California Sea Lion

California Sea Lion, intelligent, slender-bodied seal, well known for its balancing acts as a circus performer and its presence in almost every zoo. A gregarious personality, combined with remarkable speed and agility on land and lively barklike vocalizations, makes this seal easily trainable and appealing to human audiences. In the wild, these shore-living seals are found along many areas of North America’s western coast, from British Columbia southward through the United States to the Tres Marias Islands off of Baja California, Mexico. Some populations are also found in the Galápagos Islands.

Adult males, called bulls, average 360 kg (800 lb) in weight and 2.1 m (7 ft) in length. Females, or cows, are smaller, with an average weight of 110 kg (250 lb) and an average length of 1.8 m (6 ft). Both sexes have chocolate-brown coats and doglike muzzles. Males are distinguished by their larger size, as well as by protuberant foreheads caused by an internal bone ridge that anchors powerful chewing muscles. California sea lions eat squid and octopus as well as a variety of fish—herring, rockfish, mackerel, anchovies, and lampreys. They hunt in shallow waters and often compete directly with a closely related species, Steller’s sea lions, for food.

In early June, bulls set up breeding territories, or rookeries, on sandy or rocky coasts. Each bull mates with a harem, or group of cows, composed of five to twenty females. Bulls defend their harem and territory with considerable energy and strategy—patrolling the area on land and in the water, barking loudly and posturing at trespassers, and sometimes fighting with intruding males.

Each cow gives birth in the rookeries to a single pup approximately one year after conception. Mothers and newborns quickly learn each other’s calls; the mother also memorizes her pup’s scent. A mother takes her pup into the water with her early on and nurses it for an extended period of time (often a year or more), building a strong bond. As the pups grow, they form groups that frolic, feed, and nap together in the noisy rookery. When the pups are two to three weeks old, the cows mate again. Females remain near the rookeries, often on remote island beaches, while the males migrate north in the summer and fall after the breeding season.

As coastal creatures, California sea lions are particularly vulnerable to toxic pollutants and human disruption of their habitat. They are preyed upon by sharks and killer whales, and they were also hunted by humans in the past. These animals have been protected from killing and harassment in United States waters since the Marine Mammal Protection Act was passed in 1972. Still, in the early 1980s as many as 1500 per year died by drowning after becoming entangled in gill nets. Recent attempts to regulate and limit gill net fisheries in California waters have decreased the number of deaths in this species.

Scientific classification: The California sea lion belongs to the family Otariidae of the suborder Pinnipedia, order Carnivora. It is classified as Zalophus californianus.

California Sea Lion Microsoft® Encarta® Encyclopedia 2001. © 1993-2000 Microsoft Corporation. All rights reserved.