Spain’s Cliff-Nesting Gulls Are Actually Beach Bums

Picture a yellow-legged gull (Larus michahellis). Grey wings; beady eyes; a sharp, pointed yellow bill. It’s nesting on a precipitous cliffside, the surf pounding the rock face below. As the wind whips around the bird, it leans down to feed its chicks, which it keeps tenderly tucked onto the narrow ledge. The scene feels straight out of a nature documentary—the birds wild and unspoiled, the way they’re meant to be.

But cliffs may not be the gulls’ preferred habitat. Not all that long ago, Spain’s yellow-legged gulls nested on sandy beaches, often close to human settlements. What drove the birds to retreat to inaccessible cliffsides was changes to human behavior, including desperate Spaniards gathering gull eggs to survive the country’s civil war from 1936 to 1939 and the famine that followed. Now, as documented in a recent study, Spain’s yellow-legged gulls are adapting again. This time, they’re abandoning their aeries in favor of their former beachfront homes—much to the surprise of the people who’d forgotten, or never known, that these gulls are beach bums.

Almost a decade ago, Spanish ecologist Alejandro Martínez-Abraín coined the phrase “refuge abandonment” to explain why many of Europe’s wild creatures are moving closer to people. Centuries of conflict with humans had driven animals around the world away from their historical habitats, but as conservation initiatives, wildlife refuges, and changing public opinion have reduced harassment, predation, and conflict, many species are returning to old haunts in closer proximity to people, or even claiming new ones. 

Growing up in the 1970s and ’80s, Martínez-Abraín spent his summers birdwatching around Vigo, on Spain’s Atlantic coast. He remembers watching the cliff-nesting gulls. “I thought how pure it was, how wild, how perfect they were,” he says. “They looked made to breed in this remote site.”

But when he returned to the area around five years ago as a professor at Spain’s University of A Coruña, he realized that the gulls he’d grown up with seemed to be following the path of refuge abandonment that he’d defined years earlier. 

Setting out with doctoral student Nicolás Ron-Arroyo, Martínez-Abraín analyzed 46 years of yellow-legged gull breeding data to understand how and why gulls are abandoning their cliffside refuges. The history of yellow-legged gulls in Spain, they found, suggests the birds are responding to their fickle human neighbors.

Prior to the 1930s, gulls in northwest Spain inhabited beaches alongside human settlements. But as hungry people started gathering huge amounts of eggs, beachside turf was no longer a safe place for the gulls to nest and raise their young. The gulls flocked to remote seaside cliffs. Then, in the 1960s, when Spain opened a series of landfills near the gulls’ secluded habitat, the sudden food bonanza sent these nesting colonies into a decades-long boom. 

The gulls’ fortunes changed again in the 1990s when the landfills closed. Without enough food to support the inflated populations, gull numbers dropped. And it’s this stress, Martínez-Abraín thinks, that spurred the gulls to begin returning to long-abandoned nesting sites, including on human-accessible islets and even inside cities. To Martínez-Abraín, this is a perfect example of refuge abandonment. With the threat of egg harvesting long ended, the gulls are reclaiming their former beach habitat. 

Plus, now that these new gull colonies are established, they’re drawing in other seabirds, Martínez-Abraín says. Many birds like to nest near other birds, so much so that researchers regularly use decoys to draw real birds to new locales. So far, Martínez-Abraín and his colleagues have documented egrets and oystercatchers moving in to join the gulls on the beach. The newcomers, he says, take the gulls’ success as a sign that these habitats are once again safe for breeding.

“When you’re looking for a bar at night to have supper, you first check whether the bar already has people eating or not,” Martínez-Abraín says. “The birds do exactly the same thing.”

Whether the gulls can hold on to their new turf, however, is still up in the air. People in Spain aren’t typically eating gull eggs anymore, but many people in Spain do view gulls as pests, says Neeltje Boogert, an animal behavior expert at the University of Exeter in the United Kingdom who studies conflict between gulls and humans. 

“As soon as wildlife is in our habitats in a way that disturbs us, we don’t actually want that,” Boogert says.

Martínez-Abraín knows that not everyone likes gulls. “They come to playgrounds and eat the sandwiches of the children, or they defecate in the fancy boats of rich people,” he admits.

But as humans become more urbanized, and as people continue to reframe their relationships with wild animals, he says to expect more species abandoning refuge habitats for new—or perhaps old—terrain.

“It’s a new scenario of coexistence between humans and wildlife,” he says.