The season promised to be extraordinary for the Platier d’Oye nature reserve. At the beginning of spring, more than 3,000 sandwich terns, rare seabirds in France, took up residence in this area bordering the North Sea, in Pas-de-Calais. A figure unmatched for years. But in May, these migratory birds, recognizable by their ruffled black crest and yellow-tipped beak, began to die off en masse. Within weeks, the colony was decimated. Only 500 adults and 200 chicks survived the carnage.
With her colleagues, Marie Delamare, guard in the nature reserve, had to collect more than 1,500 corpses. “ I have worked for 12 years on the reserve and we had never seen that. It was shocking for us to pick up the corpse of birds we’re supposed to protect », she testifies. Those are “ at least » 10 % of sandwich terns present on French territory who lost their lives in a few weeks in this reserve, estimates the nature guard. And the same scenario was repeated in almost all colonies of sandwich terns in northern Europe, continues Marie Delamare.
- A large number of sandwich terns have died of the avian flu which is raging in Europe. CC BY–HER 4.0 / Максим Яковлєв / Wikimedia Commons
This species, like gulls, gannets or gulls and grebes, is affected by an epidemic of avian flu which specifically targets seabirds. Since the beginning of spring, the disease has wreaked havoc in the colonies present in the United Kingdom, Germany, Denmark or the Netherlands.
In France, the epidemic situation is “ exceptional in terms of its scope and the period when the detections take place », warns the Weekly Bulletin of International Health Monitoring in Animal Health of July 26. In the north of the country, the virus was detected around mid-May. Hundreds of corpses of herring gulls, for example, were found in Boulogne-sur-Mer, in Pas-de-Calais. A species that has been declining in France for several years, underlines Christian Boutrouille, president of the Ornithological Group and naturalist of the North.
An epidemic spreading south
The epidemic then gradually spread towards the coasts located further south. “ Three regions were affected: Hauts-de-France, Normandy, and now, Brittany »explains Anne Van De Wiele, head of wildlife surveillance for avian influenza at the French Office for Biodiversity (OFB), contacted by Reporterre on July 29. At the end of July, several cases of avian flu were thus identified in the department of Côtes-d’Armor, in Brittany, and in particular in the nature reserve of Sept-îles, where many gannets nest, indicated the League for the protection of birds (LPO), on Wednesday, July 27.
During the same week, cases were also identified in seabirds in Finistère, and further south, in Morbihan, reports Anne Van De Wiele. If it is too early, she explains, to communicate an assessment, the number of dead birds in France is counted in thousands. And the carnage is not over: “ We still have massive mortality phenomena in Germany, England and France »explains the veterinarian, specializing in epidemiology.
- Herring gulls, which were already in decline, are also affected by this bird flu. CC BY 2.0 / John Haslam / Wikimedia Commons
The particularity of this epidemic is the period in which it occurs. “ The big surprise we had was not seeing it disappear with the spring and the heat », explains Anne Van De Wiele. This is the time when many species of birds come together to have their young and raise them. They then live in close proximity, which accelerates the transmission of the disease. In addition, the chicks provide ideal conditions for the multiplication of the virus.
“ The chick has no immune defence, its temperature is higher… Everything is favorable to the increase in the viral load »details the head of department at theOFB. “ The transmission of the virus was incredible. A contaminated bird contaminated the entire colony. The transmission must have been done in a few days between all the European colonies »testifies Marie Delamare.
“ It becomes a real problem for wildlife »
If she hopes that the surviving birds will be immune to the virus, Anne Van De Wiele points out that it is “ very difficult to anticipate the evolution of the epidemic ». The acceleration of bird flu episodes does little to encourage optimism for wildlife in the long term. The virus arrived in France in 2006, but had done little damage there, before striking again in 2016 then in 2019, 2020 and 2021. “ Initially, this phenomenon mainly posed difficulties for domestic farms. Little by little, it becomes a real problem for wildlife conservation »analyzes Anne Van De Wiele.
She is thus worried about the gannets of the colony of Sept-Îles, in the Côtes-d’Armor: “ The populations are not that big. These reserves are therefore precious, especially since there have been enormous mortalities in Scotland, where this bird is very present. Seeing that the disease has arrived in Brittany is heartbreaking. »
- The Gannets of the Sept-Îles reserve are also victims of this epidemic. © Didier Flury / Reporterre
The disease adds to the difficulties faced by seabirds: “ All these birds are already affected by the loss of wetlands, but also by climate change and the decline in biodiversity in the oceans. They have less food »emphasizes Marie Delamare.
The other source of concern for the public authorities concerns the contamination of poultry farms by wild birds. The sector has just emerged from a catastrophic epidemic, which required the slaughter of 16 million poultry.
Farms under surveillance
Since the beginning of June, the whole of France has returned to risk “ negligible ». In the departments affected by these cases of avian influenza in seabirds, the prefectures have however put in place “ temporary control areas », where poultry are to be confined. This concerns, for example, coastal towns in the Somme, Pas-de-Calais, Côtes-d’Armor and even Seine-Maritime.
For the moment, no breeding has been contaminated, welcomes Anne Van De Wiele. The disaster scenario, she believes, would be for the virus to be transported by migratory birds on the Atlantic coast of France, where there are many duck and other poultry farms.
At their level, walkers can play a role in limiting the spread of the epidemic. If you find a dead seabird, do not touch it, and call the prefecture. If he is sick, Anne Van De Wiele advises to contact a wildlife care centre.