Pigs Might Swim
19 September, 2013
This week, I had to answer a query about seals and Inchcolm Island for a Scottish countryside magazine. It concerned the grey seal (Halichoerus grypus, meaning ‘hooked-nosed sea pig’), and when they would be coming ashore to give birth on Inchcolm island in the Firth of Forth. The enquirer also wanted to know why seals give birth in the autumn. Gales are a feature of the Scottish autumn, so it doesn’t seem the most auspicious time of year to be a young seal.
It is a good question. In the wild, most creatures give birth in spring and early summer. However, nothing happens in nature without there being a good reason, generally related to survival.
One likely factor is the presence of food. Seals eat a variety of prey – fish, shellfish, squid and octopus. Over the winter these are not present in large numbers, but they would normally begin to proliferate in the spring.
There was a very poor spring this year . Diving friends reported that water temperatures were very low and as a result sea-life – particularly shellfish – were much less abundant than normal . However, the warm summer weather would have boosted sea-life, allowing seals – particularly the now-pregnant mothers – to feed voraciously, and put on a lot of body fat.
A mother seal usually produces a single pup. It is relatively helpless when born, and totally reliant on its mother’s milk for the first few weeks. This is why mother seals need to have fed so much during the summer. Their milk is more than 50 per cent fat, and the pups grow very quickly, developing a thick layer of blubber that will protect them from the cold and sustain them as they learn to hunt for themselves.
Grey seal mothers feed their pups with milk for 16 to 21 days, during which time the pup gains an average of 30kg (66lbs). The mother might lose over 60kg of her body weight, after which she will return to sea to feed and put on weight again.
So it seems the answer to the question as to why seals give birth in autumn is simply it follows a period of intense feeding when the mother seals are at their heaviest and most able to cope.
There is still an opportunity to see young grey seals on a trip to Inchcolm, before the Priory closes for winter at the end of September, leaving the Island and its seals in peace.
Other good sites to see young seal pups include the seaside monuments of Orkney and Shetland and the islands of Iona and Bute.
Speaking of Bute, I have been asked by my colleagues in our Events Team to mention an event at Rothesay Castle at 2pm on Saturday 28 September marking the 750th anniversary of the Battle of Largs.
In 1263, King Haakon IV of Norway and his forces took Rothesay Castle for the second time (having captured it briefly in 1230). Haakon then attempted to reassert Norway’s historical ownership of western Scotland, but at Largs they were confronted and driven off by a Scottish army. It was an inconclusive outcome, but Haakon died soon afterwards, and the Norwegian claim on western Scotland was never renewed.
A re-enactment of the battle is to be held at Rothesay Castle on Saturday 28 September. The event, At Land and Sea, starts at 2pm with the arrival of the ‘Viking hordes’, followed by the storming of the castle. A number of activities during the afternoon culminate in a torchlight procession at 7.30pm, followed by live music, hog roast and fireworks. For details go to: www.historic-scotland.gov.uk/events