As the southeast trade winds push the Humboldt Current along the western coast of South America, arriving at tropical latitudes implies mixing with other masses of ocean currents, as well as physical forces, and as a result, they become the powerful South Equatorial Current (also known as SEC). Not only these waters are bringing cooler temperatures to the geographically-tropical Galápagos Islands, but they are also blooming with life as plankton thrives well in cooler temperatures, and salinity of the water is greater. This surplus of food allows species depending on the ocean’s productivity to thrive well, but most importantly, to reproduce efficiently in order to maintain its biodiversity relevancy.
Galápagos Sea Lions & Galápagos Fur Seals (fur sea lions) are marine mammals found in almost all islands of the archipelago, but not commonly seen everywhere. However, during the peak of the dry season (August & September, and also extending into October) is when most sea lion pups are born. Thus, we call it “pupping months”. Sometimes, guests ashore are lucky enough to even see a full labor process and the birth itself. After about 9 months of gestation, females are ready to give birth, and interestingly enough at the time where most food is available in the ocean. This guarantees females to produce substantial amounts of milk for good nourishment of pups. About a week or two after giving birth, female sea lions enter estrus stage and become pregnant right away. Of course, 9 months later after August or September don’t match with the best nourishment conditions. Here’s where an amazing evolutionary adaptation has been studied for years now – it’s called delayed implantation.
Delayed Implantation is a reproductive strategy used by almost 100 different mammals in seven different orders.
Here, the embryo does not immediately implant in the uterus, but it is maintained in a state of dormancy. No development takes place during this period and as a result, the normal gestation period is extended, sometimes by as much a one year. This obligated diapause is the mechanism to allow mammals to time the birth of their youngsters with favorable environmental conditions.
Sea Lion Pups Everywhere!
Since Galápagos Sea Lions prefer beaches and shallow access to the ocean, newborns have a continuous playground to stimulate certain senses and development of movement skills. While the majority of pups are born in late August, September, and all through mid-October, development continues all through their “pup stages” and this implies being playful in the water, as well as highly curious while on land. This goes on until around the months of June/July, but subadults retain their gregarious behavior by “hanging out” with other individuals. Guests love to see sea lions in general, but their puppy months leave unique memories. Sea lions are part of the BIG15 wildlife list of the Galápagos Islands.
Text and Photography: Francisco “Pancho” Dousdebés