Those earlier figures, by the way, were pure ballpark estimates, usually derived from a scholar saying, "Well, so-and-so sat on the banks of the Arkansas River and counted buffalo going by for five days and said, gee whiz, there must have been three million of them. And if there were three million on the Arkansas River, and you start looking at every river in the West—boy, there must have been 60 milion of the things." But those figures were basically just wild guesses. And so, if you scale the numbers back to something like between 20 and 30 million—which is still a lot of animals—you start approaching something more like the reality of what the buffalo herds were like.
Then, when you start looking at all the factors that could possibly have had an impact on buffalo on the 19th century, you begin to discover that there were a lot of things that were influencing buffalo populations.
One of them is this: A fluctuating climate. We've sort of looked at buffalo in the 19th century as if the climate were exactly the same on the Great Plains year after year after year, with never a variation. But anybody who has lived on the Great Plains in the 20th century knows that the Great Plains are marked by cyclical droughts. They hit significantly enough to dramatically affect economic patterns, human economic patterns, every 20 to 40 years.
And when we look at the long history of dendrochronology—tree-ring information—on the plains, and pollen analysis on the plains, and a variety of other factors, it becomes fairly obvious that climate has fluctuated considerably. Wet climates grew more grass; those climates produced more buffalo. Droughts shriveled the grass, and grasses that were hit by droughts—especially droughts that lasted any period of time—produced small herds of buffalo.
One of the great hallmarks of the climate story in America is that at about the time Europeans were arriving in considerable numbers, a major climatic anomaly known as the Little Ice Age struck the northern hemisphere. It seems to have set in, in North America, somewhere around 1550, and it lasted about 300 years. It was a time of abnormally high rainfall; a time when, especially in the American West, there were probably bumper crops of grasslands, year after year. And so, during the time when Europeans were here, and becoming Americans, and the time when horses were reintroduced to America, when many Indian groups in the West were adopting horses and becoming Plains Indians, the buffalo herds were really at a peak.
However, the Little Ice Age had to come to an end sometime, and unfortunately it did. And it happened to come to an end sometime, in the American West, in the 1840s and 1850s. At that point you begin to see a fairly rapid and dramatic decline in annual precipitation on the grasslands. And I think it's probably no accident that when you begin to look at the Indian documents, particularly calendar robe histories, kept by groups like the Kiowas, one of the things the Kiowas noted in their calendar robe histories were years of many buffalo. And the Kiowas report a year of many buffalo only one time after 1841. That happens to be the very point at which, I think, a confluence of different factors, including the end of the Little Ice Age, began to play a role in bison populations.