UC biologist documents ecological disaster one bird at a time

UC College of Arts and Sciences Professor Ronald Canterbury has dedicated his career to studying birds. His research indicates that many birds are disappearing from places where they once flourished.

Nearly 1 in 10 species in the United States are listed as threatened or in danger of extinction. Many others are nominees waiting to be listed. In fact, the National Audubon Society says more than half the bird species in the country are in sharp decline.

Canterbury has witnessed the trend firsthand as a field researcher.

“I have noticed that there are not as many insects as there used to be. Birds in the fall don’t have as much migratory fat as they need. So that’s very disturbing,” he said.

“In the summer, birds that nest in tree cavities are losing more young from heat stress because of climate change,” he said. “And they’re losing a lot of young to predators in urban landscapes.”

Canterbury’s research has focused on the golden-winged warbler, a songbird that once was widespread in the Appalachians and across the Midwest but now is rarely seen and virtually never nests in Ohio. Its disappearance coincided with the loss of wetland and forest habitat where it prefers to nest.

Researchers use state-of-the-art tools such as Doppler radar and geolocators to track the long-distance migrations of birds. But most scientists still study birds the same way they did more than a century ago: by catching them and placing a numbered band on their legs.

Canterbury has been banding birds for 35 years. During that time, he has recorded data on more than 80,000 individual birds.

Canterbury shares his research through the Monitoring Avian Productivity and Survivorship program. Its data helps wildlife managers prioritize habitat and conservation projects at the federal, state and local levels.

For the last 11 years, he has banded birds at the Center for Field Studies, a former farm in southwestern Ohio that UC leases from Hamilton County. It offers classroom space and a mix of habitats for biology and ecology research surrounded by Miami Whitewater Forest.

Canterbury teaches ornithology classes here. And budding researchers come from far and wide to learn how to band birds from him.

On a recent summer morning, Canterbury arrived at the center hours before dawn to set up 10 finely woven nets in the dark. Each stands about the height of a volleyball net stretching to the ground.

At first light, the birds began to stir, creating a symphony of calls birdwatchers call the dawn chorus. At regular intervals, Canterbury and his students walked the grounds checking the nets to see if any birds had flown into them. The stretchy nets capture the birds without hurting them. The researchers carefully untangled the birds from the wispy material and placed each in a brown paper bag sealed with a numbered clothespin indicating the location of the net.

Using the tailgate of his truck as a lab bench, Canterbury and his students removed each bird and recorded its weight and the length of its wings. A tackle box organizes the bands by size, from a hummingbird to a golden eagle.

The size, color and conditions of the feathers give researchers clues about the bird’s age. Adult females typically have a featherless belly called a brood patch that helps them incubate eggs and keep chicks warm.

As they worked, they shared trivia about the birds they caught, including a beautiful indigo bunting. These little finches are a gorgeous cerulean blue.

“Its feathers are not actually blue,” Canterbury said, removing a tiny band from a plastic film canister. “They have no blue pigment.”

An optical illusion called light scattering creates the blue color where none exists. And it’s the same with blue jays, bluebirds and blue grosbeaks, Canterbury’s student Ashley Niece said.

“Isn’t that crazy?” she said.

Niece works for the Great Parks of Hamilton County but joined Canterbury to get valuable banding experience.

“Birding is great, but it’s so different when you see the birds up close,” she said. “Birds are in decline, so I want to do my part to help. And it’s fun. I really enjoy the research. There is so much to learn about birds.”

Holly Erickson is majoring in forestry, fisheries and wildlife at Ohio State University. She is studying prothonotary warblers, pretty yellow songbirds that make a sharp “tweet, tweet, tweet, tweet” call. She wore a T-shirt emblazoned with one of the birds.

“They’re gorgeous. Their song will be ringing in my ears for years,” she said.

While there were no prothonotary warblers on this morning, she did band another yellow songbird, a chat. This bird with its parrot-like repertoire of screeches and whistles was once considered America’s largest warbler but was reclassified in 2017 into its own family, Erickson said.

“I’ve been looking forward to this all week,” she said. “My mentor was a retired conservationist. So it’s been fun getting deeper into bird research. It’s been my obsession.” 

Naomi Monroe, a first-year student at the University of Michigan, has been fascinated with birds since she was a child. As a toddler, one of her first spoken words was “duck.”

Standing in front of a net, she carefully extracted a house wren, a bird that weighs less than two nickels. But that didn’t stop the feisty creature from trying to wriggle free.

“Stop it, please! You’re very cute — and very small,” she pleaded, placing a tiny band on its leg before letting it fly back into the woods.

Canterbury said he is happy to share his expertise with the next generation of ornithologists. Their work will be increasingly important to help stem the decline of birds, he said.

What he has observed in his annual data corresponds to studies elsewhere that paint a grim picture for many species. Canterbury said he thinks the growing ubiquity of household and agricultural pesticides is to blame.

“You can go to any gardening store and buy gallons of pesticides without regulations,” he said.

Globally, researchers have found one common class of pesticide called neonics in birds as varied as white-throated sparrows and European honey buzzards. The chemicals are highly toxic to birds and are found in a variety of agricultural crops. But proving causation is tricky.

A 2020 study by the University of Illinois in the journal Nature Sustainability tied the rise of the pesticide with statistically significant reductions in bird biodiversity.

Canterbury said he has observed other alarming changes as well. Birds typically breed, migrate or grow new feathers at distinct times of the year. But more and more, he said, these activities are overlapping.

“We’ve been seeing way more overlap in molting and migration lately because the birds are stressed. They don’t have the food supply, the insects, they used to have. And that puts them at greater risk,” he said.

And that could have unexpected consequences for the gene pool since breeding plumage is a prime characteristic of mate choice.

“Some of the males are not in as good condition when they return to their breeding grounds,” he said.

Featured image at top: Student Naomi Moore releases a house wren she banded at UC's Center for Field Studies. Photo/Andrew Higley/UC Marketing + Brand