Campus news

It’s a four-egg clutch for UC Berkeley peregrine falcons Annie and Lou

Lou is a 'rock star,' both as a new mate for Annie and as a dad-to-be, Cal Falcons reports

Annie the peregrine falcon looks closely at her four rust-colored eggs of 2023.

Annie inspects her four new eggs, which were laid between Saturday, March 4, and Saturday, March 10. (Cal Falcons image)

Leaving last year’s drama behind, Annie, UC Berkeley’s female peregrine falcon, is back to her primary task at this time of year: producing a new crop of chicks. This time, she’s doing so with help from her new mate, Lou.

She laid her fourth and last rust-colored egg on Saturday morning; the first arrived the previous Saturday, March 4. That first egg was the earliest one Annie has ever laid in her past six breeding seasons on campus.

“She was seven days earlier than her previous earliest eggs. Those were laid on March 10, in both 2020 and 2021,” said Sean Peterson, an environmental biologist with Cal Falcons. “Perhaps she was comfortable with Lou and the status of her territory? Perhaps she was happy with the availability of food?

“Last year, (her egg-laying) was likely delayed due to the large number of floater birds competing for her territory. This year, she didn’t have that problem.” Annie’s first egg of 2022 arrived on March 26.

There’s no doubt, he said, that Lou is the biological father, adding that “extra-pair paternity is very rare in falcons.”

Lou, UC Berkeley's male peregrine falcon, splays his talons mid-air to scare and fight off another falcon trying to take over Annie and Lou's territory.

Lou (left) recently defended the territory he now shares with Annie from a falcon hoping to take Lou’s place. (Photo by Bridget Ahern)

Lou, who been in Annie’s life since late November 2022, “has been a rock star,” said Peterson. “He has been bringing food frequently and taking long stretches of incubation duty. Annie seems to have chosen well.”

Added Mary Malec, a raptor expert with Cal Falcons, “Lou is doing a great job taking turns incubating the eggs and has managed to cover all four eggs very well.”

Female falcons are the dominant partners in their relationships, said Peterson, and are much larger than the males.

Annie usually has laid four eggs each year since 2017; she and Grinnell, her longtime mate who was killed last March 31, arrived on campus in late 2016. Peterson said that while three eggs were in last year’s nest, “it’s relatively likely that the egg she was due to lay the day Grinnell died was laid somewhere else. Then, the ‘third’ egg was laid on the exact schedule we would have expected to see for a fourth egg.”

Helping Annie incubate the eggs and hunt for meals last spring was Alden, a male falcon that appeared at her side just hours after Grinnell’s death. He disappeared late last year.

Annie the falcon flies with wings outstretched with her beak open, as if she's calling out.

Annie has laid eggs in her nest box on the Campanile seven times since arriving on campus in late 2016. (Photo by Bridget Ahern)

But while Annie typically produces four eggs each year, they never all hatch.

“It certainly seems normal for Annie, although many peregrines do successfully hatch all four eggs they lay,” said Peterson. “Eggs can fail for any number of reasons, from developmental problems with the chick, lack of fertilization, thin eggshells or many other problems.

“We’ve always hoped she’d hatch all four eggs that she lays, but that just hasn’t been the case, so far.”

This year’s eggs are expected to hatch on April 11, according to Cal Falcons, and a hatch day party will be held outside the Berkeley Art Museum and Film Archive, where the public can watch the action on the large outdoor LED screen at the corner of Addison and Oxford streets.

First flights are expected around May 21 for any male chicks and around May 23 for any female chicks. The chicks’ sexes will be determined when they’re banded at 24-25 days old. A virtual Q&A session will be held that week with Cal Falcons experts.

Cal Falcons continues to grow its falcon fan base, which encompasses more than 40 countries worldwide, through its social media platforms — Instagram, Facebook and Twitter. The public can view the Berkeley falcons’ lives via three 24/7 webcams in the tower.