Climate change: satellites discover new colonies of emperor penguins

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Copernicus / Sentinel / Esa data

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Guano spots: a new colony on fast ice that has formed around icebergs on the ground


Satellite observations have found a series of new emperor penguin breeding sites in Antarctica.

The locations were identified based on how bird poop, or guano, had stained large patches of sea ice.

The discovery raises the world’s emperor population by 5-10%, to perhaps as many as 278,500 breeding pairs.

This is a welcome development given that this iconic species is likely to come under great pressure this century as the white continent warms.

The entire life cycle of emperors centers around the availability of sea ice, and if it decreases in the decades to come – as climate models predict – then animal numbers will be hit hard.

One forecast suggested that the world’s population could collapse by half or more under certain conditions by 2100.

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AIRBUS

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Illustration: Sentinel-2 satellites frequently imagine the Antarctic margin where emperors live


The British Antarctic Survey (BAS) used the EU’s Sentinel-2 spacecraft to scour the edge of the continent in search of previously unrecognized Emperor activities.

Infrared images from the satellites cast eight of these breeding sites and confirmed the existence of three more that had been hinted at in the days before high-resolution space imagery.

The new identifications bring the number of known active breeding sites from 50 to 61. Two of the new sites are in the Antarctic Peninsula region, three in the west of the continent and six in the east.

They are all in spaces between the existing colonies. Groups of emperors, it seems, like to stand at least 100 km between them. The new sites maintain this discipline of distancing.

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Christopher Walton

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Emperor penguins need a reliable and stable sea ice platform


It is impossible to count penguins individually from orbit, but researchers at BAS can estimate the number of colonies from the size of the groups of birds.

“This is good news because there are now more penguins than we thought,” said Dr Peter Fretwell, BAS remote sensing specialist.

“But with that story comes a strong caveat that the recently discovered sites are not in what we call refuges – areas where sea ice is stable, like the Weddell Sea and the Sea of Ross. They are all in places further north and vulnerable. who will likely lose their sea ice, ”he told BBC News.

Breeding success for emperors relies on the presence of so-called “fast ice”. It is sea ice that sticks to the edge of the continent or to icebergs.

It is low and flat and makes an ideal surface on which to lay an egg, incubate and then rear the next chick during its first year of life.

But this seasonal ice has to last a long time, stay intact for at least eight or nine months to be useful.

If it forms too late or breaks too soon, young birds will be forced into the sea before they are ready, before they have lost their down and developed waterproof feathers.

Likewise for adults. They undergo a dramatic moult during the summer months of January and February. They too are at risk of drowning if the fast ice melts and they do not have the right plumage to resume swimming.

The trends of sea ice in Antarctica over the past decades have been fairly stable, although with large regional changes. But climate models predict significant losses this century.

Even in the best-case scenario of the Paris Agreement with a global temperature increase of up to 1.5 ° C from pre-industrial times, the population is expected to decline by at least a third over the next three generations, according to experts.

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Copernicus / Sentinel / Esa data

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The largest of the new colonies is at Cape Gates with several thousand breeding pairs


It was this disturbing prospect that led researchers last year to demand that the conservation status of emperors be improved.

For now, they are classified as “near threatened” by the International Union for the Conservation of Nature (IUCN), the organization that maintains lists of endangered animals on Earth.

A proposal has now been submitted to place Emperors in the most urgent “Vulnerable” category.

Details of the Emperor’s Sentinel Research are reported in the journal Remote Sensing in Ecology and Conservation

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