In August and September, punky-crested white seabirds normally seen in southern climes descended upon the Bay Area in the thousands. Clouds of them swirled at Crissy Marsh, getting rowdy among themselves with their karr-eeks and gaks. Huge gaggles thronged the Pacifica Pier and the Alameda Naval Air Station, their tangerine beaks and hairdos standing out among the seagulls.
It terns out they may be here to stay.
Elegant terns, previously known for only breeding in a few select locations off the coast of Mexico and Southern California, appear to have established breeding grounds across at least seven sites in the Bay Area, say researchers and longtime birders. This May, birder Tony Brake uploaded photos to eBird of crowds of elegant terns and at least one egg on the shoreline of Brooks Island, a small, shrubby island that’s a half-mile from Richmond. He estimated some 1,800 elegant terns were milling around on the island.
Before 2024, nobody had ever reported spotting any elegant terns nesting there.
David Assmann, a San Francisco-based birder, says 10 to 20 years back, the terns would only show up in late summer, after breeding—and in much smaller numbers. A few years ago, he and other birders began to see them in the spring. These hordes of terns seen around this August and September were likely juveniles that had been born in the Bay a few months prior, along with their parents, Assmann says. This year, the late-summer spike in total birds reported per week in the area was nearly twice that of last year, eBird data shows.
Historically, about 90 percent of elegant terns (Thalasseus elegans) bred on just one island, Isla Rasa, in Baja California. In the 1960s their breeding grounds expanded to San Diego. Now, it seems, they’ve moved farther north.
Experts on West Coast ecosystem dynamics say the trend-setters are probably here because of El Niño and marine heat waves.
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Climate change is forcing many animals to move, with marine species moving much faster than terrestrial ones. And lots of birds—and other marine animals—show up in strange places during El Niño years, following warmer waters and moving prey. Just this year, researchers have already seen an influx of tropical boobies, as well as sightings of yellow-bellied sea snakes and white sharks. Some of these fellows are just stopping by, but some might be changing their behavior for good.
“The anchovy dynamics have shifted so much in the San Francisco Bay that I can pretty much guarantee that that’s why you’re seeing them here,” says Julie Thayer, a researcher at the Farallon Institute for Advanced Ecosystem Research, a Petaluma-based nonprofit scientific organization that specializes in teasing out marine environmental trends. “The conditions in the Gulf of California have deteriorated so much, especially with the marine heat wave and the Super El Niño, it is very likely that they do not have the food resources they need down there.”
You can see various kinds of terns fishing the Bay during the summer and fall. They fly in a beeline, swiveling their heads down to get a view of the water as they go. Suddenly, they plunge down at speed, like a Blue Angel. Their sharp orange beaks strike the surface of the water for just a second or so before they pop up again, often with a small fish. They’ll eat whatever they can get their beaks on within a couple feet deep in the water—anchovies and sardines, most of the time. Bill Sydeman, the Farallon Institute’s president and chief scientist, says, “Sardines are way down in California, whereas the anchovies are way up, and so the birds are doing great because of the anchovy stock.” He says the anchovy population near the Bay has exploded from roughly 100,000 metric tons around 2015 to over 2 million metric tons now—and researchers aren’t sure exactly why yet.
The nesting real-estate requirements of terns are simple: lots of fish, a nice beach, and little to no disturbance from humans. While most of the Bay may not seem to meet that last point, Brooks Island, which is managed by the East Bay Regional Park District, does. There, visitors are only let on the island for about six tours a year; a caretaker is the only human resident. The island is already a known residence for Caspian terns, which don’t mind intermingling with other seabirds hanging around, though elegant terns like to keep to their own gang.
So earlier this year the terns set up shop there en masse, traveling in gregarious groups as terns generally do.
Elegant terns have been known to make big moves from Baja California before. After a big increase in the Isla Rasa population, some elegant terns made “extraordinary movements” across the planet, as scientists wrote—to Ireland, Spain, and South Africa. “This might sound a little tongue-in-cheek,” says Sydeman, “but one of the greatest adaptations that birds have is that they can move easily and can travel great distances over relatively short periods of time.”
Many terns live in the Bay already, including Caspian terns (the largest terns in the world), Forster’s terns, Arctic terns, and the endangered least tern (also the world’s smallest tern species). Elegant terns are considered near-threatened by the IUCN Red List, especially because they use so few breeding grounds.
So is it good or bad that they’re expanding to the Bay Area?
In 2021, the Bolsa Chica colony in Orange County experienced a major disturbance. An unauthorized drone crashed into the beach, and all the birds abandoned their eggs—around 1,500 sand nests. Organizations like the International Bird Rescue stepped in to care for the chicks. Some of the chicks they banded that summer have been spotted up here in spots like Alameda, says Meredith Elliott, researcher at Point Blue Conservation Science, a Petaluma-based nonprofit science organization that monitors seabirds. Having a more expansive breeding area might prevent an incident like that from wiping out the whole species.
“It’s exciting to see elegant terns in the Bay Area, but it’s also a reminder that climate change is pushing species into new areas,” Elliott says. “It’s hard seeing species, especially like the elegant tern, that historically had some great breeding success in this small area, now have to move and find a new place to live.”
With nesting season now over, the teenaged terns have left the nest and begun migrating. Some will continue further north to Oregon and Washington. Others will go further south to Peru and Chile. We won’t find out if they enjoyed their stay in the Bay until the cycle begins again next summer.
