It was not to be, the arrival of peregrine falcon chicks this season at UC Berkeley. The male campus hawk, Grinnell, was dead, and his longtime mate, Annie, was alone in the nest atop Campanile, unable to hunt and incubate eggs.
But as of last Thursday, two of the eggs that biologists had predicted would not hatch have produced two fluffy, healthy chicks — a third egg wasn’t viable — thanks to the unusual and punctual arrival of Alden, Annie’s new partner, just hours after Grinnell was hit by a car in downtown Berkeley on March 31.
And after helping Annie incubate the eggs, Alden is proving to be a reliable hunter, bringing prey to the newborns and their mother while Annie raises them.
“This season has been extraordinary. We’re really swinging between the highs and the lows,” said Sean Peterson, ornithologist at Cal Falcons. “It’s amazing to me that we’ve gotten to the point where the puppies were born and they seem to be doing really well considering all the events at the start of the year. The behaviors and events we saw were very surprising and really showed how unpredictable nature can be.”
The third egg may have failed due to a genetic abnormality, or because it got too hot or too cold at some point, or it may not have been fertilized, Peterson said, adding that Annie “never had her entire clutch of eggs hatched before. .” This is Annie’s sixth Mother’s Day at the tower, where she and Grinnell made their home in late 2016, and she has now produced 15 puppies. One of them, Lux, died while learning to fly in 2017.
Peterson said an average of three chicks a year learn to fly in successful peregrine falcon nests. “When you consider that Annie has never had a nest failure, she is doing a little better than average,” he said. Two of Annie and Grinnell’s children – Larry and Sequoia – have known territories.
Last Friday, Cal Falcons hosted a Hatch Day 2022 event for the public outside the Valley Life Sciences Building, with local experts on hand to answer questions about campus falcons. About 100 people attended, some from as far away as Davis, Livermore and San Jose.
Mary Malec, one of the experts, said the guests she spoke to “seem to be very accepting of Alden”, despite the widespread grief that followed Grinnell’s unexpected death. She added that “…most people have not only accepted Alden, but think he’s the best thing that’s happened in this nest this season.”
While a hawk that loses its mate can take weeks to bond with a new one, Malec said, a study by scientist Grainger Hunt of “floaters,” or unattached adult peregrine falcons, notes that these birds “took eggs in the nest with no problem. no peer binding period, so of course this has happened before. … It’s a survival system that worked again to keep this species going.
“Coming out when he may not have real children this year will give Alden the opportunity to continue as the breeding male for years to come.”
Alden had been in Annie and Grinnell’s territory for a month or so before Grinnell’s death, Malec added, “so Annie was familiar with him.”
The new chicks — one born on Thursday, May 4, the other on May 5, Incubation Day — will be in the “baby” phase for the first 10 days as chicks, Peterson said, and will work on internal growth and development. By day 10, they will begin to grow wing and tail feathers, be able to keep warm, and be able to eat fuller meals.
About 3 1/2 weeks from now your legs will be fully grown and by the end of May they will be banded and your sex can be determined. At this point, Annie and Alden will spend less and less time in the nest as the chicks begin to explore on their own. The campus’s annual Fledge Watch, a time period where youths begin flying and volunteers position themselves near the tower to monitor their progress, is expected to begin in mid-June.
Recently, baby hawks have also hatched at the UC Davis Medical Center and City Hall in San Jose.
Malec said Cal Falcons volunteers remain on campus regularly to monitor the hawks’ activity, which became dramatic last October when Grinnell was injured by rival hawks and hospitalized. Annie did not take Grinnell back immediately after he was released in November, also showing interest in the male rival who hurt Grinnell. After Annie and Grinnell were reunited on New Year’s Day, Annie mysteriously disappeared in late February for about a week, in the midst of preparing her nest, then returned only to lose Grinnell shortly after her first eggs were laid.
Now new chicks are in the nest, rival hawks are gone and Alden has arrived to help Annie and her chicks. Said Malec, “He’s making it work.”