Through Idaho going west they found no game at all. They ate 1 horse.
They lived for more than 2 years on meat and water.
They traded for and survived on lots of roots from the Nez Perce when they were on the return trip and had to wait for the snow to leave so they could get over Lolo Pass. Corps members were down to trading buttons, ribbon, etc.. off their clothing for roots, in some cases. Deer were tough to find when they were in what is now Idaho. They did manage to kill several dozen deer though and they got some bears. They also had what was known as "portable soup" to eat when things go real tough. It had to be real chore feeding 30 plus hungry people with limited resources.
L and C found they could offer medical treatment to the Nez Perce in trade for roots, fish, horses, dogs, all of which were consumed. The Indians thought them great healers.
Lots of places and rivers in this part of the country carry names from the LC Expedition. A few have some memorable names like; Colt Killed Creek, Horse Steak Meadows, Bears Oil and Roots, Hungry Creek, Portable Soup Camp.... You can guess what they ate or didn't eat at those locations.
In one case, the group were so needing food they sent expedition member, John Ordway, and two others to go from their camp on the Clearwater River to the Snake River (a distance of almost 70 miles) to try trading for the salmon that were rumored to be migrating upriver there. The Indians said the trip would take a day, but it took 3 days to get to the Snake River and Ordway was able to trade for 27 large and fresh salmon. Unfortunately, most of the salmon spoiled by the time they got them back to the main camp on the Clearwater River.
