Breeding takes place in colonies between November and January (4) (2). Bulls (males) arrive at the breeding beaches in November each year, and start to fight amongst themselves to establish territories. Those that successfully secure and hold a territory are known as 'beach masters' (2) and will have privileged access to a harem of females (5). Throughout the entire breeding season, the beach masters are unable to return to the sea to feed, as this would force them to relinquish their hard-won territory. Instead they rely on their reserves of blubber during this period (5). Pregnant females arrive at the beaches around a month later than males (3). They give birth, usually to a single pup after arriving at the breeding beach, and mate after around a week to ten days (3) (5). Two weeks after giving birth, the mother starts to leave the pup in order to feed at sea, returning to the beach so that the pup can suckle (2) (3). She identifies her own pup by its distinctive calls (5). The pup begins to swim after two or three weeks, but it will suckle for a further eight months or more, and even up to a year (2) (3). Sexual maturity is reached at three to four years in females and five years in males (5). Hooker's sea lion feeds on small fish, squid, octopuses, crabs, mussels and other invertebrates. The occasional penguin may also be taken (3) (4). Whilst feeding, this species makes the deepest and longest dives of any sea lion in the world (6).