Lewis's Black-tailed Deer

"Curiouser and curiouser!" cried Alice
(she was so much surprised,
that for the moment she quite
forgot how to speak good English).

--Lewis Carroll, Alice's Adventures in Wonderland.

"A Curious kind of Deer"

Mule deer

Above the White River in today's South Dakota on September 17, 1804, "Colter killed . . . a Curious kind of Deer," according to Clark. It was "a Darker grey than Common the hair longer and finer, the ears verry large & long a Small reseptical under its eye its tail round and white to near the end which is black." This one posed for his portrait on a grassy slope in the Bitterroot Mountains, regarding the photographer with a curious tilt of his head.


Lewis's Mule Deer

Drouillard spotted the first "Deer with black tales" on September 5, 1804, on the cliffs upstream from the mouth of the Niobrara River in northeast Nebraska. Eight months after Colter bagged that "Curious kind of Deer," on May 10, 1805, when the hunters killed "two Mule deer, one common fallow or longtailed deer, . . . and saw several deer of the Mule kind of immence size," Lewis had seen enough specimens to write an 800-word description of the new species, systematically comparing it with the deer he was familiar with, the Virginia whitetail. Nicholas Biddle omitted it from his 1814 paraphrase, and its existence was unknown to zoologists until Reuben Gold Thwaites published his edition of the Original Journals of the Lewis and Clark Expedition in 1904.

Lewis began with what he had observed about the mule deer's habitat.

From the appearance of the Mule deer . . . we beleive ourselves fast approaching a hilly or mountainous country; we have rarely found the mule deer in any except a rough country; they prefer the open grounds and are seldom found in the woodlands near the river; then they are met with in the woodlands or river bottoms and are pursued, the[y] invariably run to the hills or open country as the Ek do.    the contrary happens with the common deer.

This species can run or trot like any other deer, but they are uniquely built to bound, or stot, with all four hooves off the ground at once. This enables them to spring up steep slopes and over obstacles at a relatively high speed, and gives them a decided advantage over most predators, including humans. Whereas the white-tails' tendency to dive for cover in dense brush would frequently frustrate the Corps' hunters, the muley's erratic leaps compounded the difficulty of making a clean kill. In fact, in the vicinity of Hudson's Bay it was commonly called the jumping deer.1

ther are several essential differences between the Mule and common deer as well in form as in habits. they are fully a third larger in general, and the male is particularly large; I think there is somewhat greater disparity of size between the male and female of this speceis than there is between the male and female fallow deer; I am convinced I have seen a buck of this species twice the volume of a buck of any other species.

Unfortunately for us, Lewis did not have the necessary equipment to weigh large specimens, and besides, we have no way of knowing how many subspecies of various sizes might have existed in North America at that time. On a broader data base today, a male (buck) mule deer can be said to average 6 Ω feet in length and weigh from 175 to 200 pounds, whereas a white-tailed buck will be from 6 to 7 feet long and weigh between 90 and 210 pounds, depending on the subspecies.2 Early in October one of the hunters killed "a Black tail Deer, the largest Doe I ever Saw (Black under her breast[)]."

the ears are peculiarly large; I measured those of a large buck which I found to be eleven inches long and 3 Ω in width at the widest part; they are not so delicately formed, their hair in winter is thicker longer and of a much darker grey, in summer the hair is still coarser longer and of a paler red, more like that of the Elk; in winter they also have a considerable quantity of very fine wool intermixed with the hair and lying next to the skin as the Antelope has.    the long hair which grows on the outer sides of the 1st joint of the hinder legs, and which in the common deer do not usually occupy more than 2 inches in them occupys from 6 to eight.

More recent statistics confirm that a mature muley's ears are indeed about 11 inches long, but conclude they average closer to 6 inches in width – the earlier to detect predators at a distance in the open country the mule-deer favors. The expedition was not in any place long enough to study the same herd of a given species in all its seasons; the reddish tint of the summer coat is typical of most deer.

their horns also differ, these in the common deer consist of two main beams from which one or more points project the beam graduly deminishing as the points procede from it, with the mule deer the horns consist of two beams which at the distance of 4 or 6 inches from the head divide themselves each into two equal branches which again either divide into two other equal branches or terminate in a smaller, . . . and two equal ones; having either 2 4 or 6 p[oi]nts on a beam; the horn is not so rough about the base as the common deer and are invariably of a much darker colour.

Antlers compared

Today, all deer are said to have antlers, while cows and sheep have horns. Both are bony outgrowths from the skull, but deer shed their antlers and produce new ones each year, with a velvety skin to carry blood as the structure grows; ovids' horns are covered by a hard keratin fiber similar to humans' fingernails, and are not shed, but continue to grow larger, year by year. The size of the male's antlers indicates his age and strength. Mule deers' antlers tend to be larger than those of white-tails, because they frequent more open terrain, while the latter prefer brushy habitats. Antlers are symbols of status in the herd, and weapons in the annual wrestling matches over breeding rights. A loser who pays the price of damage to his antlers in the combat has the opportunity to try again the following year, after shedding the old and growing new and larger ones.

Continuing, Lewis reported:

the tail which is usually from 8 to 9 inches long, . . . for the first 4 or 5 inches from it's upper extremity is covered with sho[r]t white hairs, much shorter indeed than the hairs of the body; from hence for about one inch further the hair is still white but gradually becomes longer, the tail then terminates in a tissue of black hair of about 3 Inches long. from this black hair of the tail they have obtained among the French engages the appellation of the black taled deer, but this I conceive by no means characteristic of the anamal as much as the larger portion of the tail is white.    the year [ear] and the tail of this anamal when compared with those of the common deer, so well comported with those of the mule when compared with the horse, that we have by way of distinction adapted the appellation of the mule deer which I think much more appropriate.

Some of the men in the Corps, such as Charbonneau, Labiche, and Cruzatte, may have known this animal well. Some of the the French-Canadian engagés, Lewis admitted, called it the black-tailed deer – le Daim fauve ‡ queue noire – "the wild deer with tail of black." He didn't say so, but others may have insisted it was le Cerf mulet – "the mule deer."3 So, if Ernest Seton is correct, when Lewis finally announced, "we have . . . ad[o]pted the appellation of the mule deer," he did not mean that he himself had thought up the new name, but that he personally preferred "mule deer" over "black-tailed."4 Nevertheless a fundamental ambivalence prevailed, for only a week later he reverted to the equivocal "black tailed or mule deer," either from his own uncertainty, or as a concession to the men in the party who may have had different opinions.

Lewis's study of the mule deer concluded:

on the inner corner of each eye there is a drane or large recepicle which seems to answer as a drane to the eye which gives it the appearance of weeping, this in the common deer of the atlantic states [the white-tailed deer, Odocoileus virginianus]5 is scarcely perceptible but becomes more conspicuous in the fallow deer [in this instance, the western whitetailed deer, Odocoileus virginianus dacotensis] and still more so in the elk; this recepticle in the elk is larger than in any of the pecora order with which I am acquainted.

This feature he is describing, known as the preorbital, suborbital, or lachrymal gland or crease, has nothing to do with either drainage or tears. It secretes a waxy, strong-smelling substance with unique nuances that the deer rubs on trees to mark its territory. Lewis's observation was correct. The preorbital gland of a whitetail deer is only about 7/8 of an inch long; on the mule deer it is 1-9/16 inches.6 The order Pecora, meaning "sheep-like," still accounts for all deer, as well as the horse, zebra, and rhinoceros.

Family History

Mule deer are newcomers to the genus Odocoileus, having joined its closest relative, the white-tailed deer, only about 10,000 years ago, at about the end of the last Ice Age. Like its closest relative, the white-tailed deer – and the only other species in its genus, the mule deer – evolved only in North America. The eleven subspecies now classified by the "splitters" under Odocoileus hemionus (oh-doh-co-ill-ee-us; "hollow-toothed"; hem-ee-oh-nuss; "half-ass" or "mule") are distributed from north-central Mexico to the southern Northwest Territory in Canada, and from the eastern borders of the Dakotas to the Pacific Coast.

Elliott Coues' commentaries on Nicholas Biddle's 1814 paraphrase of the journals included the current (1892) formal classifications of all the plants and animals Lewis and Clark wrote about.7 All three of Lewis's new deer were then placed in the genus Cariacus, which apparently is undefined today but clearly was a synonym for Cervus.


1. Edward Umfreville (fl. 1771-1790), The Present State of Hudson's Bay (London, 1790), 164.

2. Leonard Lee Rue III, The Encyclopedia of Deer (Stillwater, Minnesota: Voyageur Press, 2003), 84, 96.

3. Ernest Thompson Seton, Lives of Game Animals (4 vols., 1909, reprint, Boston, Charles T. Brandford Company, 1953), Vol. III, part 1, 325.

4. Raymond Burroughs, however, claimed the evidence – which he did not cite – was conclusive that Lewis himself coined the name "mule deer." Raymond Darwin Burroughs, The Natural History of the Lewis and Clark Expedition (East Lansing: Michigan State University Press, 1961), 184.

5. The eccentric Constantine Samuel Rafinesque is credited with naming and describing the Eastern whitetail. In 1832, on the evidence of a fossilized deer tooth he found in Virginia, Rafinesque chose to name the genus Odocoileus, probably a misspelling of the Greek word odontocoelus, meaning "hollow" or "concave tooth," although the logical connection is now obscure. Leonard Lee Rue III, The Deer of North America (New York: Lyons & Burford, 1997), 21.

6. Ibid, 114.

7. Elliott Coues, ed., History of the Expedition Under the Command of Lewis and Clark....1893, Reprint, 3 vols. (New York: Dover Publications, 1965), 3:1011-12.

Funded in part by a grant from the Idaho Governor's Lewis and Clark Trail Committee.