What a Maine researcher has learned studying woodchucks for nearly 3 decades

FALMOUTH — Standing in the apple orchard at Gilsland Farm, Chris Maher instantly recognized the woodchuck waddling across the grass 30 yards away. 

“There’s Torch,” said Maher, needing neither her binoculars nor the telescope she had on hand to identify the tan marmot the size of a small cat. “And, oh, look, she’s got a pup with her.” 

Trailing behind Torch was one of her several “pups” in her litter this year. Only 6 weeks old, the baby woodchuck was the size of a grapefruit, scurrying around under the watchful eye of its mother, who was nibbling clover flowers. Their burrow was just yards behind them, under the base of a tree stump. 

Maher has been studying the woodchucks, also known as groundhogs, at Maine Audubon’s Gilsland Farm since 1998. A biology professor at the University of Southern Maine, her office is 10 minutes away in Portland. 

Over the nearly 30 years of studying this population in Falmouth, she’s been answering longstanding questions about the species. Not whether they’ll see their shadow on Feb. 2, and not how much wood they could chuck if they could chuck wood, but how and why they behave the way they do.

 “They’re basically a lot more social than people had thought they were,” she said.

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Woodchucks are one of six native marmot species in North America and the least social of them all. When Maher first started reading the scientific literature on the species in the 1980s and 1990s, it said that woodchucks were solitary and territorial — but some anecdotal reports also shared they were perhaps more social than previously thought.

When Maher moved to Maine in 1997 to work at USM after years studying the behaviors of other species, she decided the social lives of woodchucks were worth examining. With the permission of Maine Audubon, she started trapping and tagging the woodchucks at Gilsland Farm. It became the longest study of woodchucks ever conducted.

While there were once three dozen woodchucks on the property, now only eight adults have multiple burrows each in the many fields, orchard, peony bushes, parking lot and underneath Maine Audubon’s outdoor classroom. Maher’s workforce has declined as well, as her busy schedule as an interim dean at USM means she has less time for student assistance.

One of the eight and Torch’s adult daughter, named Tremont, also wandered under the apple trees. After she left her mother’s burrow, she moved in next door, digging burrows under the outdoor classroom and in a field of goldenrod. 

“Born in the orchard, and basically never left home. The parallels with people are amusing,” said Maher. 

With her handheld computer, which resembles a PIN pad in the grocery store checkout, Maher took a 15-minute sample of Torch’s behavior, hitting buttons every time Torch switched what she was doing. There are codes for when the woodchucks eat, groom themselves, dig, recline or are on alert.

Female woodchucks have a territory of about three-quarters of an acre. Maher’s research found that related female woodchucks will overlap their territory, previously thought to never happen. Mother and daughter, aunts and nieces, grandmother and granddaughter are all more tolerant of sharing space than unrelated woodchucks.

But sometimes they still need to take a stand. That morning, Tremont and Torch got into a fight, squeaking at and batting each other. With their familiar relationship bringing higher tolerance, it wasn’t a “knock-down, drag-out” brawl, said Maher, just “Torch being Torch.” 

For the fight, Maher hits the button to indicate “other.”

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Maher knows that not everyone is a fan of woodchucks. 

“People kind of run this gamut between ‘I hate woodchucks, because they eat my garden, or they dig under my shed.’ Or they love woodchucks — chances are, those people don’t have a garden,” she said. 

Despite the woodchucks who keep eating the zucchini plant in her home garden, Maher maintains her affinity for the animals. Over the years, she’s trapped and tagged 630 Falmouth woodchucks.

In addition to the number on its metal ear tag, each woodchuck also gets a name, which helps her students remember them. Each year, there’s a theme: cars, cartoon characters, musical instruments and colleges. This year, she’s thinking it will be sports teams, in honor of the World Cup.

Now she’s attempting to trap and tag the pups born this year, including those of Tremont, who was born three years ago when the naming convention was Maine towns and had four pups this year.

Maher set four traps at right angles around the entrance of one of Tremont’s burrows, smearing a dab of Hannaford’s smooth peanut butter on the pressure plate that will trigger the trap to close if stepped on. Apple slices she dropped inside the metal grate increase the temptation.

Between the traps, Maher shoved wooden shingles to make a fence. Adult woodchucks will get creative trying to escape, as evidenced by tooth marks on the wood. Catching the pups is easier.

“They’re naive,” she said.

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Once a pup is caught, she’ll weigh it, take a hair sample, give it a numbered ear tag and paint a distinct mark on it with Revlon black hair dye, so she can recognize it from a distance.

Keeping track of which of these squirrely animals are related for 28 years, as well as what they’re doing and where they’re going, is no small feat. Maher’s logbook is filled with decades of notes on trappings and re-trappings of the hundreds of animals.

“Long-term studies are really valuable,” said Daniel Blumstein, a biology professor at University of California Los Angeles who studies yellow-bellied marmots. “Having decades of information gives us a whole different way of thinking about what’s going on.”

In addition to changing understandings of their social behavior, Maher has conducted numerous other studies across the course of the project, including the variation in woodchuck personalities, tracking their movement with radio transmitters, testing their paternity using DNA from hair samples and seeing if they pay attention to the alarm calls of other animals (turns out, woodchucks care what chipmunks have to say).

She’s also seen their lineages unfold across generations, such as with the woodchuck named Bonnie.

Maher first caught Bonnie in 1998. She lived for 12 years, twice the average woodchuck lifespan, until she disappeared. Her legacy living onwards, as having trapped and tagged her offspring, and her offspring’s offspring, Maher was able to track Bonnie’s bloodline for seven generations until it died out in 2018.

Maher wondered what exactly happened to Bonnie. The answer was unearthed in 2021, when Maine Audubon tore down the pavilion that her burrow had been under. Curled up underneath was the mummified body of Bonnie, identifiable by the tag still in her ear.

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Maher keeps Bonnie’s mummy in her office in a plastic tote, occasionally taking her out when she gives talks about her research at libraries, to Girl Scout troops and Maine Audubon camps. 

“It’s a highlight of the summer for many campers,” said Molly Woodring, who oversees day camp and other educational programs at Maine Audubon.

With additional assistance from a woodchuck puppet, Maher presents her research and what it’s like to be a wildlife biologist to campers each year, also often explaining what she’s doing to other curious visitors of Gilsland Farm who typically come out to birdwatch.

“I do think, like in the context of the sanctuary, and in the context of her work, (woodchucks) do become really fascinating and lovable,” said Woodring.

In a year she’ll be on sabbatical, where she’ll write up more findings and is hoping to  write a popular science book about woodchucks and her life studying them. Retirement is not too far off, and it doesn’t look like anyone else will be taking over the reins of the study.

“It will be hard to not keep coming out here,” she said. “By then, it will be 30 years of stories.”

“Animals with tags will still be running around for a little while,” said Maher.