The cacophonous alarm cries of western gulls rang out as a crane lifted a boat full of visitors onto the windswept Farallon Islands, a bustling avian metropolis normally off-limits to all but a few scientists and government employees. An immature Nazca booby, a rare vagrant from the tropics, perched on a nearby rock, seemingly checking out the scene.
A short walk turned up huge groups of common murres standing side by side, floating offshore, and whizzing by overhead, interspersed with majestic cormorants, orange-beaked tufted puffins, and pigeon guillemots that emit high-pitched metallic whirs as they take off. Cassin’s auklet chicks hid away unseen in burrows and nest boxes, awaiting their parents’ return that evening.
Every year, more than half a million seabirds arrive on the Farallones to breed. That’s more breeding birds than Oakland has people and more than any other seabird colony in the Lower 48. Just about every square foot of territory gets claimed by a pair of murres, guillemots, puffins, auklets, gulls, cormorants, oystercatchers, or storm petrels—except for what’s taken up by five species of seals and sea lions.
Located some 27 miles west of San Francisco—on clear days, mainland beachcombers can see the islands’ jagged outlines far off in the distance—the Farallones are a great conservation success story. Here birds like murres and cormorants have bounced back from much human-caused devastation, including hunting, commercial egg harvesting, oil spills, offshore dumping of radioactive waste, and gillnet-fishing entanglements. But now these birds face a newer threat: warming oceans that make it increasingly hard for them to feed themselves and their chicks.
In 2023, global sea surface temperatures reached record highs, and they’ve continued to spike in 2024. Around the Farallones, an El Niño that lasted from summer 2023 to the end of spring 2024 raised temps a couple of degrees above the long-term average and caused some birds to delay breeding, to not breed at all, or to lay fewer eggs than normal.
“They’re keeping more resources for themselves, basically, instead of putting them into reproduction,” says Amanda Spears, a Farallon Islands program biologist with Point Blue Conservation Science, a nonprofit that in partnership with the U.S. Fish and Wildlife Service has been monitoring and conducting research on the islands’ seabirds since 1968.
This year, of the dozen seabird species that breed on the Farallones, Brandt’s cormorants seem to be doing the worst. Researchers report that these fish-eating birds set up their nests as usual in spring, only to abandon them en masse and take off for parts unknown.
Once water temperatures cooled back down in May, some Brandt’s cormorants returned to the islands for a second go-round at nesting, leading to hopes that chicks will be raised after all.
Though not ideal this year, ocean conditions could also be far worse. From 2013 to 2016, a marine heat wave nicknamed “the Blob” drove water temperatures in parts of the Pacific as high as 7 degrees Fahrenheit above average. All along the Pacific coast, seabirds washed up dead, especially Cassin’s auklets in the winter of 2014–2015 and common murres the following year. “Put your favorite choice expletive here,” says Julia Parrish, a University of Washington biologist and executive director of the Coastal Observation and Seabird Survey Team. She co-authored a 2023 study estimating that “the Blob” and continued warming afterward caused millions of excess seabird deaths.
To make matters worse, an El Niño event extended some of the effects of “the Blob.” Then, in 2019, a second marine heat wave, nicknamed “the Blob 2.0,” further stressed Pacific seabirds, though not nearly to the same degree as the first one.
On the Farallones, there have been boom years as well, times when nutrient-rich cold water, driven to the surface by strong northwest winds, kick-starts a biological cascade that runs up the food chain from plankton to blue whales. “The ocean comes alive,” says Spears, who was on the Farallones at the start of California’s Covid lockdown and ended up spending 20 straight weeks there. “There’s this bloom of life.”
Overall, though, breeding success has become more variable for the Farallones’ seabirds, whose populations, which had been skyrocketing for common murres and other penguin-like alcids in the early 2000s, have largely plateaued.
“Seabirds are long-lived, so they’ve always been able to withstand a few poor years,” says Pete Warzybok, Point Blue’s Farallon program leader, who has spent over 2,500 nights on the islands, more than anyone since the last civilian lighthouse keepers left in 1941. “But when [the poor years] start to stack up … eventually you get to a tipping point where the wildlife can’t adapt anymore.”
Much like kelp forests and coral reefs, seabird colonies are particularly vulnerable to climate change, which alters the ocean in various ways, including by increasing the frequency of both marine heat waves and extreme El Niño events. And when the water warms, it can affect the size, location, and number of forage fish and marine crustaceans that seabirds depend on for food, in addition to causing toxic algae outbreaks. “The basic story is there’s not enough food to go around,” Parrish says. She notes, however, that researchers still struggle to understand exactly “why we see millions of murres washing ashore, but not loons or grebes or gulls or cormorants.”
Besides lowering prey availability, climate change also causes sea-level rise that decreases the amount of land available for nesting, and it fuels more intense storms that can wash away nests.
Seabirds do have ways of adapting. Cassin’s auklets, for example, have been found to produce two clutches during productive years, which has helped their Farallones population of around 25,000 remain stable despite several tough years. Researchers are currently replacing wooden nest boxes on Southeast Farallon Island with ceramic modules that stay cooler for the auklets when temperatures rise.
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Other species seemingly hedge poor years on the Farallones with less tumultuous nearshore colonies. A 2022 study found that while “the Blob” was wreaking havoc on nesting pigeon guillemots in the Farallones, their counterparts on Alcatraz were doing fine. “They actually seem to be buffered from those warmer conditions,” says Tori Seher, formerly the National Park Service biologist for Alcatraz and the study’s lead author. “The Bay just provides a more stable environment.”
Still, the Bay Area’s much smaller nearshore colonies could never replace the productivity of the Farallones, which, even in poorer years, remain chock-full of marine life. The islands are now home to around 500,000 common murres, a population uptick from under 100,000 in 2000. (The murres are by far the most common bird there.)
Besides climate change, researchers on the Farallones worry about avian flu, which has decimated seabird colonies elsewhere, and about nonnative house mice (which attract burrowing owls that prey not just on the rodents but also on rare and secretive ashy storm petrels). Another issue is money: Due to budgetary constraints in the Fish and Wildlife Service, Point Blue is set to lose its federal funding starting in 2025.
The Farallones are closed to the public, and very few people get to set foot on the islands. But this May, the Fish and Wildlife Service and Point Blue organized a media tour for the first time in years.
After a two-and-half-hour boat ride through the notoriously bumpy waters outside the Golden Gate, journalists took turns being transferred to a smaller boat and then lifted by crane onto Southeast Farallon Island. They then trekked to the island’s highest point, where the lighthouse stands, and passed myriad gull nests with splotchy brown eggs inside. The gulls loudly expressed their disapproval of the human intruders while also jostling with each other. One gull had its neck bloodied in a fight with a neighbor.
Closer to shore, a California sea lion grabbed her newborn pup, the umbilical cord still attached, and lurched it away from approaching waves as gulls swooped in to feed on the afterbirth. Just yards away, a massive male Steller sea lion, with a particularly enormous neck and shoulders, charged a smaller subadult. “That is awesome,” said Gerry McChesney, manager of the Farallon Islands National Wildlife Refuge, while peering through binoculars. “I just love it out here.”
