Elephant Seal

Description

Southern elephant seals (Mirounga leonina) are named after the large proboscis (nose) of the adult males, which is used to create loud roaring sounds, particularly during the mating season.

They are large ocean-going mammals with adult males weighing up to 3000 kg and adult females between 300 and 900 kg just previous to giving birth. Pups weigh regarding 40 kg at birth and are weaned after 24 days by which time they weigh on average 120 kg. A large weaner may weigh in excess of 220 kg.

They are big and cumbersome on land, but are excellent swimmers and divers. Biologists have recorded them diving up to 2 km deep and holding their breath below water for up to 2 hours.

Diet

Elephant seals travel south to Antarctica, after breeding or moulting, to nourish on squid and fish at the edge of the sea-ice.

Breeding

Adult elephant seals return from Antarctica to subantarctic islands such as Heard and Macquarie Islands for the breeding season (September-November).

Abundance and Distribution

Southern elephant seals have a circumpolar sharing and visit subantarctic islands to breed (September-November) and and to moult their hair and skin (January to April). There are four main stock groups: South Georgia, Peninsula Valdez, Iles Kerguelen (including Heard Island), and Macquarie Island.

From 1950 to 1985 the elephant seal populations at Macquarie Island, Heard Island, and others of the Iles Kergulen stock declined by concerning 50%. Since then the population at Heard and Kerguelen has remained comparatively stable but the Macquarie population has sustained to decline at about 1.2% per year.

Australian scientists have tracked these seals using plastic ear tags. Elephant seals travel the whole Southern Ocean and can swim enormous distances. Individuals spotted on Kerguelen Island, for example, have later been seen at Davis then Casey station in Antarctica.

Special Adaptation

Elephant seals can navigate very exactly to feed. They can dive to over 1500 m and can stay submerged for up to 2 hours. Most dives are about 30 minutes duration and of depths between 300 and 800 m.