Australia

Study: H5N1 Kills 75% of Seal Pups on Australia's Heard Island

Is bird flu an out-of-control threat or is the robustness of Australia's prevention strategy secure?

JUN 18·Updated JUN 19

Study: H5N1 Kills 75% of Seal Pups on Australia's Heard Island

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Above: Southern elephant seal weaner pups in a wallow at Ocean Harbor, South Georgia Island, sub-Antarctica on Nov. 21, 2022. Image credit: Wolfgang Kaehler/LightRocket/Getty Images

The Facts

According to a study published on Wednesday, researchers estimate that 13,359 southern elephant seal pups — out of a total population of 17,364 on Australia's Heard Island — have died from the H5N1 strain of bird flu since last August, representing more than 75% of the cohort. Mortality in some seal harems reached as high as 97%.
News.com.au
Guardian
Biorxiv
The H5N1 bird flu strain was detected for the first time in an Australian external territory following drone and ground surveys conducted in October 2025 and January 2026. Six of nine species tested positive, including southern elephant seals, king and gentoo penguins, Antarctic fur seals and a South Georgia diving petrel.
The Straits Times
The New Daily
Phylogenetic analysis indicates the virus was introduced to Heard Island around August 2025, likely via infected wildlife from the French-owned Crozet Islands, located approximately 1,700 km (1,056 miles) away. The findings show a continued eastward spread of high pathogenicity avian influenza (HPAI) around the sub-Antarctic.
Avian Flu Diary
7NEWS
Researchers completed 120 drone flights covering more than 1,600 km to survey the islands, compared with just 8.8 km covered by ground searches. Co-lead author Jarrod Hodgson said drones detected king penguin carcasses within dense breeding colonies that "could not have been observed on foot without causing significant disturbance."
News.com.au
ABC Australia
The study, which hasn't been peer-reviewed, warns that H5N1 poses a "severe and potentially catastrophic threat" to Southern Ocean wildlife, where large, dense breeding colonies of already vulnerable species create conditions for rapid viral transmission. Elephant seals and albatrosses face particular risk due to their low reproductive rates and late maturation.
ABC Australia
The Nightly
BBC News
Australia remains the only continent without a confirmed H5N1 case on the mainland. The federal government has invested $47 million to strengthen preparedness, including $11.2 million in the 2026-27 budget for at-risk native species resilience.
BBC News
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The Spin

Narrative A

H5N1 is completely out of control in wild animals, raging across continents with no feasible way to stop it. The virus has now wiped out over 75% of elephant seal pups on Heard Island, confirming it can cross vast ocean distances and devastate isolated wildlife populations. Fragmented surveillance and opposition to vaccination are letting this crisis spiral while the window to act keeps shrinking.

Avian Flu Diary

BBC Science Focus Magazine

Narrative B

Australia's "one health" approach — investing heavily in environmental, animal and human surveillance — is exactly why the mainland has stayed H5N1-free even as the virus devastates remote sub-Antarctic islands. The Heard Island outbreak is sobering, but it's also proof that strong biosecurity and coordinated monitoring can hold the line. Vaccine field trials for cattle are showing real promise and could be the key to finally bringing this under control.

BBC News