A seal pup, chillaxing

Heat-seeking technology gives better picture of seal pup numbers

Image credit: Diana Parkhouse | Unsplash

Wildlife experts are using heat-seeking drones to count pup numbers at one of England’s largest grey seal colonies.

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

The Atlantic grey seal is one of the rarest seal species, is protected and their numbers are carefully counted on the Farnes every autumn.

National Trust rangers have used drones in recent years to do the count on outlying islands, using aerial images which are then analysed later to survey the new population.

Now rangers are working with academics, sea mammal specialists and expert fliers to use a drone with two cameras. One films the seals from above in the normal way, while a second uses thermal imaging. This dual approach gives the analysts more accurate results.

Drones are increasingly being used to conduct wildlife counts, as an 'eye in the sky' is less intrusive and stressful for animals than having a human up close.

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

Ranger Thomas Hendry said: “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.

“This year we are still counting the seals every four days in some locations, weather permitting. 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.

“We are using a drone again this year, 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. 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 onto the smaller islands more frequently, which can be more challenging to visit at this time of year due to difficult sea conditions.”

Drones are increasingly being used for a variety of tasks involving hard-to-reach places, including monitoring seabird colonies on the Falkland Islands; delivering post to remote Scottish islands; locating fresh water sources in the seas around Easter Island, and inspecting rural roads for potholes.

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