The Devastating Impact of Avian Flu on Dalmatian Pelicans in Greece: A Story of Resilience and Uncertainty
Three years after a catastrophic 60% decline in the world's largest Dalmatian Pelican colony at Lake Mikri Prespa in northern Greece, researchers have uncovered critical insights into the loss of over 2,300 birds across Greek wetlands. The study, a collaboration between the Society for the Protection of Prespa (SPP) and the Spanish research institute IREC/CSIC, reveals that the avian flu virus was likely introduced by migratory waterfowl (ducks and geese) arriving from northern climates.
While ducks and geese carried the virus asymptomatically, they transmitted it to the pelicans via droppings left on the small islands where both groups rested. Interestingly, Great White Pelicans nesting alongside infected colonies remained unaffected by the virus. Similarly, colonies in Western Greece (Amvrakikos Gulf and Messolonghi lagoons) escaped the outbreak, possibly due to higher temperatures and water salinity, which may have inhibited the virus compared to the freshwater environments of the north.
Signs of Survival and Hope
Olga Alexandrou, a forester-ornithologist for the SPP, noted a fascinating physical marker of survival: cloudy corneas. Birds that have survived the initial infection often display a "foggy" eye, a sign that they have successfully battled the disease and are now breeding again. Furthermore, blood samples from 2023 revealed that chicks had avian flu antibodies, suggesting that survivors are passing on immune protection to the next generation.
Despite these signs of resilience, the outlook remains cautious. The 2022 outbreak was the worst ecological disaster for wildlife in Greek history, wiping out 40% of the Southeast European breeding population—roughly 10% of the entire global species.
Challenges to Recovery
Slow Reproduction: Pelicans do not reach breeding age until 3–4 years old and typically raise only one chick per year.
Predation and Climate: In 2023, extreme drought allowed jackals to reach previously isolated nesting islands, resulting in the loss of hundreds of chicks.
Viral Mutation: Scientists remain on high alert for new, highly virulent strains currently affecting Western Europe (where over 80,000 cranes have perished recently).
"For large-bodied birds with these characteristics, it takes decades to recover from such a significant blow," warns Alexandrou. "In this uncertain environment, we don't know when Prespa will return to its 2022 level of 1,400 breeding pairs."
The story of the Dalmatian Pelicans at Lake Prespa is a powerful reminder of the fragility of ecosystems and the urgent need for conservation efforts to protect our planet's biodiversity.
