Every February, as the timeless film reminds us, our lives go into a surreal tailspin as we agonize over whether the iconic groundhog will or will not see his shadow. Even if your Groundhog Day isn’t quite as angsty as Bill Murray’s, there’s still something unnerving about the notion that climate change may be rousing groundhogs (technically marmots) ahead of schedule.
So, you can imagine my concern when I learned from two highly esteemed wildlife biologists that [spoiler alert!] climate change is indeed already making its mark on marmot hibernation.
To learn why, we invited to the EcoMyths Worldview segment Steven Sullivan, senior curator of urban ecology at the Peggy Notebaert Nature Museum and intrepid leader of Project Squirrel, as well as Daniel Blumstein, professor and chair at UCLA and chief marmot fan at the Rocky Mountain Biological Lab Marmot Project.
Hibernating Marmots 101
Globally, there are 15 species of marmots—a genus of large rodents in the squirrel family. In North America, there are six species, but the two with the largest ranges are the groundhog (aka woodchuck), a lowland species which is prevalent across the country (and the only species that lives East of the Mississippi River), and the yellow-bellied marmot, which lives in the mountain west. Generally speaking, marmots live in burrows, hibernate in winter, and are highly social and communicative.
This whole hibernation thing is pretty impressive when you really think about it. Sullivan says groundhogs can be completely hidden from the world for eight solid months, which requires some amazing physiological adaptations and is essential to their survival during the winter months of food scarcity. During hibernation, their body temperature drops to almost freezing, heart rate falls from 70-80 to four beats per minute, and it will take only one breath every five minutes. If you dig up a hibernating groundhog it will “feel, look, and sound like an ice cube.”
And Blumstein points out that yellow-bellied marmots are one of the most efficient hibernators known – they’re about the size of a cat – five to six kilograms before torpor – and burn about a gram of fat a day in deep torpor.
By studying this we can advance other science, such as medically induced comas, and — even thinking of Orion spacecraft and Mars, e.g. how to shut humans down during space travel so that when they wake up upon reaching some far distant planet they can be functional and healthy.
The thing is, hibernation is dependent on a set of complex and not fully understood factors. Will climate change muck it all up?
Climate Change Matters
Conditions associated with climate change in different regions, particularly drought in the Western mountain regions and warmer/shorter winters in the Midwest, are predicted to threaten marmot survival by impacting hibernation and reproduction trends. The two most prominent and resilient species of marmots in North America—groundhogs and yellow-bellied marmots—can serve as a sentinel species in understanding the potential impact of climate change.
Marmots in subalpine Colorado are already experiencing an earlier wake-up call, explains Blumstein. Here, the snow has been melting on average about a day earlier each year over the last 30-40 years, so now, marmots are coming out of hibernation a month earlier than they used to.
As we see late snowfall and meltout, marmots have to survive longer with their fat reserves, because they are emerging earlier/before food is available and melting snowpack makes it easier for predators to find them. Meanwhile, heat and drought are drying out summer vegetation. In one year, the warmer weather and longer foraging time meant for an explosion in population, but the next year, the population crashed.
Around Chicagoland, groundhogs aren’t yet feeling the heat, says Sullivan. But it’s important to monitor this because the earlier they wake up and the longer the growing season, the more they reproduce and survive hibernation. As global warming spurs earlier emergence and longer growing seasons, those survival rates could skyrocket—and in turn mean there’s not enough food to fill all those empty marmot bellies the next year.
To sum it all up, Climate change may actually bring temporary benefits to resilient, broad-ranging species like groundhogs and yellow-bellied marmots—but any benefits would be soon offset by drought, shifts in food supply, and habitat loss.
One Green Thing: Help marmots (and the rest of us, for that matter) by curbing climate change. One great way to that is to carpool or bike your commute at least twice a week.
—As part of our partnership with Chicago Public Media/WBEZ, this content may also appear on the Worldview program page.