Pupping season leaves a lot of seals abandoned
After the storm last week, I came across a dead seal pup on the beach. It was tiny, baggy-skinned and with part of its umbilical cord attached so it was obviously newly-born or just one or two days old. ‘Phone calls about stranded live pups followed.
We have two resident species of seal in Ireland: the Common Seal and the Grey Seal. The dead pup belonged to the later species. Grey Seal normally give birth in the period extending from mid-September to mid-November whereas Common Seals pup in June and July.
In general, the life of a Grey Seal alternates between two main events: a long, more-or-less solitary life spent feeding at sea and a short social life on land breeding at this time of year. To protect themselves from predators and people, the seals usually seek the safety of offshore islands. And they do so now to coincide with the equinoctial gales that make their offshore island refuges even more inaccessible.
While things have evolved in that way to ensure the maximum survival of pups, things sometimes go seriously wrong as we saw last week with the arrival of ex-hurricane, ex-tropical cyclone or storm Ophelia, with its very strong winds and attendant storm surges. Many pupping beaches must have been inundated, drowning new-born pups and putting recently-weaned youngsters under intense pressure as they are just coming to grips with catching fish.
Pupping begins in September. Groups of pregnant cows assemble at traditional breeding grounds. Adult females are very intolerant of others at their chosen pupping site and vigorously defend their patch against other competing females. A single pup is born on land and it stays on land until it is weaned. The pup has a white coat and does not swim.
To keep their bodies streamlined for swimming, suckling mothers have internal breasts or mammary glands. When their pups need to be fed, their mothers evert their nipples to allow the pups to suckle. Seal milk is extremely rich in fat so the new-born pups pile on weight very quickly, their baggy skin and loose folds accommodating the rapid weight gain as they become rounded, barrel-shaped and obese-looking.
After about three weeks, the pups moult into their grey sea coat and take to the water. Their thick layers of fat keep them warm and sustain them while they learn to catch fish and become independent before their mothers abandon them as the pupping season ends for another year.