Limes Platalea: the invisible leap of the Spoonbills
- Nov 2
- 7 min read
Updated: Nov 3
Interview with Paco Hortas and Javier Ruiz, founders of the project that uncovered one of the most remarkable migrations between Europe and Africa.
A discovery born on the coast of Cadiz
On the beaches of Andalusia’s Atlantic shore, amid tourists and umbrellas, an extraordinary natural phenomenon unfolds every summer. Thousands of Eurasian Spoonbills (Platalea leucorodia) cross the sea toward Africa, following a migratory corridor that was unknown until recently. The discovery is thanks to Paco Hortas and Javier Ruiz, two naturalists from Cadiz who, in 2011, founded the Limes Platalea Project—a name that alludes both to the Latin for “border guarded by patrols” and to the spoonbill’s genus. Their goal was to study and document this migration route. The project operates under the umbrella of the Sociedad Gaditana de Historia Natural (Natural History Society of Cadiz).
“It all started out of pure curiosity,” recalls Paco. “In 2011, María José Morales —Javier’s wife— began seeing Spoonbills on La Barrosa beach. At first, Javier didn’t think much of it, but he soon realized it wasn’t just a passing occurrence: on some days, nearly a thousand birds were flying by.” That casual observation became the starting point of a project that would transform the understanding of this species’ migration in Europe.
The crossing mystery
Until then, it was assumed that spoonbills crossed to Africa at night or through the Strait of Gibraltar, like most migratory birds. But something didn’t quite add up. “We realized there were spoonbills in Doñana and also in Africa, yet no one knew how they got there,” explains Javier. “It was a gap in knowledge in a province with such a strong ornithological tradition.”
The two decided to find out for themselves by launching the Limes Platalea Project. Working in coordination with the Fundación Migres and the Colectivo Ornitológico Cigüeña Negra, they set up a network of observation points from Cadiz to the Strait. “Within this project we had four watchpoints: Torre Bermeja, Torre del Puerco, Cabo Roche, and Cabo Trafalgar,” Paco explains. “We wanted to know whether this passage was real or just a coincidence.”
1. Torre Bermeja - 2. Torre del Puerco - 3. Cabo Roche - 4. Cabo Trafalgar
Soon the data left no doubt. The Spoonbills weren’t crossing at Tarifa but further north, along a coastal corridor between the Castle of Sancti Petri and halfway toward Cape Trafalgar, guided by wind and tides. “There were days when thousands passed,” says Javier. “And we realised we were witnessing one of the last great visible migrations between Europe and Africa.”
An Atlantic migration
Unlike birds of prey, which depend on thermal currents to glide, the Spoonbill is a versatile flyer: it can flap its wings or glide as needed. “It’s an all-terrain bird,” says Javier. “It can make 60-kilometre leaps to reach the African coast, taking advantage of side winds.”
This ability explains why it doesn’t cross through the Strait. “The most direct route for them isn’t Tarifa,” Javier clarifies. “They follow a north–south axis perfectly aligned with Morocco’s Atlantic wetlands. It’s a distinctly Atlantic migration, not a Mediterranean one.”
The discovery redefined what was known about the species. “For years it was believed that Spoonbills migrated at night or crossed from Portugal. No one was looking here,” adds Paco. “And yet, on Chiclana’s busy beach, the crossing to Africa was taking place in plain sight.
The rebirth of a species
The Eurasian Spoonbill was on the brink of extinction in Europe by the mid-20th century, with barely 300 breeding pairs remaining. “Today it’s a success story,” says Paco. “The species has recovered and expanded northward across the continent. Now they even breed in the United Kingdom.”
Javier adds an interesting detail: “Its traditional Spanish name was averramia, because it used to nest in trees. The term espátula became popular in the 19th century, when a Spanish naturalist described the Roseate Spoonbill in South America and the name spread to this species as well.”
The species’ recovery is due to several factors: the protection of wetlands, the ban on hunting, and a more diversified breeding strategy. “They used to nest in large, dense colonies in Doñana; now there are many smaller colonies spread across the Iberian Peninsula — even in places like Gredos or Zamora,” explains Javier. “That makes them more resilient.”
An unpredictable migration
Every year, from late July to mid-November, the Cadiz coastline becomes the stage for a constant flow of white flocks. “There are days when more than a thousand Spoonbills cross in just a few hours,” says Paco. “In the project’s first year we counted around ten thousand. Today we record more than twenty thousand.”
But Spoonbills are unpredictable. “Sometimes they don’t pass when the conditions seem perfect, and then suddenly, on a terrible day, hundreds of them appear,” Paco laughs. “It depends on the winds, the rain, the breeding season in Europe… they always find a way to surprise you.”
The team also discovered a fascinating phenomenon: the returns. “When conditions over the sea are unfavourable, the flocks abort the crossing and come back to the Bay of Cádiz,” Paco explains. “They wait until the winds improve before trying again.”
So far, not a single drowned Spoonbill has ever been found — something that does happen with other migratory birds. “They have an incredible ability to make decisions and correct their course.”
The role of wind and collective intelligence
Spoonbills plan their crossing according to the wind. “When a strong levante blows, they take off earlier, looking for the right angle to ride the side current,” notes Javier. “It’s like sailing.”
That skill is combined with complex social behaviour. “The young migrate alongside the adults and learn the route from them,” Javier explains. “There’s a migratory culture that’s passed down from generation to generation.”
The team is also studying how the flocks are structured and which birds take the lead. “We want to understand whether there are hierarchies, how they communicate, and which environmental factors determine the success of the crossing,” Javier adds. “There’s still so much to discover.”
Science and citizenship
Although the Limes Platalea Project began as a scientific initiative, its social impact has been huge. “From the start, we were clear that this had to reach people,” says Javier. “We want citizens to be aware that they live in nature, not against it.”
The project now involves between 80 and 90 volunteers each season. Some take part almost daily, others just a few days a month. “We adapt the shifts to each person’s availability,” Paco explains. “And the best part is that it’s created a network of friendships. Many met here and keep coming back year after year.”
During the early years, the task was enormous. “We used to do twelve-hour shifts, from eight in the morning to eight in the evening, with a fierce levante wind blowing,” recalls Paco. “But even on the toughest days, seeing just one flock made it all worthwhile.”
From data to wonder
Over time, the project’s founders have learned to combine science with emotion. “We count the birds with scientific rigour, but we never stop being amazed,” says Javier. “When a huge flock of Spoonbills passes over the sea, it’s a deeply moving sight.”
The project has also made it possible to gather valuable information about the effects of climate change. “The Spoonbills are delaying their migration, and more and more of them are spending the winter in Europe,” explains Paco. “Here in Cadiz, we’re like the species’ customs officers — we physically count how many cross, so we can tell whether the population is growing or declining.”
A new way of looking at the beach
Beyond the science, Limes Platalea has transformed the way people relate to the beach. “What’s unique is that this phenomenon unfolds right before the eyes of thousands of unsuspecting tourists,” says Javier. “While others come for sun and sand, here you can witness one of the most beautiful migrations in Europe.”
That visibility has sparked local interest and pride. “The Chiclana town council has supported us by putting up information panels, and together with El Cuartel del Mar—which also lets us use its rooftop as an observation point—we created a Spoonbill-shaped weather vane and even a roundabout,” says Paco. “Now many people recognize the Spoonbills and explain to visitors what they’re seeing. That’s wonderful.”
The project has also attracted international observers. “Dutch ornithologists come here specifically to watch them cross,” says Javier. “For them, seeing a Spoonbill migrating here, flying low over the sea, is something unique. Nowhere else in Europe can you witness it like this.”
The legacy of a passion
Over its thirteen years of work, the Limes Platalea Project has recorded more than a quarter of a million Spoonbills. But beyond the numbers, it has inspired knowledge, connection, and wonder. “We’ve seen it all — flocks at dawn, flights skimming the water, formations shifting with the wind,” recalls Paco. “Every day is still exciting.”
The team plans to keep expanding its research with new technologies, such as drones that can observe the structure of the flocks from above. “We still have so much to learn,” says Javier. “Every answer opens up new questions.”
A spectacle by the sea
The passage of Spoonbills along the Cadiz coast is one of those natural events that reconcile science with emotion. As the project’s founders sum it up: “To see lynxes you go to Andújar, to see bears you go north — but to watch Spoonbills migrating, you come to La Barrosa, to the beach, with your feet in the sand.”
When the conditions are right and the sky fills with white wings, anyone looking toward the horizon can witness that fleeting moment when Europe and Africa touch. And as Paco and Javier like to say, “If you haven’t watched Spoonbills crossing the sky above La Barrosa, you haven’t truly seen them.”
Comments