Each spring, there’s a certain chirp to the campus. As nesting season approaches, Annie—the Campanile’s resident peregrine falcon—and her beau start hanging out around their nest more often. At the same time, hundreds of Cal Falcon Cam viewers tune in to watch as nesting season begins.

People are up at 2 a.m. watching for Annie to start laying her eggs, and about a month later, searching for cracks known as pips to start forming on the eggshell. Students are keeping up with the endless social media updates, learning about all-things peregrine falcons. A crowd forms by the Berkeley Art Museum and Pacific Film Archive (BAMPFA) big screen to celebrate Hatch Day and watch with anticipation for chicks to emerge. Bird watchers stand guard by the Campanile to get the first glimpses of fledglings about to make their first flights (well, more like a controlled fall).

Each spring, the UC Berkeley campus and greater Berkeley community watch these chicks just as—if not more—closely as their parents. By including the community in the lives of these falcons, the Cal Falcons team has helped highlight the importance of these birds to local policymakers. Multiple falcon nest cams can now be found across the Bay Area, with Annie’s offspring going on to head their own nests, from Alcatraz to San Jose City Hall. Unfortunately, peregrine falcons weren’t always this prevalent. Just 50 years ago, it was thought that peregrine falcons would become extinct in the United States.

From the brink of extinction

Before use of the pesticide DDT (dichlorodiphenyltrichloroethane) became common, an estimated 3,875 nesting pairs of peregrine falcons lived in the United States. By 1975, those numbers had decreased to just 324. Originally thought to be a relatively harmless insecticide, DDT is now classified as a carcinogen. Unfortunately, during its decades of use, DDT slowly accumulated in the food chain, affecting plants, insects, small birds that consumed those insects, and the birds who consumed those small birds, such as the peregrine falcon.

DDT primarily affects peregrine falcons and other raptors through their reproductive cycle. DDT hinders absorption of calcium, causing falcons to lay calcium-deficient eggs. These fragile eggs are unable to withstand the weight of incubation and crack under their parents. UC Berkeley’s Museum of Vertebrate Zoology (MVZ) aided in the eventual ban of DDT: By collected eggs, they helped document eggshell thinning in the peregrine falcon population and the harmful effects of DDT.

Although DDT was banned by the US Environmental Protection Agency in 1972, it was unclear if the small peregrine falcon population would bounce back. Luckily, The Peregrine Fund was established in 1970 with the goal of saving the species. Between 1974 and 1997, the Fund bred and released over 4,000 falcons, restoring falcon numbers enough to lead to their removal from the Endangered Species List in 1999.

Upon their return, peregrine falcons have taken to urban environments as a popular habitat. Similar to their preferred cliff habitats, falcons will nest on tall buildings and bridges. Peregrines have benefitted from these urban spaces, as they tend to experience fewer threats from predators and have access to an abundance of small city prey. People have also benefitted from this habitat expansion, as it provides great opportunities for birders to view nesting birds. Additionally, there’s an ever-growing number of falcon cams for locals to keep up with the falcon drama, just like UC Berkeley’s very own Cal Falcon Cam.

The story of Annie, Grinnell, Alden, and Lou… and another New Guy?

It hasn’t always been paradise for the feathered family on the Campanile, though. Annie (named after Annie Montague Alexander, founder of the MVZ and the University of California Museum of Paleontology) and Grinnell (named after Joseph Grinnell, the first director of the MVZ) first moved to the Campanile in December of 2016, using a sandbag as a nest. Lynn Schofield, a biologist at the Institute of Bird Populations, was one of the first to notice the new residents on campus. “During December of 2016, I saw a little streak go over and heard falcon noises and immediately ran out with my stuff under my arm and saw that there was a falcon up on the Campanile.” By January, both Annie and Grinnell had been spotted around the Campanile, and the excitement began to grow. Dr. Sean Peterson, who received his PhD from UC Berkeley’s Department of Environmental Science, Policy, and Management, describes how Annie and Grinnell’s popularity grew around campus. “It started to get attention beyond this little sphere of bird people and really started to catch the eye of campus in general.”

The Cal Falcons team set up a temporary nest box for the falcons, and Fiat and Lux became the first two chicks of Annie and Grinnell’s towering abode, named by the community in the first ever chick naming contest, which was held by UC Berkeley before being passed onto Cal Falcons the following year. Having nesting falcons on campus provided a particularly easy nest to track. Following evidence of courtship around the Campanile the next year, a permanent nest box was installed, supporting Annie’s nesting efforts to this day. In January of 2019, the community came together in a crowdfunding campaign to install the first two webcams to monitor the nest and Campanile balcony, leading to the Cal Falcon Cam we know today. The cameras have given researchers and the community extraordinary insight into the lives, habits, and relationships of the Campanile falcons. But even before the cameras, Annie and Grinnell were famous on campus. “People really started getting excited right away, before the cameras were ever installed,” says Schofield.

After five years of successful nests, things began to take a turn. A rival falcon started encroaching on the territory. In late October of 2021, Grinnell was found with injuries from the rival falcon. He was sent to the Lindsey Wildlife Rehabilitation Hospital, where he was healed and released in mid-November, flying back to the Campanile. Meanwhile, Annie had been courting the rival falcon in Grinnell’s absence. Upon his return, both males hung around the Campanile until New Year’s Day, when Annie and Grinnell courted, and the rival left.

Annie was in the process of laying eggs when the unthinkable happened. On March 31, 2022, Grinnell was found dead in downtown Berkeley, possibly from being hit by a car while fighting off an encroaching female falcon. “For us on the team, it was really tragic,” says Schofield. “We were sad about it because he was a unique bird that we knew a lot about and saw regularly, who we knew was a great father.” Devastation hit the Cal Falcons team with not just the death of Grinnell, but the realization that the nest would likely fail, as Annie couldn’t incubate the eggs, hunt, and defend the nest all on her own.

However, something unexpected occurred—a testament to the insight the cam provides. The next day, a new falcon swooped in, establishing a bond with Annie and adopting the chicks. “We had to mourn Grinnell,” Peterson says, “but at the same time welcome this new male, who was apparently taking over the nest in a way that we don’t really see frequently at all.” “New Guy” helped Annie raise the eggs, and April 7^th marked the start of his naming competition: He was named Alden, after Alden Miller, student of Joseph Grinnell and director of the MVZ. The nest was successful, and in honor of Grinnell, the chicks were named Grinnell Jr. and Lindsey, after Grinnell and the rehabilitation hospital, respectively.

The drama continued, though, as Alden unexpectedly disappeared in November of that year. However, it didn’t take long for yet another “New Guy” to start hanging around. After a successful courtship, New Guy’s name contest began on Valentine’s Day of 2023, and he was named Lou, after UC Berkeley graduate and naturalist Louise Kellogg, Annie Alexander’s partner. Annie and Lou had their first nest, with Rosa, Zephyr, and Luna all successfully fledging.

But the falcons of the Campanile can’t seem to catch a break. With Lou last being seen in the beginning of January, and another New Guy (named Archie this February after the UC Berkeley alumnus, gold medal Olympian, pilot, and teacher Archie Williams) mating with Annie this season, it seems that Annie—as she enters her eighth nesting season at the Campanile—has yet to settle down. “People who monitor nest turnover say there’s turnover at a nest site roughly once every four years, so this is pretty quick to have these two disappearances in rapid succession,” Peterson explains, “but it’s not totally out of the ordinary.”

“There are some joking suggestions that Annie is driving them off or getting rid of them. She’s like a black widow falcon,” Peterson quips. But this is extremely unlikely. Annie would want to keep around a male with whom she’s already successfully raised chicks. While it’s unknown why Alden and Lou disappeared, as falcons can live up to about 15 years, there’s a lot of competition for the Campanile and surrounding territory, so it’s possible that the males had been injured by other birds, moved on to territories with less competition, or fallen victim to avian flu. While the cameras provide much information about the nest, the unknowns about Alden and Lou highlight the importance of banding falcons (tagging young falcons with identification bands) for tracking purposes. Despite all the nest complications, things are looking up for Annie and Archie this year’s nesting season.

Annie’s legacy

Despite the ups and downs in Annie’s love life, she has yet to let a nest fail. With her life so publicized, Annie’s egg laying habits are impressively documented. Laying an egg an average of every 2.48 days, Annie typically lays a total of four eggs during nesting season, with three of the eggs being viable. As described by Cal Falcons, egg development works like a conveyor belt. The egg cell (ovum) begins developing in the ovaries and forms the yoke of the egg. The mature ovum is then released into the oviduct, where it’s fertilized by stored sperm. The “egg white” then forms, followed by the inner and outer shell membranes, before moving on to the “shell gland,” where a hard layer of calcium is added to the egg. After the egg is laid, the next egg is fertilized, and the cycle continues. In peregrine falcons, this process usually takes 2.5 days. This cycle can be interrupted if the falcon finds it necessary, and it is thought that Annie likely laid one fewer egg in the 2022 nest than she would have otherwise due to the uncertainty of being able to raise the chicks all on her own after Grinnell’s death.

During the egg-laying process, the parents won’t consistently incubate the eggs. For peregrine falcons, as well as other species of birds, the embryos only develop when warm. To make raising the chicks simpler once they hatch, the consistent 32–33 day incubation won’t occur until they’re all laid, so they all hatch around the same time.

Once ready, the chicks tend to hatch within a 24–48 hour window. Schofield comments, “Hatch Day is a lot of anxiety and excitement because people really care about the chicks, and you don’t know how many eggs are going to hatch until they do.” After that, the little, down-covered hatchlings start growing significantly in size. “It’s very fun because you have everyone watching, and you get to see moments like the first meal,” says Peterson. “These little chicks are starting out, and you get this window of really fun days when every day is different.” Eventually the chicks begin to develop their feathers under the fuzzy coat. Their parents continue to incubate them and help with feeding during this wild time.

Three weeks after hatching, the Cal Falcons crew determines the sex of the chicks by measuring their legs and tags each chick with a numbered identification band. Banding Day not only kicks off the naming contest for the chicks, but is also important for collecting specimens that can be used for mercury and genetic testing. A wealth of information can be collected from feather samples collected during banding. Banding also allows birders to track the travels of banded falcons in the future. Peterson describes Banding Day “It’s an incredible experience, and something that 20, 30 years ago, we never would have had the opportunity to be banding 18 chicks at this one site. That’s an incredible success story.” If you’ve been waiting to see if the 2022 chicks are Grinnell’s or Alden’s, Schofield reminds everyone that these things do take time and says those results are “coming in due time.” Banding usually occurs in May for Annie’s brood, so be sure to keep an eye on Cal Falcons’ social media accounts to stay in the loop.

Following Banding Day, it’s usually just two short weeks before the chicks begin peeking over the edge of the Campanile, preparing to take flight. The chicks will start looking out of the tower more often, spending more and more time on the decorative stonework of the tower, and eventually they will jump down to the outer ledge, deemed the “runway” or the “fledge ledge.” Peterson shares his favorite fledge story: “One year, there were two of them running around the ledge, circling. One of them was chasing the other and didn’t realize it was the end of the ledge and fell off, falling and finally catching himself, flying for the first time.” In a more typical scenario, chicks will spend up to a day there, with the parents bringing them food, until they take their first flight, or controlled fall, typically down to one of the nearby buildings. Schofield remembers a socially distanced 2020 fledge watch, when everyone was spread out around campus, 10 feet apart. “One of the chicks conveniently fledged as expected, and people were watching the chick with phones out. The gasp of the entire campus all at once spread across campus seeing the current fledge. That was a nice moment.” While uncommon, chicks have been known to miss target buildings when fledging and land on the ground. If you ever encounter one, reach out to one of the fledge watch volunteers around campus who can ensure grounded chicks are safe.

Once the chicks have taken their first flights, it’s time to learn how to survive on their own. Their parents help take care of them for another six to eight weeks, providing them with food as they learn how to hunt. This often takes the appearance of dropping food for the fledglings to learn to catch. The siblings will also be seen playing “talon tag,” where they will try to “catch” one another in an airborne version of tag, to practice their flying and hunting skills. The first year of life is a rough one for peregrine falcons, with only about 50–60 percent surviving to their first birthday. However, Annie’s brood has seen a fairly high success rate, with 16 out of 18 fledglings surviving to their move off-campus. “By all accounts, Annie has created a very successful little dynasty,” says Schofield.

While the whereabouts of most of Annie’s children are unknown, there have been a few sightings. Zephyr was seen in Vallejo in September of 2023, and Sequioa, one of Annie’s 2020 chicks, was last seen at the San Jose City Hall, until his mate, Shasta, passed away from avian flu in March of 2023. Lawrencium, one of the chicks from Annie’s second brood at the Campanile, has been successfully nesting on Alcatraz Island since 2020.

The Cal Falcons community

The Berkeley community has mobilized around this falcon family, and Cal Falcons has done an amazing job getting the Berkeley community and beyond in on the excitement of the season. In March, March Meme Madness begins, where the community warms up their comedy skills to create memes from the hilarious cam and Banding Day images. Peterson, the creator of March Meme Madness, says, “People are very clever, and I really have enjoyed what they’ve submitted.” Recent winners include “But this is my favorite loaf” and “Perhaps I would not like to science.” The community annually gathers for Hatch Day, and in 2023 Cal Falcons held the Hatch Day celebration at the BAMPFA big screen for the first time since the pandemic, where people could stop by to watch the nest cam on the big screen and ask experts their falcon-related questions. Cal Falcons even has merchandise available for fans who want to support the cam and demonstrate their love for Annie and her family, with a t-shirt fundraiser held each year during hatching season.

However, the most popular event is the annual chick naming, which typically occurs in May. Following Banding Day, Cal Falcons starts accepting name submissions for the chicks. Entries come in via the Cal Falcon social media accounts, where anyone can suggest names, as well as submissions from kids at the Berkeley Public Library. Once the submissions are in, voting opens to the public on their social media accounts. Last year, the winning names were Zephyr (named after the west wind), Luna (named after the moon), and Rosa (named after the first woman to graduate from UC Berkeley in 1874).

With a New Guy popping up every year, the community also submits ideas and votes for Annie’s mate’s name. Traditionally, the nesting pair at the Campanile has been given UC Berkeley-related names.

The reach of these falcons has gone beyond just the enjoyment of a community. Falcons are still a protected species, and work has been done to keep the Campanile nest safe. After one of Annie’s very first chicks fell victim to a window, Peterson says, “UC Berkeley was out there immediately adding bird safety features to all the windows near the tower. It was really heartening to see the response.” Cal Falcons was also happy to introduce signs last year that highlight restrictions against drone use on UC Berkeley’s campus. It’s important to keep drones away from nests right before nesting season, when falcons are most likely to abandon a nest site or alter their egg laying habits. Drones should also avoid nests with eggs and chicks, as parents defending their nest can injure themselves trying to fend a drone off.

Seeing peregrine falcons nesting at UC Berkeley has been wonderful, especially considering their near-extinction status just 50 years ago. “The fact that we were able to identify this really big ecological problem and fix it is a huge testament to human ingenuity and the ability to do things and get things done,” says Peterson. “The fact that falcons have been delisted from the endangered species list and that we now have more falcons flying around the tower than we did in the entire county at certain points is just a huge success story. It’s very heartening and a wonderful sign for what we can do as a species, as a community, to protect the life around us.” Although falcons still face challenges from unsafe buildings and avian flu, the community continues to mobilize to help this species thrive. We’ve been lucky to have such a successful nest right here on campus and to see the protections that the campus is putting in place for the birds. Stay tuned for yet another exciting nesting season with Annie and Archie.

Falcon facts

• Peregrine falcons are the fastest animals on the planet, and they use this speed to their advantage to hunt. Peregrines will search for prey high up, then nosedive toward their prey (reaching speeds over 200 miles per hour), striking their prey out of the sky. This famous dive is known as stooping.
• Peregrine falcons are highly adaptable birds. One of the most widespread birds in the world, peregrines are found on all continents but Antarctica. Individual falcons can travel very far from their original habitats.
• Like most raptors, peregrine falcons display sexual size dimorphism. Male peregrines tend to be one third smaller than female peregrines, earning males the name “tiercel,” which translates to “third” in Latin.