Taylor Fossett: From campus shrubs to city streets — How song sparrows adapt to urban life

A young brunette woman wearing a pink and purple plain shirt and a purple backpack holds up a small brown bird with its beak open — Taylor Fossett holds a brown-headed cowbird (Molothrus ater) fledgling. Photo courtesy of Taylor Fossett.

The following story was written in Fall 2025 by Ally Adams in ENGL 4824: Science Writing as part of a collaboration between the English department and the Center for Communicating Science.

When Taylor Fossett was an undergraduate, she wanted to be a veterinarian. Instead, she began studying something she knew barely anything about — neurobiology. Fossett found herself in laboratories elbow deep in textbooks, brain slices, and genomes of one species of bird, the song sparrow (Melospiza melodia). Little did she know she would fall in love with it. What began as a curiosity for wildlife shifted into research looking at how the brain and behavior of the song sparrow are shaped by urbanization.

After graduating with her master’s degree from Western Carolina University (WCU) in May 2020, Fossett found herself without a job due to the COVID-19 pandemic.

In an effort to secure a spot in graduate school, Fossett reached out to her former advisor at WCU, Jeremy Hyman, and asked if he knew of any available Ph.D. positions. Luckily, he knew of an opening at Virginia Tech’s Department of Biological Sciences in the lab of Kendra Sewall. The Sewall Lab focuses on how the environment impacts the behavior of wild songbirds through effects on underlying neural mechanisms, and with a background in biology, Fossett jumped at the opportunity.

“I started in Dr. Sewall’s lab in the summer, technically before I started my Ph.D. Our fieldwork begins in April, because that’s when the song sparrows start breeding,” she says, “so I was working as a field technician for a couple of months. It was just a way for her to bring me in early so I could learn the system and the lab and everything.”

Fossett had previously worked as a wildlife rehabber for two years before starting graduate school, which had led to a love for the clinical side of biology, but she quickly realized that the lab required much more than she was prepared for.

"I didn’t have any training in neuroscience at all. So I had to teach myself basically everything I know,” she recalls. “The point of the Ph.D. is learning how to be very independent and teach yourself things, but not having that formal training was a huge thing that I had to overcome. I had to literally sit down and read neuroscience textbooks and learn basic things, like what is a neuron?”

A brunette woman in a white lab coat with blue latex gloves on has her back to the camera. She holds a white probe into a beaker under a fume hood — Taylor Fossett prepares reagents in the lab. Photo courtesy of Taylor Fossett.

With extensive training and gained experience, Fossett fell in love with the field of neurobiology. She is now researching song sparrow brain development and how the brain is shaped by urbanization, or life in the city.

Song sparrows are one of the most common songbirds in North America.

“During the breeding season, they’re everywhere on campus…especially February through March, that’s all you hear,” Fossett says. “How do you identify a song sparrow? Well, they have brown and tan streaks across the body, and they have a brown badge in the center of their chest. The males and females look identical. The only difference is that males sing. Females vocalize, but they don’t sing like the males do.”

Song sparrows live in both rural and urban environments, and the Sewall lab has found that urban song sparrows are reliably more aggressive than their rural counterparts. This makes them excellent organisms for studying the effects of urbanization on songbird aggression.

Fossett works on multiple research projects. However, one of her projects stands out from the others: “I have a bunch of side projects in addition to my actual [dissertation] chapters I’m working on, but I would say the big one, my passion project, is the nestling project,” she says.

With the nestling project, Fossett seeks to understand how brood parasitism influences the developing brain of song sparrows. The brown-headed cowbird (Molothrus ater) is present in about 40 to 50 percent of song sparrow nests found at their urban sites, she says.

“They’re obligate brood parasites,” Fossett explains. “Cowbirds are a species of bird that lays their egg(s) in another bird’s nest, and then the host, a song sparrow, for example, has to raise that cowbird.”

Brown-headed cowbirds are native and are an important part of the ecosystem, but they are detrimental to song sparrows due to their parasitic nature, she says. When the cowbird is present in the nest, the song sparrow nestlings have reduced survival rates. This is because the song sparrows get less food from their parents; the cowbird hatches first and gets a leg up on development. The song sparrow nestlings can even get smothered by the cowbird because the cowbird is so much larger than the song sparrows.

Within her study there are 60 nestlings total: 20 urban with no cowbird in the nest, 20 urban with a cowbird in the nest, and 20 rural with no cowbird in the nest. Surprisingly, the Sewall lab doesn’t find cowbirds in rural song sparrow nests very often. The Sewall lab has three replicate urban sites and three replicate rural sites where they conduct their research. Virginia Tech is used as two of the three urban sites, with the campus split into North and South, and the third site is the Radford University campus. The rural sites include the Stream Restoration Site at Stroubles Creek, Heritage Park, and Kentland Farms.

A brunette woman with brown sunglasses on her head looks at her hand, where she is holding an adult bird that is colored brown and white. — Taylor Fossett holds an adult song sparrow (Melospiza melodia). Photo courtesy of Taylor Fossett.

Fossett’s question is this: How do developmental stressors, including urbanization and brood parasitism, influence song sparrow brain development? Specifically, she is looking at food availability and quality and how it differs with urbanization and brood parasitism.

“Urban environments have lower food availability and quality, and song sparrows eat arthropods (insects), especially during the breeding season when they are feeding their nestlings,” she notes. “So my question is, how does that cascade affect song sparrow brain development? And then the additional stressor of brood parasites preventing the nestlings from getting food.”

To understand how these developmental stressors are shaping the brain of song sparrows, Fossett looks at gene expression in the brain.

“This will give us insight into which genes are being activated or de-activated in response to these different developmental conditions,” she explains. “Simply put, it will tell us how the brain is being shaped, or organized, by these early-life events.”

For now, the researchers are limited to looking at brain measures without behavior, because nestlings don’t express aggression, but in the future, they would like to address the bigger question at hand: How does early-life organization of the brain influence behavior, such as aggression, into adulthood?

All of this research circles around a central question about urbanization: Why are urban song sparrows more aggressive than rural song sparrows, and why is that important in the context of human-induced rapid environmental change?

Rapid spread of urbanization has big implications for animals and how they adapt to the changing environment, Fossett says.

“It’s pushing animals out of their natural habitats. But it’s also presenting animals with these novel challenges that they have to respond to, and every species is going to respond very differently,” she explains. “The species I study do really well in urban environments, but there’s a lot of species that don’t. So, with that in mind, our work increases our understanding of how animals will (or won’t) adapt to urban life.”

When animals are forced into urban areas, it becomes increasingly important to understand the physiological and behavioral mechanisms that will allow wildlife to adapt to these novel environments. And with the rapid expansion of the human population, more and more animals are being pushed in and out of urban areas. Unlike song sparrows, some animals may not be as well equipped to adapt to urban environments and will struggle to survive. This, in turn, could lead to declines in wildlife populations across the globe, and we are already seeing evidence of that occurring, Fossett says. When exposed to urban environments, animals are more susceptible to pollution, environmental hazards, and health impacts because of habitat loss and increased levels of human activity, making it vital that we continue to support research efforts to understand the consequences for wildlife of human-induced rapid environmental change.

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To learn more about this research, please visit the Sewall Lab's website and check out Taylor Fossett's 2026 publication "Neuroendocrine signals of urban aggression" in the journal Hormones and Behavior.