Mexico’s Conservation Efforts Spur Dramatic Recoveries for 20+ Species of Seabirds
By Abby McBrideElegant Terns by Oscar Wilhelmy/Macaulay Library. June 6, 2020
From the Summer 2020 issue of Living Bird magazine. Subscribe now.
In 1980, a San Diego newspaper published a eulogy, of sorts, for the wildlife of Mexico’s westernmost possession—Guadalupe, a big volcanic island 150 miles off the coast of Baja California.
“Death of an Island,” read the headline. “Eaten away by goats.”
Once known as Isla de los Pájaros (or “island of the birds”), remote and rugged Guadalupe was home to more endemic bird species than any other island off the Pacific Coast of North America. That came to an end when sealers and whalers arrived in the early 1800s. They brought goats, which leveled the pine and cypress forest, and cats, which killed thousands of birds. Five of eight endemic land birds went extinct. The Guadalupe Storm-Petrel disappeared.
But in the few decades since that grim newspaper article was written, something marvelous has happened on Guadalupe. The goats are gone; the vegetation is rebounding. A colony of Laysan Albatrosses has materialized out of nowhere. Here, and on other once-devastated islands throughout the ocean waters off northwest Mexico, populations of auklets, murrelets, storm-petrels, gulls, terns, boobies, pelicans, and cormorants have been reappearing as if by magic.
Magic … and a lot of hard work. Over the past two and a half decades, Mexican biologists have pulled off a massive effort to reverse centuries of damage and restore these seabird nesting islands. Their success is a gleam of hope, in a world that is losing seabirds fast.
Global Seabird Decline
Many islands around the globe have suffered a biodiversity crisis. More than four-fifths of the world’s bird and mammal extinctions have occurred on islands. The biggest drivers of extinction are invasive mammals: rats, cats, goats, pigs, donkeys, rabbits.
When seafaring humans set foot on an island, they tend to bring other mammals with them—and seabirds suffer. Rats and cats run amok on seabird breeding colonies, eating eggs, young, and even vulnerable nesting adults. Livestock can be just as destructive. When goats chewed away the vegetation on Guadalupe, they caused erosion that affected the storm-petrels nesting in burrows in the forest.
These are pressures that seabirds can’t afford to face. Of the world’s roughly 350 seabird species, about half have declining populations. From penguins in the Antarctic to puffins in the Arctic, seabirds collectively have declined almost 70% since the 1950s, faster than every other comparable group of birds. One consequence of this loss is a broken link in the ecosystem: Seabirds fertilize the plant life on islands with their guano (feces), which is full of marine nutrients from eating fish, squid, and krill.
The seas and shores of Mexico make up one of the most important regions for seabirds in the world. With more than 4,000 islands and islets, Mexico has one-third of the world’s seabird species nesting on its islands or feeding in its waters, and is second only to New Zealand in its diversity of endemic seabirds. But with islands overrun by mammals, Mexico’s seabirds faced a bleak future on their breeding grounds.
International Seabird Alliances
Twenty-five years ago Mexican conservationists began the crucial first stage of island restoration: routing the invaders.
One of the first islands in the country to be cleared of invasive mammals was a low-lying rock within the Gulf of California: Isla Rasa, the small, unassuming home to nearly all of the Heermann’s Gulls and Elegant Terns in the world.
After years of research on Isla Rasa, Enriqueta Velarde of the University of Veracruz was certain that invasive rats were harming bird populations by eating eggs and chicks. Velarde and her collaborators, led by Jesús Ramírez of the Universidad Nacional Autónoma de México, set up poisoned bait stations all over the island, carefully targeting the invasive rodents with methods that had worked on islands around the world.
“We got advice from people from New Zealand, Australia, Galápagos, and the Channel Islands of California,” Velarde said. “And it was successful.”
Once the rats were gone, the seabirds began to breed prolifically— especially Elegant Terns, whose population increased tenfold.
A few years later, it was Guadalupe’s turn. In 2000, an NSF-funded expedition of U.S. and Mexican scientists visited the Pacific island by helicopter to assess its conservation challenges. Shortly afterward Mexican conservationists, led by former GECI director Alfonso Aguirre-Muñoz, approached their federal government about eradicating goats from Guadalupe.
“That was the turning point, when we sat with them and said ‘We can do this. We can get the funding, and we can do it right, once and for all,’” said Federico Méndez-Sánchez, executive director of the Grupo de Ecología y Conservación de Islas, a conservation nonprofit group that has worked to restore islands off of northwest Mexico since 1998.
The Mexican scientists enlisted the expertise of invasive-predator eradication specialists from New Zealand. They also sought support from the Mexican Navy, which has a base on Guadalupe.
“[The Navy] provides logistics. They take us to islands, they bring a helicopter,” said Méndez-Sánchez.
With this help, Grupo de Ecología y Conservación de Islas eradicated all the goats from Guadalupe—more than 50,000 of them—by 2007.
It was a big victory, on a big island, with a big payoff. The vegetation started to come back immediately.
“The resilience of the island is so powerful,” Méndez-Sánchez said. “It’s inspiring.”
From there, the group turned its efforts toward dozens of smaller islands up and down the Pacific coast of Baja California. In just 20 years Grupo de Ecología y Conservación de Islas removed 60 populations of invasive mammals from 39 islands: rats, cats, mice, dogs, donkeys, goats, and rabbits. With invasive mammals gone, the stage was set for seabirds to return.
Social Attraction for Seabirds
Even after the mammal invaders are removed it’s not always easy to convince seabirds to recolonize an island.
Seabirds tend to return to their own fledging locations when it comes time to breed. And they avoid nesting on empty islands, where they would be the first kids on the block.
Audubon biologist Steve Kress pioneered a method to deal with this seabird neophobia in his restoration work for Atlantic Puffins. Kress used an array of social attraction methods, including decoys and sound recordings, to entice puffins back to islets off the coast of Maine in the 1970s.
Protocols from Project Puffin have since been used around the world, including on the islands of northwest Mexico. Over the past decade, the biologists of Grupo de Ecología y Conservación de Islas have been attracting seabirds to islands by installing decoys, audio systems, and mirrors (which create an illusion of more birds than there really are). Biologists built artificial burrows to give seabirds a head start on nesting in their new homes. While continuing to remove invasive mammals and vegetation, they have also trained lighthouse keepers and navy personnel to avoid introducing new invasive species.
The Cornell Lab of Ornithology sent bioacoustics specialists to consult with the Mexican biologists on audio attraction techniques, such as building playlists of seabird breeding calls. Mexican scientists also traveled to Maine to exchange expertise with Audubon’s Project Puffin.
“We always say, it’s collaborate, collaborate, collaborate, both nationally and internationally,” Méndez-Sánchez said.
An international partnership between the United States, Canada, and Mexico—the Trilateral Island Initiative— brought substantial funding to the effort, in the form of pollution settlement funds from an oil spill near San Francisco’s Golden Gate Bridge and from DDT pollution off the coast of Los Angeles. This U.S. funding supported restoration on Mexico’s Pacific islands specifically for seabird species shared between the two countries.
“The birds move!” explained restoration ecologist Jennifer Boyce of the NOAA Restoration Center. Many birds affected by ocean pollution in U.S. waters breed in Mexico.
The collaboration was a massive success. Of 27 seabird populations that had disappeared from Pacific islands near Baja California, 22 populations have returned within the past decade. Four new species are nesting in the region, including Blue-footed Booby and Caspian Tern.
And the work continues at full tilt for Grupo de Ecología y Conservación de Islas. The group’s marine birds project director, Yuliana Bedolla-Gúzman, could not be reached for comment on this story, because she was on remote Socorro Island, working to save the critically endangered Townsend’s Shearwater.
The group’s ongoing achievements are “significant conservation gains,” said Holly Jones of Northern Illinois University, an expert on the roles of seabirds in the recovery of island ecosystems.
“The extra work they are doing restoring these islands—attracting seabirds, habitat restoration—is something that is rarely done to follow up eradications, and is likely to speed up [island] recovery,” Jones said.
“And their work at one relatively localized area has been critical in helping conserve global populations of seabird species.”
Mexico is working toward a national goal of removing all nonnative mammals from its islands by 2030. On Guadalupe, happily, the 1980 prediction that the island will “continue to slowly deteriorate” has not come true. Not only is vegetation returning to the goat-free island, but both landbird and seabird populations are growing.
Guadalupe is still plagued by invasive cats, but Grupo de Ecología y Conservación de Islas is working to remove them by 2021. In the meantime, to protect nesting Laysan Albatrosses, the biologists built a 735-meter-long cat-proof fence modeled after fences they had seen in New Zealand and Hawaii.
The year after the fence was erected, two pairs of nesting Guadalupe Murrelets joined the albatrosses inside the 150-acre protected area. The murrelets had long before been wiped off their namesake island, where most of the population once bred. Now their population has exploded to 187 active burrows in only four years.
With social attraction techniques, Mexican biologists aim to bring more and more murrelets to Guadalupe from the surrounding islets, along with other species that had been driven off the island in the past: Cassin’s Auklets, Black-vented Shearwaters, and the endemic Ainley’s and Townsend’s Storm-Petrels (recently split from Leach’s Storm-Petrel).
“My hat goes off to these folks,” said David Ainley, the Pacific seabird researcher for whom Ainley’s Storm-Petrel is named. “It’s an incredible effort.”
As for the Guadalupe Storm-Petrel: still missing. But maybe, just maybe, when the cats are gone, it will return.
Researchers are keeping an eye out, said Méndez-Sánchez: “There’s hope.”
Abby McBride is a science writer and Fulbright National Geographic Storytelling Fellow. She recently spent a year traveling around New Zealand to write about seabird conservation.
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