As the Lewis and Clark Expedition traveled up the Missouri River they documented a wild, untamed river. Their famous diaries contain stories of Native American encounters, escaping grizzly bears, and many descriptions of wildlife. Deer, elk, and bison are the highlights but beavers are the forgotten heroes.
To the expedition, beavers were a source of food and commerce. But, the diaries tell a different story. The entries describe lush riparian habitat along the 2,000 miles of the Missouri River Valley. They observed beavers in their natural habitat shaping the world around them as powerful ecosystem engineers.
Within a few decades those beavers were gone. Trappers, fur companies, and American colonization nearly wiped them out. Lewis and Clark weren’t directly responsible for the decline but their records allow us to see what the Missouri and it’s tributaries looked like at the dawn of the 19th-century.
The Expedition often mentioned hunting beavers but they also tell us what the beaver's environment looked like. One of those entries was April, 10th 1805. Meriwether Lewis described a section of the Missouri just south of the eventual site of Gavin’s Point Dam in North Dakota as follows:
“the river bottoms we have passed to-day are wider and possess more timber than usual—the current of the Missouri is but moderate, at least not greater than that of the Ohio in high tide; it's banks are falling in but little; the navigation is therefore comparatively with it's lower portion easy and safe.”
The land Lewis described was likely lush, green forests created in part by beaver power. The clever rodents cut down trees and use them to build shelters.
The dams create habitat for other species as well as storing water. The surface pressure forces water into the underground aquifers that help trees tolerate drought periods.
The 21st-century Missouri is a straight and narrow channel but historically it was a long meandering river. Beavers likely had more influence on smaller streams that fed into the Missouri but their dams played an important role in shaping the Missouri River basin.
Every time a beaver dammed a stream it's flow weakend. The dams eventually collected sediment and raised the water level. They forced the water to change course and flow in a slightly different direction.
It’s more complex as you can imagine, but this basic series of events helped shape the fertile forests and prairies Lewis, Clark, and other early American explorers ogled at.
A few days later on April 16th, Lewis remarked that beavers were very abundant and he saw the rodents fell trees up to 20 inches in diameter. Those fallen trees were a building block of the riverine environment.
In the same entry, Lewis observed that beavers only ate the bark of cottonwoods and willows. Beavers actually eat the cambium which is the layer of a tree underneath the bark but Lewis was close enough.
On April 19th, he wrote “The beaver of this part of the Missouri are larger, fatter, more abundant and better clad with fur than those of any other part of the country that I have yet seen.” Lewis also mentioned they ate nice fatty beavers. A lot of these beavers were trapped.
Like many other trappers, the Expedition used scents to lure the rodents to their death. If you’ve ever been curious what those lures smelled like, here’s a recipe from Lewis.
They mixed castor, a smelly goo beavers extricate, with nutmeg, gloves, cinnamon, and allspice. I haven’t experienced it but, castor supposedly smells like musky vanilla. If The Expedition used apples, the beavers would have been lured in by a really nice apple cider.
Later that summer Lewis traveled to the headwaters of the Missouri River in modern day Madison County, Montana. There, he named one of the rivers Jefferson after President Tomas Jefferson, another after future President James Madison, and the third after the Treasury Secretary Albert Gallitian. They combine to form the Missouri at present day Missouri River State Park.
On August 2nd, Lewis noted that beavers had built many large dams along the Jefferson River. The next day, he described one of them.
“we saw some very large beaver dams today in the bottoms of the river several of which wer five feet high and overflowed several acres of land; these dams are formed of willow brush mud and gravel and are so closely interwoven that they resist the water perfectly. the base of this work is thick and rises nearly perpendicularly on the lower side while the upper side or that within the dam is gently sloped. the brush appear to be laid in no regular order yet acquires a strength by the irregularity with which they are placed by the beaver that it would puzzle the engenuity of man to give them.”
One of the other men on the Expedition described the environment created by these dams.
“Some trees newly cut down by them. Saw ponds where they dammed up the water one dam above another which is curious to behold. passed a high bank in which was villages of bank Swallows passed large beautiful bottom prairies on each Side and bottoms of timbe.”
If you are wondering what happened to these meadows when the beavers were killed off over the next few decades? It’s simple. They dried out.
Scientist have demonstrated how critical beavers are to a riverine environment. One study found that without beavers “River corridors can transform from wet, multithreaded channel–wetland systems housing a diversity of plants and animals to a dry, single-threaded, incised channel representative of a drier steady state known as an elk grassland. Beaver removal fundamentally changed the geography of the U.S
The Lewis and Clark Expedition painted a vibrant picture of the Western United States. The reports spread far and wide and many people began streaming west in Lewis and Clark’s footsteps. Over the next few decades beavers were quickly wiped out across the west and our landscapes were changed forever. There is a growing movement to establish beavers wherever possible so hopefully we can bring back the landscape of Lewis and Clark.
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Sources:
https://lewisandclarkjournals.unl.edu/item/lc.jrn.1805-04-10#ln11041004 https://lewisandclarkjournals.unl.edu/item/lc.jrn.1805-04-16#lc.jrn.1805-04-16.02
https://lewisandclarkjournals.unl.edu/item/lc.jrn.1805-04-19#lc.jrn.1805-04-19.02
https://lewisandclarkjournals.unl.edu/item/lc.jrn.1806-01-07#lc.jrn.1806-01-07.04
https://lewisandclarkjournals.unl.edu/item/lc.jrn.1805-08-03#lc.jrn.1805-08-03.04
https://lewisandclarkjournals.unl.edu/item/lc.jrn.1805-08-02#n18080206
https://www.proquest.com/docview/2644766851/Record/1A8C4B73F61B4B68PQ/1?accountid=46208