This species of sea lion, like most sea lions, has a pronounced sexual dimorphism. Once mature, males develop a bony crest on top of their heads. Their coats range from dark brown for males to golden beige for females.
Environment and behavior
Adult males and subadults (equivalent to teenagers in human development) are extremely noisy. They bark relentlessly to attract females and drive away the other pretenders. The species is polygamous. The male arrives on the beach before the females. He defends a territory for about 45 days, on which the female will come to give birth to their baby, conceived the previous year. Gestation lasts one year, taking into account a delayed implantation period of approximately 3 months. This means that, after mating, the embryo does not develop right away. If the mother encounters favorable conditions (good diet and no disease), the fetus will develop. The baby is born between May and July. Females are fertile one to two weeks after giving birth. The mother then stays on land for one week, without leaving her child, in order to nurse. Then, she alternates between 2 to 3 days of hunting and 2 to 3 days of nursing.
The main predators of the California sea lion are killer whales and sharks. On land, the coyote is a predator of newborn sea lions.
Conflicts with fishermen, poaching and by-catching in fishing nets are the main threats to this species today. Their position at the top of the food chain also causes them to accumulate large quantities of PCB and DDT that weaken their immune systems and reproductive rates.