The return of the ibis: these biologists are teaching a flock to migrate to Cádiz

On September 8, two ultralight aircraft flew over the Pyrenees. Huge floating tricycles with a fan on their back. They hung from a yellow paraglider six meters in diameter and were followed by 35 black, very black birds, forming a strange human, mechanical and animal entourage. It was an amazing picture, like something out of an animated movie. About 100 meters below, winding along the roads linking France and Spain, several vehicles full of biologists closely monitored the expedition. And so, after a hiatus of hundreds of years, a flock of hermit ibis returned to migrate to Spain. It has not done so since the Middle Ages, when it is believed that this species of migratory bird became extinct throughout Europe.

After landing and camping in a meadow in the Alt Empordà, Johannes Fritz, biologist and experienced pilot, takes a few minutes to answer the phone and explain how it feels to lead this strange migration: "It's something surreal, to be up there surrounded by a large group of birds, to be basically part of the flock ... They could do whatever they wanted, fly in all directions, but they follow us for thousands of miles. It's incredible." It is even more so after Fritz's explanation: birds follow their "adoptive mothers". They are Helena Wehner and Barbara Steininger, the volunteers who are co-pilots in the ultralights, and who for weeks have fed them in an aviary in Austria, where they have grown up. Now they teach them the migratory routes as a mother would with her chicks. The idea is for birds to memorize the path. Afterwards, they will be released in Jerez de la Frontera and once acclimatized, they will teach this migratory route to their young and repeat it every year. It may sound far-fetched, but Fritz knows it will work. After all, he's been doing it for 20 years.

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"This is the sixteenth migration I've done in the last two decades," he explains proudly. "We already have a population of about 250 birds in the wild and about half have been raised in the wild. They have learned these routes from their elders." However, this migration is different, important. It feels kind of like the former. The destination is the south of the Iberian Peninsula and not Tuscany, Italy, as it has always been until now. "It's because of climate change," explains the biologist. "We have been forced to change routes."

To survive the winter of central Europe, the hermit ibis needs to migrate south. Fritz taught them how to do it from Lake Constance (which separates Austria, Germany and Switzerland) to Italy, crossing the Alps, the highest mountain range on the continent. Normally, they did it at the end of September, but global warming has delayed the migration of these birds, which now begin to take flight in mid-October. By then, temperatures may be mild on the lake, but they are impossible in the Alps, which becomes an impassable wall of ice. Last year only five of the 60 ibises that tried to cross them succeeded. Fritz and his team, the Waldrappteam (waldrapp means ibis in German), had to transport the rest by van. But a seasonal migration can't function like an Uber service. Another solution had to be found.

The flock of ibis flying in an image captured from the ultralight of Fritz.Waldrappteam

The solution was offered by Ingrid. This is the name of one of the ibis with which it migrated in 2022. But at some point, in the Alps, Ingrid got lost and embarked alone on a long journey to Malaga. The Waldrappteam had him marked and as soon as he knew of his new home, he picked up the phone and called his Spanish colleagues.

Miguel Ángel Quevedo Muñoz is a veterinarian at the Jerez Botanical Zoo and one of those responsible for the Eremita Project, which has been trying to increase the population of this bird in the Spanish habitat since 2003. First in captivity; for years, reintroducing it into nature, near Cadiz, at a rate of about 20 per year. When he spoke to Fritz, he quickly raised the possibility of making Ingrid's route the main one. To offer itself as a new destination, bringing together the migrant populations of Austria with the sedentary ones of Spain. "Spanish birds do not migrate, since the cold is not as intense here as in Austria," explains Quevedo in a telephone conversation. But sedentary lifestyle means that they do not join other populations and that is a challenge for the Hermit Project team: "We have to increase the genetic variability of birds," summarizes the expert.

Until now they did it with an exchange between other European zoos, something like an Erasmus of birds, through the European Endangered Species Program. Quevedo explains it with a more biblical simile: "Many zoos function as small Noah's Arks, conserve threatened species so that there is good genetic variability and that we can exchange between different zoos." But what the Waldrappteam proposed went much further. It did not go through a punctual exchange, but through the mixture of two populations. "We don't know what's going to happen," Quevedo acknowledges. "We know that they are gregarious birds, that they are going to mix well, but we do not know if the Austrian group will resume its migration back in spring, we intuit that it will and it is possible that some of the Spanish group will follow them. But maybe some stay, we'll see."

One of the adoptive mothers spends time with the flock of ibis. FERNANDEZ MICHEL

Raptor attacks

1,600 kilometers from Cadiz, Johannes has had a little scare. A bird of prey caused its ibis flock to break up and two of its specimens have been lost. "It happens sometimes," he says with resignation. "But in all these years we have only lost one bird to predator attacks." It does not seem that this incident will change his flight plan much. They came out on August 21. They will arrive, if all goes well, at the end of September.

"We travel about 120 kilometres a day, weather permitting," explains Fritz. The Waldrappteam is made up of 14 people. They have two ultralight aircraft and five vehicles. Upon landing they set up a small camp. The birds follow their adoptive mothers from one place to another, also by land. To facilitate recognition, both go with a striking yellow raincoat, the same color as the parachute.

Then they set up a portable aviary, in a couple of hours, and there they rest until the next day. Thus, day after day, until reaching Jerez de la Frontera, repeating a route almost identical to the one Ingrid made last year. "It's an explorer and an inspiration," Fritz explains of the bird. "It has become a kind of symbol of the collaboration between Proyecto Eremita and Waldrappteam."

Hermit ibises are also called northern bald ibis, a longer, but much more descriptive name. On the head they have no plumage, but a caruncle reminiscent of scars, testicles or turkey mucus. It looks like the extension of its long, curved beak. They have the crown festonada of long black feathers, like a crest. Are they ugly? Fritz does not refute this perception, but points out instead his charisma, gregariousness and sympathy. When he first crossed paths with these birds, in 1997, it was love at first sight. He worked at the Konrad Lorenz Research Center in Austria, raising crows—literally—and geese while pursuing his doctorate. In 1997, a zoo gave the center some hermit ibis chicks. They were not as docile as geese, nor as intelligent as crows. Most scientists did not develop a very special relationship with chicks, but this was not the case with Fritz, who became "their adoptive father".

Aerial view of the expedition.

By then it had already been released Flying Libre, the film with Anna Paquin and Jeff Daniels that tells the true story of Canadian naturalist Bill Lishman. Lishman guided 36 Canadian geese in his ultralight aircraft on a migration to South Carolina. When Fritz said he wanted to do something similar, his colleagues took it as a joke. But in 2002 a feasibility study was started on the reintroduction of the species in Europe. Within the framework of the Community Life project, the release of the population was authorized. "There were only 200 specimens in the wild in Morocco, but in captivity, in Europe, there were about 2,000 specimens," recalls Quevedo. "That's the great paradox of this species." So two initiatives were launched in parallel: a Central European one, led by the Waldrappteam, with a stable but migratory population; and another Spanish, with the sedentary Hermit Project. "They worked on one side, and we worked on the other," says the veterinarian. "But now we're going to do it together."

Fritz looks forward to the moment of arriving in Andalusia and thanks his new teammates. The road to get here has been long and complicated, especially in its beginnings. "It's easier now, but learning to fly with them was a challenge," Fritz says. "In the early years, we didn't have a proper microplane. It was faster than birds," which fly at about 40 kilometers per hour. That's why they had to adapt not only to speed, but to their way of flying.

Close-up of one of the birds. Waldrappteam

The flight of flocks of birds is governed by synchronized behavior, similar to that of schools of fish or swarms of insects. They can change position and flutter rhythm in a matter of seconds, tracing hypnotic and unpredictable movements. Synchronizing a plane to this flocking behavior seems complicated. There are computer simulations that have tried, but the theory, in these cases, is very different from the practice.

Fritz and his team have enough of the latter. Since 2004, almost every year, the Waldrappteam has guided about 20 young ibises born in captivity to the fields of Tuscany. In 2011, for the first time, one returned independently to the northern Alps, migrating in the opposite direction. When autumn came and he returned to Tuscany, he was followed by a group of birds that humans had not taught to migrate.

The species already had enough numbers to be biologically sustainable, it was beginning to learn the migratory routes and to teach it to the new generations. And at this moment, when the future of the hermit ibis was beginning to settle, global warming has put it in check again. However, Fritz is optimistic. He believes that there will come a time when the populations will be autonomous, but he does not put a specific date at this moment either. For now, he has 1,600 kilometers left to reach his destination. And it already advances that next year it will continue flying with its birds.

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