Peregrine falcon hatchlings typically reach the size of their parents during adolescence, but they are easily distinguished from their elders while flying. Fledglings usually display rapid, erratic flapping in flight compared to the smooth, soaring movements the peregrine, the world’s’ fastest bird, is known for.
“It’s like if you had a 12-year-old kid and give them keys to the fastest sports car there is and say, ‘Here, figure it out yourself.’” said Frank Sperlak, senior chemistry technician with Xcel Energy, who is in charge of the peregrine nesting box program at the company’s Prairie Island facility. “And that’s what they’re doing: they’re learning how to fly and hunt, they play tag.”
This year, a quintet of new fledglings can be seen wildly flapping above their home at the Prairie Island nuclear plant. The nesting peregrines at the facility welcomed five hatchlings for the first time, driving the total number of falcons born at the facility to 62.
With a first-year mortality rate of up to 75 percent, the new eyasses’ good health makes this year’s hatch an exceptional success for the program.
Sperlak has overseen the program for 12 years.
Xcel Energy installed the facility’s first nesting box in 1994 in partnership with the Raptor Resource Project out of Iowa in response to low numbers of peregrine falcons. The population had declined as a result of DDT, an insecticide banned in 1972 and linked to thin eggshells, which made it impossible for peregrine mothers to incubate their eggs.
By 1997, peregrines were spotted again at the facility. The Prairie Island facility was one of several Xcel sites to install the nest boxes, including the King power plant site. The company’s plants have served as the birthplace for more than 1,000 falcons since the nest box installation started.
With their tall structures, power plants often attract peregrines, who prefer to build their nests atop high points. Sperlak, along with a team of Xcel employees and staff from the Raptor Research Project, climbed up the latter on one of the facility’s towering power plant stacks earlier this year to band the hatchlings for tracking.
Though the falcons retained their fluffy, white feathers at the time, bearing a closer resemblance to clouds than to birds of prey, their sharp talons presented a challenge to volunteers, who banded the hatchlings with ungloved hands to prevent injury to the birds’ blood feathers.
Although the eyasses at Prairie Island look like adults, they still rely on their parents for food.
“They’re learning to hunt, but the parents still feed them. So, they’ll end up on a rooftop somewhere screeching and calling for food and along will come the parents to drop off a dead pigeon,” Sperlak said. “They make this distinctive sound — when you hear a peregrine, you’ll always know it’s a peregrine.”
The eyasses will soon master hunting skills, reaching speeds of up to 180 miles per hours as they dive for birds and bats mid-air.
“They’ll grab their prey with the talons and are going so fast, but if they don’t kill it on the strike, the other bird will just die from the speed of that dive,” Sperlak said.
The Prairie Island plant usually hosts an abundance of pigeons to hunt, but this year’s shortage in the prey population means the peregrines have to travel farther distances to hunt.
“Pigeons were their main meal here, but a wild pigeon is harder for them to hunt because it’s a lower speed and they take evasive actions,” Sperlak said. “What tends to get eaten first are these racing pigeons. People have these pigeon clubs where the pigeons go from point A to point B. They fly in a straight line and take no evasive action, so those are the ones that get picked off first.”
Xcel Energy Representative Matt Lindstrom said the nest boxes are part of the company’s efforts toward environmentally sound practices.
“We believe in our environmental responsibility to respect the creatures surrounding our power plants. Our falcon nest box program really showcases how industry and wildlife can live together and thrive,” he said. “Our partnership with the Raptor Resource Project and the countless support they provide allows us to continuously raise conservation awareness and strive to create the best nesting homes for these riveting raptors.”