The Polar Retrospective – Skuas found dead, the winner of the Iditarod race, and a new Antarctic map
The Polar Retrospective looks at recent stories from around the world’s polar regions. This week we look at the impact of bird flu south of the Antarctic Peninsula, the results of the major dog race in Alaska, and Antarctica under the ice cap.
The Polar Retrospective is a collaborative effort by the Polar Journal AG team. Each writer chooses a topic they found interesting and important in the past week. The initials at the end of each section indicate the author. We hope you enjoy it.
HPAI-H5N1 bird flu progresses in Antarctica
Dry vomiting, abnormal posture, death… Eleven dead skuas of two different species, both migratory, have tested positive for the highly pathogenic avian influenza HPAI-H5N1 south of the Antarctic Circle. “This discovery represents the most southerly record of seabird mortality […] linked to HPAIV to date,” explains the study, which was deposited on the bioRxiv preprint server on March 7.
A research consortium comprising Chilean universities and research institutes such as the Instituto Milenio Base is behind the publication. During the austral summer of 2024-2025, its members watched for signs of the disease on known nesting grounds and explored sites south of the Antarctic Peninsula aboard two Chilean vessels, Karpuj and Betanzos. “The common objective is the surveillance and monitoring of avian influenza,” explains Dr Juliana Vianna, director of research at the University of Chile and the Milenio Base Institute.
Skua mortality linked to the virus has been detected in six different locations, notably in Marguerite Bay. Further north, at Harmony Point, where last year the colony appeared to be unaffected, the researchers found eight dead skuas. Dr Lucas Krüger, a seabird specialist and co-author of the study, stresses the need for constant monitoring of the pathogen. A year ago, the disease was detected in skuas, cormorants and penguins. But the authors point out that “the expansion of the HPAIV virus observed here raises concerns about its spread […] outside the Antarctic Peninsula.” C.L.
Alabamian musher wins longest Iditarod race
Jessie Holmes claimed victory in the 53rd Iditarod Trail Sled Dog Race, reaching the finish line in Nome at 3:15 a.m. on March 14, 2025. The 2025 edition of the Last Great Race on Earth was notable for its unprecedented length of 1,128 miles (1,815 km), the longest in the event’s history. The race traditionally starts near Anchorage but was moved to Fairbanks this year due to insufficient snow in the usual starting area.
Thirty-three mushers and their teams of 12-16 dogs embarked on this challenging journey on Monday, March 3, with teams departing from Fairbanks at two-minute intervals. The extended route took them generally east to west from Fairbanks to Nome, including a southward down and back ‘loop’ on the Yukon River. Mushers faced varied terrain, from the initial forested sections to the more exposed and potentially wind-swept areas closer to the Bering Sea. The lack of snow in the south necessitated this unusual and longer path, adding an extra layer of difficulty to an already demanding race.
The Iditarod commemorates the heroic 1925 serum run to Nome and stands as a testament to the endurance and skill of both mushers and their canine athletes. This year’s record-length race amplified the physical and mental challenges faced by all participants. Holmes, a seasoned musher originally from Alabama in the Southern part of the USA, navigated these conditions to secure his win, adding his name to the prestigious list of Iditarod champions. M.W.
New map reveals the hidden landscape of Antarctica with outstanding accuracy
An international team of scientists, led by the British Antarctic Survey (BAS) with contributions from the Alfred Wegener Institute (AWI), has produced the most detailed map yet of Antarctica’s hidden landscape. Published in Nature Scientific Data on March 10, the so-called Bedmap3 is based on more than 60 years of survey data collected by aircraft, satellites, ships, and even dogsleds.
The newly refined map reveals Antarctica’s highest mountains and deepest valleys with even greater detail. One surprising discovery is that the thickest ice is not in the Astrolabe Basin in Adélie Land, as previously thought, but in an unnamed canyon in Wilkes Land, where the ice thickness reaches 4,757 meters—about as high as Mont Blanc.
These new insights are essential for understanding how Antarctica will respond to climate change. The movement of ice across the continent is largely dictated by the terrain beneath it—while ridges can slow its flow, valleys and smooth regions can accelerate it.
Bedmap3 is the third edition of this Antarctic mapping effort, which began in 2001. With 82 million data points—more than twice as many as its predecessor—it offers a significantly more detailed view of the continent’s topography, ice thickness, and grounding lines, where ice transitions from land to floating ice shelves.
A key takeaway from the updated map is that the Antarctic ice sheet is thicker than previously estimated, with a greater portion resting on bedrock below sea level. This suggests that Antarctica may be even more vulnerable to melting caused by warm ocean currents than scientists had previously assumed. J.H.
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