The UK is home to around 35% of the world's grey seal population; once numbering just 500 in the early 20th century, there are now more 160,000 living on our shores. Yet despite this recovery, continued monitoring remains essential to ensure their long-term survival.
So, how do researchers monitor seal numbers? Traditionally, they relied on volunteers conducting ground counts or aerial surveys from planes, but both approaches pose challenges when it comes to reaching remote or rugged locations.
And that's why a new, two-year initiative led by Natural England is combining Artificial Intelligence (AI) with drone surveys to track seal numbers along the Norfolk coastline.
Drone's-eye view
The project's first drone was launched in December 2024 over the beach at Winterton-on-Sea in Norfolk.
The drone’s high-resolution camera captured detailed images from 110 metres above, minimising disruption to the seals below.
Cutting-edge AI technology, known as instance segmentation, was used to analyse the images, automatically identifying individual seals and distinguishing between adults and pups, even when gathered closely together.
"The AI model detected over 8,500 seals, while the volunteers on the ground counted 6,200," explains Gabriella Fasoli, earth observation higher data scientist at Natural England.
"This difference is likely due to the drone’s aerial perspective, which provides a unique viewpoint from above, allowing for a more accurate count by detecting seals that may be hidden or less visible from the ground."
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According to Emma Milner, senior marine mammal specialist at Natural England, "the project has shown that drones and the use of AI technology can be a cost and time efficient alternative method of monitoring seal populations.
"This cutting-edge technology will help contribute to a comprehensive national picture of seal populations, allowing us to better understand population changes over time and to assess the impact of human activity on these crucial habitats, enabling better conservation efforts.
"It is our hope that in the future, the methods from this two-year pilot project can be developed to allow drone surveys at other important sites around the country, and for other species as well as grey seals."
Natural England say that volunteers on the ground will continue to play an important role in the protection of the seals.
By harnessing modern technology, conservationists are unlocking new possibilities in wildlife protection, say the researchers, from improving flood management and supporting sustainable farming to monitoring biodiversity.
Natural England have special permission to conduct drone surveys in line with best practice guidelines, ensuring minimal disturbance to the seals. The public is urged not to fly drones over seal colonies without appropriate authorisation.
Main image: Norfolk seal survey/Natural England
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