Radar satellites track Emperor Penguins through the Antarctic winter
Sentinel-1 imagery provides the first year-round satellite view of colony movements during months of polar darkness.
Radar satellites have been used to follow Emperor Penguin colonies through the darkness of the Antarctic winter, closing a major gap in efforts to monitor the species from space.
A Durham University-led team tracked colonies at Atka Bay, Coulman Island and Cape Washington between 2017 and 2024. The work is described as the first year-round satellite monitoring of Emperor Penguin colony movements.
Most previous satellite studies have relied on optical images, which cannot see through cloud and are unavailable during the months of continuous winter darkness. The new study used freely available synthetic aperture radar images from the European Space Agency's Copernicus Sentinel-1 satellites.
Standing at around 1.2 metres tall, groups of Emperor Penguins produce a radar signal that can be distinguished from the comparatively flat surface of the surrounding sea ice. This allowed researchers to map changes in colony position when no daylight images were available.
The team combined the radar observations with optical imagery from Sentinel-2 and NASA's Landsat 8. In late summer, radar even revealed trails left by guano as the birds moved across the ice, with the features subsequently confirmed in optical images.
Atka Bay lies on the coast of Queen Maud Land, while Coulman Island and Cape Washington are in the Ross Sea sector. Following colonies in different parts of Antarctica allowed the researchers to test the approach across contrasting ice settings rather than at a single well-studied site.
Emperor Penguins breed during the Antarctic winter and depend on stable fast ice attached to the coast for roughly nine months while they pair, incubate their eggs and rear chicks. A colony may move across the ice in response to cracks, weather and access to the sea.
“Satellite radar imaging is a very useful tool for understanding their behaviour during a key part of the breeding cycle.”
Dr Grant Macdonald, Durham University
The radar record can show when a colony shifts position, fragments or disappears from its expected location. Used alongside weather and sea-ice information, repeated images may help researchers distinguish routine local movement from a response to deteriorating breeding conditions.
Understanding those movements matters as climate change reduces the extent and reliability of Antarctic sea ice. Breeding failure can occur when ice breaks up before chicks have developed waterproof feathers, while colonies may relocate following repeated poor seasons.
The method does not replace field surveys or high-resolution optical counts, but it gives researchers a practical way to watch known colonies during the least observed part of their annual cycle. Because Sentinel-1 data are freely available, it could also support more consistent long-term monitoring.
Radar images are not as immediately recognisable as photographs and interpreting them requires care. Their strength is continuity: they can be collected through darkness and cloud at times when direct visits would be difficult, expensive and potentially disruptive.
The study was published in Communications Earth & Environment and involved researchers from Durham University, the British Antarctic Survey and partner institutions.
3 Sep 2026
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