South American sea lion females reach sexual
maturity at the age of 4 - 5, males at the age of 5 - 6, although males only first
achieve territorial status at the age of 9 - 10.
They have a polygynous mating system meaning that
males will try to mate with as many females as possible. Males arrive at
the breeding colonies before females in mid-December to establish
territories that will eventually contain a harem of 3 - 9 females.
Less dominant males, unable to establish
territories (peripheral males), are known to attack undefended females,
occasionally attempting to mount them.
It’s also common to see these attacks towards
pups.
Females arrive few days after the males and give
birth 1 to 3 days after their arrival. This gives a concentration of 70%
of the births taking place occurring in the time span of 2 weeks.
Newborn pups measure around 85cm and weight around
10 to 15kg. They have a black coat that will eventually turn brown to
reddish-brown after a few months. The mother usually mates about 5 - 7
days after giving birth, with the dominant male.
Although fertilization takes place, real gestation
period lasts about 9 months due to the ‘delayed implantation’. After mating, the female begins
to leave her pup temporarily to go on foraging trips offshore. After a
few days at sea, she will return to the coast to continue to nurse her
pup. This way, total lactation lasts for about 8 - 12 months. During breeding
season, which last around 50 - 60 days, male sea lions stay on the coast
and do not eat. After breeding season however, they disperse wandering
long distances.
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