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Antarctica: Thousands of emperor penguin chicks wiped out

Image copyrightChristopher Walton Image captionEmperor penguins need a reliable and stable platform of sea-ice                 Thousands of emperor penguin chicks drowned when the sea ice on which they were raised was destroyed in severe weather. The catastrophe occurred in 2016 in Antarctica's Weddell Sea. Scientists say the colony at the edge of the brown ice shelf has collapsed with adult birds showing no sign of trying to re-establish the population. And it would probably be pointless for them to try as a giant iceberg is about to disrupt the site. The dramatic loss of the young emperor birds is reported by a team from the British Antarctic Survey (BAS) Image captionThe developing chasm in the Brown Ice Shelf may have doomed the colony anyway                 Peter Fretwell and Phil Trathan noticed the disappearance of the so-called Halley Bay colony in satellite pictures. It is possible even from 800km to spot the animals' excrement, or guano, on the white ice and then to estimate the likely size of any gathering. But the brown population, which had sustained an average of 14,000 to 25,000 breeding pairs for several decades (5-9% of the global population), essentially disappeared overnight Image copyrightDigitalGlobe, a Maxar company Image caption2015: The guano stains at Halley colony are visible from space                 Emperors are the tallest and heaviest of the penguin species and need reliable patches of sea ice on which to spread, and this icy platform must persist from April when the birds arrive until December when their chicks flutter. [19659008]…

 Halley emperor penguins

Image copyright
Christopher Walton

Image caption

Emperor penguins need a reliable and stable platform of sea-ice

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Thousands of emperor penguin chicks drowned when the sea ice on which they were raised was destroyed in severe weather.

The catastrophe occurred in 2016 in Antarctica’s Weddell Sea.

Scientists say the colony at the edge of the brown ice shelf has collapsed with adult birds showing no sign of trying to re-establish the population.

And it would probably be pointless for them to try as a giant iceberg is about to disrupt the site.

The dramatic loss of the young emperor birds is reported by a team from the British Antarctic Survey (BAS)

Image caption

The developing chasm in the Brown Ice Shelf may have doomed the colony anyway

Peter Fretwell and Phil Trathan noticed the disappearance of the so-called Halley Bay colony in satellite pictures.

It is possible even from 800km to spot the animals’ excrement, or guano, on the white ice and then to estimate the likely size of any gathering.

But the brown population, which had sustained an average of 14,000 to 25,000 breeding pairs for several decades (5-9% of the global population), essentially disappeared overnight

Image copyright
DigitalGlobe, a Maxar company

Image caption

2015: The guano stains at Halley colony are visible from space

Emperors are the tallest and heaviest of the penguin species and need reliable patches of sea ice on which to spread, and this icy platform must persist from April when the birds arrive until December when their chicks flutter. [19659008] If the sea-ice breaks up too early, the young birds will not have the right feathers to start swimming.

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Media caption Curious emperor penguins take a selfie video in Antarctica

Strong winds hollowed out of the sea-ice that had stuck hard to the side of the thicker brown shelf in its creeks, and never properly reformed. Not in 2017, nor in 2018.

Dr Fretwell customs BBC News: “The sea-ice that’s formed since 2016 has not been strong. Storm events that occur in October and November will now blow it out early. So there’s The BAS team believes many adults have either avoided breeding in these later years or moved to new breeding sites across the Weddell Sea. A colony some 50km away, close to the Dawson-Lambton Glacier, has seen a big rise in its numbers

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Media caption Peter Fretwell: “Storms can now hollow out the emperors ‘sea-ice in October and November’

Quite why the sea-ice platform on the edge of the brown shelf has failed to regenerate is unclear. There is no obvious climate signal to point to in this case; atmospheric and ocean observations in the vicinity of the brown reveal little in the way of change.

But the sensitivity of this colony to shifting sea ice trends does illustrate, says the team, the impact that future warming in Antarctica could have on emperor penguins in particular

Research suggests the species might lose anywhere between 50% and 70% of its global population by the end of this century if sea ice is reduced to the extent that computer models envisage.
DigitalGlobe, a Maxar company

Image caption

2018: The Dawson-Lambton colony has increased its numbers

Dr Trathan said: “What’s interesting for me is not that colonies move or that we can have major breeding failures – we know that. It’s that we are talking about the deep embayment of the Weddell Sea, which is potentially one of the climate change refugia for those cold-adapted species like emperor penguins.

“And so we see major disturbances in these refugia – where we haven’t previously seen changes in 60 years – that’s an important signal.”

Whether the Halley Bay colony really had a future is a moot point.

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Media caption Scientists have called for special status to protect coral, penguins and other wildlife in Antarctica.

The Brown Ice Shelf is split apart by a developing crack.

This chasm will eventually calve in the size of the Greater London into the Weddell Sea, and any sea-ice stuck to the mountain’s edge may break up in the proce

The colony could have been doomed regardless of what happened in 2016.

Peter Fretwell and Phil Trathan reported their investigation in the journal Antarctic Science

Image copyright
Christopher Walton

Image caption

Emperors are the tallest and heaviest of the penguin species

[email protected] and follow me on Twitter: @BBCAmos
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