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Southern Elephant Seal
Southern Elephant Seal
Common Name:Southern Elephant
Seal
Scientific Name: Mirounga leonina
Southern Elephant Seal
Southern elephant seals
(Mirounga leonina) have a circumpolar distribution and breed
on subantarctic islands. 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 about 50%. Since then the population
at Heard and Kerguelen has remained relatively stable but
the Macquarie population has continued to decline at about
1.2% per year.
Description
Southern elephant seals
(Mirounga leonina) are the largest of all seals with males
reaching 4-5 m in length and 3 500 kg in weight. Females are
much smaller at 2-3 m in length and only 500 kg in weight.
Southern elephant seals are coloured rusty grey-brown
and are covered with thick blubber. Mature males have a large
'trunk', or proboscis which is used to amplify their vocalisations
and, together with their bulk, gives rise to their name 'elephant'
seal. They often appear cumbersome and indifferent to humans
yet, despite their awkwardness, the speed with which they
can move their bulk makes them potentially dangerous if harassed.
Size
Adult males can weigh up to 3000kg while adult females weigh between 300 and 900kg just prior to giving birth. Pups weigh about 40kg at birth and are weaned after 24 days by which time they weigh on average 120kg. A large weaner may weigh in excess of 220kg.
Behaviour
Southern elephant seals
can dive to over 1500m in depth and can stay submerged for
up to 2 hours. Most dives are about 30minutes duration and
of depths between 300 and 800m and can dive constantly while
at sea spending about 2 minutes on the surface between dives.
Diet
Southern elephant seals feed on squid and fish.
Breeding
 Southern elephant seals
breed in colonial groups called harems. A
single dominant male usually can control a harem of up to
50 females. Once harems get larger than this
the dominant beachmaster will allow assistant beachmasters
to reside within the harem. Harems can grow to over 1000 females
with over 30males.
Southern elephant seals
have a thick layer of blubber that sustains them during the
breeding season as they do not feed during this time. For
many years seals were killed for their blubber which was boiled
down to make oil.
Adult elephant seals return to subantarctic
islands for the breeding season (September-November) and to
moult their hair and skin (January to April).
Move
Southern elephant seals
travel long distances to their foraging areas. Males forage
mainly on the Antarctic continental shelf while females forage
in more pelagic areas, such as off the Antarctic shelf within
the pack ice, or near the Antarctic Polar Frontal Zone. Foraging
areas can be several thousand kilometres away from their breeding
islands.
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