I’ve seen Yellow-bellied Marmot in numerous national parks—Yosemite, Mt. Rainier, Glacier, and Rocky Mountain—but I’ve only seen young marmot in one place: Yellowstone. And even there, they rarely venture out for very long. While their parents spend time foraging, preening, and watching for predators, the youngsters seem to prefer the safe confines of their burrows, dug under rockfall and talus slopes.
So I took advantage of the opportunity I had one beautiful spring morning to photograph four or five young Marmot that spent the better part of an hour above ground, sitting on rocks, chewing on sticks, sniffing plants, and exploring their habitat. As you can see, they’re adorable little creatures, balls of fur with large, expressive eyes, bushy tails, and long whiskers. Some had lighter markings; others darker. Though I noted both their long, sharp claws and the thick pads on their paws, none seemed to have developed the long incisors that distinguish all rodents. At least, they didn’t reveal them to me.
The Yellow-bellied Marmot is one of six North American marmot species—Alaska, Hoary, Olympic, Vancouver Island, and Woodchuck or Groundhog being the others (and only the Woodchuck prefers prairies to alpine areas). All belong to and are the largest members of the squirrel family (sciuridae), a large group of rodents that include—in addition to the Marmots—chipmunks, prairie dogs, arboreal squirrels, ground squirrels, flying squirrels, and to a rodent called the “Mountain Beaver” even though it is neither semi-aquatic nor a relation to the North American or Eurasian Beaver.
Though they tend to get bad press (particularly rats and mice), much about rodents impresses. Or should. Rodents live on every continent except Antarctica, consist of more than 4,000 species, and range in size from the tiny Baluchistan pygmy jerboa of Pakistan (which weighs less than 1.5 ounces and measures barely 2 inches long, not including its tail) to the Capybara of South America (nearly 4.5 feet long and weighing up to 145 pounds). They include ecosystem engineers and keystone species, such as Beavers and Prairie Dog, creatures that shape the environments in which they live and signal their health. And, a true success story, they have evolved to thrive in nearly every climate on earth—from tundra to desert.
The fossil record suggests that rodents arose in what-is-now Asia approximately 66 million years ago—shortly after the extinction event that eradicated the non-avian dinosaurs and countless other species, terrestrial and marine. Through an extensive series of migrations over millions of years, these early rodent species spread west from Asia, establishing multiple colonies in Europe and North America. (At the time, all three landmasses were part of the contiguous supercontinent of Laurasia.) Some of the earliest rodent species to migrate to North America evolved over many millennia into completely new rodent species. And one of these, the Beaver, apparently migrated back to Eurasia from North America, effectively accomplishing a reverse colonization, according to the fossil record for the Castoridae family.
Still other rodent species traveled south into Africa, Madagascar, and South America. The three, along with Antarctica, Australia, India, and the Arabian peninsula, had all been part of the supercontinent of Gondwana allow access to early rodent species that evolved into wholly new species in their new homes.
Though we didn’t know it at the time, of course, Homo sapiens replicated the feat rodents accomplished millions of years earlier when we began a series of migrations from East Africa approximately 75,000 years ago, resulting in our own successful colonization of the planet. Who knows, maybe we should take a few rodents with us to Mars. For good luck.