Elephant seal - Mirounga leonina - regurlarly pays visits to the isle but does not breed there.

As refers the name of the site "la Mare aux Elephants" (the elephant pond) it may be thought that these animals used to be there in great number before the coming of the first visitors.

Following the intensive hunting expeditions of the eighteenth and nineteenth centuries, fewer and fewer elephant seals kept coming to Amsterdam Island. In 1987 only a few dozens of these animals were localy counted. From 1995 onwards, fewer than ten individuals still come to "la Mare aux Elephants". Those are mainly males coming back ashore for shedding.

Elephant seals are pinnipeds belonging to the greater family of the Phocidae. They present the most important sexual dimorphism among mammals. Males can weigh up to five tons whereas the smallest females only weigh about 500 kg - the heaviest of them being rarely over one ton heavy. Reproduction is polygamous, a male being able to inseminate several dozen females which will make up his harem. Each year the female comes ashore to give birth to a 30-kg pup which will be weaned when he weighs 300 kg about a month later. After this short weaning period, the female is inseminated again by the same male before she goes back to sea for another eleven months. The female will eventually come back ashore for a new breeding season.