Tuesday 17th November comments: It’s been a busy month or so as the island has transformed into a major Grey Seal nursery since late September. Whilst we worried about the lack of seals present in mid-September, we are now full into the seal breeding season and numbers have peaked across the colonies.
In recent blog posts we’ve been focussing on the pups and bull seals, but we should also take our hats off to the cow seals who actually do most of the hard work. Female Grey Seals are called cows and can be between 1.6–1.95 m (5ft 3in–6ft 5in) long and 100–190 kg (220–420 lb) in weight. In the wild bull seals live on average for 25 years but females can live well beyond 30 years of age. Cow seals give birth to a single pup between mid-September and mid-December. They will wean their pups for 18-21 days and although the pup gains almost 3lbs per day, the mother will lose about 6lbs per day (they look thin at the end of the lactation period having lost almost a quarter of their body weight – that’s one way to diet).
Once the pup is independent, the cows mate soon after on the colonies although have a delayed implantation they won’t become pregnant again until the new year. At that stage the job is done and the mothers can return to the open sea to feed and put on those valuable pounds ready for the winter ahead. Who said raising a pup was easy?