This season's first peregrine falcon egg was laid Wednesday
Mar. 22—ROCHESTER — The first egg of 2024 was laid for the peregrine falcons who nest atop the Mayo Building, with the start of a new clutch commencing Wednesday, March 20.
The clutch, or group of eggs, will continue to grow with 9-year-old Hattie
laying an egg approximately every 36 to 48 hours,
according to the Mayo Clinic's Peregrine Falcon Program. She usually lays a total of four eggs.
"Don't worry if you don't see the adults on the egg(s), as true incubation won't begin until the second to last egg is laid. The adults will keep the egg warm during severe weather, but will also leave it uncovered for hours at a time as well," Jackie Fallon, a naturalist with the Peregrine Falcon Program, wrote in a Facebook post on Wednesday.
While Mayo's peregrine falcon restoration program began in 1987, Hattie and Orton first started their "egg-laying history" in Rochester in 2017. The two falcons have occupied the downtown nest box since 2016. The pair have produced 24 nestlings with 20 surviving to
receive bands
on their feet in the spring. The bands allow biologists to identify the birds as well as information on where they travel, their lifespan, their mate and how many chicks they have.
The 2023 season included two male and two female chicks named Piper, Aero, Horus and Genesis. The
first egg
was laid on March 19, 2023, with the
four chicks hatching by May 1.
"Egg laying in peregrines is NOT determined by weather temperatures but correlates with daylight length, individual bird biology, latitude, and sometimes conflict over territory occupancy at the site," Fallon wrote in a Facebook post.
This year, Hattie and Orton have faced intruding falcons at the nest box. The falcons visiting the site were not born at Mayo Clinic. Fallon explained Hattie also "spent more energy defending the Rochester campus" from intruding female peregrines in previous years.
"Now, because the restoration program has been so successful, these types of observations are becoming more and more frequent. There is only so much space of appropriate habitat that would be appealing to a peregrine, and therefore individual birds are often testing birds that are already established on territory," Fallon explained in a Facebook post. "This is not the first intruder occurrence this year, but it is the first time we've confirmed that an intruder was an immature bird. These encounter and territorial disputes by adults towards an immature bird can be serious but are often less intense than an encounter dispute would be between two adults."
A live camera of the peregrine falcon next box is available to watch at
