Weaners prepare to migrate

Weaners balance blubber and muscle

Swim school workouts help

Weaners prepare to face their lives in the open ocean in March. They venture into the surf to practice diving, swimming and holding their breath. Watch a video on the Friends of the Elephant Seals YouTube channel.

The atmosphere on the beach is peaceful, following the drama of breeding season. A few bulls remain on the beach, resting up, unconcerned with the weaners.

The bulls are at their thinnest, having lived on their blubber for more than three months. The recently weaned pups are at their fattest.

Blubber into muscle

Feeding ended when their mothers left. Until they begin catching fish on their first migration, they rely completely on their blubber.

They take this time on the beach to exercise, improve their swimming skills in the surf and turn some of that blubber into muscle. They are more likely to be in the water at night, but you may see them splashing around during the day. Their life deep in the ocean will require them to hunt in the dark depths.

Balancing blubber and rest

Generally, bigger is better for elephant seals, but there’s a balance. Size, weight and blubber figure in dominance, staying warm, and having physical resources to survive. Pups need enough blubber to draw on after they stop nursing to launch them into success in the ocean. They need to dive and catch prey to feed themselves.

Blubber is buoyant, though. Fatter weaners struggle to dive to depth where they can hunt and feed.

Two scientists at UC Santa Cruz have followed adult females, “to better understand the behavior of a wild animal trying to find food while trying to avoid becoming food.” Roxanne Beltran and Jesse Kendal-Bar evaluated data from tracking devices. They found the females balance the need for food against the danger of sleeping, depending on how light it is.

During the light of day. the seals are at risk of being attacked by sharks. They are safer resting deep in the dark ocean depths during the day. Thin seals who need to put on blubber are more inclined to risk resting during the day, when it’s lighter, and spending more time feeding at night, when they don’t have to dive as deep to forage.

As they put on blubber, they are more inclined to rest at night, when they are safer. They are safer awake than asleep, but they have to sleep sometime.

The researchers call it the Lightscapes of Fear. They intend to use this insight to inform research on other, land-based, species.

Weaners are in danger during their first migration. Only half of them survive to return to the beach in September.

Stranded weaners

Underweight and exhausted weaners may strand on local beaches. If you see one on the beach, call the Marine Mammal Center operations center in Morro Bay at 415-289-SEAL (7325). They will send out a team to evaluate it and rescue it if necessary.