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

After months of drama for longtime Berkeley hawk duo Annie and Grinnell, and doubts that these eggs will hatch after Grinnell’s death on March 31, Annie and her new mate, Alden, have dedicated themselves to care, hopefully they will produce three babies within the next week. (image Cal Falcons)

The wait for three peregrine falcon chicks to hatch atop the UC Berkeley steeple begins on Friday, May 6. To celebrate, the annual Hatch Day celebrations, 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 9am to 3pm and will include the chance to see live footage of what is happening in the nest, local hawk experts answering questions from visitors, and hawk related art projects.

“There will also be telescopes that people can look through to see if they can spot the hawks on the Bell Tower,” said Lia Keener, a senior on the Cal Falcons team. And with final exams approaching next week, “we hope this little social event helps students relax,” said sophomore Yuerou Tang, who is also helping with Hatch Day.

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

Alden the hawk flies across a blue sky, his injured left foot dangling and his wings spread.

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

Not all reddish-brown eggs may hatch on Friday – and, in a few years, one or more won’t hatch at all – but this is likely the day the action is likely to begin. A brood of peregrine falcon eggs typically hatches “about 48 hours from the first to the last egg, with more eggs toward the previous side of the hatch window,” Peterson said. “If they start hatching on Friday, we’ll pretty much know by Monday if anyone doesn’t hatch.”

Schofield said: “Hopefully the chicks will all hatch on the 6th. The very early morning of the 6th is the most likely time for the first egg to hatch, based on past years.

Last year triplets of hawks were born – two of them on Saturday April 16, at 3:00 and 12:00 and the other on Monday, April 19, just before 6:00 – to falcon parents Annie and Grinnell; a fourth egg has not hatched. The couple started raising chicks on the bell tower in 2017 and together they produced 13 chicks. One, Lux, died while learning to fly.

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

Annie the Hawk flies in a gray but clear sky, with her wings outstretched.

Annie, who has resisted the death of her longtime companion, Grinnell, drones flying near her nest and lone hawks trying to conquer her territory, has emerged strong and mated once again, this time with a hawk that the public called Alden. (Photo by Bridget Ahern)

In the past few weeks, Peterson said, it has been “smooth sailing” for the new couple. Some detached hawks stop by the tower to evaluate their chances of a new home or a new mate, but none stayed long. Annie is incubating the eggs most of the time and Alden is the main hunter of their food.

If the chicks hatch on Friday, they will be tied as part of ongoing research with the Santa Cruz Bird of Prey Research Group. Bird banding is a formal program through the United States Fish and Wildlife Service that can reveal how long a bird lives and the movements between its native site and the nesting site, which a hawk typically chooses when it is between 2 and 4 years old. years.

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

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

Annie and Alden, the current pair of Berkeley hawks in the Belfry, stand in their gravel nest and closely observe the eggs Annie laid this spring.

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

Public interest in the Berkeley Hawks has grown about 20% in the past month since Grinnell’s death and Alden’s arrival, according to social media data from Cal Falcons. Initially, the group of biologists and volunteers expressed concern that the three eggs would not hatch at all after Grinnell’s death, as Annie could not both incubate and hunt for her food.

But then Alden showed up and was greeted by Annie, who wouldn’t have had to bond with a new mate, had he found one, for weeks. He immediately began to help her incubate the eggs and brought her meals.

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

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

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