The Galapagos islands are home to about 50,000 sea lions, making them the most common marine mammal on the archipelago. They are seen all around the islands, and their friendly and inquisitive nature will be sure to make them a highlight of your visit to the Galapagos. Nicknamed dogs of the sea, sea lions portray characteristics that are not too dissimilar from our four-legged friends. Often seen basking in the sun whether that be on beaches or benches, and swimming rings around unsuspecting snorkelers.
Galapagos sea lions are one of six species of sea lion. They are likely to be spotted around the shorelines of most islands. You can usually see large colonies on the islands of San Cristobal, Isabela, Espanola, South Plaza, North Seymour, Rabida and Bartolome. Sea lions range mainly from light to dark brown, with a streamlined bodies. They have powerful front flippers used for swimming, reaching speeds of up to 24 mph (40 kph). These features make them efficient hunters, especially of sardines which are their main prey. The sea lion’s rear flippers can be rotated under its body to walk very efficiently on land. In fact, they can move faster on land than most humans for short distances! This may be hard to imagen as you watch them basking in the sun. Galapagos sea lions are endemic to the archipelago and are part of the eared seal family – having external ear pinnae.
On the archipelago, there are two types of sea lion colonies. Harem and bachelor colonies. Female cows live in harem colonies, which are sometimes controlled by one dominant male bull. However, most males tend to hold territories on beaches where females live, as opposed to holding direct harems. The more dominant the male is, the more land he has in his territory, and therefore the more females are available for him to mate with. The bulls aggressively defend these territories from other male rivals or interlopers, and the bulls that don’t manage to acquire a territory containing females tend to form bachelor colonies away from the female haulouts. The mating season usually occurs between July and December but can differ from island to island.
Sea lions live on the Galapagos islands all year round but if you are particularly interested in seeing sea lion pups, you should try and arrange your trip between July and November. When cows give birth, a single pup is born. They spend their first-week bonding closely with mum, developing a unique call to distinguish themselves from other pups of the nursery group. The mother then hunts for food by day, and the pup suckles milk in the evenings. Pups are dependent on their mothers for the first year of their life, although they do also learn to hunt and feed before then. Female pups are more independent than their male counterparts, venturing out to sea and diving for their food much more frequently.
When young, there is little difference to tell male from female sea lions. However, as they mature into adults, males can be substantially bigger – 2-4 times bigger! Adult females weigh around 100kg (220 lbs) whereas males on average in the wild weigh about 250kg (550 lbs). Males also tend to be a darker brown and will develop a prominent raised forehead called the sagittal crest by about 10 years of age. The differences in size, color, and weight between male and females are called sexual dimorphism.