The Weaner Within

I’m up to more white shark research, and my new favorite thing is weaners. No, it’s not what you’re thinking—”weaners” is the highly scientific term that the marine biology community has assigned to freshly WEANED (get it?) northern elephant seals, and boy are they cute!

Named for the schnoz on the adult bulls, elephant seals are the second largest seals in the world (the honor going to the even more enormous Southern Elephant seal). Full-grown northern elephant seal males can reach up to 4,500 pounds and over 13′ in length, while the females are much smaller at (only) 1,500 pounds and about 10′ in length. Known to be the favored prey of the great white shark, the elephant seals of the Farallon Islands get special attention from scientists. Each season the seals are tagged, counted, and monitored to help keep track of their health and population.

The dark elephant seal pups are born in December/January and weigh in at about 75-80 pounds at birth. But they don’t stay small long; pups gain 8-10 pounds a day from over the course of 28 days, reaching up to a whooping 250+ pounds from nursing alone! For the next two months they’re “weaners,” left behind in the rookeries while their mothers mate with one or more of the dominant bulls and then return ocean to eat for the first time since giving birth.

Alone on shore, the weaners spend their time playing, sleeping, and practicing their swimming skills in puddles. By February/March their hunger drives them to the sea, where they will teach themselves to hunt and dive off shore for the next six months.

In the fall the pups will be referred to as “yearlings,” but sadly at least 50% don’t live to see their first birthday. The ocean is a dangerous place to be an infant, and even hauling out of the ocean is fraught with peril. White sharks patrol the shores of northern California from September to November, waiting for exactly the opportunity a returning yearling represents: a naive and tasty 300+ pound mammal with a body mass made up of almost 50% fat. Every living thing must to eat, and white sharks are no exception. But for now the pups are beside their mothers, fattening up in safety—just a few more weeks until their inner weaner is unveiled!

Huge thanks to a biologist named Jane who keeps a fabulous blog about Farallon Island elephant seal happenings; all of these photos were taken by her during the 2011 and 2012 breeding season. For more about elephant seals from the Marine Mammal Center, click here.

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