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Most doctors in training don’t begin a new semester expecting to learn about birds. But after her first year studying at Harvard Medical School, Lynn Hur was hooked. “It’s become one of my favorite activities,” she says.

Hur came to the hobby courtesy of associate professor Rose H. Goldman, who incorporates bird identification into her Practice of Medicine class to help sharpen students’ clinical diagnostic skills. In lecture, for example, Goldman asks students to differentiate between a Great Egret and Snowy Egret by homing in on details such as size, beak shape, and foot color that distinguish the slender, white birds. Until classes went virtual during the pandemic, Goldman, an avid birder, also led students on birding outings.

At first blush, it might not seem like cardinals and carcinomas have anything in common. But Goldman believes the process of discerning similar birds isn’t all that different from examining the subtleties of a patient’s rash to determine whether to treat eczema or test for skin cancer. “I personally feel that my powers of observation and memory have really improved from doing birding. But I have no way to prove that,” Goldman says.

With her unusual teaching strategy, Goldman is hitting on something that neuroscientists know well: Gaining deep expertise in a subject area can change your mental scaffolding, literally rewiring your brain. To better grasp this process, brain and memory researchers have long turned to birders (and occasionally med students) as a go-to group of test subjects—even in foundational cognitive research.

As recently as three decades ago, most neuroscientists theorized that humans’ keen ability to distinguish between similar faces was somehow special. They even suspected our brains had a particular area dedicated to face processing. But when Isabel Gauthier, then a young cognitive neuroscientist at Yale University and now at Vanderbilt University, went looking for this fabled region in the late 1990s, she quickly discovered that this “face area” of the brain was actually several sectors involved in recognition.

By scanning brains of experienced birders using a recently invented functional MRI machine, that these areas weren’t dedicated to sorting facial information alone: A bird and a friendly face could activate the same brain regions. “Faces aren’t special,” Gauthier says. “They’re a case of expertise.” As it turns out, people can fine-tune their ability to distinguish among any similar-looking objects, from faces and cars to skin conditions and birds. All it takes is exposure and practice.

This observation helped open the door to new avenues of perception and cognition research—and birders continued to participate. According to Thomas Palmeri, another Vanderbilt University neuroscientist who has recruited volunteers through the American Ornithological Society and local Լ����Ƶ chapters, birders make excellent subjects because it’s easy to find enthusiasts with a wide range of skill levels, and they are more likely to participate in community science–style surveys.

In his work studying visual expertise and memory retrieval, Palmeri ran his subjects through a series of bird identification tests. He used the data to build computer models that simulate real-time decision-making processes in the human brain. What’s useful, he says, is that all birds share the same broad set of features—feathers, beaks, two feet, two wings—but are still incredibly varied. To identify a specific warbler or hawk, a birder might spot and synthesize its markings, silhouette, shape, movements, and sounds in seconds. “It’s not about just ‘bird, bird, bird,’ ” Palmeri says. “It’s identifying a specific species and even subspecies.”

Developing this kind of perceptual expertise shifts the patterns of firing brain cells, or neurons, according to Gauthier’s findings. The more a person learns and practices, the more often a signal moves between neurons, and the path becomes easier to traverse, like a well-trodden hiking trail. This phenomenon, called neuroplasticity, may enable experts to distinguish between objects more quickly, seeing them as a whole and ignoring distracting or superficial features, she says.

Glory Kim, a Harvard School of Dental Medicine student and another alum of Goldman’s bird outings, recalls experiencing this rewiring firsthand. “At some point, when you see a bird, you automatically gather all these context clues and your brain just converges very fast on what it is,” Kim says.

Over time, expertise can even change the structure of the brain itself. Parts of the cerebral cortex may become slightly thicker as a person’s visual and auditory know-how deepens. This makes it easier for experts to add new information to their mental repertoire, says Erik Wing, a neuroscientist at Rotman Research Institute in Canada.

Wing, a birder himself, studies how these changes influence memory. In published in 2022, Wing recruited birders of varying experience levels and asked them to identify images of both familiar and non-familiar birds. The results demonstrated that long-term knowledge of avian species helped people to more easily remember new birds. For example, an experienced Boston birder visiting San Francisco might be unfamiliar with local species at first. But thanks to their neural scaffolding, experts will have a relatively easier time learning, and may even retain knowledge better as they age, Wing says.

So, can medical students in Goldman’s class improve their diagnostic skills by birding? Possibly—but the correlation isn’t direct. “It’s not like because a person is really good at birds, they’re going to be better at cars,” says Gauthier.

However, breaking open that field guide could help uncover innate skills in perception. For example, a person who has a knack for birding might also be gifted in a visual diagnostic field, like dermatology or radiology. And vice versa: Someone who naturally gravitates toward the visual side of medicine might be a sharp birder. Wing’s research also suggests that developing the frameworks and tools for birding helps a person sharpen their focus in other areas. “If you get practice tuning your attention toward different features that are more diagnostic or less diagnostic,” says Wing, “that is, I think, a valuable thing.”

Whatever’s at work in their brains, Harvard students Kim and Hur have continued to enjoy birding since Goldman’s class. For both, it’s become an indispensable outlet for dealing with medical school and pandemic stress. They’ve even begun sharing their hobby with classmates by coleading a student birdwatching club. And though she can’t always escape into the woods, Hur tries to sneak in birding as much as she can. “I’m in a busy part of my medical education right now,” she says. “But I do carry my binoculars in my backpack at all times.”

This story originally ran in the Spring 2023 issue as “The Birding Brain Boost.” To receive our print magazine, become a member by .