Gearing up for a Winter with elephant seals

Male e-sealI had never thought about how large elephant seals really are until I was standing next to a sleeping bull elephant seal for the first time, feeling exceptionally small. I have been going to Año Nuevo with the Costa Lab since April 2016 as a fortunate participant in the field course BIOE 128L, yet I had never encountered a full-grown male elephant seal until recently. The males had departed the breeding ground by the time I started volunteering with the Costa Lab, so the largest seals I had been exposed to were adult females. Don’t get me wrong, full-grown female elephant seals are also sizable animals, especially when you consider that all 5 foot 2 inches of me is closer to the size of an elephant seal pup than to an adult female!

Even though he was only taking a nap, I was pretty excited to see my first bull elephant seal. Soon enough, the beach will be FULL of seals, both incredibly large and adorably tiny. The elephant seal breeding season begins with the start of each year when thousands of seals return to the rookery to mate and give birth. Male elephant seals try to quickly establish breeding harems in the best areas of the beach so that they can have access to as many females as possible; the males who can best keep females in his area while simultaneously keep other males out will have a better chance of passing along more of his genes to the next generation. Usually, only the largest bull elephant seals can maintain these large harems, and less dominant males are lucky if the get the chance to develop a smaller harem. Meanwhile, the females are trying to stay close to the dominant male so they can give their next offspring the best genes they can while also nursing their newborn pups.

Needless to say, the elephant seal breeding season sounds quite chaotic. Given the tumultuous activity coupled with the monumental size of the adult males, I had better get used to being one of the smaller mammals on the beach this Winter.

Kelly Shrader

Kelly is a fourth year Ecology and Evolutionary Biology major currently working on completing a senior thesis with the Costa Lab regarding the first migrations of weanling northern elephant seals.

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