Due to its isolated location far from the mainland, the Galapagos archipelago is home to just six mammal species. This unique ecosystem supports two types of bats and two types of rice rats, none of which you are likely to encounter on your journey. In contrast, two other species—Galapagos sea lions and Galapagos fur seals—will typically appear often during your Galapagos adventure. You may round out your mammal watching with views of bottlenose dolphins, while a sperm whale sighting would be a rarer treat.
Click on the links below to navigate to each species.
Galapagos Sea Lion | Galapagos Fur Seal | Bottlenose Dolphin | Sperm Whale
GALAPAGOS SEA LION
The most common native mammal you will see during your journey is the Galapagos sea lion, a subspecies of the Californian sea lion, which inhabits most islands. There are an estimated 50,000 individuals in the Galapagos. Territorial bulls can weigh up to 550 pounds and have exhibited aggressive behavior, including chasing swimmers from the water and biting people if harassed, so do not approach them too closely. On the other hand, females and pups are amiable and spirited and will often have fun swimming with snorkelers. Typically, sea lions live to approximately age 20. Females reach sexual maturity at age 5; males are capable of mating then, too, but usually do not do so until they are older. Dominant males patrol and guard particularly attractive beaches, territories that may contain up to 30 females. The dominant male will have mating access to these females, but only for as long as he is able to keep other males at bay. Defending a territory is very demanding work, and males may go for days without getting much food or sleep. After several weeks putting up this front, a harem-master may become weary and susceptible to defeat, causing him to lose his position to a new, well-rested male.
Females become sexually receptive once a year. The gestation period lasts 9 months and the (usually) solitary pup is born around the beginning of the dry season. After nursing her pup for a week, the mother will return to the water to feed. Thereafter, she will continue nursing, after her fishing trips, until the pup is 5 or 6 months old,
when it learns to fish on its own. Even then, the pup will continue to supplement its diet with its mother’s milk; some females may even nurse two pups, born in subsequent years, at the same time.
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GALAPAGOS FUR SEAL
You will see endemic Galapagos fur seals less frequently than Galapagos sea lions, which they resemble only superficially. Upon closer inspection, fur seals look quite different from sea lions. They are smaller and have a wider and shorter head shaped more like a bear's. A fur seal’s ears are also more prominent, and their front flippers are larger than the sea lion's. Fur seals and sea lions share many similar mating and social behaviors. One main difference is that male fur seals tend to defend territory from the land, while male sea lions defend from the water.
The fur seal’s coat is very dense and luxuriant, consisting of two layers of hair. Their thick fur attracted the attention of hunters who decimated the population in the 1800s in pursuit of their valuable pelts. Because of their thick fur, these animals hunt at night and spend the hottest part of day
hiding out in cool caves. This secretive behavior helped the species survive the sealers’ depredations. Today, fur seals are fully protected and the population has completely recovered; there are currently almost as many fur seals as sea lions, but the seals' more elusive habits explain why visitors see them less often.
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While not native to the Galapagos, the bottlenose dolphin is a frequent visitor to the islands. They can appear any time our boat is moving and often put on whimsical shows that delight travelers. Their distance from the boat varies: some will frolic right alongside the vessel, others will dance near the bow, while still others will execute flips off on the horizon. If you spot them at night, the swimming dolphins cause the ocean to shimmer with bioluminescence as they churn up thousands of miniscule
phosphorescent organisms that glow when disturbed. Common and spinner dolphins are less frequently seen. An encounter with these highly intelligent cetaceans is one of the highlights of any Galapagos adventure.
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During the 1800s, the sperm whale was hunted to the brink of extinction. The upwelling waters around the islands provide optimal feeding grounds for these marine mammals, which were hunted by the thousands as the industrial revolution demanded more whale oil in its early years. Once people began extracting oil from the earth, sperm whales were spared, but the history of the whaling industry left its mark on the Galapagos Islands. It is rare that visitors to the islands have an opportunity for an up-close encounter with a sperm whale,
since they frequently make long, deep dives as they feed, but it is not uncommon to see a sperm whale's spout on the horizon or its giant belly rise to the surface in the distance.
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