Friday, 12 December 2014

Fur Seals

Apologies it's been so long since the last update. We've been hectic busy here with the spring arrival of the penguins, petrels and albatrosses as well as the summer staff – the returning base commander, new technician, a couple of senior scientists and our replacement field assistants. We'll be spending the next few months here working with and handing over to them.

As I was away at this time last year I missed one of the unique experiences of Bird Island; the fur seal season. This started seriously around the beginning of November when the big males started establishing territories on the beach. At 2m long and weighing around 150kg they are by no means the largest seals in the sub-Antarctic but they will not give ground to anyone. As they are more like sea lions than the phocids (elephant and leopard seals as well as the grey and common found around the UK) they are very quick and agile on land.

Charging up river, a male Antarctic Fur Seal.
A male arriving at a crowded beach will have to charge up the river (where no one holds territory) fighting off other males from either side. If cornered he will try and be repelled by a demonstration of superior size, but it won't take much for them to start fighting – biting and thrashing – and the majority have scars somewhere on their upper body.

The males are holding out for the return of the females. They face an equally difficult charge up the beach as they will try and be herded into harems. The largest males with the best locations will have the best chance of attracting and keeping them, outside our window one big guy is keeping his eye on 31 ladies and their pups.
The males can weigh as much as five times the weight of a female. They will typically hold their breeding territory for 20 to 40 days, during which time they will largely rely on the food reserves stored in their body fat.
The pups are born within a few days of their mothers returning from the ocean. Cast an eye over the colony at the right time and it won't be long until you see a female writhing round and giving birth to a little puppy that quickly shakes off its birth sack, opens its eyes and starts crying for food. There's a lot of calling as the mums and pups bond with each other as it's not long (about a week) before the former head back to sea to feed and when they return they need to recognise their young by call and by smell.
Female and newly-born pup taking its first look at the world. 
A female working out which of these two attention-seeking puppies is actually hers.
Once left alone the pups start to interact with one another, climbing, sniffing and play fighting. If there's no one else around they will happily play with their own flippers.

Dreaming of milk, a content pup.

Less than 1% of the pups are born blonde. With very few natural predators (the occasional leopard seal or orca) they tend to survive as well as the more typical black ones though they stand out more.

A stand off between a pair of puppies enjoying the chance to play while their mums are away.

A definite winner in this little battle, though the loser was straight back up for another bout.


95% of the world population of Antarctic Fur Seals Arctocephalus gazella is based around South Georgia with population estimates of 1.5 to 4 million. This has hugely increased in the last 50 years, by which point they were nearly hunted to extinction. Bird Island, being largely inaccessible, was one of their last strongholds.

Much of the science and research being done on these species focuses on finding out where they feed, what they're feeding on and how keeping track of how healthy the population is. Other projects have focused on their genetics and learning more about mother-pup interactions. I've been helping out over on the special study beach where the pups are weighed and samples of their umbilical cords are taken for genetic analysis.  

While some pups put up much more of a struggle than one would expect of their 5kg frame, others fall asleep in your arms.


Jerry.

1 comment: