Satellite images trace emperor penguins’ struggle to survive

New Australian research using satellite imagery to monitor the location of emperor penguin colonies in East Antarctica shows the birds are struggling to adapt to rapid changes in their environment.

Australian Antarctic Division seabird researcher Barbara Wienecke said that for almost a million years, emperor penguins have responded to changes in their preferred breeding habitat, the fast ice zone of the ‘Antarctica, moving to new locations if their chosen area becomes unsuitable.

But the recent premature loss of their fast ice habitat and record low sea ice extent in 2022 and 2023 have led to breeding failure in some colonies. Scientists fear that these recent events herald a rapid deterioration in ice conditions, to which penguins have limited ability and time to adapt.

“Emperor penguins need stable sea ice for around 10 months a year to successfully breed and raise their chicks,” Dr Wienecke said.

“If their breeding platform disintegrates before the beginning of December, while the chicks still have their downy plumage, it is likely that they will all perish. If it disintegrates before the end of December, the chicks without waterproof plumage will die.”

As long-lived seabirds, Dr Wienecke said emperor penguins can cope with disruptive events, provided they do not occur frequently.

“While they can move to new breeding grounds, their potential to adapt to accelerating environmental changes and a shorter sea ice season is limited, as they cannot shorten the time chicks have needed to grow and develop,” she said.

Dr Wienecke, sea ice scientist Jan Lieser and seabird experts Julie McInnes and Jonathon Barrington used the European Space Agency’s (ESA) Sentinel-2 satellite imagery to examine changes in the habitat of reproduction and ice conditions between 2018 and 2023. The research is published in Research on endangered species.

“Satellite imagery is a very useful way to determine local and regional variability in coastal ice habitat,” Dr Lieser said. “From this, we can assess the adaptability of emperor penguins to rapid changes and the impacts of habitat change on breeding success.”

The team examined satellite images covering 6,000 km of East Antarctic coastline between September and December each year, the time when chicks rise and fly away. The team manually recorded the locations of the colonies each year as well as the distances between the colonies and the nearest fast ice edge.

Adults must be close enough to the edge of fast ice to be able to access open water and feed. But being too close compromises breeding success if the ice breaks before the chicks can survive at sea.

“Thirteen of the 27 colonies we studied in East Antarctica are at risk of reduced or complete reproductive failure, due to habitat loss, and nine of these 13 colonies experienced reproductive failure reduced or complete at least once during the six years of the study.” » said Dr. Wienecke.

A colony has completely disappeared, but individuals may have joined other colonies in the region. Some colonies have moved to new habitat types, including ice shelves and ice tongues, but these areas can be negatively affected by iceberg calving events that alter local conditions.

Previous population modeling studies predict that 65% of emperor penguin colonies could become “near-extinct” (doomed to extinction) by 2050. However, Dr Wienecke said the incredible variability in The location of colonies, relative to sea ice, made it difficult to model population trends.

She said the new study shows that medium- and high-resolution satellite imagery is a useful tool for annual monitoring of emperor penguin colonies and coastal ice habitat throughout Antarctica, alongside counts at ground and air.

“Continued Antarctic-wide monitoring is essential to quantify the impact of changing fast ice conditions on emperor penguins and the cumulative impacts of other threats such as disease,” Dr Wienecke said. “Satellite imagery allows us to identify the location of emperor penguin colonies each year and assess local environmental conditions, which is essential to understanding the consequences for each colony.

“This image analysis should be carried out in combination with ground and aerial counts of penguins within colonies, where possible, to assess changes in local populations.”