ROCHESTER — On the roof of the Mayo Building — some 300 feet above ground — Tom Behrens is reaching to retrieve an adorable young bird, a chick that looks like a cluster of cotton balls with big yellow feet.
For parents of this little peregrine falcon, however, it's far from a feel-good moment.
They repeatedly swoop at Behrens, at one point knocking him in the head. Scolding kack-kack-kack-kack calls are so loud they drown out a freight train rumbling nearby and the midday carillon concert just across the street.
Yet, it's Behrens and naturalist Jackie Fallon, not the birds, who are the old hands around this nest. During 35 years at Mayo Clinic, they've been up here most every spring, risking the wrath of peregrines to collect young birds for banding before safely returning them home.
"The defensiveness starts escalating as soon as that first egg drops," Fallon said. "They've got a lot invested in those chicks and the eggs and all of that. We're just a giant predator as far as they're concerned — and we keep coming back."
Across the United States, it's nesting season for the peregrine falcon, a remarkable raptor that weighs just a few pounds but can fly more than 200 miles per hour. Once endangered, the birds are flourishing in part because of a habitat provided by a surprising ally — that emblem of American business, the skyscraper.
Tall buildings in urban areas resemble the historic homes of peregrine falcons, which were known to nest on soaring cliffs near water, said Fallon, a vice president with the Midwest Peregrine Society. Many Midwestern cities are located near rivers or large bodies of water, Fallon noted, and provide plenty of prey.
From buildings in Seattle, Omaha and Baltimore to structures in St. Paul and Minneapolis, webcams this spring are broadcasting the latest installments in a peregrine falcon recovery that spans power plant nests in Wisconsin, chicks on a university tower in California and — new this year — a courthouse aerie in New Jersey.
At Mayo, which is marking the 35th anniversary of its peregrine falcon program, a webcam drew more than 112,000 page views last year.
Peregrine falcons have helped control a pigeon population in Rochester that otherwise was making a mess for staff to clean at the clinic campus, said Behrens, who is Mayo's unit head for facilities operations.
His department made the nest, tends to it and likely is the most affected by peregrines. Window washing, rooftop work and other exterior maintenance must be scheduled around nesting season, when the falcons fiercely defend their territory.
"They pretty much own the skies in downtown Rochester," Behrens said.
Not every city of 121,000 people has a skyline, but tall buildings have been part of Mayo Clinic's presence here since the late 1920s.
That's when the clinic opened the 297-foot-tall Plummer Building, which briefly held bragging rights as the tallest building in Minnesota. Across the street, the Mayo Building, which is usually home to the peregrine nest, stretched to 20 stories by the late 1960s.
"I think the reason why we have high buildings to begin with is efficiency in patient care," said Matt Dacy, director of the clinic's Heritage Hall museum. "You were able to have a highly integrated vertical structure that allowed easy mobility of patients and staff. Who knew that was a perfect environment for the falcons?"
Jean Sherlock Matheny spent many hours over the past 11 years on the clinic's campus as her husband sought care for heart failure. She passed the time looking out windows and watching from various angles for peregrines.
An artist in Lake City, Sherlock Matheny made a study of the birds for a large oil painting. This winter, during her first visit to Mayo since her husband's death, the sight of a video about peregrines in the lobby, she said, displaced her sadness for just a moment.
"It was a comfort," Sherlock Matheny said. "It really was."
That's a message the clinic hears from other patients, including those who watch the livestream on hospital room TVs.
"Nature is healing," Fallon said. "Nature is calming. And we brought this little bit of nature into downtown Rochester."
By the 1960s, peregrine falcons were eradicated in the U.S. east of the Rocky Mountains. In Minnesota, the last known nesting pair was seen in 1962 at Whitewater State Park, nearly 30 miles east of Rochester.
The chemical DDT was the culprit, Fallon said. A federal ban on the insecticide set the stage for restoration efforts that initially aimed for 20 nesting pairs in the Upper Midwest. Today, there are more than 350 peregrine couples across the region. They produce between 600 and 700 chicks per year.
Minnesota alone has more than 70 nesting pairs, including Hattie and Orton, the falcons raising their young this spring at the Mayo Building.
Hattie hatched in 2015 from a nest at the University of Minnesota's Mayo Building. Fallon banded the bird and later named her in part for Hattie Mayo, wife to one of the physician sons of the clinic's founder.
The peregrine found her way to Rochester and mated with Orton, who came from a different nest in Minneapolis. The birds have been at Mayo Clinic since 2016, producing 24 eggs thus far and 16 falcons that have survived to fledge.
Over time, the peregrine parents have become more defensive of their nest and offspring — particularly Hattie, who like other females is the larger of the two.
When Fallon and Behrens collect the chicks for banding, they're always accompanied by maintenance workers who hold brooms or umbrellas high in the air as protection. The idea is not to strike the peregrines but to give the birds decoy targets for their attacks.
Last spring, Hattie swiped her talon across Behrens' scalp and drew blood, even though his son-in-law was trying to provide cover.
"I thought he hit me over the head with a broom!" he recalled. "I go, 'Why'd you hit me?' It took me a while to realize Hattie just nailed me."
On a rainy day last month, Behrens was careful to wear his hard hat as he climbed to the roof.
Inside, Mayo held a ceremony where Fallon placed bands around the legs of four young birds. They're banded so that researchers can collect data on peregrine lifespans, reproductive successes, how far they travel and overall population. The raptor offspring also were named in a public contest that drew more than 1,700 suggestions.
One will go by Rebel. The names Nova and Comet harken back to the comet and supernova that graced the nighttime skies in 1987, when Mayo launched its program. And the fourth bird was named Tom, after Behrens.
Over the years, peregrines at Mayo have produced a total of 70 young falcons. If the past is a guide, Behrens' work with the birds will continue in the coming weeks as they start learning to fly.
"I'll get a call on a Saturday from a police officer saying, 'One of your birds is on the ground here stopping traffic,'" he said. "There's times where I've chased them down the middle of the road, and all of a sudden they're up over a car — and then the one actually quick grabbed onto a stoplight upside down."
"I'm just a maintenance guy — I take care of buildings," he added. "And everything has revolved around this falcon program."
