroduce a bunch of extinct Pleistocene species into North America. Cheetahs were on the list, along with lions and Asian elephants (like these from the Bronx Zoo). The idea was that human hunting caused these species, and many more, to go extinct, so we ought to bring them back. The ecologists in the room all thought this was madness incarnate.

On a vaguely related topic, Salon.com has an article about elephant hunting. As in any conflict over the management of a large, charismatic species in a complex landscape, the debate is over the extent to which people ought to manage the natural system. In this case, elephants in southern Africa are overgrazing and damaging trees. The scientists interviewed all seem to agree that elephants are becoming overpopulated through much of their range, and that some form of controlled culling would be justified. Of course, various groups oppose killing elephants.

I won’t recapitulate the article, even though there are some great statistics and some sensible debates over appropriate wildlife management. I will lift this quote by Ron Thomson, a game warden in Zimbabwe, which expresses the debate perfectly: ?We need to let wildlife uplift people. Elephants are not sacred. You tell me why we should favor 40-year-old elephants over 5,000-year-old baobab trees. We should be managing biomes ? floral and faunal entities ? not single species.?

The counter-argument is that people should leave natural systems to themselves. The trees the elephants are destroying only grew because elephants were over-hunted in the past. Elephant populations are too high now because of artificial watering holes, and the solution is to close access to the holes and let the elephants die down to a sustainable level.

This all brings to mind Aldo Leopold’s classic essay, Thinking Like a Mountain, and this passage in particular:

I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer. And perhaps with better cause, for while a buck pulled down by wolves can be replaced in two or three years, a range pulled down by too many deer may fail of replacement in as many decades. So also with cows. The cowman who cleans his range of wolves does not realize that he is taking over the wolf’s job of trimming the herd to fit the range. He has not learned to think like a mountain. Hence we have dustbowls, and rivers washing the future into the sea.

I don’t know much about elephants. I know the picture above is of Asian elephants, not African. I know they are smart and live a long time. I don’t know how to manage African savannas, nor elephants or any other member of that community. I don’t know the people involved in the article, and I think they are all reasonable people who are working through complicated questions exactly as they should.

The short quote from Mr. Thomson above is a direct descendant of Leopold’s land ethic. The conflict in any conservation scenario is between preserving the system or preserving some component of the system. When we modify the natural world, we take on responsibilities. That ?we? can be a home owner who lets her cat run around outside and eat birds. She ought to take some action to protect bird nests and migrant birds passing through. A factory that pollutes a river ought to be held responsible for cleaning the river. As Leopold points out, a rancher who eliminates predators from his land ought to take responsibility for maintaining deer populations at sustainable levels.

This gets tricky when you get to the level of the nation or the world. In The End of Nature , Bill McKibben points out that in this age of acid rain, global climate change and ozone holes, human actions have altered the weather. No matter where you go, the air, the water, the view, and the systems at that site have all been influenced by humans. How much? Is it harmful? It depends. Sometimes there’s no harm done, or very little. Who bears the responsibility for managing those systems? Who should bear the cost?

The article on elephants mentions that fences have been built to prevent elephants from destroying farms and houses, and to keep poachers out, too. In addition to the other ecological factors that are allowing elephant populations to grow, those fences may themselves play a role in the growth. For whatever reason (debate over the mechanism is ongoing) fenced populations tend to grow very rapidly. Limits on emigration play a role and reduced predator mobility probably has some effect in smaller organisms.

By limiting emigration, you keep individuals in high quality habitat. When something wanders away from its home, it is likely to pass through some bad neighborhoods. A grassland species might have to cross a forest, for instance. It is more likely to get attacked there, and it may eat something toxic. It may settle in a nice new grassland, but be unable to find a mate. One way or another, its chances of leaving the gene pool increase. Fences prevent that.

In this day and age, not having a fence is too high a mortality risk. The chances of an elephant getting killed or moved to a new area are enormous if it were to wander into farm fields, let alone start bumping houses are much higher than they would have been 50 years ago. The fences are a solution that causes a new problem. The solution isn’t to do nothing. If we are artificially increasing elephant populations through our management decisions, we ought to balance that decision out. Culling is an appropriate solution and should be on the table. Non-lethal management should be on the table too.

I won’t get into a long thing about this, but the history of bison isn’t so different from the elephant situation. They were plentiful, then hunted nearly to extinction. Effective management brought them back, and wild populations are where they should be. The populations are doing well enough that there are ranches that raise them and make money from hunters who want to bag a bison. Not so different from what the Africans seem to want.

Listen to the album Elephant by The White Stripes.