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Meet Mary Geis, the Montana Biologist Who Spent 30 Years Studying Bluebirds 

By Jewel Alston
Male Mountain Bluebird looking out of nest box
A male Mountain Bluebird in a nest box in Montana. Photo by Will Sebern/Macaulay Library.

In the foothills outside Bozeman, Montana, there’s a winding path known as the Mountain Bluebird Trail. For more than 50 years it’s been a breeding ground for intellectual curiosity and bluebirds alike. On cool summer mornings, sky-blue Mountain Bluebirds twitter from fence lines, bringing food to little chicks thriving in more than 300 wooden nest boxes.

The trail has come a long way since 1969, when it sported just 12 nest boxes fashioned from cans and milk jugs. It began its transformation in 1975, thanks to the work of Mary Geis, a biologist who transcended social norms of the day and blazed a trail through male-dominated graduate school. Over the course of nearly 30 years, Geis collected detailed records of nearly 1,500 Mountain Bluebird nests.

Each nesting season, Geis and a small group of volunteers kept meticulous notes and submitted data to the Cornell Lab of Ornithology’s North American Nest Record Card Program. This historic collection, along with 30 others, is being transcribed and digitized as a part of the Nest Quest Go! project. ​Now 95 years old, Geis is one of the few living contributors to the collection, with a life story that encompasses major shifts in society and technology.

Geis discovered her passion for ornithology as a teenager, during afternoon outings with the Natural History Club in her hometown of Oyster River, New Hampshire. At the time, she recalls knowing “the difference between a magpie and a robin,” but she was keen to learn more. During World War II, Geis studied zoology at the prestigious women-only Smith College in Massachusetts. Upon graduation in 1947, she took biologist jobs on Martha’s Vineyard and in Washington, D.C., and then taught natural history to elementary students for the Massachusetts Audubon Society.

forest ranger trainees at Yosemite in the 1950s
Students at the Yosemite School of Field Natural History. Mary Geis is in the top row, second from right. She graduated in the top of her class, in 1951 at age 25. Photo by Ralph Anderson/Yosemite Online Library.

After years of living in the Northeast, Geis was longing to explore the world. ​Leaving behind a reluctant boyfriend, she took off to California’s Sierra Nevada mountains and the Yosemite School of Field Natural History. In 1951, at age 25, she graduated at the top of her class and worked as a forest ranger for a year before applying to graduate school.

Cornell University and the University of Montana offered Geis admission to their masters programs, and ​she chose to continue her adventure out West—only to face men who didn’t think ornithology was a shareable space. “Men didn’t believe women should be doing that sort of thing,” Geis said, noting that her professors used to seat her in the back of the classroom where it was hard to hear. “I had to ask to be moved to the front,” Geis told me.

Despite the challenges of being the only woman, Geis stayed focused on her studies. Scooting around in her motorboat on Flathead Lake in Montana, Geis counted nests of Canada Geese to investigate their  population fluctuations and inform hunting and management practices. In 1954, she published Biology of Canada geese (Branta canadensis moffitti) in the Flathead Valley of Montana and became the first woman to publish an academic paper for the University of Montana’s forestry school.

Mary Geis leads a group of women hikers through a field near Bozeman Montana
In Bozeman, Montana, Mary Geis led weekly Tuesday hikes through the 2000s. Photo (2004) by Erik Peterson/Bozeman Daily Chronicle.

Shortly after graduation, Geis married her fiancé, Anthony, and settled down in Bozeman, Montana. There she taught at a public school and became involved with the Sacajawea Audubon Society, where she met Louis Moos, the founder of the local bluebird trail. When she took over the project from Moos in 1979, ​the Mountain Bluebird population was just a fraction of what it is today.

“I was doing it because I got interested in what was going on,” Geis said. “I wanted to know why this bluebird nested here, what destroyed its nest, and what that sparrowhawk [American Kestrel] was doing on the birdhouse.”

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In a 1980 report she took note of the practical value of birds—what today we would call their “ecosystem services,” writing: “Besides the pleasure we all get from having the swooping swallows, the flashing bluebirds, and the musical wrens and chickadees around… I am also convinced that they have a beneficial effect on insect populations in our area.” In a back-of-the-envelope calculation using some of her nest box data, she credited the local Tree Swallows with eating some 1,000 pounds of insects each summer.

When Geis wasn’t recording observations collected from the trail, she was leading nature walks for the Bozeman Women’s Activities Group, teaching natural history for the Sacajawea Audubon Society, or leading Girl Scout troops. A fellow women’s group hiker, Karin Utzinger, recalled, “It’s like going out with a guide or a naturalist. She knows the flowers, the birds, even the scat.” Geis led these group hikes every Tuesday into the early 2000s, when she was well into her 70s.

Mary Geis and Lou Ann Harris working with birds on Montana Bluebird Trail
Mary Geis (left) and Lou Ann Harris in 2007, at work on the Mountain Bluebird Trail near Bozeman, Montana. Geis turned over the project to Harris in 2009, when Geis was about 82. Photo courtesy Lou Ann Harris.

In 2009, Mary Geis passed the torch to Lou Ann Harris, who currently runs the Mountain Bluebird Project. “When she started taking me on the trail, she taught me everything she knew and nothing fazed her,” Harris told me.  The project now has three separate trails, where volunteers help conduct weekly nest checks from April–August. To this day, these volunteers are still reporting nest records to NestWatch.

All told, when combining nest records from the Moos, Geis, and Harris eras, the group has amassed more than 50 years of data on Mountain Bluebirds. Geis and her volunteers began collecting this data using pencil and paper. Now nest checkers enter data by computer or smartphone, and scientists can aggregate those records with others across the continent, via NestWatch.

What fueled Geis through so many decades of research and teaching? “Intellectual curiosity, I guess,” she said, noting that it helps to be born with a sense of adventure and, perhaps, a bit of patience. When it comes to developing knowledge, she said, “It’s not a matter of time, it’s a matter of wanting to know.”

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American Kestrel by Blair Dudeck / Macaulay Library