Friday is Hatch Day for UC Berkeley’s growing peregrine falcon family

These three rust-colored eggs contain the latest falcon chicks for Annie, the falcon on Berkeley's Campanile.

After months of drama for Berkeley’s longtime falcon couple, Annie and Grinnell, and doubts over whether these eggs would hatch following Grinnell’s death on March 31, dedicated tending by Annie and her new mate, Alden, hopefully will produce three babies by next week. (Cal Falcons image)

The hoped-for hatch atop UC Berkeley’s Campanile of three peregrine falcon chicks starts Friday, May 6. In celebration, annual Hatch Day festivities, canceled for two years during the pandemic, will return with fun and educational activities on the south side of the Valley Life Sciences Building.

The outdoor event, hosted by Cal Falcons, will run from 9 a.m. to 3 p.m. and include a chance to view live footage of what’s happening in the nest, local falcon experts answering visitors’ questions and falcon-related art projects.

“There will also be telescopes out for folks to look through, to see if they can spot the falcons up on the Campanile,” said Lia Keener, a senior on the Cal Falcons team. And with final exams approaching next week, “we hope this small social event helps students relax,” said sophomore Yuerou Tang, who’s also helping with Hatch Day.

Then, at 3 p.m., a live Hatch Day Q&A on YouTube will be held with Cal Falcons ornithologists Sean Peterson and Lynn Schofield.

Alden the falcon flies through a blue sky, his injured left foot dangling and his wings outstretched.

Alden, Berkeley’s new male peregrine falcon, is distinguishable by his injured left foot, which dangles when he flies, and his dark “chinstrap” cap and tail. (Photo by Bridget Ahern)

Not all the reddish-brown eggs may hatch on Friday — and, some years, one or more don’t hatch at all — but that’s the day the action is likely to start. A clutch of peregrine falcon eggs typically hatches “about 48 hours from first to last egg, with more eggs toward the earlier side of the hatching window,” said Peterson. “If they start hatching Friday, we’ll pretty much know by Monday if any aren’t going to hatch.”

Said Schofield, “We’re hoping the chicks will all hatch sometime on the 6th. Very early morning on the 6th is the most likely time for the first egg to hatch, based on past years.”

Last year, triplet falcons were born — two of them on Saturday, April 16, at 3 a.m. and 12 noon and the other on Monday, April 19, just before 6 a.m. — to falcon parents Annie and Grinnell; a fourth egg didn’t hatch. The pair began raising chicks on the bell tower in 2017 and together produced 13 chicks. One, Lux, died while learning to fly.

This spring, Annie laid two eggs before Grinnell’s death on March 31. A third egg was laid two days after he died, and its parentage is unknown. Annie welcomed a new mate, Alden, to the nest just seven hours after Grinnell was found, run over by a vehicle, in downtown Berkeley.

Annie the falcon soars through a grey but clear sky, her wings outstretched.

Annie, who has weathered the death of her longtime mate, Grinnell, drones flying near her nest and lone falcons seeking to take over her territory, has emerged strong and has mated once more, this time with a falcon the public has named Alden. (Photo by Bridget Ahern)

For the past few weeks, Peterson said, it’s been “smooth sailing” for the new pair. A few unattached falcons have stopped by the tower to scope out their chances for a new home or a new mate, but none has stayed long. Annie is incubating the eggs most of the time, and Alden is the primary hunter for their food.

If the chicks hatch on Friday, they will be banded as part of ongoing research with the Santa Cruz Predatory Bird Research Group. Bird banding is a formal program through the U.S. Fish and Wildlife Service that can reveal how long a bird lives and the movements between its natal site and nesting site, which a falcon typically chooses when it’s between 2 and 4 years old.

Peterson said feathers will be collected from the chicks during banding and could be used to assess the paternity of the chicks as part of a broader effort to understand falcons’ relationships in the Bay Area.

By mid-June, the babies will have grown enough to attempt to fly.

Annie and Alden, Berkeley's current falcon couple in the Campanile, stand in their gravel nest box and look closely at the eggs Annie laid this spring.

Annie (left) and her new mate Alden check out the eggs that Annie laid this spring. (Cal Falcons image)

Interest by the public in Berkeley’s falcons has grown about 20% in the past month, since Grinnell’s death and Alden’s arrival, according to Cal Falcons social media data. Initially, the group of biologists and volunteers expressed concern that the three eggs wouldn’t hatch at all, after Grinnell’s death, since Annie couldn’t both incubate them and hunt for her food.

But then Alden arrived and was welcomed by Annie, who wasn’t expected to bond with a new mate, if she found one, for weeks. He immediately began helping her incubate the eggs and brought her meals.

“It was a really compelling story for a lot of people,” said Peterson. He said that, aside from the U.S., the top countries glued to Cal Falcons’ social media posts are Australia, Canada, Japan and Italy.

Artwork, stories, videos and other material memorializing Grinnell continue to be shared by the public with Cal Falcons, but “there is a ton of interest in the new family,” he said. “Everyone is really pulling for a happy ending for Annie and Alden.”