Pups are weaned, moving to independence

 Pups wean to independence

Adult seals breed for next year’s pups

Many mothers have weaned their pups, who now rest in groups (pods) at the base of the bluff. They’re staying clear of the ruckus of breeding among the females who are still nursing and preparing for their short migration.

The mothers come into heat as nursing concludes. Bulls vie for breeding rights, sometimes coming to blows.

Beachmaster imposes discipline

The beachmaster, usually the biggest bull, rules the females in his section of the beach. Less dominant males are constantly looking for opportunities to breed females at the edge of the beachmaster’s influence. The dominance hierarchy helps reduce actual fighting. Bulls recognize each other’s unique vocalization, as if each one had a name. Bulls who have fought in the past don’t have to fight again to establish who is boss.

Weaners face the world

Pups are born with black coats, which help keep them warm. Being born on the California coast in December and January makes that important for pups who have little blubber when they are born. In that month of nursing, they gain about 200 pounds. Nicely rounded now in blubber, the pups molt their black coats for their first brown and tan coat. After molting, they are countershaded darker on their backs and lighter on their bellies, a form of ocean camouflage.

Weaned pups have to learn to hold their breath, swim and dive before they leave the beach on their first migration. At sea, they will have to learn what to eat and how to catch it. The PBS program Animals With Cameras documented how they practice.

Wildlife cameraman Gordon Buchanan, who narrates with a Scottish brogue, worked with Ano Nuevo researchers Patrick Robinson, director of the Ano Nuevo Reserve, and Roxanne Beltran, assistant professor of ecology & evolutionary biology at UC Santa Cruz, to equip four weaners with cameras to record 16 hours in their lives. Watch the results at the 44-minute mark.

The cameras revealed unexpected behavior. Under water, the weaners interacted with each other more than the scientists’ expected.

“I’m surprised by how active and interactive they are,” Dr. Robinson says, as the seals cavort in their watery home. “They’re completely solitary at sea,” says Dr. Beltran. “So the fact that these guys are interacting with each other is weird. I wonder if they are just learning from each other.”

The video shows that the weaners hold their breath on land as well as in the water. Eventually, they will hold their breath for 15-20 minutes on each dive to feed. The video records one pup holding his breath for almost 12 minutes.

“It doesn’t look like they are doing much here,” says Dr. Beltran, “but I think what they are actually doing is figuring out how to become breathless divers, so that they can find food on their first trip to sea. Just like we would train for a marathon by doing little runs, they’re doing little breath holds to basically figure out how they can get down to food on breath holds.”

The weaned pups are living on their blubber until they depart on their first migration. That blubber makes them buoyant in the water, though. The pups have to work to dive, and seem to help each other stay down.

The video shows them chasing fish, although they don’t catch and eat any. It also shows them playing with plastic trash and kelp. Play is important to young animals’ development.

“In these seals, it may help build those important diving skills, that later they’ll rely on,” says Buchanan.

Glimpsing the seals’ life underwater is thrilling. I watched it over and over. The entire show includes video from loggerhead turtles, tiger sharks, and gannets.

Buchanan calls the elephant seals “elite ocean divers.” Dr. Robinson observes, as they swim underwater, “They’re more graceful than I thought, based on how they are on land.”

 Read online here.