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title: "Highly Pathogenetic Avian Influenza hits older seabirds hardest in one study: implications for long-lived albatrosses?"
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# Highly Pathogenetic Avian Influenza hits older seabirds hardest in one study: implications for long-lived albatrosses?

*![Sandwich Tern Farne Is FJ0A5168 35937297300](https://acap.aq/images/stories/acap/Birds/Sandwich_Tern_-_Farne_Is_-FJ0A5168_35937297300.jpg)  
A pair of Sandwich Terns engage in mutual display on the United Kingdom's Farne Islands*

 Wouter Courtens ([Research Institute for Nature and Forest](https://www.vlaanderen.be/inbo/en-gb/homepage/), Brussels, Belgium) and colleagues have published open access in the journal *[Nature Communications](https://www.nature.com/ncomms/)* showing that older Sandwich Terns *Thalasseus sandvicensis*are more likely to succumb to Highly Pathogenetic Avian Influenza (HPAI) than do younger birds. The implications for long-lived ACAP albatrosses and petrels warrants study,  as the following texts taken from their publication attest.

 “We show that HPAI-related mortality during the 2022 outbreak in northwestern European Sandwich terns was age-biased, with older individuals disproportionately affected, while mortality was not biased by sex.  This pattern suggests that HPAI did not act as a random mortality source, but selectively removed individuals that likely contribute substantially to population growth. … Seabirds – including penguins, albatrosses, petrels, gannets, gulls, terns and auks – share life-history traits such as delayed maturity, low annual reproductive output, and colonial breeding, making them particularly vulnerable to adult mass mortality events caused by infectious diseases.  The loss of experienced individuals could reduce the reproductive output, delaying recovery, and increase the risk of long-term population declines. … For seabirds already facing multiple pressures, including climate change, overfishing, predation, and habitat loss, the emergence of HPAI adds an additional source of vulnerability in an increasingly unstable world.”

 The paper’s abstract follows:

 “In recent years, highly pathogenic avian influenza (HPAI) A (H5N1) clade 2.3.4.4b viruses have caused mass mortality events in seabirds worldwide, raising concern for long-lived species with low reproductive rates. Using 28 years of ringing data together with individual-level data from the 2022 mass mortality event in northwestern European Sandwich terns (*Thalasseus sandvicensis*), we show that mortality was biased towards older individuals, while no sex bias was observed. HPAI-related mortality increased from approximately 5–10% in young breeders to more than 40% in the oldest individuals. This age-biased loss likely removed the most experienced individuals from the population. Our findings highlight a previously underappreciated mechanism through which HPAI outbreaks may impair the resilience of long-lived avian populations.”

 **Reference:**

 Courtens, W., Ballmann, M., Fijn, R. *et al.* 2026.  Avian influenza amplified age-related mortality in a long-lived seabird.  *[Nature Communications](https://www.nature.com/articles/s41467-026-76726-7#citeas)*[17, 8653 doi.org/10.1038/s41467-026-76726-7](https://www.nature.com/articles/s41467-026-76726-7#citeas).

 With thanks to Rob Simmons.

 *John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses* *and Petrels, 25 August 2026*