In Brittany, an “unprecedented” avian flu epidemic strikes wild birds

The LPO station of Ile-Grande (Côtes-d'Armor) monitors the colony of northern gannets, located in the largest ornithological reserve in France of Sept-Iles, by drone.  August 24, 2022.

Since the beginning of the summer, a severe epidemic of avian flu of the highly pathogenic H5N1 strain has hit the coasts of Brittany. A viral cyclone of which the Sept-Iles, the largest ornithological reserve in France with its 280 hectares and its 136 species, form the epicenter. Located on the border between the continent and the Atlantic Ocean, the Ile-Grande League for the Protection of Birds (LPO) station blends into the landscape with its stone and wood construction. It is in the front row to follow the evolution of these species.

“By the number of birds affected and the occurrence of this epidemic in the middle of summer [la grippe aviaire sévit généralement en hiver], the situation is unprecedented”, says Pascal Provost, the curator of the reserve. And serious enough to have forced the center to close its doors on July 13 to species that tested positive for the influenza virus: sea and herring gulls, gannets, the first death of which had been identified on July 1er July. At the same time, a prevention system has been extended throughout Brittany by the public authorities. On August 12, a press release from the prefect of Côtes-d’Armor reinforced and expanded “surveillance and biosecurity measures throughout the territory”.

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The members of the station are on a war footing. To count the losses, Pascal Provost observes the screen which displays in real time the population of northern gannets living on Rouzic Island, the easternmost of the reserve. “This camera shows a spawning area that is still relatively spared. You would then think that there is no problem”, remarks another employee of the LPO. But the reality is quite different.

Delicate estimate

The screenshot of one of the cameras distributed on the island shows, on July 26, a colony at a still normal density. But another image, dated August 16, bears witness to the ravages of avian flu, with depopulated nests and numerous corpses.

The population of gannets gathers on this site about 19,000 pairs. Under the effect of the virus, “the colony is completely disintegrating”, laments Pascal Provost. Additional proof of this excess mortality, the curator presents a “control zone” housing a hundred nests. At the beginning of July, she still had forty-one chicks; on August 16, they were only eight to have survived the epidemic.

Rouzic Island, August 24, 2022, in the Sept-Iles archipelago.  It is a nature reserve where landing is prohibited and where gannets usually come to breed.

Between the corpses that have already disappeared, those of young people taken away by predators and birds that have disappeared at sea, estimating the number of victims is proving difficult. “For the moment, we only know that there are about twenty species affected”, comments Romain Morinière, the director of the LPO station on Ile-Grande. Among them, gannets, terns, gulls, seagulls but also some mammals having consumed an infected corpse, such as the red fox.

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