Enriqueta Velarde rarely stops, and when she does it's only because it's too dark to do anything more. She falls into a sleeping bag nestled inside another sleeping bag enclosed in a decades-old woven Yucatán hammock that once belonged to her great-aunt, which folds around her like a chrysalis. She snores enormously in the night, a familiar lullaby to 33 generations of gulls hatched and raised in the colony behind the hut. At first light she awakens and fights free of her cocoon.
Enriqueta Velarde.: Julia Whitty
"What's that noise?" I ask.
She's standing in front of the window in our room brushing her waist-length hair.
"It's the great blue heron."
I roll out of my hammock and grab my binoculars. This is one of countless mysteries from 1980 that Velarde has since solved. It takes me a while to see what she knows: up on the hill, a perfectly camouflaged 5-foot-3-inch-tall bird of the quiet seashore or lakeside, stalking as if on stilts and stabbing its six-inch-long bayonet at any gull foolish enough not to abandon hope and eggs. Gulls by the score are mobbing the heron, screaming on dive-bombing guano-firing runs. But the heron is an eating machine, stalking and stabbing, robbing eggs and chicks from one gull pair after another, swallowing their entire season's reproductive effort down its snaky neck.
In 1980 we'd puzzled over the morning clouds of mobbers but were never able to identify the intruder they were fighting. Mostly we were on guard for human interlopers, since one of our primary purposes then was to protect Rasa from the incursions of unregulated sightseeing ecotourists and from fishermen who raided the tern colonies and sold the eggs as aphrodisiacs. Both economies decimated the birds' population, driving it from an estimated high of 1 million in 1940 to maybe 5,000 in 1973.
In 1980 we intercepted two raiding parties, one friendly, the other not so, though both backed down before they got any eggs. And that was pretty much the last of them. News got around that Rasa was defended by a small, smiling but unyielding woman. Plus, Velarde befriended many would-be poachers and charmed them with her ready supply of jokes and impressed them with her annual migration, as predictable as a bird, to live on a waterless bedlam, often alone, seemingly happy. The fishermen respected her eccentricity. They also succumbed to the seductiveness of her story. That these waters—home to rare sea turtles, fish, porpoises, and whales—were among earth's most biologically productive. And that these islands—home to unique birds, bats, lizards, and snakes—were as irreplaceable as the Galápagos Islands and a genuine Mexican treasure.
"Over time the people in the fishing villages forgot about eating seabird eggs," Velarde says. "And have you noticed how the terns, though skittish, aren't as skittish as before?"
Given protection, Rasa's excitable wild birds grew tamer. Yet their numbers did not rebound. Not 5 years after the egg raiders all but disappeared, and not 10. Were the 30,000 elegant terns of 1980 all there would ever be on earth? The problem, Velarde suspected, was the island's other intruders: the hitchhikers who'd arrived with 19th-century guano miners—alien rats and mice that grew fruitful and multiplied on Rasa's three-month bonanza of seabird eggs and chicks. At night, Velarde says, she would hear the frantic alarm calls of the parent birds, helpless as their chicks were being gnawed to death.
So between 1993 and 1995, Velarde paired up with Jesús Ramírez, a Oaxacan from the Ecology Institute of the National Autonomous University of Mexico, to conduct a rodent eradication. They followed a New Zealand model that involved setting out hundreds of anticoagulant bait stations in every valley, hillside, and beach on the island. For two months they checked and rebaited each station every day, working throughout the winter, when the seabirds were away and the starving rodents were suffering their annual population crashes. But before the monitoring could be completed, Ramírez was killed in a car wreck in Mexico City.
"He spoke often of tequio," says Velarde, "the Aztec word the people of Oaxaca use when they talk about communal effort, the practice of able-bodied adults coming together to build a house or a school. When the time came to do the follow-up monitoring on Rasa, many people came forward in his memory—his girlfriend, siblings, friends, and colleagues—his tequio, assembled to complete his work." Their efforts confirmed that Rasa was free of rats and mice, a rare successful double eradication that holds to this day.
Velarde weighs gulls' eggs on the beach near her hut. : Julia WhittyIn the late afternoon Velarde leads the way across the island, stopping every few steps to scan with binoculars. We spy a few pieces of PVC pipe slowly disappearing under drifts of powdered guano. These are the last remnants of the bait stations deployed by Ramírez. "I never could bring myself to remove them," she says.
She's headed across a rocky hillside crisscrossed with the trails built by men who once mined up to 10,000 tons of guano a year from this island. Heermann's gulls nest in the remains of their tracks. It's been a couple of weeks since they laid their eggs, and the embryos are stirring, driving the gulls to ever more aggressive attempts to repel us. They scream so insanely in our ears and shit so voluminously upon us that I cringe. I remember melting down at this point in the 1980 breeding season, standing alone in a gull colony and screaming at the birds to shut the fuck up. Velarde is unflappable. She points with her clipboard at objects of interest: a nest with a dried seahorse in it; a nest with two eggs and a bleached chick skull in place of the third egg, a slightly Hieronymus Bosch incubation triptych.
Since the rodent eradication, the number of elegant terns has skyrocketed. The 240,000 Heermann's gulls have remained steady, though they've radically rearranged their nesting success. Velarde knows this because she's marked and counted seemingly countless eggs and nests and has banded around 36,000 chicks over the years, creating one of the most comprehensive seabird databases on earth.
Now she's leading the way to parts of Rasa she's monitoring in hopes that the rodent eradication may have enticed back seabirds long gone from the island—rare murrelets and shearwaters, secretive birds of the open sea who come ashore only under cover of night to nest in burrows. During the day, the adults leave their chicks alone underground, where they are utterly defenseless against rodents. At some point during the rat-beleaguered 20th century, these birds abandoned Rasa. Velarde hopes they may now find their way home again. That, she says, would be the ultimate memorial to Jesús Ramírez.
Eradication is a paradoxical conservation tool. The antithesis of life—poisons, traps—is used to revive life. It's like chemotherapy for the wild. All of these campaigns trace back to the late 1950s, to a handful of keystone progenitors in New Zealand concerned about the fate of white-faced storm petrels, diminutive seabirds who also come ashore only at night. Hobbled by legs designed to dance on water, not walk, these birds shamble down their burrows on the crutches of their wings, leaving them easy prey for alien rats. In 1959, funded with a whopping £5 from New Zealand's Wildlife Service, members of the Forest and Bird Protection Society scattered a common household rodenticide around the petrels' burrows on two tiny islands. It worked.
Since Velarde's and Ramírez's pioneering work on Rasa, alien predators and herbivores have been eradicated from 29 other Mexican islands at an astonishingly low cost of about $23 an acre. The once-bleak prospects of 88 endemic populations of tropic birds, lizards, land birds, trees, succulents, and wildflowers have been revived. More than 200 Mexican seabird breeding colonies have been liberated from destructive menageries of rats, mice, cats, goats, dogs, donkeys, sheep, rabbits, and pigs. Many reinvigorated Mexican species—including elegant terns and Heermann's gulls—now swell the ranks of US wildlife during their nonbreeding seasons.
But Velarde's work wasn't finished. Boosted by US donors and with the help of a few American researchers, she recruited a team of dozens of Mexican scientists to travel the Gulf of California on Mexican navy boats and undertake the first census of its more than 240 islands, a Darwinesque endeavor impelled by a modern urgency. The collaborative research confirmed the region's unique yet precarious biodiversity and led in part to Mexico receiving $25 million from the Global Environment Fund in 1992, followed by the creation of Mexico's first marine reserve, in the northern Gulf of California, and culminating in UNESCO declaring the islands of the Gulf a biosphere reserve in 1995 to preserve and restore natural ecosystems and develop sustainable alternatives to egg-gathering for local people.
A famous cartoonist created a series of graphic novels where beautiful women, bad guys, and handsome heroes sparred over the dangers of introducing alien species to the islands.
The original keystone idea that the Gulf of California was a Mexican treasure of unique biodiversity began to trickle out to people living in the Gulf's remote fishing outposts. Velarde initiated an education exchange with the indigenous Comcÿac people, learning from them about these islands and waters, their traditional home, and training their students as citizen scientists. She invited students from a local fishing village to visit Rasa and join her fieldwork. She participated in an innovative program that hired a famous cartoonist to create a series of graphic novels where beautiful women, bad guys, and handsome heroes sparred over the dangers of introducing alien species to the islands. The comic books became wildly popular, says Velarde, the fishermen eagerly awaiting the next installment.
By 11 o'clock on Rasa, the temperature in the sun, a.k.a. the entire island, is well over 100 degrees. Velarde is working fast in a gull colony full of birds sitting on eggs and gaping with bills wide open to relieve their heat stress. She holds in her lap a bird wearing a handmade straitjacket and a hangman's hood, each scrap of cotton used and reused so many times over the years that they're stained a guano camouflage. The bondage kit subdues the bird, allowing Velarde to weigh it, take its wing and bill measurements, and extract a blood and feather sample, the whole alien abduction process lasting five minutes before the animal is set free to return to its eggs. Some of these banded birds are 25 years old and have been data-mined so often by Velarde over the years that they're now virtually impossible to catch.