Mountain Beaver - Aplodontia

"...one of the most remarkable
animals discovered by Lewis and Clark"
--Elliott Coues

hat "small animal about the size of a squirrel" with the fur of which Lewis wished his "Tiger Cat" capote to be lined, may have been the one that he soon learned was locally called sewelel. At Fort Clatsop on February 26, 1806, he wrote the following comments on this "new"--that is, new to science--species of mammal:

Sewelel [suh-WELL-ul] is the Chinnook and Clatsop name for a small animal found in the timbered country on this coast. the natives make great use of the skins of this animal in forming their robes, which they dress with the fur on them and attatch together with sinews of the Elk or deer. I have never seen the animal and can therefore discribe it only from the skin and a slight view which some of our hunters have obtained of the living animal. the skin when dressed is from 14 to 18 inches in length and from 7 to 9 in width; the tail is always severed from the skin in forming their robes I cannot therefore say what form or length it is. one of the men informed me that he thought it reather short and flat. that he saw one of them run up a tree like a squirrel and that it returned and ran into a hole in the ground. the ears are short thin pointed and covered with short fine hair. they are of a uniform colour, a redish brown; tho' the base of the long hairs, which exceed the fur but little in length, as well as the fur itself is of a dark colour for at least two thirds of it's length next to the skin. the fur and hair are very fine, short, thickly set and silky. the ends of the fur and tips of the hair being of the redish brown that colour predominates in the ordinary appearance of the animal.I take this animal to be about the size of the barking squirrel of the Missouri.1 and beleive most probably that it is of the Mustela genus,2 or perhaps the brown mungo itself.3 I have indeavoured in many instances to make the indians sensible how anxious I was to obtain one of these animals entire, without being skined, and offered them considerable rewards to furnish me with one, but have not been able to make them comprehend me. I have purchased several of the robes made of these skins to line a coat which I have had made of the skins of the tiger cat. they make a very pleasant light lining.

Mountain Beaver Hand-colored lithograph by John James Audubon from Quadrapeds of North America (1845-48), Vol. III, Plate CXXXII, No. 25

ur human impulse to name everything has made an imposter of the "mountain beaver," for it is not a beaver, and it does not confine itself to mountain habitats. It does not build dams on streams to create ponds, either, or dwell in lodges made of sticks. In dry areas it favors the proximity of small streams, but it is strictly a land animal, living in communal underground burrows much like a prairie dog's. In rainy climes it shelters the entrances to its burrows with little tents of sticks covered with leaves. The mountain beaver is so attached to an underground existence that it is rarely to be seen in the light of day, and consequently is hard to capture--which might explain why the Indians seemed not to understand Lewis's request. The only place on earth where it can ever be seen is in the Pacific Northwest of North America.

This rare, primitive little rodent, which somewhat resembles the woodchuck and the muskrat, belongs to the same mammalian order, Rodentia (ro-DEN-tee-uh), as the more familiar flat-tailed beaver, Castor canadensis. The order consists of 39 families, 389 genera, and 1,702 species. The so-called mountain beaver is the only species, rufa (ROO-fuh; reddish), in the only genus, Aplodontia (ap-lo-DON-ti-uh), in the family Aplodontiidae (AP-lo-don-TEE-i-dee). Aplo is a Latin word for simple, dontia means teeth. That means the aplodontia must keep chewing its entire 5- to 10-year life--fleshy and woody plants, principally--in order to keep its teeth under control. It also grooms its teeth on "beaver baseballs," chunks of stone or clay of about that size which it encounters in digging its dens. Its Indian name, sewellel, is said to have come from the Chinookan word swalál, which refers to a robe made of this animal's skins.⁴

The mountain beaver is less of a show-off than its larger and more notorious cousin the genuine beaver, partly because it doesn't have a flat tail with which to spread its alarms. In fact, it has only a vestigal tail, which may account for Lewis's misunderstanding. Perhaps its best attribute has been that despite the old appeal of its pelt in Indian wearing apparel, no one else has found it to have any merchantable value.

--Joseph Mussulman, 07/04

1. Lewis's standard for his comparison of the sewellel with the "barking squirrel of the Missouri" or prairie dog, which he had first seen on September 7, 1804, was close; the latter averages one or two inches longer than the mountain beaver.

2. The genus Mustela belongs to the the family Mustelidae, which includes weasels, ferrets, minks, otters, and badgers.

3. Mungo was a name for the mongoose, a native of Nigeria and the Congo.

4. Couse's detailed annotation on the history of the sewellel's common and Latin names illustrates the progress of the scientific discipline of classification and nomenclature between 1806 and 1892:

Fortunately [Lewis and Clark] gave it a name by which it could be called, and which has passed into our language....It seems by the later researches of George Gibbs into the unspellable jargon of the Columbia River Indians, that "sewellel" is their name for the robes, mistaken by Captain Lewis for the name of the animal which furnishes the skin, and that the latter is "show'tl" in Nisqually....It was first technically named Anisonyx rufa by Rafinesque (Amer. Monthly Mag. II. 1817, p. 45). In 1829 Sir John Richardson renamed it Aplodontia leporina in the Zoölogical Journal, IV, p. 335; and this naturalist described and figured it fully in the Fauna Boreali-Americana, 1829, p. 211, pl. 18 C, figs. 7 to 14. Correcting the faulty orthography of this generic name, and coupling it with the prior specific name given by Rafinesque, I called the animal Haplodon rufus, in the Monographs of N. Am. Rodentia, 1877, p. 557, where its anatomy, as well as external character is, is given at length, with all that was then known of its history. This name is the one by which it has since been known to naturalists. I understand that the whites on the Columbia call it the "mountain boomer"--a queer name, which I hear applied to the red squirrel (Sciurus hudsonius) by the natives of the mountains of North Carolina, where I happen to be penning this note (Aug. 9th, 1892). There is a second species of sewellel in California, Haplodon major.

Coues (1842-99; pronounced cowz), the most prominent naturalist of the later 19th century added copious annotations to Nicholas Biddle's paraphrase (1814) of the journals of Lewis and Clark, and published it as History of the Expedition Under the Command of Lewis and Clark (4 vols, 1893; reprint, 3 vols.; New York: Dover, 1965), 847.

References

The Encyclopedia of Mammals. Edited by David Macdonald. New York: Facts on File, Inc., 1984.

National Audubon Society Field Guide to North American Mammals. Edited by John O. Whitaker, Jr. Rev. ed., New York: Knopf, 1996.