537 Dead Penguins Found on One Antarctic Landing Ramp

More than 537 dead Adélie penguins lay on a single landing ramp in the Danger Islands, an area just off the Antarctic Peninsula. The ramp is roughly the size of an airport runway. Researchers found the carcasses in March 2024 while investigating a reported die-off in the region. The team initially suspected a viral outbreak, specifically avian influenza, which had recently reached Antarctica.

Dr. Ralph Vanstreels, a wildlife veterinarian with the University of California, Davis, led the investigation. He and his colleagues sailed to the islands to sample the birds. They found thousands of dead penguins and other bird species across the islands, but the exact total is unknown because the team had to work quickly. Vanstreels noted that icebergs could trap their vessel, forcing a rapid departure.

The team collected samples from the deceased birds and analyzed them in a mobile laboratory on their boat. By the end of the first day, they had preliminary results. The samples contained bird flu, but the virus load was low. This contradicted the hypothesis that avian influenza killed the birds, as the carcasses were fresh and should have contained higher viral levels if that pathogen was responsible.

Months later, scientists in the Netherlands examined the tissue samples under a microscope. They identified bacteria in the tissues, indicating that the penguins died from avian cholera. This bacterial disease is distinct from human cholera. The findings were published in October in the journal Proceedings of the Royal Society B.

Avian cholera is not considered a major threat to humans because the strain affecting birds differs from the strain that affects mammals. Vanstreels stated that the risk of human infection from a bird outbreak is low. However, the disease kills birds worldwide, particularly in cold environments where the bacteria thrive. Researchers have known about the disease for decades, but the last time they looked for it in the Antarctic Peninsula was 25 years ago.

The origin of the outbreak remains a subject of scientific inquiry. One theory suggests that the bacteria were introduced to Antarctica decades ago by researchers who brought poultry from the United States. Dr. Amandine Gamble, an assistant professor at Cornell University, noted that the strain found in the penguins is very close to one found 5,000 miles away on Île Amsterdam in the Southern Indian Ocean. This connection suggests that Antarctica is more biologically linked to the rest of the world than previously thought.

The discovery highlights the need for continued monitoring of diseases in the region. Vanstreels emphasized that while bird flu is a major concern, other diseases may be operating in parallel. The Antarctic Treaty, which has 58 parties including the United States, France, Japan, and Russia, governs the continent. No single government controls Antarctica, so international collaboration is required to track pathogens that move across the globe.