Whether you call him groundhog, woodchuck, whistle-pig or use the full genus and species name, Marmota monax, the nation’s premiere animal weather forecaster has been making headlines as Punxsutawney Phil for decades.
The largest ground squirrel in its range, groundhogs like Phil are found throughout the midwestern United States, most of Canada and into southern Alaska. M. monax is the most widespread marmot, while the Vancouver Island marmot (M. vancouverensis) is found only on one island in British Columbia.
In total, there are 15 species in the genus Marmota, found around the world from as far south as the Jemez Mountains of New Mexico and the Pyrenees Mountains of Spain, north to regions of Siberia and Alaska so dark and cold that the marmots must hibernate for up to nine months of the year.
Hibernating to escape tough times
Marmots, including all the actors who have played Phil over the years, are the largest “true” hibernators: animals that enter a torpor that reduces their biological functions to a level closer to dead than alive.
Because this phenomenon is so interesting, scientists pay attention to all aspects of marmot anatomy and physiology. Basic observational science like this is important to advance our understanding of the world, and it sometimes leads to discoveries that improve human lives. Marmot studies are the foundation for experiments to address obesity, cardiovascular disease,
mpox, stress, hepatitis and liver cancer, and they may inform work on osteoporosis and
organ transplantation.
Aging seems to nearly stop during hibernation, as the marmot heart rate drops from nearly 200 beats per minute when active to about nine during hibernation. Similarly, their active body temperature can be 104 degrees Fahrenheit (40 degrees Celsius) – about the same as a dog or cat – but plummet to 41 F (5 C) when hibernating. Humans, in comparison, become hypothermic at a core temperature of 95 F (35 C).
Fueling feast and famine
Marmots’ only source of energy during the hibernation period is stored fat, which they may metabolize as slowly as 1 gram per day. But even that is a large amount when it must suffice for more than half a year.
So, marmots need to double their weight during the summer, even in places where the season is only a few months long. To do so, they double the size of their hibernation-state gastrointestinal tract and liver, and then carefully select the most nutritious plants, including legumes, flowers, grains and grasses. Despite their corpulence, they can also climb trees to eat buds and fruit.
Gardener, architect and menu item
The digging and seed dispersal that accompany foraging create flower-filled meadows. Some marmots, like Mongolia’s Tarbagan marmot (M. siberica), are keystone species whose presence is associated with increased diversity of plants and predators.
