The Corps of Discovery entered the Columbia River in mid-October 1805 at its confluence with the Snake, traveled along the river from shore to shore, and emerged at its mouth on November 7, 1805, before overwintering at Fort Clatsop at Astoria and returning home the following spring past many of the same landmarks. In 1805-06, Lewis and Clark recorded obstacles and discoveries along the Columbia and, under President Jefferson's instructions, took careful note of the plants and animals of the West and met with Indian tribes to record their customs, languages, populations, religions, food, clothing, and willingness to trade with Americans. In all, the expedition recorded 178 plants and 122 animals never previously described, and during the winter at Fort Clatsop, Oregon, Meriwether Lewis described 35 mammals, 50 birds, 10 reptiles and fish, and 5 invertebrates, of which 11 mammals, 11 birds, and 2 fish were new to science. Their journals provided in some instances the first and sometimes the only detailed descriptions of the region's different native peoples.