Wolverine, Gulo gulo luscus
On one other occasion Meriwether Lewis mentioned seeing an animal he couldn't identify, or clearly associate with any species he knew, and which, because he saw it so fleetingly, he was unable to describe in sufficient detail for us to ascertain its identity.
On 12 August 1805, in the vicinity of Lemhi Pass—the divide between the Missouri and Columbia River drainages, and still within what today is the normal range of the wolverine—Lewis wrote:
We saw an animal which we took to be of the fox kind, as large or reather larger than the small wolf of the plains—its colours were a curious mixture of black, redish brown and yellow. Drewyer [interpreter and hunter George Drouillard] shot at him about 130 yards and knocked him down, but he recovered and got out of our reach.
We may interpret his assertion that "it is certainly a different animal from any that we have yet seen" to mean it definitely was not the same as the one he shot at two months earlier from a distance of only sixty paces, or about thirty yards. But what could it have been?
Speculation has brought up several possibilities. Elliott Coues, who in 1892 commented extensively on Biddle's paraphrase of the original journals, footnoted both events with the remark that it was "probably the wolverine or carcajou, Gulo luscus." Reuben Gold Thwaites, editor of the first publication of the original journals (1904), thought the animal Lewis encountered on June fourteenth might have been a wolverine or—perhaps granting Lewis the benefit of the doubt—a cougar. But judging from photographs, which is certainly easier than drawing conclusions after a fleeting glance at some distance in the wild, the wolverine looks more like a species of bear than either a "small wolf of the plains" or a wild feline. Journal editor Gary Moulton suggests both critters were wolverines.