Food Theft Among Seabirds: A Link to Avian Flu Transmission

Seabirds, known for their food-stealing behavior, could play a significant role in spreading avian flu. This finding provides scientists leads on where to monitor outbreaks within susceptible bird populations. The H5N1 avian influenza virus has raised global concern. Since 2021, it has impacted millions of birds and has rare potential transmission to humans.

A recent study in the journal Conservation Letters emphasizes this food theft, termed "kleptoparasitism." Frigatebirds and skuas exhibit this behavior by forcing other birds to regurgitate their prey. As such, researchers from UNSW Sydney, BirdLife International, Deakin University, and Monash University conducted a thorough analysis. They evaluated existing data on distribution and behavior of frigatebirds and skuas, looking for records of avian flu contraction.

Focus on Disease Spread

Lead author Simon Gorta from UNSW highlights the study's potential. It could shift understanding of how and where the virus spreads. This knowledge is crucial in determining transmission among various populations and geographic areas. He states, "Understanding transmission is critical to monitoring". Effective management practices are particularly important for at-risk species and regions.

The H5N1 virus, first introduced in 1996, has become increasingly problematic. The current strain, 2.3.4.4b, has exhibited extreme spread capability. It has resulted in hundreds of thousands of seabird deaths since 2021. This strain has migrated from Eurasia and Africa into North and South America. It reached Antarctica in early 2024 and is now classified as a panzootic.

Seabird Vulnerability

Seabirds, especially those reliant on marine resources, suffer greatly from this panzootic effect. Co-author A/Prof. Rohan Clarke expresses worry over the risk seabirds face due to disease. "Seabirds are one of the most threatened groups of birds" globally, he noted.

Professor Richard Kingsford also commented on seabird susceptibility. The close contact during breeding promotes risks through shared resources. The practices of predation and scavenging further compound this vulnerability. Researchers pinpointed kleptoparasitism, a widespread behavior in species like frigatebirds and skuas, as an aspect to investigate.

Understanding Transmission Pathways

Kleptoparasitism refers to one bird stealing prey from another by forcing regurgitation. If the target bird carries the virus, the regurgitated material may harbor a high viral load. Consequently, this regurgitated food could spread infection to the kleptoparasitic bird, which may then affect other birds. This pathway can introduce the disease to new populations, especially during migrations spanning thousands of kilometers.

Alex Berryman from BirdLife International explains the migration aspect. If kleptoparasitic species contract the virus during travel and contact other birds, the disease could spread to previously unexposed regions. "Migrations may critically facilitate virus transmission," he warns.

Monitoring and Preparedness

Even though Australia has not yet faced this specific strain, early monitoring efforts are underway. Mr. Gorta points out the importance of preparing for H5N1's potential arrival in Australia. "Birds globally are under greater threat than ever before," he states, emphasizing the need for thorough research and management.

Migratory kleptoparasitic birds may be among the first to contract the virus, and their behavior warrants attention. Understanding these ecologies can vastly improve strategies in combating avian influenza. Focused efforts will aid Australia’s National Avian Influenza Wild Bird Surveillance Program in being ready for this emerging threat.

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