Heat-seeking drones count pup numbers in UK grey seal colonies

Drone flights are less intrusive for protected Atlantic grey seals

A drone view of seals on the land. Drones with heat-seeking cameras are being used on the Farne Islands to help with the census of pup numbers. Photo: TerraDrone

A seal pup on the Farne Islands during the annual census of one of England's largest grey seal colonies. PA

An operator flies a drone over the Farne Islands during the census. PA

An area of the island where seals have been spotted by drone – the blue patches show the presence of adult seals. PA

The islands, off the Northumberland coast of north-east England, are an important haven for thousands of seabirds and hundreds of adult seals, and are looked after by the National Trust. PA

A thermal image showing seals on the islands. PA

The Atlantic grey seal is one of the rarest seal species, whose numbers are counted meticulously on the Farnes every autumn. PA

The last survey was conducted in 2019 with a record number of 2,823 pups born, an increase of 62 per cent since 2014, and numbers were thought to have continued upwards since. PA

Heat-seeking drones are being used to count pup numbers at one of England's largest grey seal colonies.

The drones get above the action to record the protected Atlantic grey seals in a manner that is far less intrusive than human counting by close-quarters observation.

The Farne Islands, off the Northumberland coast, is an important haven for thousands of seabirds and hundreds of adult seals, and are looked after by the National Trust.

“We are using a drone … which as well as filming the pups is fitted with thermal imaging technology to help make the count more accurate and less stressful for the seals,” said ranger Thomas Hendry.

“The drone gives us an excellent view of the islands and from the clear images we can count the total numbers of seal pups born on each island.

“It also allows us to see on to the smaller islands more frequently which can be more challenging to visit at this time of year due to difficult sea conditions.”

The drone aerial images will be analysed to properly survey the new population.

One drone films the seals from above in the normal way and a second uses thermal imaging to give analysts more accurate results.

Drones are increasingly used to count wildlife because they are less intrusive and stressful for animals than having a human up close.

“The increase in numbers in recent years is thought to be down to the lack of predators or disturbance and the fact that the grey seals are generalist rather than specialist feeders,” said Mr Hendry.

“Once born, they're sprayed with a harmless vegetable dye to indicate the week they are born. Using a rotation of three or four colours allows the rangers to keep track of the numbers.”

The last survey was completed in 2019 with a record number of 2,823 pups born, an increase of 62 per cent since 2014. Numbers are thought to have continued upwards since.