Common Name:
California sea lion
Scientific Name:
Zalophus californianus
Habitat/distribution:
The habitat range of California sea lions spans from British Columbia, Canada down to the Pacific coast of Mexico including Islas Marías and the Gulf of California.
Body size & Physical characteristics:
Males and females start to exhibit sexual dimorphism by age 4 or 5 when reaching sexual maturity. Adult males measure 2-2.5m in length and weigh 200-300kg, they are dark brown and may sometimes have lighter coloured fur on their backs. Males have an iconic sagittal crest (‘bump’) on their heads that is not found in any other otariid species. Sub-adult males are similar in colour but do not have a developed crest and are smaller in size. Adult females are tan to light brown and measure 1.5-2m in length and weight 50-100kg. They do not have a sagittal crest.
Behaviour (e.g. sounds, foraging):
California sea lions make a dog barking-like noise. Unlike Steller sea lions, for example that make more of a consistent and long ‘roar’, California sea lions ‘bark’.
California sea lions can be seen holding their flipper up out of the surface as they float motionlessly. They can be seen doing this on their own or in groups. It is thought that this behaviour helps them regulate their body temperature.
Life expectancy:
20 – 30 years
Diet:
Depending on their specific habitat range, California sea lions eat a large variety of fish, cephalopod, and crustacean species. Most commonly, they feed on anchovies, mackerel, rockfish, and sardine, as well as octopus and squid. A sea lion’s diet can change depending on prey availability and abundance at that time.
Predators:
Their main predators are humans since they are commonly entangled and killed by fishing gear, or directly killed due to human-animal conflicts. Some killer whale pods that feed on marine mammals could prey on California sea lions they might encounter.
Reproduction:
Sea lions are a social ‘polygamous’ species consisting of groups of multiple females with their pups, where one dominant male will guard them and defend their territory, especially during the breeding season in summer. Females will usually birth a pup every year in early summer around May. This coincides with the time she will be weaning the previous year’s pup and getting ready to care for that year’s newborn pup.
Population:
Overall, globally their populations have been increasing since 1975. However, it is important to note that different rookeries may have different population trends depending on the time scale and geographic location. In general, population in the USA have been increasing in the last few decades totaling to around 2-300,000 individuals, whereas some populations in the Gulf of California, Mexico have shown a declining trend totaling around 15-20,000 individuals, most recently. It is hypothesized that this could be linked to changes in diet quality.
Conservation status:
IUCN Least Concern (2021)