麻豆社

Males:

• Males are much bigger than females.
• Males arrive on the breeding beach and fight to establish a mini-territory. The most desirable territories are near the sea but above the high water mark. That location is what the females are after so that is what the males fight to obtain.
• A territorial male will have up to 27 females in his patch (average 15 females).
• Males will not be able to hold a breeding territory until they are 6 to 10 years old.

Females:

• The females arrive at the colony a couple of weeks after the males do.
• They mate 6 to 8 days after giving birth
• The female leaves to feed at sea a week after mating (i.e. 13 to 15 days after her pup is born). She will stay away for 3 to 5 days.
• She will return for 1 to 3 days to nurse the pup.

Pups:

• At birth a pup weighs 4.5 to 6.5 kg. Male pups are the heaviest ones.
• The pup will consume 2.9 to 3.5 kg of milk when the mother is back for one of these nursing bouts.
• Male pups use the milk they drink to make more lean body mass – muscles and bones – and less fat reserves. Female pups use the milk to make bigger fat reserves and smaller bodies.
• When the mother is away at sea the pups live off their fat reserves.
• Pups first enter the sea when they are 2 to 3 months old, but are not good swimmers until they are 4 to 5 months old (i.e. until they are weaned).
• Pups are born with black fur.
• They become silver-grey at 2 to 3 months old when they moult their black fur. • They become the adult brown colour later when fully grown.
• 24% of pups die in their first year of life.
• They become sexually mature when 3 to 4 years old.