A new study led by the University of Otago–Ōtākou Whakaihu Waka has revealed that scavenging behavior in wild birds significantly influences the types, quantity, and diversity of viruses they carry. The research, published in Current Biology, highlights the role of migratory birds in the global spread of viruses, including bird flu. Lead author Dr. Stephanie Waller, from the Department of Microbiology and Immunology, emphasized that while the role of birds in virus transmission is well-known, the influence of ecological factors on viral diversity and spread is still not fully understood. Aotearoa New Zealand is an ideal location for such research due to its geographic isolation, which limits the spread of many viruses, but also its connection to international ecosystems through the migration of birds from regions like East Asia, Australia, and Antarctica. Between November 2023 and April 2024, researchers collected over 1,300 samples from 31 wild bird species. They identified 118 avian viruses, 107 of which were previously unknown. Some of these viruses had close genetic relatives found as far away as Russia and the United Arab Emirates. Additionally, the study uncovered 12 mammalian-associated viruses, including those linked to hedgehogs, rabbits, and sea lions. The research found that scavenging birds—such as southern black-backed gulls and subantarctic skuas—had more diverse viromes, or collections of viruses, compared to non-scavengers. This is due to their exposure to a wide range of viruses through their diet, which includes dead animals and other organic matter. Senior author Professor Jemma Geoghegan explained that these scavengers act as natural sentinels for viruses circulating in the environment. Their high mobility allows them to transport viruses across ecosystems and geographic regions, making them key players in the spread of diseases like H5N1, a highly pathogenic strain of bird flu. Although H5N1 was not detected in this study—because the samples were collected before its arrival in New Zealand—the findings suggest that monitoring scavenging species could provide early warnings of such viruses entering the country. This information is crucial for wildlife conservation, especially for New Zealand's vulnerable endemic species that may be at risk from viruses introduced by invasive or migratory birds. The study underscores the importance of understanding ecological factors in managing and preventing the spread of infectious diseases.