Bighorn sheep
Native herbivores such as the moose are found in small numbers near waterways, especially at lower elevations. Moose populations in northwestern Wyoming and other areas of North America have been on the decline since the end of the 20th century, possibly due to a parasite. There were an estimated 739 moose in the forest in 2006 which is almost 300 fewer than there were 20 years earlier. Other ungulate species are much more common and there are over 20,000 elk (also known as wapiti) and 40,000 mule deer. Bighorn sheep and mountain goats inhabit the rocky terrain and highest elevations. During the winter, one of the largest bighorn sheep herds in the lower 48 states congregate in the region around Dubois, Wyoming; however, their numbers since 1990 have been diminished due to disease transmitted from contact with domesticated sheep and goats. An estimated 5,000 bighorn sheep are found throughout the forest and a small but stable population of 200 mountain goats reside in the northernmost portions of the forest. Bison and pronghorn antelope are two other ungulates that live on the forest and have sustainable populations.