They are sometimes seen porpoising, or jumping out of the water, presumably to speed up their swimming. Most pups are born in June or July and weigh 13-20 lbs. They nurse for at least 5-6 months and sometimes over a year. Mothers recognize pups on crowded rookeries through smell, sight, and vocalizations. Pups also learn to recognize the vocalizations of their mothers.
Breeding takes place a few weeks after birth.
Males patrol territories and bark almost continuously during the breeding season. California sea lions are opportunistic feeders and eat such things as squid, octopus, herring, rockfish and mackerel. In turn, sea lions are preyed upon by killer whales and great white sharks. Sea lions are known to have such diseases as pneumonia, caused by a parasitic lungworm, and a bacterial infection called leptospirosis, which affects their livers and kidneys. Other problems for California sea lions involve humans.