Seal of approval for visitors

THE visit to the Dublin coast of an exotic creature from the Arctic ended in tragedy recently.

The young hooded seal came ashore in a distressed state and died a few hours later. The carcass has been sent for post-mortem examination.

We have two resident seal species, the grey and the common, but others visit our shores occasionally. They are mostly lost souls wandering far from their normal range. A creature shot near Roundstone in 1855 may have been a harp seal but the victim sank before its identity could be confirmed. Fergus O’Rourke in his Fauna of Ireland (1970) mentions the capture of a ringed seal in Galway Bay in 1895. The animal was taken to Dublin Zoo where “it lived for some time”.

The walrus appeared for the first time in 1897. This iconic seal has taken a shine to the Donegal coast; there have been about two dozen sightings there in recent years.

According to Alli McMillan, of the Dingle Wildlife and Seal Sanctuary, three young hooded seals have been rescued. Two of them died. The third survived and was released by the Naval Service 300km off the north coast.

There are similar records from British and mainland European coasts. A female ‘hoodie’, named Eve, visited Friedrichskoog in Schleswig-Holstein last August and she was taken into custody. After convalescing at a German sanctuary, she was satellite tagged and returned to the sea. Eve headed for Orkney but changed her mind before getting there and turned southwards to the east coast of England where she got into trouble again. Rescued by the Natureland Seal Sanctuary in Skegness, she made a full recovery. There being little point in releasing her so far south, it was decided to take her to Iceland where, hopefully, she might have the sense to head north to colder seas.

The Icelanders, however, would have none of it. Eve might be carrying an infectious disease, they feared, so they refused her an entry visa. A young male hoodie, named Sahara, travelled even farther than Eve.

He was captured in an exhausted state in Tenerife and spent four months recovering at a sanctuary there. Then he was flown to Britain, taken on to Orkney, satellite tagged and released.

The hooded seal is not only a great wanderer, capable of covering hundreds of kilometres, it’s also an accomplished diver. It can reach depths of 1,000m and stay down for up to 50 minutes.

The seal gets its name from a balloon-like sack which hangs from the face of the mature male. The sack can be inflated until it’s as big as the animal’s head. Males also have a membrane in one nostril which they can blow up into a red ball. It ‘pings’ if shaken. The balloons are used to warn off rival males and impress females.

This is a large animal. Males, up to 2.5 metres long from nose to tail, can weigh 400kg and are very aggressive. Females are smaller. Males compete with each other for access to females; the bigger the bull, the more matings he is likely to secure.

Mothers haul out on the ice to give birth to their single pup. Care of the newborn is notoriously short in seals. Irish grey seal pups are abandoned by their mother after three to four weeks. The hooded seal pup is on its own after three or four days, the shortest lactation period of any mammal.

The hoodie’s milk, which is 60 to 70% fat, is said to be the richest produced by any species. It contains so much nourishment that the pup doubles in size before its mother deserts it.

Meanwhile, eager males are waiting in the water; the female will be pregnant again within days. ‘Delayed implantation’ suspends the development of the embryo so that the birth will occur at the same time the following year.

It has been suggested that the Dublin hoodie died through ingesting sand. Marine animals don’t need to drink; they get their fresh water supplies from the bodies of the fish they eat. Hoodies, apparently, drink melting ice. When none is available, a thirsty seal may turn to eating sand which makes it sick. Can this be true?

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Saturday, July 31, 2021

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