No, the seagulls don’t stay there, circling above the beaches of the Hérault, squinting at the swimmers’ picnic. Some gulls, the name of those coastal birds that howl over our heads, are incredible globetrotters. This is the case of the Sandwich Tern, a bird with slender wings and an elongated beak, a cousin of the seagull and the gull.
One of them was equipped by scientists, in the spring of 2022, with a GPS beacon, in Sète (Hérault). A year later, the Conservatory of natural spaces (CEN) of Occitanie, at the initiative of this high-flying survey, revealed the impressive journey of this bird.
The Sandwich Tern is a (very) migratory bird
Because if this scientific study was originally intended to observe the possible impact of wind turbines, installed off the coast of the Mediterranean, on the behavior of these birds, in particular on their search for food and their reproduction, the data have also shown how the Sandwich Tern is a (very) migratory bird. “The wintering grounds of Mediterranean terns are known thanks to some chick ringing operations, but everything remains to be discovered about the migration dynamics of these birds”, explains the CEN of Occitanie. But the simple banding of birds does not allow us to know their journey precisely. “If we manage to find these birds, we simply know that they have moved from one point to another, explains to 20 minutes Olivier Scher, who led this project at CEN d’Occitanie. You never know what happens between the sites where they are observed. Now, thanks to the miniaturization of electronic parts and their resistance to hazards, a GPS beacon could be placed on a bird. And that sings everything. From now on, we no longer miss anything about his migration.
Fasten your seatbelts, here are the details of the incredible journey of this volatile sailor. After the failure of its brood, on June 12, the bird first visited some nearby colonies, in the corner, in the Camargue. It was not until June 24 that he began a world tour: the Sandwich Tern reached the Italian coasts, visiting Pisa, then Naples, before reaching the Adriatic Sea, and the shores of the Gargano National Park. On August 26, she turned towards the Neapolitan coast, where she took it easy until the end of October.
A road trip to the deep south, before returning to Sète
The GPS beacon followed her, then, in France, before a road trip towards the South: Gibraltar, Agadir and the National Park of Khenifiss, in Morocco, until December 6, before a break at the border between Western Sahara and Mauritania. This is where this bird spent the winter, warm, until April 25. Before reaching Europe, via the Strait of Gibraltar, on May 1, and, finally, returning to his homeland, his breeding island, in Sète, on May 5. In one year, this Sandwich Tern will have flown more than 10,000 km. “What surprised me were the distances covered, and the round trips, confides Olivier Scher. We do not realize the journeys that these species are able to make in a day. »
For science, these details are of tremendous interest. “What is interesting is that we know her precise route, we know where she went, where she stayed, on what dates, at what speed, etc. “, explains to 20 minutes Frédéric Jiguet, professor at National Museum of Natural History of Paris, and deputy director of the Bird Population Biology Research Center (CRBPO), who led this amazing project.
An interest in education on biodiversity issues
But these exciting results are also an ideal way to communicate on biodiversity issues. “I, for example, used this data for an educational project between a class in France and a class in Senegal, continues the professor, specialist in birds. These stories are important because they show how much we share, from one point to another of the globe, in terms of animal life and biodiversity in general. When wind turbines are installed in the Gulf of Lion, it does not only impact the Tern in the Gulf of Lion. »
Sometimes this coastal species pushes a little further still, its travels around the world. “A bird from the same colony, in Sète, which had been ringed, was seen this winter in South Africa”, confides Frédéric Jiguet. Before reuniting with his friends, when the fine weather arrives, on the lido de Thau. Here, in Sète, 3,000 to 3,500 pairs, or 80% of the Mediterranean population of Sandwich Terns, reproduce each year.