How international trade almost wiped out the North American bison

Economics, even ecological economics, isn't something I'd ordinarily write about on the Oikos Blog--it's not really the blog's purpose, and it's not something I'm really qualified to write about. But I'm making an exception to plug a very interesting exercise in ecological economics by my Calgary colleague M. Scott Taylor.

From 1870 to the late 1880s, the American buffalo (bison) population declined from about 10-15 million to 100. The decline itself isn't a shock--settlers were spreading west, and hunting buffalo and grazing cattle as they went. But the decline was much less steep before 1870. Why the sudden crash? Various explanations have been proposed, to do with things like changes in Native American hunting practices, hunting by the US Army, and the expansion of railroads. None of these explanations are especially convincing.

In a new paper in the Dec. 2011 issue of American Economic Review, Scott uses a combination of theoretical modeling, empirical time series analysis, and historical research to develop a much more convincing explanation, to do with technological innovation and international trade. It turns out that, just before the crash began, tanners in England came up with a way to tan buffalo hide into leather, which previously had not been possible. This instantly created a massive new international market for buffalo hides; previously there wasn't a big market for any buffalo product. Scott uses old trading records to infer that around 6 million buffalo hides, representing a kill of about 9 million buffalo, were exported from the US from 1871-1873. The combination of a technical innovation, a huge international market, open access buffalo hunting, and fixed world prices (buffalo weren't a large enough fraction of the world leather supply for their decline to drive up prices) appears to be what ultimately drove the American buffalo to the brink of extinction.

The echoes of this crash still reverberate today. The buffalo slaughter of the 1870s was widely deplored at the time as wanton and wasteful. Some of those who witnessed it first hand, including Teddy Roosevelt, John Muir, and William Hornaday, founded the conservation movement in the US. One of the first and greatest successes of that movement was the creation of the national park system, including Yellowstone and its tiny remnant buffalo herd. And there's a lesson for today as well: when small countries worry that the combination of technological innovation and global markets will decimate their natural resources, Americans ought to be willing to listen--because the US was once in the same boat.

I've seen Scott give a talk on this work, and can attest that it's a really nice piece of science. I really like the fact that Scott put in the effort to develop every possible line of evidence, including combing through historical records and building a theoretical model, rather than just relying on those bits of evidence which he found easiest to access or develop. Too often in ecology, and probably every field, investigators follow the path of least resistance and focus narrowly on whichever lines of evidence which they find most convenient or congenial to work with. And then ignore or argue with people who've come to different conclusions based on different lines of evidence. I also like Scott's effort to be as quantitative as possible, for instance by estimating how many buffalo hides were exported. It turns what otherwise would've been a theoretical model plus suggestive historical anecdotes into a quite convincing story.

See also further discussion at Conversable Economics (on which this post is based).