San Simeon Sea Elephants Posturing

Two young northern elephant seals spar in golden light at Piedras Blancas, near San Simeon. The animals are adolescents and the fight is play, a run-through of the postures and calls that adult bulls use to settle rank, staged in a season when no mating is possible.

Researchers think that kind of rehearsal is how the skill gets built, though they treat it as an inference rather than a settled result. The stakes it points toward are severe. Northern elephant seals have one of the most lopsided mating systems known in any mammal.

At the Año Nuevo colony up the coast, as few as five bulls out of 180 accounted for up to 92 percent of the copulations biologists observed. Of 91 male pups followed from birth, only 19 lived to breeding age; three of those inseminated an estimated 121, 97 and 63 females, while eleven never mated once. Size does much of the sorting, with a bull's mass on arrival explaining roughly 29 to 44 percent of where he lands in the hierarchy. The rest is settled in contests that begin exactly like this one.