On September 21, 1805, while crossing the Bitterroot Mountains and before they had reached the Nez Percé, Meriwether Lewis described several species, new to European science, in his journal. Besides the black woodpecker, now known as the Lewis Woodpecker, he described the Stellar's and gray jay, the varied thrush, the blue and the spruce grouse, the mountain huckleberry, the Sitka alder, and the western red cedar. Only the thrush was previously known.
Lewis had been given special instruction from the best natural scientists in the United States before leaving on this trip in order to be in a position to properly take specimens of "new" species and to record them in his journals. He collected seeds from crops grown by the Indian tribes that they met. These seeds were to be replanted by Thomas Jefferson in Virginia and by botanists in Pennsylvania. By the end of the expedition, Lewis had "discovered" and described 178 plants new to European science; over two-thirds of these were from west of the Continental Divide. There were also 122 "new" species or sub-species of animals, among which were the prairie dog, the plains horned toad and the pronghorn.