Summary: Researchers suggest that kleptoparasitism, or food theft, among seabirds could be a transmission pathway for the H5N1 avian influenza virus, potentially explaining its rapid global spread.
Estimated reading time: 5 minutes
The deadly H5N1 avian influenza virus, responsible for millions of bird deaths worldwide since 2021, may have found an unexpected transmission route: the food-stealing behavior of certain seabirds. A new study published in Conservation Letters highlights this possibility, focusing on a behavior known as kleptoparasitism.
Kleptoparasitism: A Potential Viral Highway
Kleptoparasitism is a feeding strategy where some seabird species, like frigatebirds and skuas, force other birds to regurgitate their prey. This behavior, while a normal part of these birds’ ecology, may now serve as an unintended transmission path for the highly pathogenic H5N1 virus.
Researchers from the University of New South Wales, BirdLife International, Deakin University, and Monash University collaborated on this study. They analyzed existing data on frigatebird and skua distribution, behavior, and movements, while also searching global databases for records of these species contracting the virus.
Simon Gorta, the lead author from UNSW Sydney’s Centre for Ecosystem Science, emphasizes the importance of understanding transmission routes: “Understanding transmission is critical to monitoring and management efforts, particularly when at-risk species or regions are involved, and it’s helpful to understand threats to other animals and people.”
A Global Threat to Avian Populations
The current H5N1 strain, known as 2.3.4.4b, has shown unprecedented spread compared to previous strains. Since its detection in 2021, it has killed hundreds of thousands of wild seabirds and expanded its range significantly. The virus has reached Antarctica in early 2024, earning it the classification of a panzootic – a pandemic among animals.
Seabirds, already one of the most threatened bird groups globally, are particularly vulnerable to this outbreak. Associate Professor Rohan Clarke from Monash University notes the grave concern this poses to seabird populations.
Professor Richard Kingsford explains that seabirds’ vulnerability stems from their breeding habits: “Transmission among seabirds is a real concern because of their close contact and potential contamination of communal resources on densely-packed breeding islands, as well as particular behaviours like predation and scavenging of infected individuals.”
Long-Distance Spread Through Migration
The study highlights how kleptoparasitism could lead to long-distance transmission of the virus. Many seabirds, including kleptoparasitic species, migrate over vast distances. Alex Berryman, Red List Officer for BirdLife International, points out that these birds can cover tens of thousands of kilometers during migration. If they become infected and interact with other birds soon after, the disease could spread to new, previously unexposed populations and regions.
Preparing for the Inevitable
While the H5N1 2.3.4.4b strain has not yet reached Australia, experts are treating its arrival as a matter of “when” rather than “if.” Monitoring efforts are underway for early detection.
Gorta states, “We have identified that migratory kleptoparasites, alongside predatory and scavenging species, could be some of the first species to become infected when H5N1 reaches Australia.” This insight will contribute to Australia’s National Avian Influenza Wild Bird Surveillance Program and help prepare for the virus’s potential impact on vulnerable subantarctic islands.
Glossary of Terms
- Avian influenza: A highly contagious viral infection that occurs naturally in wild aquatic birds and can infect domestic poultry and other bird and animal species.
- H5N1: A highly pathogenic strain of avian influenza virus.
- Kleptoparasitism: A form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food.
- Panzootic: An outbreak of an infectious disease that spreads through one or several species of animals over a wide geographic area.
- Seabirds: Birds that are adapted to life within the marine environment.
- Frigatebirds: A family of seabirds known for their kleptoparasitic feeding behavior.
- Skuas: Another group of seabirds that often engage in kleptoparasitism.
- Viral load: The amount of virus in an infected person’s or animal’s bodily fluids.
- Subantarctic islands: Islands located in the Southern Ocean between 46° and 60° south latitude.
- Zoonotic disease: An infectious disease that can be transmitted between animals and humans.
Quiz: Test Your Knowledge on Avian Flu and Seabirds
- What behavior among seabirds is suggested as a potential transmission route for avian flu? a) Nesting b) Kleptoparasitism c) Diving d) Mating
- Which of the following is NOT mentioned as a kleptoparasitic seabird in the article? a) Frigatebirds b) Skuas c) Penguins d) Both a and b are mentioned
- As of early 2024, the H5N1 virus has reached which continent? a) Australia b) Europe c) Antarctica d) Asia
Answers:
- b) Kleptoparasitism
- c) Penguins
- c) Antarctica
Further Reading
- World Organisation for Animal Health: Avian Influenza Portal
- BirdLife International
- National Avian Influenza Wild Bird Surveillance Program (Australia)
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