Shocking! Huge colonies of emperor Penguin chicks died in Antarctica.

Shocking! Huge colonies of emperor Penguin chicks died in Antarctica. 

Emperor penguins are an iconic symbol of Antarctica.Emperor penguin colonies experienced unprecedented breeding failure in a region of Antarctica where there was total sea ice loss in 2022. The discovery supports predictions that over 90% of emperor penguin colonies will be quasi-extinct by the end of the century, based on current global warming trends.

Antarctic Survey discussed the high probability that no chicks had survived from four of the five known emperor penguin colonies in the central and eastern Bellingshausen Sea. The scientists examined satellite images that showed the loss of sea ice at breeding sites, well before chicks would have developed waterproof feathers. 

Emperor penguins are dependent on stable sea ice that is firmly attached to the shore ('land-fast' ice) for the majority of the year, from April through to January. Once they arrive at their chosen breeding site, penguins lay eggs in Antarctic winter from May to June. Eggs hatch after 65 days, but chicks do not fledge until summer, between December and January.

At the beginning of December 2022, the Antarctic sea ice extent had matched the previous all-time low set in 2021. The most extreme loss was seen in the central and eastern Bellingshausen Sea region, west of the Antarctic Peninsula where there was a 100% loss of sea ice in November 2022.

The sea ice disappeared before the start of the emperor chicks’ fledging period, during which they develop their waterproof adult wings and learn to swim. The birds most likely either drowned or froze to death — they couldn’t regulate their body temperature after getting drenched, the research said.

The study, ‘Record low 2022 Antarctic sea ice led to catastrophic breeding failure of emperor penguins’, was published on August 24 in the journal Communications Earth & Environment. It was conducted by Peter T Fretwell and Norman Ratcliffe of the British Antarctic Survey (Cambridge) and Aude Boutet, an independent researcher based in Paris.

Since 2016, the Antarctic sea ice extent — the total region with at least 15% sea-ice cover — has been shrinking with the total area of frozen water around the continent reducing to new record low levels almost every year. This puts more than 90% of emperor penguin colonies at risk as they may go extinct by the end of this century, if Earth continues to get warmer at the present rate.

Sea-ice and the emperor penguin breeding cycle;

The role of stable sea ice in the emperor penguin breeding cycle is crucial. “Emperor penguins spend their whole breeding cycle on the sea ice. They need it to last from early April until late December,”

The birds arrive from the sea to their preferred breeding sites on sea-ice in late March to April. They court and mate, and then lay eggs in May and June. Eggs hatch in August after which parent emperor penguins take turns to feed their chick. “The chick grows quickly and by December starts to lose its grey downy feathers and replaces them with sleek black waterproof adult plumage,”

By late December or early January, the fledgling period comes to an end, leading chicks to go into the water and look for food themselves. Therefore, the sea ice on which emperor penguins breed needs to remain stable between April to January to ensure successful breeding.

Five known emperor penguin colonies occur in the central and eastern part of the Bellingshausen Sea. There are, from east to west,

1.  Verdi Inlet. 
2.  Smyley Island. 
3.  Bryan Peninsula. 
4.  Pfrogner Point.
5. Rothschild Island. 

All of these colonies were discovered using medium resolution satellite imagery in the last 14 years. and their populations counted using very high-resolution imagery.

Verdi Inlet colony;

Verdi Inlet colony was discovered by satellite in 2018 and has been present each year in the Sentinel2 satellite record between 2018 and 2022.

In September 2022 the colony was once again visible in Sentinel2 imagery, but very small—consisting of just 4 brown pixels. Between the 31st of October and the 4th of November the land-fast sea ice in the bay broke up. This ice had entirely dissipated by early December and no sign of any staining from guano could be found in the local area.

Smyley Island colony;

Smyley Island colony was discovered in 2009 by Landsat satellite imagery. Very High-Resolution satellite imagery has been taken of it during most years since then to reveal that numbers vary between 1000 and 6500 breeding pairs with a 10 years average of 3500 pairs

when the fast ice broke up some time in mid-November. In this year, the colony had split into two groups approximately four kilometres apart. In Sentinel2 imagery from early December, the sea ice had clearly broken up leaving only loose pack ice and a few large bergs. It appears that at least some of the penguins had moved onto the foot of a large berg which was grounded near the coast. Whether any of the chicks survived on the berg is unknown.

Bryant Coast colony;

The Bryant Coast colony was discovered in Landsat imagery in 2014. It has had a number of population estimates by VHR satellite image. 

In 2022 the colony was visible in mid-November in Sentinel2 imagery but appeared smaller than normal. By the 25th of November, the sea-ice edge was approaching the colony location and by the 29th the fast ice had broken into pack. There was still evidence of brown staining on some of the broken pack ice. However, a few days later on the 2nd of December this brown staining had disappeared from the pack ice, suggesting the abandonment of the colony. No other evidence of the colony could be found in the local area.

Pfrogner Point colony;

Pfrogner Point colony was discovered in 2019 and only one VHR satellite population estimate has been conducted, estimating the population at 1200 pairs. The abandonment of the colony was confirmed by VHR imagery captured later in the month (26th November). By the 12th December 2022, all the sea ice had dissipated. This confirmed that no penguins were visible, either on the shelf or the surrounding sea ice by this time. The reason for abandonment of the colony site if difficult to say with certainty.

Rothschild Island colony

Rothschild Island colony is the furthest north of the five sites, located in a bay between Alexander Island and Rothschild Island. It is a small colony, averaging ~700 breeding pairs.

The location of the colony is in an embayment between Rothschild and Alexander islands and the presence of many icebergs suggest shallow water. The geometry of the bay and the presence of icebergs may have helped to stabilise the sea ice at this location and afforded protection from breakout until after the chicks had fledged.

Rothschild Island colony;

Rothschild Island colony is the furthest north of the five sites, located in a bay between Alexander Island and Rothschild Island. It is a small colony, averaging ~700 breeding pairs.

The location of the colony is in an embayment between Rothschild and Alexander islands and the presence of many icebergs suggest shallow water. The geometry of the bay and the presence of icebergs may have helped to stabilise the sea ice at this location and afforded protection from breakout until after the chicks had fledged.

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The reasons behind this year’s record low ice covers aren’t clear yet though. There is a lack of satellite data and scientists haven’t been able to confirm if the drop in sea ice is due to either natural variability or climate change.

“Climate models show very large variability in Antarctic sea ice, but this should perhaps be taken with a pinch of salt, because the models generally struggle to simulate the past changes in Antarctic sea ice.”