Freely accessible satellite tv for pc radar imaging is getting used for the primary time to assist monitor colonies of endangered emperor penguins in Antarctica all through the winter months.
Usually satellite tv for pc photos want daylight to be helpful, and Antarctica is darkish within the winter. This has meant that colonies have been hidden at a important time within the emperor penguin breeding cycle, when eggs are laid, chicks hatch and adults participate in these iconic huddles.
Virtually 70 colonies of emperor penguins, lots of which have by no means been visited by people, occupy the sea ice that’s fixed to the shoreline surrounding Antarctica.
Now utilizing synthetic aperture radar (SAR) , an instrument working on satellites that sends microwave pulses right down to Earth, and measures how these pulses return, our analysis group has been capable of monitor what the penguins do throughout these months.
Not like different types of satellite tv for pc imagery, SAR isn’t reliant on daylight, or affected by cloud, and due to this fact gives radar imagery of Antarctica by way of the darkish polar winter.
SAR’s sign is delicate to the properties of what it interacts with, and has been used for years within the poles to analysis issues just like the properties of sea ice and melt on glaciers .
When taking a look at SAR photos from the free European Area Company satellite tv for pc, Sentinel-1 , displaying the placement of an emperor penguin colony throughout winter, my group began to note a brilliant white splodge of pixels shifting round in opposition to a backdrop of darkish, easy sea ice.
Options like icebergs or tough sea ice can look brilliant in SAR imagery, but it surely did not make sense for these to be shifting round at the moment of 12 months, when the ocean ice was fastened and steady. Might it’s the emperor penguin colony?
We quickly discovered the identical factor on the places of different colonies – clusters of brilliant shifting pixels on steady ice. We had been then capable of acquire optical photos from September when the daylight first begins returning, and examine them with the SAR, and confirmed it was certainly the colonies we had been observing.
Monitoring by way of the entire 12 months
This discovering opened up an thrilling alternative to trace colonies all through the entire breeding cycle, by combining SAR photos in winter with optical photos in spring/summer season, and all utilizing freely accessible knowledge that has been routinely collected for years.
We went again by way of eight years, from 2017 to 2024, and adopted three of the biggest colonies year-round. We had been capable of observe their motion, generally even every day from early within the winter till chicks develop their first feathers in December and January.
We noticed that colonies had been usually much less cell within the winter, earlier than spreading out and shifting higher distances within the spring and summer season. Curiously, we discovered that the Atka Bay colony moved up from the ocean ice onto the glacier ice that flows from the continent in seven of the eight years within the early spring. The colony did this regardless of the ocean ice – the usually most well-liked habitat for the species – being steady. We’d like extra analysis to know why that is.
Satellite tv for pc distant sensing has been a vital device for observing the emperor penguins in the summertime months since 2009. It was found then that colonies may very well be present in satellite tv for pc photos due to the darkish guano stains they depart on the snow and ice. General, these observations have revolutionised our understanding of the species and have led to the invention of many extra colonies.
After a interval of stability, Antarctic sea ice has declined markedly since 2016 and likely entered a new state , characterised by decrease extent and elevated instability. Earlier this 12 months, emperor penguins had been added to the Worldwide Union for Conservation of Nature’s red list and categorised as endangered, predominantly resulting from projected declines in sea ice.
This makes higher understanding and monitoring of emperor penguins extra essential than ever. The flexibility to watch colonies all through the breeding cycle utilizing freely accessible, routinely collected satellite tv for pc knowledge creates alternatives to raised perceive their response to altering environmental situations.
Grant Macdonald receives funding by way of a Pure Environmental Analysis Council venture. He’s a member of the Inexperienced Celebration of England and Wales.
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