Northern Elephant Seals (Mirounga Angustirostris) get their name from their unusually long trunk like noses and were hunted to near extinction during the 19th century. All Northern Seals are descended from one small surviving group which has resulted in a limited gene pool and compromised immune systems. They are also heavily subjected to the effects of global warming, with the el Nino of 1997/1998 resulting in an 80% pup mortality. Entanglement in fishing nets, collisions with boats and even cars as well as deliberate illegal shooting claims the lives of hundreds of these seals each year. Their Appendix II listing on CITES was lifted in 1997 though they do still receive protection under the US Marine Mammal Protection Act of 1972
A large bull with his eyes on a prospective mate
BREEDING
Breeding season runs from December through till March, with large males arriving early to fight and set up territories. Higher ranking bulls will also gain more access to females, so competition can be fierce. Successful males can impregnate up to 50 females in a single season.
Peak pupping time is in January, with females giving birth around a week after arriving on shore. Pups are born with a black coat and weigh in at 30kg and measure +/- 1.5m in length. The black coat is shed when the pup is around one month old.
Sexual dimorphism in Northern Elephant seals is pronounced
Females will mate shortly after giving birth and only once the pup is fully weaned will she leave to go foraging. The pup will live off its own fat reserves for the next month or two before it goes out to sea to hunt for its own food. For the duration of their stay on land, neither males nor females will eat, sometimes for up to 3 months, with males losing up to 35% of their total body weight.
During July, Northern Elephant seals will once again return to shore for what is known as a “radical moult” During this time they will shed their previous coat and it comes off in thick sheets along with their old skin.
The black coat is shed when the pup is around a month old
Adult males reach sexual maturity between 4-6 years, though territorial status only comes when they are between 8-12 years old. Males, which can be 7 times larger than females, measure around 4.5m long and weigh in at a massive 2 300kg. Females reach sexual maturity at between 3-5years, weigh around 750kg and measure 3.6m long. Males live for +/- 17years and females for 22.
Northern Elephant Seal (Mirounga Angustirostris), Youngster at play
INTERESTING STUFF
They are renowned for the great distances over which they migrate twice a year. They are the only mammals known for a biannual migration and no other animal migrates over such a long distance. Overall, bulls can spend around 250 days out to sea and travel at least 21 000 km. Females spend up to THREE HUNDRED days at sea and can cover 18 000 km quite comfortably in a single year.
Although mating battles between males are fierce, they are protected by a pinkish “chest shield” which is made from keratinized skin.
Only male Elephant seals have the proboscis
Sleeping Northern Elephant seal