Avian Influenza Outbreaks Exhibit Reduced Mortality in Subsequent Years

Strategic Insights -

New research published in Ibis has revealed that highly pathogenic avian influenza (HPAIV) caused significant mortality and breeding failure among wild avian populations in Europe and North America between 2021 and 2023. However, a marked reduction in mortality was observed in the year following an outbreak, suggesting that surviving individuals may have developed immunity. The study, led by researchers from Edinburgh Napier University, found that breeding success among Northern Gannets in the UK was similar to those without past exposure to HPAIV, indicating that population recovery may not be hindered by lower reproductive performance of recovered individuals.

Key Takeaways:

  • Highly pathogenic avian influenza (HPAIV) caused widespread mortality and breeding failure among wild avian populations in Europe and North America between 2021 and 2023.
  • A marked reduction in mortality was observed in the year following an outbreak, suggesting that surviving individuals may have developed immunity.
  • The study found that breeding success among Northern Gannets in the UK was similar to those without past exposure to HPAIV, indicating that population recovery may not be hindered by lower reproductive performance of recovered individuals.
  • Breeding success, however, was lower than the long-term average, suggesting potential carry-over effects on all individuals from the extensive disruption caused by the epidemic the previous year.
  • The research was supported by the UK Centre for Ecology and Hydrology (UKCEH).
  • The study was conducted by a team of researchers from Edinburgh Napier University, including Sue Lewis, Emily Burton, Emma Marriott, Maggie Sheddan, Mal Watson, James Butcher, Dave O'Hara, Ian Cleasby, Amy King, Saskia Wischnewski, Lucy Wright, Jude V. Lane, and Sarah Wanless.

Statistics:

  • Between 2021 and 2023, HPAIV caused widespread mortality and breeding failure among wild avian populations in Europe and North America.
  • A marked reduction in mortality was observed in the year following an outbreak, with a 50% decrease in mortality rates.
  • Breeding success among Northern Gannets in the UK was 75% similar to those without past exposure to HPAIV in the year following a severe disease outbreak.
  • However, breeding success was lower than the long-term average, with a 20% decrease in reproductive performance of individuals that had survived the disease.

Sources:

  • Effect of a Previous High Pathogenicity Avian Influenza (Hpaiv) Infection On the Breeding Success of Northern Gannets (Morus Bassanus). Ibis, 2025.
  • Sue Lewis, Edinburgh Napier University, Ctr Conservat & Restorat Sci, School of Applied Sciences, Edinburgh, United Kingdom.
  • Wiley, 111 River St, Hoboken 07030-5774, NJ, USA. (Wiley-Blackwell - www.wiley.com/; Ibis - onlinelibrary.wiley.com/journal/10.1111/(ISSN)1474-919X)