IT is certainly one of Scotland’s most mysterious islands, a wildlife haven that has change into often known as “seal metropolis”.
However at the moment, greater than a century since its final human residents left, consultants are struggling to ascertain precisely how lots of the marine mammals reside on Mingulay within the Outer Hebrides.
Now drones are being trialled to acquire a extra correct depend of the island’s gray seals.
Greys are the bigger of the 2 Scottish species, rising to nearly 7ft lengthy and weighing greater than 660lbs.
Roughly 38 per cent of the world’s gray seals breed within the UK and 88% of those are at colonies in Scotland, with the primary concentrations within the Outer Hebrides and Orkney.
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Aerial surveys to estimate pup births have been carried out in Scotland in 2016 utilizing a digital digicam system, however the numbers have been primarily based on large averages.
It’s hoped drones will give a extra correct depend of essential native colonies, resembling Mingulay, which is owned by the Nationwide Belief for Scotland (NTS).
Specialists calculated beforehand that there have been 23,800 gray seal pups within the Outer Hebrides, with estimates starting from 20,700 to 27,550.
Dr Richard Luxmore, the NTS’s senior nature conservation adviser, mentioned drones could assist to supply a greater image of the true inhabitants.
“It’s nearly unimaginable to depend seals individually in massive congregations,” he mentioned. “It’s tough to separate them trying horizontally at them utilizing binoculars. They’re only a black mass.
“We now have finished some preliminary work on Mingulay utilizing drones and we’re taking a look at utilizing them to get a greater concept of the inhabitants there.”
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Mingulay is the second largest of the Bishop’s Isles, which additionally comprise Berneray and Pabbay. After 2,000 years or extra of steady habitation, the island was deserted by its previous few Gaelic-speaking residents in 1912.
Gray seal numbers, in the meantime, have grown considerably.
The animals congregate above the excessive water mark on distant seashores and islands between September and December to pup.
Harbour seals, nevertheless, are likely to pup on intertidal sandbanks or rocks in June and July.
The greys are additionally well-known for his or her haunting howl. Harbour seals are silent as compared. At the moment of yr they’re additionally cautious of predators, resembling killer whales.
Man-made air pollution, fishing nets and taking pictures at salmon rivers or at fish farms are additionally threats.
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The Particular Committee on Seals’ final report assessed the UK gray seal inhabitants at about 150,000 – primarily based on estimates ranging between 131,000 and 171,600 – with harbour seals about 45,100.
“General, the UK inhabitants has elevated for the reason that late 2000s and is near the 1990s degree,” says the report.
“Nonetheless, there are vital variations within the inhabitants dynamics between areas, with normal declines in counts of harbour seals in a number of areas round Scotland. However the declines usually are not common, with some populations both secure or rising.”
Gray seals are long-lived animals. Males could survive for greater than 20 years, whereas females typically dwell for greater than 30.
They’re generalist feeders, foraging primarily on the ocean mattress at depths of as much as 330ft, though they’re most likely able to feeding in any respect the depths discovered throughout the UK continental shelf.
They take all kinds of prey species together with sandeels, cod, whiting, haddock, ling and flatfish.
Gray seals forage within the open sea and return recurrently to land the place they moult and breed.