Public Release: 

Lewis and Clark notes reveal history of human impacts

Oregon State University

CORVALLIS - Native Americans had a major impact on the wildlife of the American West for hundreds of years prior to European settlement, a report from Oregon State University indicates, based on data from one of the most accurate surveys of its time - the journals of Lewis and Clark.

It is a myth that vast areas of the West existed in some sort of pristine state, largely unaffected by humans until the 1800s, the research concludes. In fact, the larger wildlife such as deer, elk or buffalo that were hunted by Native Americans appear to have populations that may have fluctuated greatly, up and down, based on the hunting pressure on them decades or centuries before European settlers ever arrived.

Such concepts are important to understand because modern wildlife and ecological management practices often use pre-European settlement as a "baseline" for later comparisons, with the implication that humans were having little or no impact on the environment at that time.

That assumption is inaccurate, the OSU researchers say.

"Humans in North America have always interacted with their environment, and this has been going on for a long, long time," said Andrea Laliberte, a rangeland remote sensing scientist who did this study while a graduate student at OSU. "Our findings indicate that even the relatively low human population densities that were present before European settlement show a considerable impact on wildlife. It would be almost impossible to determine what these lands looked like without humans."

The new study, which was just published in the journal Bioscience, essentially concluded that in the early 1800s, large game animal populations existed in much higher numbers where human populations were low. Where Native American populations were higher, the animals existed in fewer numbers, to the point of near extinction in some locations and instances.

To help unravel the ecological mysteries of the past, Laliberte and OSU professor of forest resources William Ripple turned to the journals of Lewis and Clark, which were written during their historic journey from 1804-1806. Thomas Jefferson, who was a scientist and ecologist in addition to being president, directed Meriwether Lewis and William Clark to take note of many ecological features as they traveled across the largely unknown continent. As a result, they crafted a journal that has been celebrated for 200 years for its level of scientific detail, daily observations and careful accuracy in reflecting the natural and ecological conditions of the time.

The OSU researchers used this data in a computerized geographic information system to create a new view of nine large mammalian species that were commonly observed on the trip, the degree of human influence on animal populations at various locations, and the status of wildlife in five ecoregions.

"Part of what we now understand is that by the time of the Lewis and Clark expedition, the West and its wildlife had already experienced a major period of transition," Laliberte said. "Prior to the arrival of Columbus in the Americas around 1500, the estimates of Native American population in North America ranged from 2 million to 3.8 million people. But by the time major western settlement by Europeans began in the 1800s, up to 90 percent of the Native Americans may have died from smallpox, measles and other diseases that had already swept the continent after being introduced by Europeans."

What this implies, the researchers say, is that during the Lewis and Clark expedition, the large game animals of the American West should have been under dramatically less hunting pressure by Native Americans, and actually at a point of some abundance compared to where they may have been when there were millions more Native Americans hunting them. And, in theory, there should have been more animals and more species where there were fewer people. That's exactly what the Lewis and Clark data revealed.

For most of the trip, large game animals were found in sufficient abundance to easily feed Lewis and Clark's group of explorers, who used them as their primary food - an average day's consumption for the traveling party was either four deer, one elk and one deer, or one bison.

Where the populations of Native Americans were lower, the animal abundance increased and some species, especially buffalo, elk and antelope, appeared almost tame. The explorers wrote that they were "so gentle that we pass near them while feeding, without appearing to excite any alarm among them, and when we attract their attention, they frequently approach us more nearly to discover what we are." Animal populations decreased significantly near Native American settlements, the study showed.

One interesting finding was that in areas between where Native American tribes were in conflict with one another, the animal abundance was higher - in August, 1806, Capt. Clark noted that "I have observed that in the country between the nations which are at war with each other the greatest numbers of wild animals are to be found." This is consistent, the OSU researchers say, with other studies which have found a greatly increased biodiversity and wildlife abundance in "buffer zones" where, for one reason or another, humans rarely intrude. One modern example, which is rich in wildlife and biodiversity compared to areas around it, exists today in the demilitarized zone between North and South Korea.

In the Columbia Basin, one of the areas with the heaviest Native American populations on the Lewis and Clark trail, almost all of the usual game animals were very scarce. The explorers ate some of their horses and 195 dogs during transit across this region.

"Many people have a vision of very little human influence on the land around the time of the Lewis and Clark expedition," Ripple said. "That wasn't the case. The impact of humans, even then, was far greater than most people appreciate. And as we develop ecological theories and management practices today, we must be careful about what we consider pristine. With wildlife in the West, it was not in 1806."


By David Stauth, 541-737-0787
SOURCES: William Ripple, 541-737-3056
Andrea Laliberte, 505-646-4144

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