On the website Quora.com, someone recently asked about the mammals one sees in Yellowstone Park, so I tried my hand at an answer. I’m not a real animal person, being more enamored with things that stay in one place like geysers, hot springs, flowers, lakes, waterfalls, and mountains, yet I have personally seen all but the rarer animals in my many visits to Yellowstone.
The big mammals—sometimes called “charismatic megafauna” with tongue in cheek—are the bison (around 4000 currently), the elk (8,000 to 10,000), the moose (very scarce, and more often seen in neighboring Grand Teton National Park), and both grizzly and black bear (several hundred of each).
The gray wolf population is hovering around 100. Mule deer are much more common than white-tailed deer. Then there’s the pronghorn (commonly but incorrectly called antelope)—my favorite animal for being so beautiful, graceful, and fast. Their population fluctuates around a couple of hundred seen in northern Yellowstone, as are bighorn sheep.
Coyotes are very common, less so the red foxes and mountain goats (the latter considered to be migrants to the park). Mountain lions, bobcats, and especially lynx are there but almost never seen.
Small carnivores you might see include badgers, river otters, and raccoons. Then there are the most common rodents: yellow-bellied marmots, Uinta ground squirrels, muskrats, red squirrels, and the tiny pikas or coneys. Beaver have become more numerous in recent years.
And this is just a sampling. There are many smaller mammals like voles, mice, bats, and shrews.